I,ve been out of the loop awhile , just wanted to get caught up on any new 20s or potential class developments .

I,d like to see something similar to the B class rules be the basis of a F-20 classification .

It is nice to see the Tybe 500 inc 20s and a F -18 class .

I would like to see a cross between the M-20 and N-20. Wide, but not a uni-rig (for distance).
Stronger than an M-20 for repeated beach landings, but lighter than an N-20.
Some way to shorten sail in distance race when foul weather strikes.

Under $20,000 USD with basic equipment

Blade 20..... at 10' wide, 400 lbs, carbon mast and beams...

Matt? Please? For us fat guys?

Eric,

make it 8 foot wide (easier trailering/assembly), put two feet wings on either side, alu beams but carbon mast and make it 330lbs (still buildable in vinylester/glass/foam or even plywood). Put something akin to the Tornado rig on it (or use a Tornado rig), and you have a fast package for the heavyweights.

I'll put up with the extra setup hassle to have the hulls farther apart.

Gone are the days when I have two hours in the afternoon for a quick sail. A kitchen pass may earn me a weekend or two of racing, so an extra 1/2 hour on each side (setup, breakdown) doesn't seem that outrageous.

If there is a way to ensure the hulls stay true and parallel with quick installation, that would be best

Same here, i actually take the extra day away from work to do nothing but drive and set up, it keeps the stress level down and gives plenty of time for messing about with the boat.

Sounds good Rolf . 330 Lbs w wings .

The T is 370 --close enough to race evan up .

How wide do wings need to be to = the advantage 10 ft beam provides . My guess is you would need to calc hull weight plus the beam measurement difference and arrive at an equivilant {theoretically} wing size from hull distance.

ie hull weight = 100 LBS * 1.5 beam meas. dif. = 150 ft lbs .

150 ft lbs dif. equates to a 300 LB 2 crew being out .5 ft further or 300*0.5 =150

So the wing should be the beam dif 1.5 ft plus .5 or two ft total out from the hull on cat with 8,5 beam to eqalize ft lbs of righting leverage of the 10 ft beam cat --on average .


I raced H-21s in the Prosail series back in 88 with wings, they were great and much easier to trap level from , they made nice seats between races too .

One error newbys made was not tying in the wings and running spin blocks off them . When the force of the spin pulled them out you had a wing flying all over on the end of the sheet .

Dangerous ,but kinda funny to see a sailor new to wings trying to catch the wing flying 20 ft into the air .

Have fun .

I really miss sailing this time of year here in the frozen GWN .

We gonna see you in Tybee this year Carl?

Thanks for asking Trey .

Wow -I would love to race the Tybee 500 again ,it looks like a great lineup of teams and people for 07 .

The ol I-20 has another 500 miles left in it -have the gear- trailer -van -equipement -know how etc , think it would be my 9th Tyee and 1000 mile race, so if you know of an independantly wealthy sponsor, crew and or ground crew that would like to team up --let me know <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" /> {joking kinda }

have fun all

http://www.tybee500.com/register/entries

Carl,

Would we need to consider the difference in the distance of the mast from the leeward hull as it relates to righting moment. Half of 8'6" id 4'3" and half of 10' is 5'. Does the extra 9" on the leward side offer advantages?

I think you have to consider total beam differences as the cb {center of Bouyancy } is the leeward hull and the lever arm is the beam measurement.

The masts centered being equal you have 9 inches to leeward and 9 to weather of added leverage .

In lighter winds {non trap}conditions the added beam or wings are a non factor.

1.5 extra beam * a 300 lb crew = 450 ft lbs of added leverage .

The hull weight needs to be factored in as well from the the 10 ft beam to the 8.5 beam {see previous post } .

That is 1.5 beam dif.* 100 lb hull = 150 ft lbs

A 300 LB crew needs to be out .5 further to compensate for hull weight of the 10 ft beam version or 300*.5 = 150 ft lbs

The total being 2 ft wings .

Think that's right. some can argue differently for valid reasons , but that's always part of measurement rating eqalizations.

I would like to see something like Rolf noted form into a new B class / Formula 20 class with room for experimentation and development , of course I have for the last decade or so . <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

Carl,

it will happen. Just make a concensus on the design envelope, which is mostly in place from last winter or the winter before. Then build boats and get the craze going.
I know I will build one based on the alu Tornado rig, but it will have to wait until I have the F-16 ready and blessings from my wife. Why the Tornado rig? Becouse it is highly developed and fast out of the box. Plenty of tuning information available, plus I know the rig intimately from the years I have been sailing tornados. Having a surplus of cheap used alu masts dont hurt either.
The F-16 will be used for class racing and solo sailing, hopefully with the kids. The "F-20Super" is to be my distance race and distance racing machine.

There has been enough talk, get some hulls buildt and cobble together some platforms. Getting some protos on the water will do a lot to show manufacturers that there is a market for this kind of boat.

If you guys are going to form a F20 class why not make the width 12 feet. If you want the narrow boat, race an F18. If you are going to a 10 foot boat, might as well go all the way to 12 foot.

My 2 cents...

Why 12 foot? The ancient and most used formula for width is half the length. 8 foot is advantageous becouse it is legal trailering width. In low wind areas it's also advantageous with a narrow boat.

But whatever, just get some boats on the water and lets sort them out afterwards.

I have been sailing an SC20 for over 10 years now and once you go with a wider boat, you never go back. If you are going to go with a boat wider than the trailerable width, you might as well go all the way.

