New single hander from San Francisco

Use this forum to discuss the latest changes in the class
Karl Wittnebel
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Post by Karl Wittnebel » Fri Dec 23, 2005 8:46 pm

If anyone can sail a narrow Moth, I'd say any sort of shape you'd care to put under an IC at 75cm beam would be sailable by someone. Certainly it is a bit of a challenge tacking when the aft hull shape is veed, as it just wants to tip over instantly before you can get the seat over. But I've often thought that making the boat look as much like a cat hull as possible is probably a good idea - regardless of whether it is optimal for planing. In reality it seems you want to go through the water as much as over its surface, as long as the pointy end stays up in the corners. Where prismatic plays into this I've no idea, but here again the cats may be showing the way with lots of rounded volume down low up front.

Fore/aft balance is important in the current boats, and quite important in cats from what I've heard. I do not think any amount of t-foil will change that, though others much more experienced than I in these matters would beg to differ.
Karl Wittnebel
NC USA 193 (Lust Puppet)

Karl Wittnebel
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Post by Karl Wittnebel » Fri Dec 23, 2005 8:49 pm

Paul -

Can you post an image or two of the shapes you're running numbers on, just to give the rest of us an idea?

Thanks,
Karl
Karl Wittnebel
NC USA 193 (Lust Puppet)

Andy P
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Post by Andy P » Fri Dec 23, 2005 9:46 pm

At moth beam ( 300mm) there is no stability issue with round or square sections - there is effectively no stability with either.
I have found that ( for moths ) the theoretical advantage of less wetted surface of the circular arc sections, is balanced by the better volume for immersed depth, and planing lift of the squarer hull sections.
Hence the compromise of roundy sections fwd, and flatter squarer aft, this also keeps flat areas by the mast and aft for planing lift.

The new IC will be at the crossover between planing and high speed displacement ( cat or moth ), and maybe testing will show which side of the divide is the way to go.

My latest design revision shows prismatic of 0.55, and wetted area of 2.77 sq m. ( moth is only 1.5 sq m !)

The stealth 16 foot cat uses T-foils, and this makes it easier to sail downwind in a blow. - so IC may benefit from T-foil, especially if the seat is in a fixed position.
The canoe stern ( ie pintail double ender ) should mean only a low drag penalty for having an immersed 'transom'.

Steve Clark
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Post by Steve Clark » Fri Dec 23, 2005 11:24 pm

I usually don't get too fanatic about all the calcs and ratios because beyond what I already spout of to give a general idea of what kind of boat this is going to be, I'm not sure what the really mean. There is so much happening dynamically that running static calcs except to give yourself some guidance about how you are changing the shape is really pretty useless.
That being said, the thing in the shop, Currently named "Wonk" has a design displacement of 147 kg, A prismatic of .57 and wetted surface of 2.85 m^2. All looks about like I think it should except back aft where the PVC pipe has proven smarter than I am and has redesigned a foot of the boat a foot from the stern.
So nice to be able to change your mind!
SHC
Beatings will continue until morale improves

Johan Backsin
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Post by Johan Backsin » Tue Dec 27, 2005 2:11 pm

We should pay close attention to how difficult the new IC will be to sail. Most current IC sailors would agree to that we do not want a (noticeable) more difficult boat to sail, even if the IC is less difficult to sail than its perception. If Anders P who has top boat handling skills in the fleet is concerned it probably means something.

I have myself an interesting experience. My previous IC US-186 was a very easy boat to sail. Built out of the “west coast” mold and with a soft dacron mainsail it was very enjoyable to sail on the SF Bay. Tacking was no more challenging than gybing even 20 knots wind in SF chop. Very enjoyabe boat and a regret i sold it.

My current US-214 built on the NOGO-55 hull with a much rounder section mid/aft is a totally different beast. To get competitive in 6-12 knots wind and heavy helm (96Kg), I built a very powerful rig. Especially the kevlar mainsail was full with a powerful leach. I think the west coast sailors can attest that it fulfilled the objective making it fast in medium air despite its heavy helm but to a price. For me, it was impossible to tack in 20 knots, and very challenging above 12 knots. I simply couldn’t sail it.

Bottom-line.

1, We should closely evaluate how much more difficult the new IC is to sail --- Read tack in heavy air. The Moth is not a desired reference point.
2, The small 10.6sqm sail area – If rigging it to be competitive in light/medium air for a heavy helm it also becomes very or difficult (or impossible) to sail in heavy air.

Johan

Paul Scott
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Post by Paul Scott » Tue Dec 27, 2005 4:03 pm

Karl-

Be glad to, as soon as I get my office put back together- prob 1st week of Jan.

