What would you do with 40 sqm/430 sq' of sail?

Have you ever wondered what the fastest rig and hull would be if there
was a limit on sail area, but everything else was open? cat, tri, foiler,
planing mono, canting keel, sloop, cat rig, kite, etc, etc. As far as I know
there has never been a class with the only rule being sail area, apart from the very specialized Speed Week boats.

I would like to propose one.

Sail area, (including spars) is 40 sqm/430 sq'. Everything else is open.
The sail area is low to keep costs down and encourage efficiency
and innovation.

The purpose of the rule is to find the fastest, most efficient boat and
rig type with this sail area both around the buoys and offshore.

I would like to propose 2 courses, although there is no reason why there
could not be others before or after, or at different locations.

First course: A race 3 times around an approx one mile diameter circle on
San Francisco Bay using government buoys and a gate or rabbit start. This
format requires no yacht clubs, committees or outside assistance. Although a yacht club or similar for pre and post race discussions would be welcomed. There could also be more than one race to vary the weather conditions and increase the fun.

The race will be organised by email. Everyone on the mailing list will be
told the buoys, what the rabbit boat looks like and where and when it will
be starting. Email your finishing times and excuses at the end of the
day.

No entry fee, no prize, no protests, no measurement or handicap nonsense.
Just a bunch of boat owners sailing round the bay as fast as they can and
talking about it afterwards.

Of course, if a sponsor or yacht club wants to come along and
organise/complicate it, so much the better.

Race day is a fortnight before the solo Transpac in June 2008.

Second Course: The solo Transpac 2008. Boats will need to comply with
the SSS NOR and Sailing Instructions.
http://www.sfbaysss.org/TransPac/transpac2006/index.html

Two such totally different race formats would be a great test of what is
fast and what is not in a variety of conditions. Boats could be optimised
for and enter either, and this is to be encouraged as the more data
points, the more we find out. However, for most people, the real interest will be in the boat that can do both well.

Please feel free to discuss what sort of craft you would design, but more importantly, start building it to see if you are correct.

regards,

Rob Denney

 

Cool concept!

Rob, so, what craft are you bringing to the start line? Just need to know what we'll be up against before puttin the $ where our mouths are & trash talkin' our undoubted speed potential on the course & developing a great range of post race xcuses for not bringing home the glory, I reckon you've gotta have a TROPHY & propose that some piece of bashed up boat be burnt & put in a jar (Vegemite) so the victorious can hold it aloft after shooting champers all over the other competitors from the podium.Seriously though its a nice pure concept that could have all manner of craft competing especially on the inshore course. Regards from Jeff.

 

430

Rob, I think it would be exciting to consider the design of a boat with the only limitation being 430 sq.ft. of sail. That's right in the range of many sportboats around 24'.
But SA is not the only restriction in your proposal: you've introduced the requirement, if I'm reading it right, that the boat has to be solo sailed; is that right?
It could get real interesting if the limit was really just 430sq.ft. SA and ,in my opinion, might produce boats with wider appeal.
I couldn't possibly afford to build one in either case but it sure is interesting to contemplate...

 

My solution...

To me... small boat + big sail = lost of speed. Basical like early race cars... most powerful engine, and a small light car and make it pointy on both ends.

So I would use the full sail area.. as little boat as possible, make it thin and long... and a long heavy keel to keep it up right.

 

There's been planty of such classes in the past. The 30 Square metre for one... http://www.30sk.com/fotos/index.html Long thin and light with tall rigs would be the way to go. Of course for ultimate speed a catamaran would be quicker.

 

G'day,

Jeff,
Would love the opportunity and excuse to burn dsome of the bits out the back, but there is no need for a trophy, this is just for fun and interests sake. Glad you like the idea.
My boat will be a 15m/50' proa which should weigh 500 kgs/half a ton on the start line, considerably less for the round the buoys stuff. Cost about $AUS18,000/$US13,000 and be very simple to build. Windward hull is nearly complete, weighs 27 kgs with the bunk and a shelf to add. Waiting for some carbon to finish the rest of the boat.

Doug,
The sail area is the only rule for the boat. Each course will add it's own constraints, whether it be crew sizes, bouys to round or whatever. The round the buoys race is for as many crew as you want.

