I sailed Hobie 16s for many years but stopped when my kids were born... now they are teenagers I find myself drawn back to the sea. Just designed and built a 21ft stitch and glue outrigger canoe to exercise with but have my eyes on an F16.

Looking at the Vipers and Blades that are in the club here, I want to try to design and build an F16 of my own design.

The materials I can easily get here in Singapore are clear NZ pine, meranti and meranti marine plywood ( thinnest 3.6mm ), divinycell PVC foam , epoxy resin, carbon fibre cloth ( 200g/sq m or 250 g/sq m ), glass cloth and kevlar and carbon tow. What would be the best option without having access to a female mold.?

I was thinking over male mold frames either
1) 6mm pine strip covered with carbon fibre 200g/sqm
2) meranti marine plywood sides with pine strip bottom and fibreglass ( lowest cost option )
3) 6mm divinycell cut into strips for planking and carbon fibre 250gm/sqm

4) Hot wire carve blue EPS foam into a boat shape and cover with carbon fibre cloth

what do you think?

Thanks in advance

Shane

I know that Scott McCook has been experimenting with F16 building methods. Why not have a chat with him? Especially as he knows what is available in your locale.

I'd go with the lowest cost option
A) If you make a mistake during construction it wont cost too much
B) If you make a mistake with the design it wont cost too much
C) In a couple of years you may want to adapt the design or you may feel the construction is a little heavy or not stiff enough etc you haven't wasted too much money on your hulls
D) If it gets totaled due to a collision again you wont have wasted your money.
If it works first time and you have a fast F16 then you could always make another using more exotic materials.
In the mean time keep us informed on your decision

Strip planking is very time consuming compared to bending divinycell/foam into a female mould and laminating. Ref: http://woodastic.blogspot.com/

If you go with ply, buy a sheet or two and check the quality of the wood, gluing and finished sheet. Check for delamination when boiling, voids, uneven layers of wood etc.

A quote from a boat building website :
Murphy's law for boatbuilders is that you won't find your mistake until the glue has set, and Welsfords law for boatbuilders is that the mistake that can't be fixed with lots of epoxy and fibreglass hasn't been born yet.

Think you missed a bit Mark......

Heaps of ways to go about it. I designed and built a pair of F16 hulls out of foam and double bias glass in a female mdf jig.

But to go down this route you really need a fair bit of composite building experience or a helpful friend with said experience.

PM me if you need a hand with preparing the hull shape. I'm an engineer specialising in naval architecture and do that stuff all the time. Check out Gato's bloog on his F12 builds. http://www.gust.ax/

Oh, and don't go down the blue foam route. It might be cheap and quick to build but that'll probably be the only benefits with that method.

Thanks for the quick replies, its very encouraging...

J Alani,
I will ask Scott thanks.

Mark,
Point taken, I did waste a lot of time and money with my stitch and glue canoe. But it was fun designing, solving problems and building. What a change from my day job at the bank ( used to be an engineer but banks pay better)

Rolf,
I had heard a lot of bad stories about meranti ply in the US websites but I found the marine ply here to be of good quality. I went through several sheets when I built my canoe and there were no voids and good veneers used. Only thing is that the thinnest I could get was just under 4mm thick....and I dont think meranti ply bends as well as okuoume.

NCIK,
thanks for the offer, I will take you up on that. I am thinking the underwater cross section should be semi circular and the plan view of the hulls should be 2 circular arcs. So if I put the equation of a circle into a spreadsheet and vary the radius until I get the arc i want, I should be able to get a table of offsets of the width of the hull every ft. Then I draw a semicircle at each point to get the mold frames.

Why meranti? Few good experiences with meranti in high stress applications where you want low weight, as far as I know.
3.6mm is less than 4mm, so that further reduces strength. Are you planning on glassing the boat inside and out (adds weight)?

I think on this site about 18 months ago, a group set themselves up via a blog site to design and build a F16 which would be made avaialble to all who were interested. I think a number of regular readers of this forum were involved, is that design still kicking about ?

Have a look at the method John Lindahl is campaigning in building his LR2 and LR3 A cats, gives a very strong structure and very light weight hulls plus it quite well documented. Google should find it no problem.

There is also a very good boat design and build section on this cat sailor forum at the bottom of the list of forums and also another good resource is /www.boatdesign.net/forums/

Best of luck but one tip, which is it going to be a single hander or a dual hander, they are quite different designs.

Rolf,
Your blog is very interesting since I have i have a supply of 6mm clear pine strips 5m long.... What cloth did you use for the outside and the inside of your Blade?

I made a fuselage for a scale model glider using balsa strip in the same way as you built your Blade - left /right halves but when it came to joining I had problems with warping/ twisting. Eventually I tapped them together and when it cured I discovered that the fuselage had a built in twist.... did you have any problems with twist in the left and right halves?

Thanks,

Shane

160gsm I think it is. Dont remember exactly what we bought two years ago. We apply it +-45 deg to the wood fibers.
I would consider removing 1mm or even 2mm from the strips if I was going for a min weight boat, depending on the weight of the wood and how much epoxy it soaks up.
Strip planking is slow!



We dont know yet. First match up is hopefully next week or the week after. It takes time to do 6 identical hull half panels but we are now almost done with panel #7 and well into #8.
As long as both sides are glassed the material is relatively stable. I have checked with experienced strip plank builders and they are in favour.