There is a point where the added righting moment is larger then what the leeward bow can carry. The wider the platform become vs. length and bouyancy, the easier it will be to pitchpole the platform. The Tornado is 20x10foot, and it is wide enough. I can count on two hands how many times I could have wished for more RM over the last 7 years. But we have raced in uncountable times in weaker winds where we really wished we could have got it up on one hull. It is a severe handicap in the light stuff when narrow boats can fly a hull while the wider boats are locked down with both hulls in the water.
If you live in an area with predominantly strong winds, the extra width and RM makes sense. If you live in an area with medium/weak winds, the extra RM becomes an handicap. Especially as in my opinion the "F20Super" should be designed for sailors a little bit heavier than the current classes. But, why not? Go for it and compare the performance to more narrow boats.. Over time the boats who compete will find the 'sweet spot' for how wide they should be. As long as the rig and sailarea is defined, the RM and optimum width can be calculated.

Carl, we'd love to see you out there. I have some Nigerian friends that are sending me a $10,000 check for a sunfish, I think I'll just forward the rest to you so you can do Tybee, sound good?

Get some change together, I'll find you an able ground crew, and show up! You'll only need about $3500-4000.

Too funny --thanks Trey .

I have an I -20 for sale in the classifieds { have others cats} and I've recieved about a dozen of those e-mails from "overseas buyers" that want to run the 10 k sunfish type scam .--sheeeesh .

It is nice to see some F-18 teams signing up for the Tybee 500 this year.
And Again I would love to race the Tybee again , it is such a great group of folks, each team competative, but everyone sharing a common love of sailing /racing and a great 500 mile adventure up the E coast together. Each day a fresh start and new race .

Have a great time .

Hi,

I saw a big yellow cat drive by, trailered, in front of my house a few days ago. I live in Homestead, Fl. Can anyone tell me who has a big (20') yellow cat who lives in Homestead, Florida?

Rick

What about the CFR as the next 20 footer? Makes sense, being developed and is lightweight

Rolf,
I've been out of the loop for some time with a PC melt down and I'm just going through old posts and found this one.
I think you are right on the mark.
Sure when it's blowing dogs off chains the wider beam is handy but how often do we sail in those conditions compared to conditions under 15 knots where the difference is likely to be balanced out by the slower tacking of a wider platform. Then look at the amount of time you sail lighter winds where lifting the windward hull becomes an advantage due to the reduction in wetted surface and corresponding reduction in drag.
It's worth trialling a 10ft beam on a modern hull shape.
The desigbn could have two jib options. A self tacker for bouy racing and larger overlapping jib for distance stuff.
Designing a platform to take a standard T rig makes good sense and is in fact a part of my plan with the additional jib option for distance stuff.
However I think to build such a boat in commercial numbers it will probably have to have an 8 ft beam.
When trying to appeal to larger numbers you can't beat convenience.

Just the way I see it.

Regards,
Phill

Your computer also failed? It must have been to hot "down under" this summer as Marcus also had some computer trouble. Overheated harddrive? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

I dont think there is any chance of a commercial operation betting good money on a new 20 footer at a reasonable cost before before there are some homebuildt prototypes and interest. What is needed is someone to get busy in their garages, build a boat and form a class. The basic platform parameters are pretty clear and discussed to death earlier.. Come to think about it, the F20Super and the F12 have a lot in common, but I think both classes will see prototypes and some interest.

About the strip-plank project we have discussed.. I am about ready.

Rolf,

The motherboard died in my lap top.
After a very long time they elected to replace the lap top rather than fix/replace the motherboard.

I agree about getting a prototype on the water.
Hopefully the 3rd quarter this year or 1st next should see a prototype sailing.

Regards,
Phill

Hey Matos,

That was probably Mike Phillips and his Marstrom 20...

Lambert's old M20 or another one?

Lambert and Livingston were sailing a white CFR 20.

Hey, what would a wing mast do on the N20?

Besides violate the SMOD regulations....

This years MKL winner!

Ha...

I laughed at the post of the big Garfield..

Does Mike Phillips live in Homestead, Fl?

Does he need a crew member, 180lbs? <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Yes, he lives in Homestead. As far as crew goes, I don't really know. He is a great sailor and very competative.

The M20 and CFR would be a start to a F20HT class possibly... but you would have to standardize widths. I think they have talked a/b making the CFR's wider, but I don't know if/where that has gone.

Will,

Do you know the weight of the M20 AND CFR20?

M20 sloop rig 120kg?

CFR 20?

Regards,
Phill

They were both roughly the same with the CFR being a bit heavier. I would say they are very close now since they changed the masts on the CFR. 120 kg would not be a bad guess, but they are both uni's not sloops.

Really, there are three boats out there that could kick a 20ht class off, nobody mentioned the Eagle Carbon. I think I heard a rumor way back that Vector was doing a 20, but that's old info and may have died a long time ago.

In my mind, I've wondered where the 20 ft'ers are going to go from their current state with the I20 being the fastest/most popular ride out there. An F20 would be great, but that would mean somebody else has to build one. F20"ht" might be more viable as hulls are out there from more than one builder now.

I think M Murray would be there in a heartbeat if a 20HT class took off. I would still want something to singlehand though.

So, after a discussion I had on the phone today... what about a F20ht class? The 20's don't seem to have a lot of the same problems the 18ht's had... Thoughts? feelings?

Design envelope for a F20ht class? I am in for a homebuilt 20 footer, but not down to the weight of a M20 or similar.

We have discussed this before on this group, ad nauseam. There is interest, but not many willing to commit before there is some activity. If you want a class to grow, consider cost and ease of use (e.g. legal trailering width, glued beams etc.).

