Hi Mark, Lets look at it another way :
Both boats sail over the back of big wave, go bows down & pitch into back of next wave.

Heavy boat has more momentum with bows in the "going down" position, less "apparent" bouyancy. Oh yes, and a bigger engine !
I can hear the crew shouting "dive ! dive ! while the skipper dons his snorkel & mask.

Light boat has more "apparent" bouyancy, pitches into back of wave & slows down due to less momentum, allowing the bows to go into "recover" mode, where it`s bouyancy has a chance to start lifting the bows. Bows pop out & boat begins to accelerate quickly, resisting the capsize or pitchpole (more energy is converted to forward motion more quickly, so less energy is converted to the tendency to push the boat over sideways or forwards.

I`m sure Robbie Daniels knows what he`s talking about, but I don`t think we can compare two different hull shapes, platform widths & the major difference between sloop rigged T and Unirig Maerstrom boat, attached airflow will be influence greatly by this difference alone. Would be more fair to compare old 1979 Tornado with new 2004 Tornado to judge behaviour, I think the newer T`s have lost a good bit of weight.
Or take 1x Hobie 16, fill it with 50kg of lead, put up a Hobie Tiger rig, then compare it to the standard Hobie 16.
I think we all know the answer to that one, and no, I won`t test-sail it !

Cheers
Steve

Not Quite. The momentumn acts at the center of mass. Therefore, say the rigs were identical, the heavier hull would maintain the boatspeed longer with little pitching effect (its weight acts at essentialy the same elevation as the resistance (wave form drag). This then gives the crew a longer time to react in.(To drive off, let the gust pass, or get both hulls under them, sheet in the jib completely to choke the main...) Also, the light boat, in decelerating, rapidly feels the actual wind (off the wind, the apparent wind shifts aft, to becoming true wind) as the boat slows.At this point the slower the boat, the bigger the wind/boat speed difference. In wild conditions, this wind even on a stalled out rig, will drive you stern over stem. And you have nowhere to go. Just like boat speed needs to be maintained for a smooth jibe. (From a fellow SA by the way)

Steve, your argument sounds reasonable, and a couple months ago I would have been totally on your side…

You are basing your hypothesis on one boat design…and the logical conclusion from that basis is the one you arrived at…. however what if we were talking a different hull shape? One that had more volume forward? One that had an extreme crown to the deck that resisted pitch pole to a much greater extent than the Mosquito? You might get a totally different result when loading it up with more sail area…because it was designed from it’s inception to handle it.

Like your self, I would like to get the lowest reasonable weight. However after seeing the boat that won the Steeple Chase, I have to admit there is a lot more to the picture than just weight. The SC 20 that won is an absolute beast…something like 550 lbs?, repairs and all. A hundred lbs over class weight…(the way people talk around here, five pounds over minimum would be the “kiss of death”)…and it still won…Why? Because it is a superior “DESIGN”.

It all starts with the platform…that is your foundation…if the platform has taken in the design features that are necessary to reduce pitch poll to a minimum then the option to increase sail area open up. I say that as it seems that the most talked about limiting factor to catamaran speed is the ability to drive a Catamaran hard without pitch pole. If you are not worried about “going over the handle bars” all the time you can keep your “foot on the gas” longer.

As far as the Tornado’s of 2004 being lighter, I could be wrong, but I was under the impression that the weight is exactly the same as when the class was conceived, and while the strength of the hull has continued to improve, the weight has remained constant.

Bob

Steve, David, and Bob:
You guys all make some very interesting points.

Maybe for high wind/wave conditions:
1) With lower volume bows lighter is better?
2) With higher volume bows heavier is better?

Who else has experience comparing light vs heavy cats in high wind conditions in cats with higher volume bows? What I'd really like to compare is something like Taipan 4.9/F16 to I17R in higher wind/wave conditions. Anyone sailed both?

Also, to be clear, it would be nice if there could be some agreement as to which designs have high vs low volume bows. Here's my stab at it (but please feel free to correct me if I'm wrong):

1) Higher volume bows:
a) "lighter" cats: Taipan 4.7, Blade, Auscat/Flyer/Marstrom A-cat's, newer T's
b) "heavier" cats: I17R, Tiger, Nacra F18, SC/ARC, H17, TheMightyHobie18, older T's

2) Lower volume bows:
a) "lighter" cats: Mosquito, Stealth?? (John, please correct me if I'm wrong)
b) "heavier" cats: FX-One, Fox, H16

Note: I might be wrong about Stealth's bows but I got the impression they were fairly narrow; may not be applicable because of Stealth's unique T-foil rudders.