Before you get to carried away with your design Nick very kindly helped me with mine (still on drawing board, money being the main reason). I also initially thought of a semi circular hull cross section but after Nick crunched the numbers there wouldn't have been enough buoyancy. Now there is a relatively flat section to the bottom of the hulls.
The semi circular design had approx 250mm (10") of draft with 180kgs on one hull or 100mm (4")of draft with 80kgs on one hull.
The non semi circular design had 200mm (8") of draft with 190kgs on one hull or 120mm (5") with 90kgs on one hull, with a slightly wider flatter section between the Center board and Main beam the depth of draft would be even better.
I found an interesting article not so long back (can't find the link now) but instead of using foam (core cell) strips along the length of the hull they decided to lay a lot wider 600mm (24")foam vertically they reckon the benefits were stronger, lighter and fairer. I guess you have to be pretty handy with the hot air gun whilst forming the required curves in the core cell.

keeping it semi circular would give the minimal wetted area and make it easy to do mold frames without CAD.
My proposal for the 16ft hull

max width 13.5 inch tapering to 1.5 inch at the bow and 10.75inch at the transom...

hull would be 19 inch high at the bow, 24 inch amidship and 14inch at the transom.

Max depth and height would be 5ft from the stern, coinciding with the middle of the daggerboard.

Would that work?

Shane

PS I can imagine using 24inch wide PVC foam... its quite stiff, how wil it conform to the curves of the hull....unless you have a female frame and apply heat while vacuuming it

Shane
I'm a raw beginner when it comes to stuff like this!! So I'm basically repeating what I've heard in the past. As far as I can see if you're happy with your ideas then just go for it, you never know what the outcome will be. I just wouldn't like to see you wasting your time and money on a design which although could be easier to build doesn't perform so well on the water.
Your overall design dimensions to my mind aren't out of the ordinary so you'll have yourself a F16.....
Probably the best wet pussy you've ever ridden!! (friday night humour)

How about something like this.
I would go with a flatter bottom my self.
Where you put the center board is a function of where your center of life for upwind sail area is and how much weather helm you want.

Why consider meranti?
Its readily available here in Singapore and light red meranti is about the same density as pine. Its a bit brittle I hear but made into plywood that problem doesnt seem to manifest.

Why simple semi circular forms?
I couldn't find any plans for F16s on the Internet. So I want to make this design free and available for any home builder to build. In my other hobby, aeromodelling, scratch builders are a dying breed so I hope that all the scratch builders who are building kayaks and Moths will come over to cats so there is more info on the Internet.

MarkP,
What is the max width of your hull?

Shane

Wow Lesburn,
Thats very close to what was in my head. The only changes I would make are to have the for'ard sections go from vertical sides amidships to more of a teardrop section at the bow. that would reduce weight forward. And same for the after sections behind the trampoline so that if you trapeze way behind your footing is at a better angle to help from being slung forward in a near pitch pole. I think the Viper has a good design there.

i am thinking of adapting a method of building model airplane wings where you laminate a skin of glass/ wood strip on mylar sheets then vacuum bag to a flat surface. When cured, the mylar is peeled off, the sheet can be cut to shape and applied to the mold frames for the hull sides. It would still be flexible because only one side of the wood strips would have fibreglass, the other side would have the fibreglass applied after the rest of the sheeting is done. The advantage is that sheet has one side practically faired and finished because the mylar will leave a glossy perfectly smooth finish. If this method can be used for the hull sides, half the fairing is taken care of..

Still have to work out the details...

Need some info on scantlings..

For Okoume plywood F16s -
What weight of cloth is used and what thickness for the okoume plywood?

For strip planked F16s - What thickness wood and what weight cloth?

I can easily get Alumimium T5 hardness of circular section for the cross beams. Are these suitable? 100mmm or 125 mm?

thanks,
Shane

For strip planking: 4mm norwegian spruce and a layer of 160gsm cloth put on diagonally on each side of the wood. That is what we use.

For okume, you dont need glass as far as I know.

100mm beams are good.


One of my co-workers in the office is heavily into scale RC airplane models. He is putting the finishing touches on a Tiger Moth just now

Just some quick feed back on the lesburn design...

"Teardropping" the sections like pilgrim said would be good as it would improve the water line and decrease fore deck area.

Push the buoyancy forward. This design has no where near enough volume up front. This doesn't hurt the hydrodynamics of the boat and will give you more downwind stability. Just have a look at wing sections and how "full forward" they are.

The other recomendations if you are going to build an F16... keep the platform as stiff as you can, solid beams and stiff hulls.

Also, don't forget 80% of a boats performance comes from the rig... so give some thought to who will do this and how it will integrate with the platform design.

Besides that, I guess if you want to see how we think an F16 should be done, have a look at the VIPER.

Good luck and hope to see you on the water.

That design was a quick throw together.
I am not in the boat design biz.
As to construction..
I have used 4mm okume ply for tortured wood construction in the past (a-cat and 18Sq) but for strip planking I think it would be to thin to get a proper tongue and grove joint. As to the beam issue I am using 4" (125+/-) .069 wall 6061 T6, these beams are leftover from an 18Sq project from 20 years ago. I am working on a oval carbon tube design to fit to my boat next year.
Coming from a 18Sq background (and having not sailed a cat with a crew in a very long time) I am unfamiliar with the dynamics of an F-16 so any thing I suggest should be take with a few grains of salt.

Thanks all. Will put something down on paper soon... this what I finished and launched last week...

Pilgrim

One suggestion I would make is to buy a used Taipan and use that as a base for you to build your F16. The hulls are one part of the whole package, and there are a lot of motivated sellers at the moment who have left or planning to leave Singapore and need to offload their boats.