To grow a new class from infancy I think you need a very strong manufacturers support or a homebuilding option. A combination is best, like what the F-16s did.

I think people are finding out now how hard it is to start a new sailing class.

Wouter

Yup!

The necessary combination of dedication, sparkplugs, prototypes and hype are not present yet. But just you wait, it will happen <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

I know that I am getting fatter as I get older, and so is my crew, so the F20 class is definitely where we are headed!

F20 or F20S(uper)/F20HT? I assume you mean the latter, which is the same thing for me.

well you are more then welcome to help out I'm sure... <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Yes, but I don't know about F20HT. Would that be a uni-rig? I prefer a jib for distance, as some portion of a distance race invariably ends up a beam reach.

I am not sure, but I think a sloop rig works better on that point of sail?

So for me -
10ft beam, 20 ft. length
boat weight under 350 lbs
sloop rig with spin
Wing mast shape (maybe)
double trap
daggarboards you can raise/lower from opposite hull (foils, maybe)
mast controls (outhaul, downhaul, rotator) led to skipper position
Trampoline easily removed from hulls (to facilitate breakdown for travel)

350lbs or 159Kg is a sensible min weight. Much like the B-class used to be.
I have suggested earlier that a new 20 foot formula class should be based on the old B-class design envelope with some additions. E.g. upwind sailarea 25square meters and 45-50 downwind, double trapze and the an affordable min weight attainable for home builders. The rest like daggerboards, mast controls, mast crossection etc. to be determined by the builders. No foiling, except alternatively for T/L foils which dont exceed the platform max width.

To make sure the boats are versatile, I would definately require them to be rightable by crew in all conditions. Further, all championships should include a distance race.

But we have discussed this a lot earlier. What we need is the magical mix of interested sailors with the will to get some boats in the water.

By the way.. Are you just day dreaming, or are you ready to commit yourself on a project? Would you be willing to modify a boat or even build it yourself, or will you not get involved unless you can buy a ready boat? Very few beasts like this around by now, except the Tornado and perhaps some ARC models?

Dont mean to be blunt, but it would be refreshing to hear that someone was ready to go further with a F20(S/HT) <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

make the weight 300

In an article or add a while ago in Multi hulls International I saw a cat called an"Exocet" low profile with tunnel like shaped hulls claims of 15knots in 10knots of air upwind <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />,20ft,lightwieght, roto-molded and looked futuristic anybody know whats up ? I believe also it was from France...

Unfortunately, I have neither time, ability, nor the space to design or build my own sailing craft. The closest I ever get to that sort of thing is gelcoat repair.

Another N20 is on my agenda for December 2007 unless there is something out there as user-friendly and significantly better in that price range

I guess I would be willing to modify an N20 to 10' beam if it wouldn't damage anything. How would that change the forces and vectors? I'm thinking specifically about the shrouds and bridle arrangements.

Rolf

I think that if you look at the three big boat classes which have emerged in the EU in the last 3 years, (VX 40, the Decision 35 and the Ventillo M2 (28 feet(, you will find that the common thread is that each class is designed to compete in a major series. Moreover, these are SMOD classes which allows the factory to get behind the effort and promote it as part of their buisness plan.

A Formula 20 class will only get going when you have a race....eg the Worrel 1000 or Tybee 500 which promotes the class, or a high profile buoys series that draws the interest of the pros or serious sailors.

The niche for a formula 20 is for sailing teams 360 and up! While I fit that boat.... I am not sure how many teams are out there for this niche.

(The Tornado and F18's are sailed by the same sized teams... IMO... essentially a Pro class and an amatuer class in the F18s with some cross over)

I dont know much about the Decision35 or the Ventilo M2. I think I read somewhere that the Decision35 was ment to stop an arms amongst pretty well off racers on the lakes in Switzerland? The Alinghi cat was one of the most extreme examples of this?
The VX40s are a creation of Mitch and Herbie, trought their TornadoSport company, and it is a commercial venture. I dont know how much Marstrøm contribute in the effort? But your point is well taken, you need manufacturers and builders to succeed. Not only in supplying the boats, but supporting the class.

I agree that you need something like a Worrel1000 or other high profile event, but what should come first, the boat or the event? Chicken and egg paradox in my opinion. The F-16 class grew without a major event trough their versatility, usability, affordability and performance. I am more inclined to that model for starting a class and growing it step by step instead of betting everything on a high profile event (which might fail).

360lbs and up sounds good. Obesity is becoming a problem in the western world <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> I am pretty sure the average weight will increase in the future. If you are lighter, get some sails to fit you within the design envelope. Light teams can also be fast until the wind really pipes up, but how often do we sail in those conditions (as Phill pointed out). However I think there are more 'heavyweights' struggling to keep the match weight in other classes in the western world than the other way round. Except for the Star class..


I can't speak for others, but there seems to be interest. I also firmly believe we need some new boats on the water before this comes any further. The right mix of people is also needed, but I dont see them here right now.

Ah... which of the two models to pursue. The F16 model or the high profile SMOD model.

I would note... that at the time, the F18 class was growing. The F20 class was fracturing apart and the 16' footers were an after thought. Wouter and the others saw the niche and developed the boats by home builds, modifying existing boats and enrolling builders over time. Its still not a big class... but it certainly has potential for lot of people who single hand..., are of small stature, or want to start sailing with a kid in a high performance boat.

Meanwhile, the F18HT class took advantage of the exchange rate and NO 18 foot racing class in the USA and tried to build a circuit of races. The Worrel being the most prominent. Most of the races survive.... the class did not.