Personally, I think the more the merrier. If boats with slightly more or less sail want to race, they are welcome. Equally, if someone wants to "race" in company with the solo Transpac in a crewed boat, they are welcome. There is also nothing to stop other courses and formats being used. I chose these two formats to start with as they are as different as they could possibly be, so will give more data points about which is the fastest set up. And because I am doing the solo transpac so will be in SF at the time.

gggGuest
The sqm rules were an attempt to do this, but it failed to do so. http://www.sitecenter.dk/hbh/brugerdefinerethtml/ Didn't fail as a class, they are hugely popular and lovely boats to sail. They were also restricted to monohulls, I am more interested in ultimate performance, which includes monos, cats, tris, foilers, different rig configurations etc.

regards,

Rob

 

Didn't the square metre boats, like the Suicides, Frei Renjollen and (I think) D CLass cats also suffer from the fact that unrestricted length classes tend to hit an area of diminishing returns?

As far as I can see, the best boat for a fixed sail area tends to be very, very long - which means you can often end up with a boat with a massive hull and a comparatively tiny rig. It will beat the boats in its sail-area class, but it can be slow for its length, bulk and expense. That is, after all, why the classes listed above all ended up putting dimensional limits. The 22 square metres ended up at something like 42 feet long, and as far as I can find out while they look beautiful they are pretty damn slow for a 42 foot long racing machine, or any boat of their price. That's why the 22s and (I think) 30s ended up with restrictions, and in fact ended up with two classes; a long expensive boat and a shorter, cheaper but only slightly slower boat.

This is not meant to be throwing cold water on a very interesting idea, it's just that there have been problems when this has been tried before.

I'd love to see what comes out of the concept, Rob. Sounds like a VERY interesting boat.

 

G'day,

Answering these questions is the reason for the rule. My take on it at present is:

Those are all long keeled boats where the point of diminishing returns occurs relatively early. It has not been tried on fast boats, apart from speed week designs, which are pretty specialized. We have huge experience with what works on boats which are overcanvassed for their length. We have no idea of where the limits are for fixed sail area boats. We cannot even agree on what hull type would be fastest, much less how long it should be.

A fixed sail area boat will be slow for it's length compared to the same length boat with unrestricted sail, but why should length be more important (apart from marina fees) than sail area or weight? The long boat will have a nicer motion, be more seaworthy and easier to sail, all else being equal. It will also be much cheaper.

A long hull does not need to be massive. There are structural arguments (related to shell buckling) for smaller cross section hulls and if we get away from the need to have high bows to keep the foredeck dry, then a long hull can have a very low bow. This is more pertinent to multis, but also applies to monos.

Chris, I don't suppose you find it interesting enough to sell some of your fleet and have a go? Base it on your knowledge of boat history and what has worked and what has not and it would be a fascinating boat.
-
regards,

Rob

 

430

Sure would be interesting to see what a two person bi-foil mono or multifoiler would do...
It's completely feasible to do such a boat using this sail area between 22-24' with upwind foiling capability in a wide range of conditions.Hmmmm...

 

CT249 - Rating a boat's speed as a function of its length is only one way to skin the cat. If two boats , A and B, are the same speed and boat A is 10m long with 20sqm of sail, and boat B is 5m long with 30sqm of sail, I would consider boat B to be slow for its sail area, not boat A to be slow for its length.

Anyway, for the race round the cans, I think I'd go for a supersized C class cat.

 

Hi All:

I would add another stipulation: A cost limit of 10,000 Euros per square meter.

BTW, does this sail area limit apply to 'all sail set' or merely to 'all working sail'.
Extra points should be awarded for creative cheating.

I would expect a fair fight between multihulls and canting keelers. I understand that San Francisco bay can get quite rough at times and I don't know how well foilers like rough weather.

Has a foiler ever crossed an ocean?

Bob

 

Up to about the 1930's, '40's, or maybe even '50's, I would agree. But since then we have gotten down wind planing, light fast multihulls, canting keel monos (that , I understand, can plane upwind), and now foilers. None of which really long length is going to help that much.

I would almost expect a trend toward the other end of the length spectrum (20 to 30 footers).

Bob

 

Length seems to be paying mightily with the big round the world catamarans which are the fastest distance boats on the planet. And even on the speed 500m it did awfully well with the likes of Crossbow up to the 70s.