Using this method you can learn how the platform works, how it all fits together, and then optimise your F16 with new hulls. Plus once you have finished your hulls, then you have the rest of the boat readily available. It may actually be cheaper, depending on the deal you make, to buy and build your F16 this way as opposed to buying all the parts and importing in seperately.

Getting a new mast in and buying all the blocks and ropes and sails can certainly add in costs quickly.

I am also in Singapore (sail the A-Cat and a Moth), but involved with Taipans for a very long time and F16s, so have a few ideas here.

Cheers
JC

HI JC,
Yes, it would certainly be easier and probaly cost the same but it wouldn't be as much fun. I sail occasionally with David Lee on his Taipan and he has offered me a share in his boat but I have this urge to try out my ideas and to build a boat. Its like an itch, if you scratch the wrong place you wont get rid of it....

My ideas are basically that for the hull, if you have a smooth curve to the underwater shape, correct volume distribution and a fair hull you have a good hull shape. Then you need to be at the minimum weight and the whole thing has to be stiff. A lot of the speed is in the rig but most of all the sailor.


DIY is a compulsion...

Shane

This is at table of the hull half-widths in inches, stations are 12 inches apart. The bow is Station 0. Above the datum line the hull can be vertical sided, below the datum line, the hull is a semicircle with radius as in the table. Its basically a circular arc, formula of a circle is r^2 = x^2 +y^2
y = sqrt ( r^2 - y^2 ) - put this into a spreasheet and input R=1410 inches and you get this arc...

HULL WIDTH 13.50 INCHES TRANSOM WIDTH 10.96
STATION 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0.75 1.64 2.61 3.48 4.25 4.92 5.48 5.94 6.30 6.55 6.70 6.76 6.70 6.55 6.30 5.94 5.48

The bow will have a bulb of radius 0.75"

OK, no problem Shane. Good to hear you have the passion to go through with this. Know that space to build boats in Singapore is virtually non-existent since 90%+ of housing is apartments/flats.

There are a few boat owners who would be keen for any bid on their boats as some are no longer in the country, so thought cheap way to get the rest of the boat components.

But for build ideas, let me know if you want help as I have a few ideas of how to improve things. There are a few things that can be improved around the beams and boards which noone is really doing and quite hard to put into a production boat due to the tooling required, but can be utilised in a home build as you are doing everything from scratch.

Send me a PM if you want.

JC

Hi Shane
Unfortunately I don't work in inches, so the dim's for my single handed design are 300mm (12"approx) wide at the front beam, 295mm (11.75"approx) at the rear of the C/B case and 270mm (10.62"approx) at the transom.
The depth of the hull under the front beam is identical to both the Stealth, Auz Tool & Bimare AJ, roughly 460mm (18.25")

Thanks Mark,
Your single handed design is slightly narrower and with less height which is to be expected. I am about 90kg and with a crew of around 50-55 kg I would need the extra volume. So far I think I am in the ball park....

Shane

I have to ask, has anyone thought about flat bottom/hard chine?

I did think about hard chine because its so much easier to build but I dropped it because of the following reasons -

Advantages of hard chine
- easier to build
- tracks better
- chine probably resists leeway

Disadvantages
- more wetted surface area
- cross flow is obstructed by the chine. I believe there is slip which causes the water flow to be at a slight diagonal to the axis of the hull. In a rounded hull, this is not a problem but for a hard chine I think the boat has more drag in some situations.
- looks amateurish next to the rounded white plastic factory jobs

I don't think it will make the boat faster but I chose round hull because I think it looks cool and I want to try and build it.

Shane

Hard chines can look cool as well, if that is what is wanted. I dont know for sure how bad/well hard chine hulls will do compared to round hulls in real life.

Rolf,
what is the target weight for the each bare hull of your Blade? What size are your cross beams?

thanks
Shane

The target weight should be 23.5kg for each hull. We have not done a thorough calculation to try and predict our weight. One hull panel (one side of the hull) comes in around 8kgs on our scales. Add bulkheads, deck stringers, transom, decking, beam seats and eventual fittings.

Our beams will be 100mm in diam, carbon tube.

Thanks Rolf,
Thats something to strive for...but my calculations so far yield 25.5kg per hull... guess i have to thin the wood i will be using...myabe I will planedown the thickness at the bow and stern.

Carbons tubes are the ultimate!May I ask what weight of cloth you are using for the carbon beams and how many layers?
I assume you are going to bolt a traveller track onto the beam..

Shane

Carbon tubes becouse alu tubes was more expensive than carbon. Believe it or not.
416gsm uni and regular 0-90. 5 layers is the current plan but will be re-checked before we wet out the epoxy. Currently testing the process and setup by making glass tubes. Much cheaper to do that wrong.

Traveller track will probably be glued and bolted.

Rolf, on the beams, are you going to glue them to the hulls or drill and bolt them? I would think glue would be the best way to go but then you can't get them apart easily either.

And very illegal according the F16 class rules.

Well some day I might actually read all the rules...some day. ;^) I thought carbon beams were illegal as well? Or carbon anything?

Carbon is LEGAL, and I think if you wanted to, you could build the whole boat out of carbon if you'd like. At least, I think.


Mike

We are for sure going to bolt the beams to the hulls. Glued beams are somewhat impractical when it comes to long distance transportation and storage during winter.

At the moment carbon is legal. There was a proposal to ban it in the class with the reason being to try and keep costs in control.