IMO, the market niche of sailors at 360 and up is squeezed from two directions. the heavy weight owner can find a flyweight but strong crew and go compete on the F18's. If that is not enough for them... the existing Nacra 20 provides just enough juice in this niche to stop all development of an HT boat from most buiders point of view.

IMO, In the USA, I would count on home builders and sailors interested in the custom M20 or the Eagle 20 flavors to modify or build boats that are trying to win the elapsed time records of the Miami to Key Largo Race, The Mug Race, The Statue of Liberty Race on the East coast,
Those race will prove the speed potential... If the boats sail well... they will also be perfect for windward leeward racing if you can get a group of similar performance boats to the line at one time.

In europe, Texel and Carnac come to mind as events that you would target with your HT 20 projects. I don't forsee a big buoys racing scene developing around the 20's. There is simply too many options with the F18's.

In the end... I think of the HT20's much like the keel boat sailing in the USA... They mostly race handicap on point to point or 1 big circle a day on the bay and once or twice a year they actualy do three days of windward leeward races (NOOD and Labor Day Race Weekend)

Mark,

I am isolated in the outskirts of Europe, on the western coast of Norway. There is not much I can do, but what I can do will be done. E.g. there _will_ be a new 20 footer here in a not too distant future, under an alu Tornado rig. I dont think running an event here will draw a crowd, even if it could be quite spectacular.
Check Google Earth,
64°51'48.93"N
11°14'13.59"E
to
62°28'47.72"N
6°12'20.56"E

Lots of nice scenery here, and predominantly northly mixed with western winds. Lots of places to stop, and all logistics could be done over the coastal express (http://www.hurtigruten.com/en/default.aspx). Start and finish can be extend as far north as you could possibly want, while Bergen would be the logistical endline as the coastal express ends there: 60°23'19.17"N, 5°11'54.77"E

I think you have a good point on what direction the growth can come in the US. I dont see it happening tough, as there are no boats buildt professionally and homebuilders are far between. But things are happening, so perhaps there will be a new breed available in some time.. Things are happening on the homebuilding front with new building techniques, so perhaps homebuilding also becomes "easier".

Amongst the races here in Europe, the Round Texel is the one to participate in, with the Dutch open race week during the week before. But building the class is all about fun, affordability and activity at the local level (you and I know a bit about that from the tornado class).

I dont like the name F20HT, as it is too close to the F18HT and you in the US have some sore memories. F20S(super) or F20HP (high performance perhaps)?


Thanks for your interest by the way! I am certain the Tornado would be highly competitive in an F20HPS(orwhatever). Could even replace the centerboards with some daggerboards and inserts for even better windward performance?

Comparison to keelboats is down right blasphemous <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> Certainly we could do better than that.

Anyway, until the right mix of people get together and things start happening, this is all hot air, but fun hot air. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Rolf et.al.,

I tried to run a search for references to books on how to build your own boat. I presume using the GRP (glass reinforced plywood, correct?) method?

Where would one start with this type of thing? I know it would most likely cost more to home-build a boat (in time and materials), and that's assuming there are design plans already out there....

How did you and other home-builders get started? I'm not an engineer, either....

There is the eXploder 20. Not new though.

http://www.exploder.info/eng/content/view/46/130/

The standard work on boatbuilding for us is "The Gougeon brothers on boat construction". It's a very good read if you are interested in boatbuilding, wood and epoxy.

One can also build a one-off foam/glass/carbon/kevlar. Look at Ian Farriers site for more info about this.

Then you have the Derek Kelsall system (KSS), which can be downsized to one-off beachcats.


I got starte by following plans and learning by my mistakes when (mis)interpreting the plans.

I've been reading on hull materials from some marine surveyor who is really upset about how poor the cored hull construction methods are.

The author touts that foam doesn't stick to the epoxy (no matter what method is used), they don't resist impact well, bad with heat/water/UV, etc.

The balsa cores are the only "marginal" cores in the author's opinion, and they absorb water & rot (which leads to failure, but not 'catastrophic' failure)

In addition, he points out, the labor costs are higher because of the skill needed for core bonding, infusion, etc.

For any high stress application, the surveyor points to solid core construction (which undoubtedly must be heavy)

Are cored hulls primarily employed for weight savings only? What other advantages do they offer?

Cored hulls are lighter, stiffer and often stronger than solid laminates (they also offer better insulation in colder climates). It is true that they might be more fragile than solid fiberglass if thrown up on a reef or similar, but that is not what you build boats for. It is considered kind of outside the design envelope <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
I suspect the surveyor you have been reading about is yearning for past ages.. Look at the most extreme boats and how they are designed and you will find sandwich laminates. The same is true for mass produced boats and modern aircraft parts. In short, cored composites are here to stay and when done right they are both long lasting and better in all ways than solid fiberglass or traditional wooden boats (some of the woodies are quite amazing even by todays standards. Both traditional boats/spars and epoxy/wood construction). If you want some good PR for wood/epoxy, try to get your hands on the Gougeon book.

Good points. "Old" sailors have commented that today's boats suffer pressure dings much more easily then "old school" boats, and I presume this is due to the cored nature of the hulls.

Of course, "old school" boats are probably the reason most "old" sailors have back problems!

Is there a good reference on composite materials (other than the ISO manual) that could be used (such as kevlar) to add a bit more ding resistance but still keep the weight lighter than solid fiberglass hulls?

And have they improved the bonding between foam core and glass? The surveyor photographed several cases from well respected power boat builders where a particular product line (boat model/class) had issues with poor core/glass bonding, despite the use of various bonding agents.