If you add to the rules that a boat must finish both events to qualify then I'd be very suprised if a long light catamaran wasn't the winning craft.

 

Rob, I'm afraid selling the full fleet wouldn't pay for the mast!

I have to admit that I regard development design as a fascinating spectator sport these days. In some very small ways I've done one recent "design conception" (putting a small rig on the WIndsurfer One Design to make a junior class) and while it was hardly original or complex, it means I'm now busy running a class and training sessions! It's also been interesting to see how a big "hull" and small rig copes. Even in boards the same rules often seem to apply; big hulls with little rigs make for plenty of speed proportionate to rig size.

I do reckon your idea could be a great class, and probably way better than just limiting LOA which is a pretty ancient idea.

PI, I fully agree that speed-for-length is only one way to measure a boat's performance, and that short boats with big rigs as often pretty innefficient in many ways.

All I was saying is that historically, classes with only sail area restrictions have tended to end up creating boats that were quite slow for their length and cost, compared to more moderate boats.

What's the best boat?

Boat A at 10m and 20sq m?
Boat B at 5m and 30sq m?
Boat C, at 7 m and 25 sq m? (Perhaps cheaper AND faster than A or B)
Boat D, 20m long and 20 sq m? Perhaps it would beat Boat A and win the 20 sq m class, but be so large and overcanvassed for its length that it would be dull to sail and expensive to own.
Boat E at 5m and 50sq m? It would beat boat B but cost waaaay more and be harder to sail.

I ran some figures once that indicated (from memory) that on a straight proportion of speed-for-sail basis, the most efficient (non foiling) dinghy of them all was the Laser 4.7. The standard Laser, on that basis, is arguably more efficient than the non-foiling Moth, I think. I bet a Laser 4.7 is faster on a speed-for-sail basis than a foiler Moth in many conditions and possibly overall; but which is more exciting? If you were to design a new boat to achieve maximum speed-for-sail, would you end up with something with a giant hull for its rig which may not be cheap or really exciting?

So I'm basically just wondering - does the totally unrestricted route (whether it's sail area or LOA) end up with the fastest possible design for those specifications, but at the cost of ending up in the area of diminishing returns? I'm not saying Rob's boat will end up being a boring or expensive boat, merely wondering about where the class could end up. We often see the faults in the boats we have, and then look at possible alternatives with rose-coloured glasses.

I don't mean to be attacking Rob's concept (which is a good one) merely to be trying to foresee problems that could perhaps be avoided. Since every rule or class gets pushed in unexpected areas, wouldn't it be a good idea to seek possible flaws and weaknesses so that they could be plugged as soon as possible?

Sharpii, maybe length is still vital these days, depending on what conditions and fleet you sail in. The 18 Foot Skiff designers reckon an 18 "should" be about 22 feet long, and the optimum length would only get longer as technology (read expense) increases. The foiler Moths use stern gantries to maximise effective LOA to spread their footprint. Nigel Irens reckons the 60' tris are too short for their rigs.

Even in windsurfers, the Formula boards (about 8kg, 12.5sq m of sail, about 7' long) are often much slower than the old IMCO Raceboards (16kg, 7.4 sq m of sail, 12'6" long) or even an original Windsurfer. On a speed-for-sail basis, a 5m rig on one of the old 15' "Dart" U-bottom displacement windsurfers would normally probably win; but with no restrictions it would be an incredibly expensive board and rig and very difficult to sail in any conditions.

Please note again, this is not meant to be attacking the proposed class. Any class has some areas where it's less than perfect; the one I launched a while ago has many and varied flaws, but it still seems to be working.

 

430

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Bob, Williwaw did a lot of ocean cruising but I don't have time right now to research it further; more info may be on Tom Speer's site.
DAK HYDROFOILS - Williwaw
Address:http://wingo.com/dakh/williwaw.html Changed:6:10 PM on Sunday, May 8, 2005
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I'm convinced that a well designed "sportboat" foiler would win this contest hands down at least in inshore racing. Because of the SA the foiler would have to be fairly small which would probably impinge on it's ability in a transpac type race.
But a canting keel foiler could be built-not too much larger- to do the job in a configuration that would make the boat rightable in the event of a capsize or pitchpole...
Under Robs' rules I think his boat is the most likely to succeed in a transpac type event.