I think the way the rules are currently written it does not matter. A min tip weight on the mast, min weight of the platform and non-glued beams pretty much makes the use of carbon a non-issue. The potential performance difference is limited with these rules and the cost to go with carbon is significant. If some one want to have bling they can, but IMO with these limits it still will not win you any races.

Agree 100% with Matt on carbon use and the class rules.

Our carbon use is a special case due to some very special logistical issues. Like having to import suitable sections while the carbon weavers is in our backyard. Carbon beams is a really poor way to use carbon.

I think part of the reason for non-glued beams is that the width of the platform wouldn't allow the boats to fit into a container. Goodall was the one who pushed this from memory. A-Cats can get away with it as they are narrower and just can fit into a container.

Well Rolf, my only real concern here is about drilling holes into carbon tubes, through bolting them, and any potential crushing if over-tightened, or cracking if there is any slop, at the drilled hole area.

Are they (the tube builders) going to beef them up in the area of the holes to be drilled?

You are speaking with the tube builder to be
There will be compression chocks inside the tubes to handle compression loads and to stop any deformation. Just like what you find on a Marstrøm Tornado.

Drilling holes is not that bad, as long as there is no movement of the beams while they are under load. Overtightening bolts on beams is a big no-no in any circumstances. Stripped nuts inside the hull or crushed alu beams is no fun either.

Carbon beams are legal. Glued in beams are not. That is where my illegal coment was coming from.

Finally some activity on the forum again. It has been way too quiet for some time now!

Since there is some interest on the topic, here is the post about the first test tube we made, in glass. Learnt a lot, but there is still more to learn before we wet out any carbon: http://woodastic.blogspot.com/2009/05/first-tube-test.html

Rolf - No 45 degree fibres in your beam? Might be trickier to build by hand but definitely better torsion properties with some.

There will be 45deg fibers in the beams, yes. Will have to lay up uni to do that. I'll dig out the lamination plan and post it before we go. Still building hull panels so the test tubes are a side project for now.

I got some Divinycell PVC foam to test out - 6mm H60. A bit underwhelmed... not the magic material I thought it would be - flexible, and feels soft wonder why it costs so much more than blue foam or foam core from the Art shop..

The best way I've seen for a home builder to do beams is by Dr Mark Drela of MIT. You need to get low temp prepreg carbon unidirectional and roll over an aluminium tube thats covered with mylar release film. You have to build a makeshift oven but it only needs 275 deg Fahrenheit. You need to bind it with shrink tape before you stick it in. First the outside heatshrink tape tightens, then the epoxy liquifies and the excess soaks into the paper as the carbon fibers get compacted, then the
epoxy gels and finally solidifies.
http://www.cstsales.com/carbon_prepreg.html

$40 per pound - maybe 7lbs per beam? $280 for hitech carbon beams...

Unfortunately, I dont think they can ship prepreg to Singapore since it needs to be kept refridgerated.

Shane

Pilgrim, the advantage of divinycell over your blue foam will be in the shear strength. This is the crucial property when designing a foam sandwich structure. The flexibility is actually an advantagous feature not only in building but also in the strength of the final structure is it means the skins will take the majority of the load instead of the foam. Most people would use primarily 80kg foam for your application. The 60kg will bruise easily unless you put a lot of glass/carbon over it.

Thanks Scarecrow, will keep that in mind. If I do use divinycell I will probably go all the way and use carbon fibre. The extra USD 1500 or so will repay itself if I ever want to sell the boat.. I love wood but people are unfairly prejudiced against wood in boats except for teak.

Drew up the forms incorporating some of the suggestions that Ncik gave - more volume by using a constant radius circular chine and a narrower transom.. Here are the hand drawn forms... I now realise it looks weird because I dont have the waterline horizontal..the transom bottom should be aligned with the bottom of the bow
drats.. I
I'll redraw it tomorrow but now its late..

Looks like a "modern" hullshape. I am not qualified to voice any opinion other than that.

Have you decided on a building method yet?


Keep it up, and do create a blog to document the process if you get to the implementation stage.

Looks pretty good.... the real trick now is to draw up the corresponding water line and kiel line and make sure you're happy with them.

Just another quick note, and this may happen later.... see if you can let the lines flow a little more.... not just straight line to a radius. This will make it easier to get a nice surface when you get to that stage. This is pretty important in CAD modelling but the same can be said in the real world.

http://en.wikipedia.org/wiki/Geometric_continuity

Try the other way around:
Fee!ship
or the free version of delftship. Don't ask me which one is better.

The basic idea is that you control the shape of the hull indirectly with a few parameters. Main characteristics as displacement, prismatic and block coefficient, water plane area etc. are immediatly calculated. As a result you get the section shape and a hull surface which fulfils geometric continuity. You can even check which parts of the hull are developable.
A few hours spend in lofting can save days in the workshop...

Cheers,

Klaus

Thanks all, still a bit green so I will probably try to Keep it Simple.. Freeship is fun to play with and one day I will understand how to use it fully...

Hey Rolf, now that the word is out, we are all coming over! You got a couch? ;^)

http://www.msnbc.msn.com/id/33178495/ns/world_news/?GT1=43001

This probably belongs in that "drill" trainwreck of a thread
There is lots of room here and we could need some new people.. You are going to hate both the summers and winters though, especially if you settle north of the artic circle which is where there is a lot of room.

Tim,
Rolf has a couch and plenty of whisky too!