I think the surveyor said that it's no use to add carbon to the e-glass unless you add enough carbon to assume the whole load (he was speaking in regard to chainplate anchoring). I think I follow his logic on that, as I presume if the glass separates, there won't be enough carbon fibre to carry the load, increasing likelihood of failure.

"Ding" resistance is a product of the core used and the laminate on top. A heavier core often results in less dings. But it's always weighted against weight of..

Delamination is an issue, but not often. You can go over the top and fill the foams surface with a thickened mix of epoxy before you add glass, but that's heavy. The same goes for infusion <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" /> Delamination is not a large problem today as far as I know. Technology must have improved since the early days, but I dont know the spesifics. Vacuum bagging is probably part of the solution.
Powerboats see far different loads than our beachcats, it's probably two different worlds engineering wise (I am no engineer, so I am guessing).

Carbon on top of E-glass is a waste unless you design it so the carbon is able to take all the load. Glass and carbon stretch at different lengths, so the carbon takes all loads until it snaps, then the E-glass can start taking the strain. It's like you hang a 100Kg weight from your roof in a bungee. The bungee stretches rather a lot, but if you add a steel chain and hang the weight on both the chain and the bungee the chain will take all the load unless you shorten the bungee (or almost at least, you can always do something funky with the setup, but you get the idea).


We are getting quite far away from the subject: New 20foot beachcat designs..

Looks like someone just answered my vision with the M20 and tornado rig. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> Check the main forum post on the new 20 launched at Texel.

Slightly off topic, but... still on topic.

With regards to construction, when J-boats moved to SCRIMP (aka "infusion") several (~10?) years ago, they started using what they called "resin rivets" (first boat was the J80). The core has holes in it that allow resin to bond to resin on both sides of the core.

Outside of the current splotches of Nacra 6.0's and H-20 camps, the only available "fast" 20 footer available to the regular guy is the Nacra 20. All the other 20 footers are out of reach ($$) for the guys that are attracted to to the 20 foot boats. F 20 or HT 20 is going to need to be very affordable to be successful, there are too mant other viable options at this time.

Will,

a bit late for a reply, but "resin rivets" sound like a problem marketing put a spin on. I dont see much advantage to "resin rivets", but they do add weight and cost.

Eric,

I think you are wrong. Price is not the selling point as new boats are "too expensive" anyway. What is needed is the right combination of people and a good product.
I think there is a market for 20 footers, as the last I heard there was interest for homebuilding a new 20 foot design. Homebuilding a boat is an commitment off the scale compared to just buying a boat.

And I would add.... A series of 5 events that the boat would compete in against all comers for line honors.

For example:
Texel in Holland
Statue of Liberty Race in NYC
Mug Race in Florida
Miami Key Largo Race in Florida
Race to Oxford on the Chesapeake Bay

These events are similar to what the Ventilo M2 class is doing or the descion 35's one designs are doing . (M2 is a 27 foot three man cat sailed on the swiss alpine lakes the D35 is a 4 man boat.)

Also, a circuit of high profile buoy races would help the class grow... These events are less clear to identify.

So, do 20 foot boat buyers race more bouys or distance?

Seems the F18 and F16 guys do a lot more bouys than distance. Are we missing the marketing angle for distance sailors? Bouy sailors? or both?

Being in FL, I think that an I20 (or other 20ft design)is optimal (for me). Racing here offers the best of both worlds awesome distance races: Steeplechase, Hogsbreath, Hiram's, Tybee (someday), Macho Man, etc. And also great buoy racing: Tradewinds, JPOR, Eustis, Carlisle, etc. The I20 is the perfect boat to do all those races on.

I personally would agree with you Karl...

It would seem the design of the N20 makes it ideal for windward/leeward bouy races (small jib, high aspect main, asym spin). I think the M20 builds on this and would, in some circles, be considered a 'better' bouy boat

The length makes it a bit more comfortable in the chop compared to smaller boats, and more room = better sailing long distance. With the bigger jib, the N6.0 with spin sailplan would be advantageous. The low rear beam clearance on the N20 has occasionally lodged complaints by distance sailors

But what, in the opinion of current sailors/owners, is the 20 foot "niche". This would appear to be the place to begin to build a product/fleet around.

Kind of like building the F18-HT for the bouy niche and the Capricorn for distance (except put a bigger jib and a reefing main on the sailplan)

Just to add more complexity to the argument, what would be the ideal crew weight to design for, for the ideal 20?

I would guess 360 lbs +/-.

I'd concur. Somewhere around 350 US pounds minimum crew weight. I'd consider something around 380 US pounds as the "ideal" weight.

I typically race at around 380 and do pretty well. At the 5 rum regatta I was significantly lighter than that, probably in the 330 t0 340 range, and in the light air, we were very fast.

Aerynt,
I think the 20 ft boat should be designed for a weight of 160kg (360 lb) and up. This should not prevent lighter sailors from competing without penalty. It is just that the boats optimum all round performance should be more easily extracted from the boat by its intended target market.
I see the target market to be the larger sailors that want to sail a two up boat, both around the bouys and long distance.

Just the way I see it.

Regards,
Phill

thanks for all the opinions, I'm off to see the designer of the new LR2 next weekend to discuss the possibilities of a new 20 design

Exciting! Keep us posted...

Aerynt,

Are you looking at using the LR2 as a model for this design. Scale it up and make the changes needed to support, extra crew weight, jib, spi and double trap. Or are looking at a completely different design and thought process?