Comments?

Jerry

Hi David, just to clarify my point, you wrote :"This then gives the crew a longer time to react in.(To drive off, let the gust pass, or get both hulls under them, sheet in the jib completely to choke the main...)".
Based on what I found when going from heavy boat to light boat, with the lighter boat, NONE of your stated reactions were necessary ! I`m sure if you ask an A-cat sailor they might tell you the same thing. To depower the light boat upwind, use the rudders to feather the boat into wind a bit, you gain height & speed. Obviously this works more on boats with boards than non-board boats - I know that if you try this technique on a Dart 18 she will stop dead in the water, the technique in sailing a Dart fast upwind is to play the mainsheet until your arms fall off, one of the reasons I "upgraded" to a light, fast centreboard boat with a moderate sailplan. Being lighter with less sail area means being able to push harder downwind without worrying about submarining. The Mosquito hull shape is almost identical to Tornado, fine entry bows which pop out easily without much loss in speed, so the momentum issue is no big problem. As I said, my opinion is based on actually sailing both boats in the same conditions and noting the difference in how they actually perform, not by analysing theoretical knowledge. Downwind I can understand your position, but I think it depends on hull shape as to whether the boat has a tendency to bury bows or not, and I think that how quickly the boat pops out & accelerates to it`s full speed, the less tendency it will have to go nose-over. A boat doing 16knots boatspeed in 20 knots of wind will have much less apparent wind in the sails, it`s only when it stops that you have a gain in power in the sails, so the solution is to sail a well-designed boat that won`t go nose-over easily, and if it`s howling, stay back (I`m talking non-spinn boat here). It`s not difficult to grasp, even if you`re a novice. On that point, and I think that was the spirit of Jerry`s question, a novice won`t head out if it`s 20-25knots, until his confidence is up. Also, capsizing is just part of sailing and is a sign that at least you`re pushing hard. An easy-to-right boat makes capsizing more fun. I`m qualified to write this after putting in 5 capsizes in 3 races, and still ending up 4th at our Nationals !
I think that if you`re comparing different weight boats that have different hull shapes it becomes more complicated, and I`m certainly not going to get into that, except to say the following (and it`s not criticism on anyone`s way of doing things, just my observations ) :
One way to build boats is to make them light, with moderate sailplans. Because of this combination they can have slimmer hulls which cut through waves more easily & won`t slow down that much when they do, since they need less bouyancy to counteract the power of a bigger, more powerful rig. I`m thinking A-cat, F18HT, Tornado etc. The Australians pioneered this way of building boats & will, it seems, always be the leader in this field. (possibly because the Americans have followed the opposite route !)
The Other way is to make the boat heavier, load up the power to compensate, but then the hulls NEED to be fuller to load up the bouyancy (both to overcome the extra power & to "equalise" the increased weight). Also probably need to widen the beam to compensate for extra power. The American designers seem to prefer this route. That`s why the Supercat has it`s fuller hull shape, and the Tornado has the slimmer shape. It`s not each designer thinking differently, it`s about each designer creating hull shapes that work together with the chosen weight & sailplan. There`s no right & wrong, both ways work, have their own sets of pro`s & cons etc. My personal view is that boats with fuller bows tend to slow down more when the nose goes in than boats with finer bows, I could be wrong here, but there`s more drag in a fuller bow. And a heavy boat with it`s nose pointing down is likely to pursue that direction with much enthusiasm, given that it has more momentum, a bit like hammering a nail into a piece of wood with a really heavy hammer..

Cheers
Steve

Jerry,

It all comes down to ratios, not if your're ligter or heavier.

Example :

An F18 will get you into trouble just as quickly as an F16 despite the first being heavier; only the sheet loads are higher on a F18. The F16 singelhander (Not doublehander) is noticable more sensitive in the momentum department. However the difference between F18 (330 kg total) and F16 doublehander (257 kg total = 78 %) is not sufficient to make much difference in wavy conditions. Compare to A-cat = overall = 150 kg = 45 % of F18 overall. This is the reason why nearly all most singlehanders

A Prindle 16 (135 kg) will get you less quickly into trouble than a lighter F16. This is not because of weight but because of the ratio between platform and rig dimensions. On the other hand the heavier Hobie 16 (150 kg) and Prindle 18 (160 kg) (also very comparable in sail area) will get you more quickly into trouble than the lighter Prindle 16.