Yeah, that was a bit unfriendly of me

Of course I have a couch, I even have a full blown guestroom so it is possible to stay for quite some time. Please do come over but complaining about the weather is a "no no" (we are on the seventh week of rain and temps around 3-5degC now).
I can not seem to make a dent in the whisky department so any help there is appreciated. I am running low on the japanese "Gould&Gould" though.

Holland ranks as the 6th best country to live, its like Norway but warmer.
Forecast for tomorrow is 19c and 20 knot winds, too bad I have to work.
This summer has been extremely good anyway with some of the best sailing ever, I'm surprised we dont rank higher because of this.

Maybe we should make a list of which country is the best place to live for a sailor!

I'm Corsican. Best place for sailing ever.

But I live in the UK. Sometimes I'm wondering why.

you wonder why ??? me too , If I had a chance Id be off from this "sinking Ship" we call the uk faster than a rat up a drain pipe

Corsica vs Uk no brainer

There has to be a woman involved in that history. Corcica/France or the UK..

Rolf: I take it you have never been among the French

Sure I have. They are an unique breed with good and bad sides like everybody else
The french endorse multihull sailing, got to like that.

Now corcicans I have never spent time with but they seems like an interesting people. A people unleashing Napoleon , being part of shaping king Carl Johan (http://en.wikipedia.org/wiki/Charles_XIV_John_of_Sweden) and inventing the "vendetta" must be quite something.

I was wondering what it would take for you to re join us. I know that he who shouldn't be named hasn't been here for a long time but I wasn't expecting you to chime in on this thread. Welcome back Codblow, what happened at the Scottish Stealth Champs etc etc.

I'm not going anywhere the water's cold... the tropics are where you want to sail. If you have to wear a wetsuit to sail you can keep it... Sydney or Hawaii is about the coldest I would go to sail....

To be fair guys all us foreigners, be it NZ, French, Scotish, Welsh all live here by choice, no point wingeing about it. As to why, its called a good safe bet for work and employment with a safe bet of weather and housing.

Now for me those things never really came into it, just the best looking women in the world seem to walk up and down the streets on a daily basis

*cough* *splutter*.. there you go, now I have to wash my screen

When did Wayne move to Milan??

:^)

Beauty is in the eye of the beholder but one should always look at the mother in law for future reference.

Yeah, and I'm still looking to -behold- that gal with the green Nike's!

It has also been said that beauty is in the eye of the beer-holder...

Update of build - Cut out the frames

Built the mold using plywood. Flat sides make this easier and quicker to build. The key to boat building is finishing it before you run out of steam.

I covered the mold with the plastic film that is used here to cover books, I think its PVC. Then my friend Kenn and I tacked the foam to the frame with nails.

The foam is roughed out using japanese Ryoba saw, 60 grit sandpaper and an Olfa paper cutter. At this stage I have only used a week of my annual leave... one more week and its back to work...

Technical stuff

Divinycell foam H80 thickness 10mm is used throughout except for the transom, major bulkheads and the area around where the centreboard exits which use H160 density.

Strip are cut to apporx 13-15mm width for strip planking using a large Olfa paper cutter and an aluminium channel for a guide. H80 cuts like medium density balsa wood and H160 like heavy balsa... no need to get a circular saw. No dust with a cutter...

I fiiled in the gaps in the strips with epoxy mixed with lighweight filler. I didnt edge glue it while assembling but put it all together with nails and tape and after the foam strips are in place I went over it with a spackle knife. On the first day I filled in the gaps between the nails and the tape, then after the epoxy cured 12 hrs later I removed the nails and tape and spackled the rest of the hull.

Applying plastic to the mold, tacking the foam to the mold and the first pass of spackling took a whole day working from 9am to 11pm with my friend helping me out for most of the time.

Shane

Questions

I am planning to layup the foam using a single layer of 200g/sq m carbon cloth with a double layer in the centre of the hull from the chainplate area to the 1m for'ard of the front beam. Outside layer of carbon will be 0/90 in one layer ( the cloth is 1.5m wide ) and the inside layer will be -45deg/ +45 deg with a double layer in the centre of the hull from aft of the centreboard to for'ard of the front beam.

Is this enough?

I also plan to have a sheer clamp from Divinycell and cover is carbon fiber to help increase the gluing are when I glue the deck to the hull. An alternative is to use a timber sheer clamp instead. Any thoughts on this?

Thanks

Shane

Looking good Shane.

Can't help with your questions, but for chainplate location, what have you referenced this against? If taken from the Taipan, then this can be moved further aft. Taipan location was to allow the main to get out as far as possible, as people were sailing straight downwind at the time of design. We no longer do that, so can move chainplate aft and this takes some of the load off the chainplate due to the triangle to hold the mast has a large base. Boyer tried to get the Taipan class rules amended to allow this about 7 or 8 years ago.

This is what I have done on my homebuild Taipan F16. I've repositioned the side stay 200 mm further aft and I have never experienced any negative effects. Even when sailing without a spinnaker the boom never seems to go out far enough to touch it. The sail may however, up top, but you'll sail with some very large amount of twist when that happens. My sailing style doesn't seem to include this profile and it almost never happens with me. Note, that I do sail a numbers of times without the spinnaker, when I just want to sail around for an hour or so and not do all the rigging work. Just throwing up the mainsail and go like an A-cat works well for the short sailing trips.

Main point of this post is however that in my opinion TaipanFC has a good point. You can place the sidestays further back without any penalty. The benefits in lower stresses and a more tight forestay are significant though. Going from 500 mm to 700 mm is a large modification.

Best of luck building your boat !