Paul
"Exuberance is better than good taste" -Flaubert

Bob Lewis
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Post by Bob Lewis » Wed Jan 11, 2006 7:03 am

<font face="Arial">Just thought I'd drop in to say that I completely agree with Anders and Johan. I had exactly the same experience with the NOGO hull shape. It is not fun to sail in any challenging conditions, where great joy could be had with the standard nethercott shape. This may have more to do with cross section shape than width, I don't know. It does point out though, that for probably many, the standard nethercott shape is the limit of instability. The rules should force a hull shape that is fun for Joe Average Canoe Sailor. If the rules allow a fastest shape that only a funded Rohan Veal can enjoy, then I don't think it will be good for class growth.

Bob Lewis</font id="Arial">
Bob Lewis
Vancouver

Karl Wittnebel
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Post by Karl Wittnebel » Thu Jan 12, 2006 12:02 pm

Would agree NoGo hull shape is more tender than a standard Nethercott. Would not agree that standard Nethercott is the tenderness standard by which all canoes should be judged.

I spent my fair share of time swimming at Worlds in Bill's NoGo. But most non-IC sailors would say that ALL canoes are too skinny to sail in breeze. With some thought I got the NoGo to tack. Bill seems to make it go OK in heavy air, as does George Saunders, who I dare say is even bigger than Johan. Eric Chase has one, and so does Del. Do they think the boat is impossible to sail, or even unreasonably difficult? I have not heard them complain. Ditto for Ted Van Dusen. So it is clearly not an impossible boat to sail in 20 kts. I would say Lust Puppet is more difficult to tack, and I enjoy sailing that boat. Tender boats just put a premium on boathandling and systems that work 100% of the time.

Bill's multichine boat, built by John Williamson, is as narrow as Lust Puppet, but easier to sail. That was the intent of the design, and it succeeded. I would not say it is any more difficult to tack than a NoGo. I enjoyed sailing it in about 15kts despite the fact that the seat carriage and rigging is suboptimal. With a decent setup the boat would be a complete gas. So skinny boats are not necessarily more difficult to sail.

If things get skinnier it will probably be important to keep the waterplane close to max beam in the after sections of the boat, in order to provide some stability for the corners. A v-bottom may be faster in light air and in a straight line, thanks to lower wetted surface, but that comes at a price in stability.

Anyway talk about development has convinced some people to build ICs, which is more than can be said for the past several years. This in itself is a sign of health.
Karl Wittnebel
NC USA 193 (Lust Puppet)

Paul Scott
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Post by Paul Scott » Fri Jan 13, 2006 3:39 am

For what it's worth, when I was sailing really round Div. II boards, I never depended on the hull for stability, but on the centerboard, whether I was moving or not. You guys may already do that(?). Speedboards were 14" wide, and stability wasn't that much of an issue. Foot straps helped I suppose.

But it appears to me that getting the seat across seems to be one of the main difficulties with the rounder hulls? It occurs that some help with moving the seat might work using, say, bungie cords? Rather than muscle? I tried it with my decrepit IC, many decades ago, although it (the IC) disintegrated before I could figure out a way to retension on the new side. I suppose the stress from the bungie cords didn't help. Did get the seat to go one way fast, though. At least enough travel to get the seat centered, so I could stay sitting down/skidding on the ride to the center. Lots of Ivory Soap for lubrication made for some nervousness when the seat was all the way out. And I had to keep the whole thing heeeled to weather to ride the seat down. The idea was to have a flange 3 feet out on the seat so that when I was on the new tack I could push against it with my butt to chicken hiking status, and then figure out how to get the rest of the way out. Kind of an automated seat. Seemed like I did not have enough hands/wits/time/stretch/smarts to get things retensioned while under way so the seat would be ready to go the other way. That and the bicycle brake handles I was using as triggers kept slipping and rusting, and the seat wouldn't stay in one place with all the soap on it, and I had to jump up and down on the end of the seat to get it unloaded enought to start the slide. It was a quest for faster boat handling in tacks/gibes.

Funny, the bicycle brake handles worked OK as (2 position) preset outhaul adjustments on my windsurfer boom- squeeze for flat sail upwind, let go for fuller sail downwind. Kind of hard on forearm muscles. But that was before I used them on the seat assembly.

Paul
"Exuberance is better than good taste" -Flaubert

andersp
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Post by andersp » Sat Jan 14, 2006 8:58 am

Sorry Karl, but you are wrong about Erich's and Del's opionions about the NoGo hull. They both say it is significantly harder to tack in a blow. Not that they sail them much anymore, but that is another story. The Swedish "slurp" had a reputation of being a very tippy boat, but I am not sure if it was the boat or the sailors that were tippy. Could have been the heavy aluminum mast too.