You see; it is not about weight that much; it's far far more about the ratios between the different parameters, of which weight is just one of many.

These example fully contradict your summary.

Best boats for novices are the ones with mild behaviour and robustness (damage) but quickly novices get the hang of things and will do better on a more refined platform. My advice is always to just get a cheap secondhander that you can sink without going backrupt and than after 1 or 2 years upgrade to a more refined boat.

I love my Prindle 16 (my first) and still have it but I soon switched to Prindle 18 and F18 after getting my basic skills in order.

>>a lighter cat may in fact let one learn more quickly due to it's greater feedback but might be more frustrating in the process.

Nothing is more frustrating than a cat that doesn't groove in light air. I love my Prindle 16 but making that one go well in light winds requires alot of skill. Far more than you need to know about handling a modern boat in heavy winds.

I would also like to add that a boat with less tune and trimtools also requires more skill to handle. Example. a boom less main is more difficult to control and handle in the heavy stuff than a boomed main. Novices feel that they are better of with a boom less main but actually they are worse off. In a blow you must use the traveller of the boomless main to depower and not the mainsheet. If you do you the mainsheet than the main will twist and curl only to get it's old shape back with a bang when the angle of attack crosses a threshold again. Makes for a lively ride.

See what I'm getting at ?

Differentiate between marketing talk and physics.

I personally found my smaller ligthweight Toyato a lot easier and comfortable to drive when I just had my drivers license than the big station wagon of my parents.

Wouter

Hi Bob, Jerry Dave.

Bob, I agree on all points, just a few things to think about :
Would the 550lb Supercat have won the same race if there had been a 350lb Supercat at the same event, with the same crew weight & skill level on both ? (I know you don`t get a 350lb SC, just for discussion purposes.) My money would be on the lighter equal "superior design" boat.

Regarding "keeping your foot on the gas longer" I`d back a lighter boat with LESS sail area, given that all other design issues were equal.

Agree - a platform DESIGNED to carry more power can probably handle it, but then hull volume, weight etc all go up. See "Playstation" for where we end up.

How does all this relate to Jerry`s original question : Not at all.
Is the lighter boat less forgiving than the heavier boat ? If they are different designs, it becomes a tough question, as there are so many other variables that come into play.
All other design issues being equal, I`d say light = more responsive = more "twitchy" & sensitive to crew weight position & reaction, so I`d have to agree that lighter = less forgiving to a novice, but in my experience the lighter boat takes less effort to sail, and is always going to be easier to right. Hey, my whole platform weighs 10kg LESS than I do (and I`m only 67kg). And it`s made out of trees & epoxy, no hi-tech carbon stuff, in fact it`s "reinforced" with polystyrene ! I find it much less work to sail, and can push it MUCH harder than my older boat. Less forgiving ? They don`t call me the capsize king for nothing !

I think there`s a lot to where you put the weight : Heavy platforms do have some disadvantages, HALF the weight of the hulls is forward of the front beam, which will do nothing to assist in making the boat pitchpole-resistant.
Half the weight of the hulls is also to leeward, not helping resist capsize.

Cheers
Steve

Hi Steve…

“Would the 550lb Supercat have won the same race if there had been a 350lb Supercat at the same event, with the same crew weight & skill level on both? (I know you don’t get a 350lb SC, just for discussion purposes.) My money would be on the lighter equal "superior design" boat.”

My money would be on the lighter one as well…I think we are both on the same team here…My point was that the hull design is just as important a factor as weight…and in the particular case of the Steeple Chase, it appeared to be the deciding factor. It seems that the aspect of synergy in design is lost when we go off in some of these discussions. Weight is important, very important…but so are a host of other factors…I was just trying to remind us of that. Sometimes we get tunnel vision.

“Regarding "keeping your foot on the gas longer" I’d back a lighter boat with LESS sail area, given that all other design issues were equal.”

Again I agree with you, but most times the design issues are not equal.

“Agree - a platform DESIGNED to carry more power can probably handle it, but then hull volume, weight etc all go up. See "Playstation" for where we end up.”

Steve how much more weight does a boat have to incur to redistribute volume to the bows? How much more weight does a boat incur when heavily crowning the foredeck? These are things that would help any boat design prone to pitch poll, and should cost nothing in the weight department...in fact the crowing of the fordeck should make the foredeck stronger/stiffer with no additional material by virtue of the curve...another "weight free" advantage.