Wouter

I was going to place the chainplate 68cm aft from the centre of the main cross beam which is the same as the Viper. Since I plan to use the Viper sailplan, mast and sidestays it would be easier to get the tuning done if I have the basic dimensions the same.

Shane

http://www.mcmc-uk.com/video/epoxy-foam.html

When you get to foils, this may help. Looks like a good way to build them. Especially to make them consistent.

Thread over at Sailing Anarchy about foil building, http://forums.sailinganarchy.com/index.php?showtopic=101093

Yes, I was talking to my composites supplier about the epoxy foam... trouble is I would have to make a female mold which is a bit troublesome. Unless I design the board to be used in a Taipan or Viper then I could have a sideline supplying boards to the Taipan or Viper fleet.

Retirement plan?

No, too early!

Any ideas on where to put the main beam? In the middle of the boat, slightly forward or slightly aft of middle? I think the Viper has it 2 inch forward of the middle but I gather that the current thinking is slightly aft of the middle so that you get more hull forward of that mast which helps if you want to push it harder downwind.

Any thoughts on this?

Shane

Applied the carbon fibre cloth yesterday. one piece of 200g/ sq m 2x2 carbon twill weave. Used too much epoxy because I didnt vacuum bag. Its just too big for one person to layup well... there are some bubbles which I have to fix.

[img:center]http://pics.livejournal.com/goodworks/pic/0000ayhh/[/img]

Shane, I'm sorry you're not getting much response to your thread. Why not try Mike Shappell at the "Man Shed"?

http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=199401#Post199401

I guess people are busy with family, christmas etc.
Really impressed with what you've done in such a short space of time though Shane. Amazing!

I look forward to seeing pics of the finished hulls (as, I'm sure, do you!! )

Pilgrim, A few tips,

Carbon on the outside is very vunerable to chafe and wear from beaching etc, put a layer or even two or 3 in the susceptable areas such as the bottom and trapezeing feet areas of glass. It won't add much weight as it has the benefit of mopping up the excess resin from the carbon layup.

I simply wet out the carbon and then place a layer of glass over the top, squeegee ( using a plastic filler applier )the glass into the carbon and you can soon see if you need more or less resin. I tend to layup a heavy glass cloth and then a very fine layer as this tends to flatten out the twill and therefore you need less filler and paint. Enevitably when you are fairing the outside before painting you can rub through the glass but it is obvious where as the carbon is not and much easier to repair.

In relation to the beam, it really depends on whether you are intending to be a single hander or double. If single then you can place the beam way back as per the A Class but with a two hander it becomes impractical as you need to be able to get the crew through under the sail, Bitsa is a bit extreme and even single handed it is tight. There are other benefits to having the beams back such as you need less volume up front and in theory should be a better light air performer without sacrificing Spinny down wind safety. Again Bitsa seems really difficult to bury the front as the Spinny clew is only about 1 metre ahead of the front of the hull even with max length pole.

The rear beam is much more tricky as it is really dependant on your rudder system and how long the arms of the rudder connection bar is. The system I used of gantrying out the rudders is too time consuming and I'm not sure that practical. Stick with the conventional I would say.
Fire the questions off as I'm sure there will be an answer.

Hi Wayne,
I do have a band of carbon cloth 100mm wide the length of the bottom and I plan to cover the whole hull with lightweight glass cloth. I have to get rid of some bubbles first... will cut an X shaped incision with my Dremel cutoff disc, fill with epoxy and put them back with a carbon cloth patch over it. Next time I will do the cloth in parts instead of one big 5m x 1.5m piece for the whole hull - I was too ambitious for a solo effort.

I do like the way your rudders are out back so you have good leverage on the tiller arms. I've been thinking how to do that with carbon rods and I might do something similiar.

Shane

Shane, using carbon as you intend can cause more problems than solve, a 100mm additional band without other layers transfering the load to the single layer, will cause such a hard edge between the layers that it will almost certainly crack the inner layer of the two. Always use carbon for stiffening and glass to transfer the loads + act as wear layer.

Everyone seems to think Carbon is the great thing to use, it very often is the wrong material and should be used with caution. An all carbon boat will weigh marginally less ( probably only 3 -4 kilos to a well built glass boat ( and how many of us are not 3 -4 kilos over weight ), cost 3 times more than glass, most certainly will be far less duriable and twice as hard to repair when you ding it.

It is christmas time.. I think I am +5 kilos just from christmas with the family so I certainly dont worry about carbon

From the picture it is hard to say what is bubbles, what is distortion in the cloth and what is bubbles. I really liked the plants and the bamboo in the pic though as we have about 100cm of snow the last week.
Putting on the cloth in one piece is OK if you organize the work. Ie starting at the middle and working outwards to both sides with one batch of 100grams epoxy at the time. Kayak and canoe builders do it all the time. A slow hardener might be better if you find the epoxy kicking too fast.


You are working fast, hope to get an on the water report soon.

Wayne,

any hope for a followup on how your snuffer works and more pics?

Wayne,

Thanks for your input. I will have a glass layer over everything for wear resistance. I dont think carbon is that bad. In aviation , models and full size, there is ample use of carbon in staggered multiple layers that allow taper in skin thickness without hard spots and stress concentrations to develop.
I also thought about the placement of the main beam and decided to place it 5 cm aft of the center. I will keep the rear beam 2m aft of the main beam like the Viper which leaves me 40cm between the rear beam and the transom. Thats a bit short so I will have to engineer a gantry like the Bitsa.