Obviously the LR2 would be the boat to base it on if its possible to do so.

have you seen these recent posts?

http://boatdesign.net/forums/showthread.php?t=18037&page=5

Yes,

I keep up with this and keep in touch with Ian, John and Fred. But thanks. A 20 version definately could be interesting. My other cat is a Tornado. I like the 20" platform. I wonder what changes would need to be made to the platform other than LOA and beam to the boat to support the 160kg. Keep me informed as you progress.

This is the designers first pass at my boat, some things will get changed but I'm mostly happy (delirious happy perhaps?)with what they produced.
Spec so far:
LOA 6.1m
Beam 4.45m
Board down draft 1.34m
Beach weight 149 kg
Sailing weight 315 kg
Main, Jib & Mast 30.7 m^2
Medium Reacher 24.75 m^2
Big Reacher 32.8 m^2

The last couple of pics will be how it folds up to travel with.


Aerynt

2nd picture

3rd picture

4th picture

5th picture

6th picture

First trailoring picture

Second trailoring picture

That is pretty cool looking, but I just want to ask, it looks like you have a daggerboard/centerboard coming from the center of the boat. Would the structure for that not add alot of weight that could be eliminated by just using regeular dagger boards which it looks like the boat has?

Like I said that is a really cool boat and I am definently not an expert, but those are my thoughts.

4.45m wide? Are you counting on the banana boards to stop you from digging the bow in?

I am wondering why there are two snuffer openings, and what looks like an inner forestay? Would be less complex with just one snuffer opening? Why is the 'central pod going all the way to the rear beam? Do you have a target weight, hull volume, mast length and sail area?


It is something new! Hope you get your dream buildt, and that it's not too expensive.

Gree, normally I'd agree with you about the structure and weight, but because of where the mast is (and associated loads)I don't think much as added to accommodate the centerboard. I saw the results of an ansys FEA of the beam/pod arrangement and the largest loads are at the mast step and that area hardly deflects at all, the board loads are minor compared to them. The center location has more to do with the banana boards than anything else and they might be removed soon anyways, they were added as a sort of insurance policy that I don't think is necessary after watching a bunch of LR2 videos. As that boat goes up and down hill and you watch the horizon, the top of the mast is always going forward, the boat just never pitches, even down hill in 12-15 knots and with 8 knot gusts and the crew sitting against the main beam, the bow never goes in more than 40-50mm. Not sure how they do it, but its like watching a train on rails.

Rolf, think I addressed the banana boards above, the 2 snuffers are for the 2 reachers, last I heard the wind can change strength during a race. The centerpod only goes back to the wingmast step, aft of that is a plug in compression tube and forward the prod plugs in also, whats not shown is a small inverted "v" striker under the mast step that is tied to the prod under the forestay and to the bottom of the rear beam. Weights and sail areas are in my first post above, think that the top of the mast is about 10.4m off the water and as I was told, total hull volume is irrelevant to most everything. As for expensive, it already is expensive and I haven't started to build it yet.
Aerynt

Rolf, forgot to mention there is only one forestay and no inner, the extra 2 "stays" shown are actually just the halyard lines for the 2 reacher tack positions
Aerynt

Well, I have already read a few people dogging on your design in the general forum, don't listen to them. That thing looks badass, I am sure that if it is well built it will go like hell!

Has this one been introduced to the forum yet? http://www.tek-kat.co.uk/gallery.html Its pretty scary to see a cat without a bridle supporting the forestay.
The 1st boat is out sailing and looking good at times.

Why not foils?

Too much work or too much stuff to break?

Easier/cheaper to develop planing hull?

Is a wave piercing hull better for a 20 ft. design than the standard shape for coastal use?

Looks very cool.

At a glance the center of effort for your main and jib look too far aft. Unless you are planning on some type of hooter setup for upwind in addition to the main and jib. Still think when it gets windy and the hooter comes down the helm would be very unbalanced.

Good luck with your project!!!

Mike Hill

Mike, the designer uses a 6 deg freedom of motion model, not being a designer I can't tell you how it works, but it does spit out all loads, motions and accelerations and what Ive seen so far tells me it should be easy to sail in any condition thats been modeled so far. The flip side to that is that we are not yet at a final configuration, so it may all change yet.
Aerynt

Thought I might also add that the hull is designed from the waterplane down by some fancy method that I got told I wasn't paying them enough to be told about, but if you look at videos of the A-Class there are no broken waves, no quarter waves and the bow wave is an unusual shape, so I guess it works. From the previous they can get all the pressures on the hull and that in turn is added to all the other forces which is probably why they can make the hull look so damped in pitch irrespective of speed or wind pressure.
Aerynt

Aerynt, I'm looking for insight into why the LR2 appears to be so efficient, care to let us know what you have learnt from working with the designers on your boat ?
Q

Q, I have already said enough, if you want to learn more then I suggest you do what I did and write a cheque.
Aerynt

Is that what these catsailor forum postings are all about ?

Basically we have only seen flat water pictures/video's in what may well have been very stable wind conditions.

An old seaman once told me :"On calm seas, every vessel claims mastery of floatation"

It will take a whole lot more to proof the concept.


Wouter

Ahh Wouter, we bow to thee and your onimpotent knowledge of all....what happened to sanity and admitting that some posts in the other groups might actually be true?
Q

Wouter,

You just do not let up do you?

Since we're on designs, I saw the picture of that C class cat with foils..

Why are the foils so far back (the forward foils). And why are the rudder foils that far back as well?

Couldn't they move all of that forward instead of having those bows tilt so far upward?

You dont just want to balance the boat on the foils over the water, but balance the side forces from the rig as well. Pulling the mast back lets you push the boat harder downwind as you have more bouyancy forward. Hence you want the rig pretty far aft.