Bob

ALL true, but I got to fight for the heavy underdog. It is the same old song I sing. The Hobie 18 is a great boat, and you'd never guess to look at it.
Lighter is always better, of course, but as Bill will remind you, a little lighter is a lot more expensive (on a production boat) Building your own boat is the most expensive of all in USA, because you have to pay yourself minimum wage by law, and the hours logged are astronomical.

Let me throw all of you a curve.

You are not really comparing apples to apples

Most old heavy boats have low aspect ratio rigs (short masts) and most new light boats have high aspect ratio rigs.

One aspect of stability is resistance to perturbations. You can do some very complex analysis or come up with a simple measure. A good measure is base divided by height.

Imagine a floor lamp. If it is short with a big base and your 8 year old son hits it, it is probably ok. If it is really tall with a small base, the same impact will push it over.

With boats the 8 year old, is wind gusts and puffs on the sails. Being pushed over is stuffing the bow or in the extreme, a pitchpole.

A quick dumb way is to compare length/mast height

If you get a little smarter, throw in the weight of the lamp base - boat length*boat weight/mast height. Because the buoyancy is proportional to the weight, this kinda takes care of the buoyancy near the bow. Really it is probably something like reserve buoyancy integrated over length , but that is way beyond this.

It is not really the length, the beam plays a part so lets use the diagonal ( square root of the length squared plus the width squared)

Also it is not really the mast height, it is the CF height. For a really triangular sail; like a H14, it is 1/3 the mast height and for a really straight roach A-class sail it will be close to 1/2 the mast height.

Take a stab at calculating Boat Diagonal*boat weight/CF length. bigger number imply better stability.

Keep in mind, this does not tell you how slow the boat is or how it behaves when it hits a limit. For example a barge is really stable but it would suck on a race course. The real key is balance and that is something to talk to the designer about

Steve, Wouter, Bob, Dave, and Carl:

Guys, some really excellent discussion from all parties and some really interesting points made. I really appreciate everyone's constructive tone even though there are differing opinions and these are complex issues. I ask these questions becuase I have an open mind and appreciate hearing both sides.

I really did like the discussion on the combination of factors including lower bow volume + fine entry + light weight + smaller rigs vs higher bow volume + heavier weight + larger rigs and the tradeoffs involved.

Although this all involves balance between rig power and total weight, heeling vs righting moments, and hull shape (volume distribution, fineness of bow entry, etc) and is less dependent on one variable overall such as weight, I still would think that it is possible that there is a sweet spot for weight, ie, a point of optimization, for a certain set of conditions.

One critical issue then is: what are the conditions one wants to optimize for? Light wind and flat water? Heavy wind and waves? A wide range of wind and waves?

I would think that A-cats are optimized for ligher air, F18's are optimized for heavier air; does it seem logical that there might be a sweet spot for boat weight (ie, some intermediate weight, maybe 250 lbs) which along with a properly powered rig and hull design is optimized for a BROAD range of winds and as a result would not only be faster ON AVERAGE over a wide range of conditions but would also be relatively easy to handle in the extremes?

Thanks again guys for the excellent discussion.

Jerry

You can fill a 500 page book with that !

The number of factors involved won't allow it to be fully discussed in just a few posts.

In danger of repeating myself I would like to repeat a newer version of the basic question

Why does a 122 kg M20 with 150 kg crew on board suffer from lack of momentum while a 135 kg Prindle 16 with 150 kg crew on board doesn't ? This is considered a lightweight baot the latter a normal weight boat. The momentum difference between both is less than 5 %.

(This included the new PRODUCTION version weight of the M20 which has been determine by Texel committee in 2003)

Indeed we can now expand the question to why this difference is felt, but that may involve many many pages filled with text.

Wouter

Wouter,

You ask some interesting questions but are your really comparing apples with oranges?

Before I get on with my reply, I would like to state that you (and so many others) know far more about boat theory than I do (or probably ever will) . So the following is an attempt to explain the scenario you discribed based on my current (limited) understanding and intuition. But this won't keep me from trying!

My argument:

These two boats are similar in weight and momentum but different in length, hull/bow shape, mast height, and sail shape/aspect ratio. M20 obviously is longer, has a taller mast, and a higher aspect raio square top sail. I'm not sure of their bow and hull shapes and volumes, but I suspect that the P16 plows/cuts through the waves whereas the M20 bow rises over them more prominently.