Rolf,
The cloth was distorted in places when I was draping it dry over foam. I smoothed it with a wide brush after draping. I applied the epoxy working from the middle to the ends. I use a 24 hr cure epoxy so I had enough time but it was very tiring because of the sheer area of the hull. When I applied the epoxy with the plastic spackle knife over the cloth I noticed that parts I worked on before had 2-3 cm air bubbles that just kept on returning even after I smoothed them down repeatedly with the spackle knife. The curved hull bottom was not affected and only the vertical sides.Next time I will cover the hull in parts and vacuum bag the cloth to the foam.

Even with a flash coat of epoxy applied to the foam beforehand, I used much more epoxy than I expected. The cloth was not shiny after application so I dont think I flooded the cloth so it must be that the Divinycell soaked up the resin like a sponge. I am anxious to weigh the hull...


Shane

You might have closed the pores in the foam with thickened epoxy (epoxy+microballons) mixed to a slurry and applied before placing the glass. (20/20 hindsight is not difficult, especially not while behind the keyboard).
I dont have much experience in glassing foam parts without vacuum. With wood it is imperative to not glass while the temperature is rising. Outgassing from wood is a problem. I dont know if divinycell is similar. What I do know is that the more you work the cloth after epoxy is applied, the harder it becomes to do a good job. Pushing air into the cloth.
When applying cloth over large pieces, I find it best to roll it on really carefully. Cloth that have been folded is never 100%, neither is cloth that have had any kind of force applied to it as it stretches and wrinkles so easily.
If I can choose, I prefer to put on the glass in a horizontal position. I find it much easier to get a good result if gravity helps me. Draping/applying epoxy to the "bottom" of the part first will distort the cloth when you come to the "flat" hull side.
You probably know all this from your RC building. I am just throwing out information that might be useful for others reading the forum.

Did you weight the resin and cloth before applying? If you do, you can track your progress while applying the cloth.

I think you are doing well. Keep up your efforts and you will be sailing soon. We have spent 1.5 years on our strip plank boats..

I primed the foam with clean epoxy ie no filler... that might be my problem. Next time I will use epoxy + microballoons... It really soaks like a sponge. I used about 3kg of epoxy for 1.5kg of cloth ( 7.5 sq m x 200g ). I dont think the cloth was oversoaked because it had a matt appearance. I think the epoxy went in to the foam.

I have to keep up the momentum otherwise I will lose interest and that will be a disaster.

Shane

I would have sealed the foam as suggested.. a micro-balloon mix.. sanded smooth and then applied the cloth. Foam eats epoxy!!


good luck

Happy New Year to all!

Figured out why I got the buubles under the cloth.

I started out by pouring epoxy from the top middle and worked my way to the ends. It was working great at first but as I worked to the ends, the action of pulling the resin down at the ends pushed the cloth towards the middle and caused the cloth to bunch up and buckle creating bubbles.

so to summarise the mistakes I made so far...

Mistake 1 - Used clean epoxy to prime the foam, should have used epoxy mixed with microballoons or Q cell.

Mistake 2 - Allowed the cloth to bunch up in the middle when applying epoxy at the ends during layup. Should either have used vacuum bagging or should have worked the spackle knife sideways towards the ends instead of top down.

Shane

I have started a blog and new pictures will be there.

http://goodworks.livejournal.com/

I do hope to get some answers to my questions but if I cant I'll just give it my best guess and move on... If the boat works others can follow and if it breaks I'll document what I think went wrong and how I intend to fix it. Its a bit disappointing how little detailed information is available.. so I hope that others who want to try homebuilding will have a path to follow.. albeit strewn with the debris of my failures and misteps.

Shane

Looking good Shane. Sorry can't help with the technical details, never done what you are doing.

However, where did you the carbon from? XSP? Going to try an experimental mast on the moth so need to make a base for it.

Great!



How about giving some of the builders/designers around a call, or take measurements directly off a boat if you need that kind of information.

Could you restate what you need to know? I'll fill in what I know or can find out. We want to keep you going on that project.

I think Phil Brander had an indepth site for building a timber F16.

Anyone know where it is?

Without wishing to detract from what Shane has already done, IMO there are a huge loads of information about on building in Carbon and Glass and even greater amounts on boat building in general, but it is a pain to find quickly and time consuming to piece together but then if it was all so easily available then we would all be building our own boats.

Shanes approach of just getting on with things is possibly the best way in reality as I seemed to spend far to much time researching things but I'm not sure it could lead to small mistakes that turn into major problems. Fortunately the type of small scale construction we are using is pretty forgiving and with just a bit of over engineering we seem to not break to many bits.

My recommendation to anyone contemplating building a boat is to look at the LR2 blog as a possible alternative method, it is a good and easy path to follow and builds pretty good boats relatively quickly.

What Wayne said! (Unless you have perverse ideas about actually building becouse of the process and wanting to do something special like an F16 with the finish of a grand piano)
(And if Shane was building to plans, things might be a bit easier, but there would still be questions).


Here you go Pete:
http://www.thebeachcats.com/index.php?module=pictures&g2_itemId=11955

Thanks Rolf. Isn't it time to update the "View from the Office" thread?

How about use this thread as a dumping ground of good links and information that would be useful to the amateur homebuilder. Can post a link, say what was good or bad, what worked, what didn't, improvements. Would go a long way to helping people like Shane who are starting out on these projects and help grow the class.

I tried to contact a designer but no response. I would even buy a set of plans for reference but nothing modern seems available eg Blade or Viper era. I took some measurements from a Viper because I plan to use Viper sailplan and mast. Chainplate distance from main beam = 68 cm, main beam to rear beam 2m.