Anders
Anders Petersson
IC SWE-105

jimc
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Post by jimc » Sat Jan 14, 2006 9:26 am

Don't underestimate the importance of the mast/setup etc. I did my "try a Canoe" in Colin's very sorted boat. My own cheap secondhand one, with tin mast and wood seat and seat carriage, is a *lot* more difficult to sail. I bet that modern sorted Canoes are a great deal easier to sail than Nethercotts were when the design came out. Anyway, must go and finish making this plastic mast...

Andy P
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Post by Andy P » Sat Jan 14, 2006 11:35 am

I know some people think that moth sailing comparisons are not relevant , but I think that the moth rig developments over the last 20 years are relevant. so here goes anyway!

The first narrow boats could handle more sail power, so there was a trend to big head mains, and fuller sails, and using metal masts.
More power in light - medium winds, but very hard to tack in strong winds.- The only way to tack would be to let the kicker right off to get through the wind, and get started on the other tack, then kicker on again.
The sails got flatter, with more open leeches, but with even bigger head shapes.
The sails set with more twist ( or maybe more open leech), but were actually faster and just as powered up as the old full sails, and with carbon masts and lighter sails ( more stable material, fewer battens) were (are) easier to use.
Tacking is now just a bit difficult in very strong winds.

Later developments see the introduction of sleeve luffs and camber inducers - these now universal type sails hold their shape much better in strong winds, keeping fullness and drive forward, and making tacking easier in strong winds.

see this pic for a hooked up lower leech on IC.

Image

Andy P
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Post by Andy P » Sat Jan 14, 2006 11:38 am

Image

maybe this works

( can you edit posts so you can correct mistakes like this? )

RLM
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Post by RLM » Sun Jan 15, 2006 4:00 am

Back in the late 1980's, when Bill Beaver and I were looking at the Slurp modification that eventually Bill built as Lust Puppet, Bill the Naval Architect ran some stability analysis. Suprisingly, the waterplane area of the Nethercott and Lust Puppet looked about the same at about 15 degrees heel. We concluded that there shouldn't be too much of stability difference between the two hulls. We were wrong. In fact when we first got Lust Puppet in the water, both of us wondered if Bill had built something that was unsailable. Some changes to the rigging and the blades, some more time in the boat and eventually I could get Lust Puppet around the course to good effect, winning the US Nationals sometime in the 1990's (91? 92?). Still it has always been a hull more suited to the light air and slop of the Chesapeake Bay. When Bill and I took our learnings from Lust Puppet and applied it to a tweaked Nethercott (NoGo55) we narrowed the aft sections as much as possible. When going from Lust Puppet to the NoGo55 hull (as I have done and now Karl Witnabel has done, Karl owning Lust Puppet and sailing Bill's NoGo55 in the Worlds) hull stability become relatively better not worse. However if you go from a fat ass Nethercott to a NoGo55, I can see there is a problem. But realize, my perspective is as a Chesapeake sailor. I have only sailed in San Francisco in the 93 Worlds. I finished about half the races. I have the greatest respect for the SF IC sailors and the conditions they sail in and it is my opinion that Lust Puppet would need an exceptional helm to survive in SF. If the SF sailors say the NoGo55 is a harder boat to sail in a breeze, I bow to their opinion. I have always found it one of the greatest stengths of the IC that I could have just as much fun in 3-12 kts on the Chesapeake as the SF crowd could have in 15-22 kts off the Berkeley Circle. I hope the class never loses that.

Rod Mincher

P.S The Lust Puppet project was initially undertaken to see if we could develop an easy build IC that would attract new sailors that did not have access to a mold. After sailing Lust Puppet we rapidly concluded this was not a hull for new IC sailors.

Karl Wittnebel
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Post by Karl Wittnebel » Mon Jan 16, 2006 11:36 am

Well, this may be semantics, but the distinction is important. To my knowledge no one prior to Johan and Bob had claimed the NoGo was almost impossible to tack in 20kts. I have never heard Erich or Dell or Ted say that about their boats (granted I do not see Del or Erich very often). I do think the NoGo is more difficult to tack than other Nethercotts, as I wrote above, but not at all impossible. I know that it feels like an aircraft carrier next to Lust Puppet, which may in fact be impossible to tack in 20 kts and chop; I am still negotiating a lot with LP in any sort of breeze. That's why I highlighted the virtues of the multichine boat above - might be a good compromise between the hull shapes.
Karl Wittnebel
NC USA 193 (Lust Puppet)

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