When a bow associated with a given mass hits a wave it is impeded to some degree. This impediment by a wave is associated with some amount of raising of the bow by the wave (more pronounced on planers than cutters but present in both). Fist, for the moment let's assume that the two boats in question raise their bows the same amount. Whatever the amount of bow rise, two ramifications would be: 1) loss of forward momentum due to energy needed to raise the bow (approximately the same on both boats due to similarity of mass), and 2) bow rise would be tranmistted to the rig - bow goes up, top of mast rocks BACKWARDS, and this backwards motion of the mast would be MAGNIFIED (proportionally) by a longer hull length (bow to mast base) and mast height. So even if we assume the bow rise of the two boats was identical then the backwards rocking of the M20 mast would be greater. Result: rising bow rocks mast backwards which stalls or detatches sail flow making it impossible to keep the boat powered up or trim the sail during this episode, and this effect is more pronounced on longer boats with taller rigs. Finally, since the M20 has a squarehead sail vs the P16's pinhead, even if the mast lengths were similar, the squareheaded M20 would be further disadvantaged because more of its sail area (proportionately) would be impacted by this effect. Since this effect keeps happing wave after wave, with each wave there is even less power in the sail than the wave before providing less power to drive through the next wave. This allows successive waves to raise the bows even more than they did initially when the boat was more powered up creating a vicious circle. So even a slight increase in masthead rocking in the M20 vs P16 would accumulate quickly due to rapid recurrence making a BIG diffference between the two boats ability to perform in these conditions.

I'm not familiar with the P16 vs M20 hull/bow shapes/volumes but I suspect that the M20 bows are more bouyant due to the greater size of that boat and for all I know it's more of a planer and the P16 more of a cutter. If these are true, than the M20 bows would actually rise slightly more than the P16 despite similar mass and the effects on backward rocking of the mast would be proprotionately magnified even further.

One more issue which would be interesting to understand in this regard is: I would imagine that higher aspect ratio sails (ie, shorter chord) could be more susceptible to stalling or detatched flow than lower aspect ratio sails under similar conditions. Just an instinct. If so, then this would be another factor influencing the different outcome. Anyone know the hydrodynamics of this and if higher aspect sails are more "critical" in this regard?

Jerry

Jerry, I hope you are not going to decide on a boat just based on theory and physics and hydrodynamics and momentum, etc. With boats, as with cars, our hearts often overcome our brains. e.g.: You may have every intention of buying an SUV, until you see a sports car and fall in love.

Hi Jerry,

Here`s a question you asked earlier :
"Who else has experience comparing light vs heavy cats in high wind conditions in cats with higher volume bows? What I'd really like to compare is something like Taipan 4.9/F16 to I17R in higher wind/wave conditions. Anyone sailed both?"

Correct me if I`m wrong, but this is probably the question that you really want answered. Don`t know the I-17R, but have seen it on the Inter web-site, nice boat. I don`t know it`s specs, I presume it`s a bit heavier than Taipan / F16, or you wouldn`t be asking.
This one is difficult to answer, different designs, different lengths, different rig heights & aspect ratio sailplans etc. Also, comparing it to Taipan is different to comparing it to other F16 designs, they are all different from eachother & will have different behaviour characteristics in different conditions. Best to test sail all boats you have your eye on, if at all possible.


Next question :
"One more issue which would be interesting to understand in this regard is: I would imagine that higher aspect ratio sails (ie, shorter chord) could be more susceptible to stalling or detatched flow than lower aspect ratio sails under similar conditions. Just an instinct. If so, then this would be another factor influencing the different outcome. Anyone know the hydrodynamics of this and if higher aspect sails are more "critical" in this regard?"

Don`t think we should be studying your sailplan under "hydrodynamics" unless you want to know how it behaves while submerged !
Aerodynamically you`re correct though . High aspect wings on aircraft with less chord are more efficient at producing lift than low aspect, but are more sensitive to angle of attack & are easier to stall (detach airflow). They also produce LESS lift than low aspect sails AT LOWER SPEEDS, however their higher efficiency compensates for this, so a low aspect sail will feel more powerful, but have the power closer to the boat, where you want it in high winds, while a high aspect sail will generate more lift higher up, making it better suited to lighter winds. That`s why it`s important to have your rig set up so that the top of the main twists off in strong wind, to depower the top of the rig & allow the lower half to produce the power, thereby staying upright.