Questions

1. please critique my layup plan. Using 200 gm per m carbon cloth over Divinycell H80 overall, with 30g /m glass over that for a better finish. 0/90 deg orientation on th eoutside , -45/+45 inside of the hull.

Doubler of 200 g carbon starting 2m from tip of bow to 1m from transom 0/90deg orientation .

Deck doubler of 200g carbon starting 1.5m from bow tip to transom 0/90 deg orientation.

Local reinforcement of 200g /sq m cloth under beams and chainplate area -45/+45 deg oreintation. Local reinforcement of 300g/ kevlar under beams, chainplate and forestay anchor point to insulate metal from carbon and provide protection.

2. Should I have a sheer clamp to attach the deck? Timber? or Divinycell foam?

3. Bulkheads under Main Beam and Rear beam. Should I use plywood ( 10mm? ) or 200g carbon/H160 foam/carbon sandwich ?

4. Deck hardpoint under the beams - should I have 10mm plywood replacing the H80 foam or can I use H160 to replace the H80 foam?

5. Thinking of a 10mm diameter solid carbon extrusion covered in kevlar for a sidestay anchor instead of a 2,5mm stainless chainplate. More for the 'cool' factor but also to avoid crevice corrosion in the stainless steel. Worth the trouble for the cool points?

6. Broad centreboard like the Taipan or High Aspect ratio like the Viper? Asymetrical or sysmtrical foils?

7. Should there be a bulkhead at the chainplate position?

8. Do I need diagonal stringers between bulkheads as a hull stiffener and to give torsional strength?

Thanks in advance

6.

Have the topsides of the bow quite rounded. Makes a big difference when you have buried the bows, helps them to recover.

High aspect boards is definitely the way to go. Does mean you need to build them stronger to take the sideways forceloads.

I think Phill Brander still supplies the Blade F16 plywood plans?

The measurements you need is from bow to chainplate, bow to main beam, bow to daggerboard and bow to rear beam.


1: Layup schedule. I can not advice you there.

2: Unless you have a way to add a fillet and glass tapes on the inside of the hull after putting the deck in place, I would do a shear stringer. I am comfortable with wood stringers. Alternatively a flange of some form. At least you need some extra glue surface area to stop the deck from popping off.

3: 10mm bulkheads are overkill. 4mm ply with cutouts will do. Foam/carbon is lighter, but I can not help you with the laminate schedule. I have done some foam/glass bulkheads and they did fine on a Tornado, but I am not comfortable on advicing you on foam/carbon/glass.

4: Ply is a possibility, or a nice spruce or WRC plank with some hefty reinforcement in fibers. If going with foam/carbon, you will want to make this part as stiff and strong as possible to minimize flexing and wracking.

5: If I was to do carbon chainplates I would do it like Farrier does. Be careful with alignment and size it for shock loads.
http://www.f-boatmart.com/images/P/F-22chainplate400-01.jpg

6: High aspect ratio, symmetric. Important part of the boat to get right and with high quality on the build and surface. Asymmetrical have been tried in other classes and have not paid off sufficiently yet, except in the C-class AFAIK.

7: Yes.

8: Not neccesarily. Depends on your layup schedule.


To get tips on layup schedules you could try getting hold of guys like Bill Vining, Kevin Cook etc here on catsailor.com. Remember that what you get here is advice given with good intentions. The advice might be spectacularly wrong and lead to catastrophic failures..

Rolf,
I sent 2 message to Phil through the forum message utility but didnt receive any reply. Will try again.

Thanks for your reply. The layup I use is based on the LR2 layup with the extra strength of doublers in the middle part of the boat.

Think I will go with the timber sheer clamp but use carbon/h160 foam/carbon bulkheads and maybe composite chainplates.

Shane

Hi pilgrim,

1) Unless I know the loads and required stiffness, I would use a symetrical sandwich (i.e. 0/+-45/90 inside and outside) with the most fibres in direction of the main loads (from stern to bow?) but not too far from 30%/40%/30%.
If I understand you right, you want to use 200g inside and 200g outside, and midships reinforced by another 200g + 200g? Sounds a bit oversized. I would locate the areas where you need reinforcement (i.e. between the beams, along the keel, where you put the feets for trapezing and righting, around any force introduction. You can use glass instead of kevlar for insulation, does the same as good as the other.
2) yes, timber or large radius CFRP L. It needs to be strong, hence no foam. It will add so much integrity and durability for so less weight.
3) Sandwich would be enough. Add a bulkhead under the attachement for the bridle wires as well
4) I would do epoxy plugs around the bold holes, but hardwood is also possible if protected from moisture.
5) Possible, but I would prefer metal, because it will not break, just bend, if hit. And so far I bend this on all my boats...
6) if you sail single hand: symetric, if you sail dh, you could have asymteric ones. But the boards must be slightly larger, since only one is in the water. Profile and thickness are much more important than aspect ratio, area is more important than aspect ratio. A too small board with high aspect ratio will be a bad performer. DH needs more board area than SH. You can contact me for profiles better than std NACA sections.
7) yes
8) no, but you could have and reduce the weight of the carbon clothes of the sandwich skins.

Ok some words of my background:
I am an engineer with degree in aviation and working for a larger airframe builder for preliminary aircraft design, so I am neither an expert for CFRP nor manufacturing. I have never build a boat, but some parts and repair jobs. Hence be sceptical with my input.

Cheers,

Klaus