I see.

I must have flunked "Foil" class. Good thing I went into microbiology instead of engineering.

It great to see some making efforts on new designs and 20 classes . thanks so much .

Agree Rolf , what surprises me is that we still use the basic Marconi rig configuration developed 100 += years ago .

Why don't we have multihull specific rig configurations using its wide platform and more advanced tech we see in boardsails ie . carbon fibre masts with a huge range of shapes placed on more aft raked adjustable rig configurations .

With the exception of expensive fragile C Class wings there has been relatively little progress .

Cognito ie

http://www.youtube.com/watch?v=JGihC_0eC1w

Wings aren't practical but we can make advances in rig configurations along with foils .

If I could just win the lotto I,d try to develop some ---take care --have fun

Carl,

there have been lots of testing done with other rig configurations. The AYRS annals are full of them. None have been as good as the "marconi" rig upwind and downwind with spi. "Good" in this context means speed, ease of handling, reability, cost etc. etc. etc. Unless there is a significant breaktrough somewere, which I think is unlikely, I think the "marconi" rig of today will stay for a very long time. The only development I see coming is increased chord for wingmasts.

I noticed that there is a winged A-class to come very soon. It will be very interesting to see both the performance and the reaction within the A-class.. How many think it will be banned in no time? I know I do..

Thanks for the info Rolf.

I think there is room for improvement , what I tryed a while back was a one third height A frame support using the wider cat platform. A better rig might be a sailboard type sail that could be hung from the A connection and provide a wide range of full or flat shapes and rig heeling angles to help provide lift . I drew this concept out years ago but have never been able to develop the ideas .

A wing was put on an 18 sq some time ago {Wild Turkey} as you know -
http://www.catsailor.com/forums/showflat.php?Cat=0&Number=53650&an=0&page=78

I think the weight of the wing and its lesser upwind performance on an A class cat might render it uncompetative as the sailing techniques and rigs of A s are so developed nowdays.

Wings are potentially much faster downwind and can work at higher angles , Wild Turkey if set at too high an angle would just create so much power it dove or flipped , A class cats have less beam and very narrow low volume hulls , so there are the basic trade-offs .

Good to read your posts Rolf , I and many enjoy reading them . take care .

Hi Everybody,

As many catsailors, I am primarily interested in high performance boats, I have been sailing A-Cat for 15 years, still involved in, but more as potential home design, home made boat.
Investigating A Cat project I realized that B-Cat is probably the best trade-off for many reasons, as long as you can find crew easily.

A-Cat main issues issues are:
1-Storage of the boat
Usually, at least in France, your A-Cat is not welcomed on a traditional Cat parking because each time you have a tempest, the old laser or Hobie 14 recklessly hooked on the ground, flies across the parking and usually land on your carbon toy. As a result to avoid insurance problems, most of sailing club avoid ACat or is is at your own risk.
So if you don't have a garden/parking to keep your boat safe on the trailor at home, you sail winsurf or F18.

2- Relative cost of carbon laminate (DIY perspective)
For a Acat you will buy 220g/ square meter laminate, which is only 30% cheaper than 440g you will use for B-Cat hulls.
and it is nearly the same amout of work.
As a benchmark just compare the M 20 price with the new Marström A Cat price.
Everything else equal, the 500g laminate used for the M20 is probably more forgiving than the 300g used for the A-cat,
and will probably last longer, which makes the M20 even cheaper if in addition, you consider both boat life's expectancy.
As a result a M 20 using foam instead of honeycomb would be perfect and probably cheaper.

Remarks about width, weight and sail area are very interesting, and to be consistent with the "aging sailor's population" argument, I woul notice that A -Cat is easy compared to F18 which is easier than Tornado.
Physical requirements for heavy , overwidth, combined with hudge sail area is out of reach for most of the over 45 sailors but former Tornado champions.
I would love to have a 140 kg F20 I could sail with a 55 kg girl friend so with a 145 kg crew fully dressed.
I would prefer a single mainsail without jib for simplicity weigh, cost and aerodynamic efficiency.
No jib means much less stress on the fore parts of the hulls, as you don't need to maintain hudge tension on your jib's leading edge, and overall lead to a lighter boat.
According to my experience with A-Cat the higher centre of sail area for uni-rig is not an issue as long as you have less parasit & induced drag and as long as the top of the sail can be twisted enough with downhaul, pre-bend and ....
Lighter boat means less sail area and less stress on the crew, especially for the spinnaker's slave.

3- The F20 Class issue.
Reference to a customized B- Class rule is probably the solutions.
In order to adress the crew weight issue, we could consider sail area combined with max weight corrector (5kg).
Lighter crew will have a smaller mainsail with lower sail center, higher aspect ration lower induced drag winward and lower max lift downwind.
According to the number of rocket scientists, engineers and PhD on sailing forums I feel confident that this issue will find a smart solution.
In addition, sailing area adjustment could be applied for old Nacra 20 or Tornado, in order to start a fleet with all existing 20.
If the 20 Class favors a not too exclusive boat concept, affordable on a $$ perspective, and not exhausting for the crew, especially if DIY solutions are developped, it could take off.
Easy to fold and unfold the boat is also part of the cost, as for ACat, overall cost is also related to storage issue, at least for some of the potential owners, and a 2 parts mast will be optimum.