Comparing Taipan to Mosquito is an interesting one, since the Taipan is essentially a Mosquito on steroids (check Taipan history). They both weigh much the same (M=100kg vs T=105kg), same length hulls. Taipan is 1ft(30cm) wider, more bouyancy in the hulls & a bit more rocker aft. The mast is 1,2m longer on the Taipan, and it carries 3,5sqm more sail area (before spinnakers). The extra width & higher bouyancy enable the Taipan to carry more sail higher up than the Mozzie, but because of the equal length, the Taipan has to back off a little earlier than the Mozzie in 20knots plus. From what I`ve heard the Australian Taipan class rules prohibit them from racing if the wind is above 22 knots, (I could be wrong, if so please correct me)while the Mozzie is very comfortable in a bit more than that(up to 28-30knots, we won`t start a race in more than that). It`s because we have less sail area lower down. Doesn`t help us in the light stuff, but you`re asking about high wind & waves.
If you`re sailing in high wind & waves a lot, I`d pick the longer boat, even if it`s a bit heavier. I do have a problem if it`s 50% heavier though, I think there`s a fine balance between all design elements which either make a boat a pleasure, or a pig.

Between the Mozzie sailplan & the Taipan, if anyone is interested. I`ve superimposed a drawing of the Mozzie over a drawing of the Taipan which I got from AHPC`s web-site. I scaled the Taipan so that the mast length is 8,5m as per their specs, and found that their hull length is a bit shorter than the 4,95m, but then it is a jpg which I`m scaling in Autocad, so not that accurate, but it gives the idea.
Both show rig without spinnakers.

Cheers
Steve

Hi Bob, you wrote this :

"Like your self, I would like to get the lowest reasonable weight. However after seeing the boat that won the Steeple Chase, I have to admit there is a lot more to the picture than just weight. The SC 20 that won is an absolute beast…something like 550 lbs? "

So I went to the race report, and found some interesting things :
Day 1 : light winds, shifty conditions etc, it`s not abnormal for one boat to extend a massive unassailable lead in these conditions, no discredit to Bill & Eric, but it can happen to anyone (except me. It NEVER bloody well happens to me !). They were also sailing the SC20 "Tall Rig", so I`m assuming that it`s not the standard version of the SC20. Now, all that extra weight they had from 20 years of repairing the boat. as you put it, was compensated for by the Tall Rig.
Day 2 : Conditions were more testing, "around 20 mph out of the south". Now the lighter I-20`s beat the SC20 by 25 minutes, granted they put in a capsize, but it shouldn`t take 25 minutes to right a beach cat (unless it`s really heavy with a tall rig ) so I`m guessing they couldn`t push as hard as the I-20`s before digging the bows in (see pic from the race report).
I have no doubt the Standard SC20 may have even been better suited to conditions on day 2, with a lower aspect rig (perhaps it would have not capsized ?). Now imagine you were to build a SC20 out of epoxy foam sandwich etc & make it as light as a Tornado !
C`mon Bill, just try one !

Cheers
Steve

Jerry,

What boat are you thinking about now?

Bob Curry

Hi Steve

I can appreciate you trying to make sense of some of this living on the other side of the Atlantic, and having only what is reported to go by…I would be at the same disadvantage trying to make sense out of something happing in your neck of the woods.

Here is the web site with the History of the SC/ARC products…http://www.aquarius-sail.com/ that may give you a bit more information on the design/construction and philosophy behind Bill Roberts’s designs, and Tom Habermans eye towards quality construction.

I had the pleasure of meeting Mr. Roberts for the first time this past weekend. He generously offered to show me the new ARC 17 he had at his home, and explained (and showed) to me the reasoning behind the set up on my 1994 SC 17.

I do not want to rehash the whole SC/ARC design debate again. But for the life of me I cannot understand why Bill Roberts and SC/ARC draws so much fire, and is plagued with so much inaccurate information. His designs are sound; they fundamentally solve problems encountered by all beach cats, with greater success (resisting pitch polling, more resisting to turtling, easier to right, the ability to carry greater usable sail area, and greater helm balance with spinnaker).

Lots of other companies make claims that their boat can do this, or their boat does that…Bill goes out on the race course and PROVES IT!… with on the water results….in real races…in real world conditions. Even with sever handy caps like sailing a 23-year-old boat that is 100 lbs over weight.

If you go by hypostasis based on false premises, you end up with a P-16 being a better design than a M-20… like in one of the posts above.

How come when Eric and Bill win the first day of the Steeple Chase “it’s a fluke” (winning by 42 min the first day against the I-20 that came in first the second day) But the second day when they are 25 min behind that particular I-20, it is because they were over canvassed, no mention that the SC 20 finished the race with only one rudder.

“Day 2 : Conditions were more testing, "around 20 mph out of the south". Now the lighter I-20`s beat the SC20 by 25 minutes, granted they put in a capsize, but it shouldn’t take 25 minutes to right a beach cat (unless it’s really heavy with a tall rig ) so I’m guessing they couldn’t push as hard as the I-20`s before digging the bows in (see pic from the race report).”

How hard can you push with a broken rudder? And look at how much of the field they still manage to beat even with one rudder! How well do you think an I-20 would have faired if they had lost one of their rudders?

As far as the picture goes, if you had ever had the opportunity to sail a SC product, you would know that the boat was designed to burry the bow with no ill effects…when most people see that picture they would assume the boat pitch polled immediately after the picture was taken…because they have experienced just that when this level of bow dive was encountered on any other hull design. However, any SC/ARC owner would tell you it is just indicating the boat is being pushed hard down wind because it can dive the bows all day long with impunity.

Or how about the ARC 17, It won the Trade winds regatta…a new, US built board less beach cat wins the open division and hardly a mention of it any where…If it would have been a Hobie or Performance Catamaran, or AHPC product we would have been seeing it and reading about it everywhere.

All these little assumptions and miss-statements just add to the cloud that obscures the high quality and superior design aspects of the SC/ARC line up. Most… if not all the criticism I have read has been by people who A) Never owned a SC/ARC product, B) Saw one once, being sailed (or attempted to be sailed) by someone without a clue of how to sail C) Never actually sailed, or saw one, but heard that….

All this anti SC/ARC rhetoric is “one” of the factors that has kept the numbers of SC/ARC products on the market small…

“Now imagine you were to build a SC20 out of epoxy foam sandwich etc & make it as light as a Tornado!”

Steve, I bet Bill and Tom would love to…if they had assurances that someone would buy it…people throw numbers around here for raw materials such as Carbon fiber…but they must have no business knowledge, they don’t factor in the time it takes to make a “perfect plug”, the molds themselves, the maintenance of the molds, the cost of the property and buildings the boats are made in, the completed operations insurance, the light and water bill, tools, safety equipment, fees of disposing of hazardous waste, workers compensation insurance ( probably about $40 per hundred of wages paid), a living wage to their employees, office staff, office supplies, web site, customer service…and a thousand other things…so yes if you are a back yard builder this doesn’t affect you, but a boat building business in the US drowns in government regulations, fees and mandatory insurance.

ARC 21 @21’-6” weighs 400 lb, 33’ mast, 282 sq/ft main/jib, 346 sq/ft spinnaker.
I-20 @20’-0” weighs 390 lb, 32’ mast, 246 sq/ft main/jib, 270 sq/ft spinnaker.
The ARC 21 is 1’-6” longer, a foot taller mast, 36 sq/ft more in Main/Jib, 76 sq/ft larger spinnaker…yet is only 10 lbs (doubt if the sails are included in either boats weight) more than your “lighter” I-20. Plus the ARC is Epoxy/foam sandwich, and the I-20 uses Vinyl ester resin/foam sandwich (not as strong).

You will find that the ARC product line is already made out of epoxy/foam sandwich…as far as the Autoclave manufacturing method ( like the Tornado), Bill has already addressed that issue…very few cat sailors are ready to fork out the kind of money for a boat built from that technology…it is not like you see a Marstrom Tornado in everyone’s back yard.

How does this all relate to the original post? It’s all about the total design, and the way each aspect of the design interplay…it is not just about the weight…a poor design in carbon fiber autoclave construction, would still be a poor design.

I hope you take this the right way Steve…I am just trying to give you the other side of the story…the more correct information we have to go on, the better. It seems there are few if any SC/ARC products in your area on which to base a “hands on” opinion. Sorry if this post come accross as defensive...obviously I am very passionate about SC...If you get a chance to sail one you will understand why.
Regards
Bob

Bill told me that they capsized because they hit one of the many mud banks, and that is also what broke the rudder. It took them about 10 minutes to right the boat and get it off the mud bank and back into deep water.