If Class development is not supported by a boat factory, it could be by carbon fiber manufacterers, and by the Class Association which has a good bargaining power compared to lonely home builders.
Nothing precludes the Class Association to rise fees in order to develop a mast mould with a mast builders, and keep costs as low as possible.Todays a new Nacra F18 alloy mast is not really cheaper than a Marstrôm Tornado carbon mast??? market driving force probably?? marketing ??
The same for the crossbeam, in addition with a fixed width it is possible to create pierce-wave beams (see link:http://18ht.free.fr/Avancement/V016/Calculs/Images/ImgRDMPoutre.gif) which allow less free-board for the hulls and
hence less weight. The link does not provide a true picture of the crossbeam. It is a 100 mm circle under the mast and it moves gradually to a flat ellipse at the gunwhale, does not require dolphin-striker, and are plug in the hulls with some "conical" adjustment, so no metal, no bolt no screw, and easy to fold and unfold especially without jib.

Carbon mast and crossbeam would be available for home-build projects as long as they pay association's fees.

Look forward reading your comments, in the meantime I have to go back to my A Cat problems.

Cheers everybody

EK

Erwankerauzen,
Are there any particular numbers that you are considering other than weight.
Beam width?
SailArea?
Mast height?
I think 140kg would be achieveable with no jib for a home builder even when building from ply. However I think the jib is an assett that would be sadly missed when doing distance races or courses other than windward leeward.
Regards,
Phill

Phill,
Yes, of course, I consider other number, basically customized B Class numbers:
For the sail area, as the boat is quite light,we have a virtuous circle, not too much sailing area is required and it becomes physically affordable for seniors, even in long distance race. So 21/22 square meters seems to be reasonnable for a 140 kg (310 lbs)crew, and bigger sail area for heavier crew, until 24.5 square meters for instance)
For mast height, I target something about 10.5 meters in 2 parts with the junction at the spreader level, in order to have a 6.4 meters parts + a 4 meters parts, for easy storage purpose, also it means the hound will be at 8 meters height.
For the crossbeam width B Class rules are OK, around 3.1 meters.
About the jib, I agree with your argument, but I think the heavier the boat, the more this argument holds.
Long talks with the HOBIE TIGER designer, MR J Valer have provided me another view, the lighter the boat more the relative importance of aerodynamic drag increase, and therefore a split rig (jib+ main) providing hight lift seems not optimum for light boats.
A Cat are quite fast in long distance races, as long as spinnaker is not required.

Thank you to mention that 140kg is achievable for home builders with a single main sail plan, also it is cheaper.

The basic idea is to concentrate the technology where it is most efficient ( mast for obvious reasons) and curved pierce-wave croosbeams because it will provide additional degree of freedom for hull design(ie: curved means that the middle of the crossbeam is higher than at the hull junction, so for the same freeboard the hull designer can move the rear crossbeam aft, and get the same clearance above the water.
Or lower the freeboard or a mix of both.
If the crossbeam is piercewave with an elliptical section at the hull junction( 3.5 / 1 lenght/height ratio)the drag coef can be 1/20th of the basic circle section), so you can lower the freeboard significantly and save weight, or use a cheaper technology for the same weight, or put more stuff per square meter and build longer lasting hulls.
Also no jib means fast preparation between the road trailer and the water.
In fact I seek a big A Cat for my light girl friend and me.

Cheers

Erwan

Erwan,
Thankyou for your answers.
I was just wondering if there was much in the way of common ground between our ideas.

It seems like you are thinking more along the lines of the M20 type specs but a little heavier.

It will be interesting to see your project unfold.

Regards,
Phill

Phill,
You are right a M 20 a with more investment in the design than in the pure construction technology. So I would prefer foam instead of honeycomb, and achieve heavier hulls in order to have a cheaper and more friendly-user boat.

It is and will be a project, nothing is scheduled unless the beam issue can be solved.
Cheers

Erwan

Erwan,
I have concerns regarding the structal integrity, weight and platform rigidity of your beam design along with the increased setup time.
I am not saying it would not work because I have not tried it and would be very interested in seeing how things work out for you.
I will look at trying wings to increase righting moment without having to run a tilt trailer or increase setup time.
The wings stay on the boat and just fold up when being trailed.
I know there are many who believe what I'm planning will either not work or not be practical. But still think I can make it practical and also make it work well.
But like you I'll never know unless I give it a go.

Good luck, I hope your concept all works out.

Regards,
Phill

Your remarks target the actual issue, my only benchmark is the TomCat F18 HT project.
The curved crossbeam has been engineered by Mr Guillaume Verdier who is actually in charge of Safran a racing monohull.
For the F18 HT they have not used prepeg just basic epoxy in mould abd they achieved 10 kg and it is stiff enough to avoid a dolfin-striker.
As far as I know the prototype seems very stiff. The crossbeams are plugged into conical housing on the hull's deck, a bit like for centerboard.
The max height of the hull is 46 centimeters, because crossbeam section at the deck level generate very little drag.
Their boat seems to be very stiff, but it is also a consequence of the hull's stifness.
Of course set up process will be 15 minutes longer, but the only alternative is to make the bet that your carbon platform is not at risk when you are working 600 km from your sailing club. For a Hobie 14 no brainer, but for a 20 000 + € toy, I prefer to be organized accordingly, and the cost is to unfold completly the boat for storage, I will have the same issue with a A-Cat, so 3.10M width is OK;
I think your project makes sense, the only issue is a "legal" one: If you want the same leverage and righting moment, your overall width would have to be highter than 3.10, unless you fold the leeward wing to meet max width class rules, otherwise you give up righting moment.
The next step is to find a cheap tool/ construction process in order to use prepeg&autoclave for the first crossbeams.

Cheers

EK