Windward performance?

[Stephen Ditmore]

The Singlehanded Transatlantic Race is often a windward race in large measure, and it's been dominated by trimarans.

Where monohulls are concerned I don't think narrow and light is necessarily the right answer for windward performance. All that length will just mean extra whetted surface if you don't have the stability to make use of it. The right answer will depend on many things. What size boat are we talking about? How much hiking / crew weight on the rail? Are wings, hiking racks, trapezes, windward side water ballast, or other forms of movable weight permitted? How much wind will it be sailing in? I think all these things will effect the optimum.

Pointing ability is pretty much a matter of the lift/drag ratio of everything above the waterline and the lift/drag ratio of everything below the waterline. Speed will be a function of sail area at low wind speeds, and of stability (and length if stability is sufficient) at higher ones.

Development sometimes moves from small boats to large. If you took the Mistral hull shape from the Classic Moth class and scaled it according to:
- length & fairbody draft by scale factor x
- beam by scale factor x^(2/3)
I think you'd be in good shape. The Mistral combines a lot of rocker with a V shaped midsection. Plans are available for $20 from George Albaugh at www.mothboat.com

[dionysis]

Original question was for a fin with bulb, but you are right: a cat would do the trick.

[dionysis]

Stephen,

I keep thinking of all those waves: skinny boats perform better in waves, and their relative lack of windage is a real factor to windward. I agree heavy is better than light in heavy weather, but it is a matter of degree.

[Stephen Ditmore]

If a lot of weight on the windward rail is not an option and a deep bulb keel is an option, then I agree that a narrow, moderately light (but not extreme) boat would probably be best. The America's Cup boats are quite good to windward, but would be better if they could be made slightly longer, all other things remaining same.

Adrien is a boat designed to go to windward.
www.vdh.fr/gb/le_bateau/caracteristique.htm

On flat water, where crew weight can be moved to windward, scows, for instance, are fast.

The Mistral Moth is interesting in that it's narrow on the waterline but wide on deck. In a way it's like the giant New Zealand boat in the 1988 America's Cup, but built to conform to the Classic Moth rule which does not allow wings jutting from the hull. It has a sweet shape, and goes to weather very nicely. It's also easy to build from sheet material.

[SailDesign]

Quote:
"Therefore, it is pointless to continue on this topic."

Won't disagree on that. Just sad that anyone's personal experience should be "unbelievable" to someone else. I was there, and I know what the log read and what the boat was doing.
Do you find "MariCha's" 500 miles per day unbelievable, too?

[Paul B]

It appears the Hard Feelings you referred to are just your projected feelings.

I don't see anything sad about questioning things that don't make sense in the physical world. I have educated friends, mostly engineers, in Hong Kong and they tell me about their encounters with ghosts (a cultural thing). I choose not to believe them.

I also question claims about UFOs, regardless of the CV of the person telling the tale.

I do believe the accomplishments of MCIV. To my knowledge they did not claim to plane upwind at a 28 degree AWA in 20 knots of breeze into a 4 foot swell. In fact, I predicted their performance:

http://www.sailingworld.com/forums/r....pl?read=17123

[shu]

Regarding Steve's experience planing to windward.
1. My original statement was to the effect that without alot of people on trapezes, a fixed keel boat could not plane to windward. Modern open 60's have either water ballast with wide beam or canting keels, both of which have a similar effect to putting crew on the wire. It was my understanding of the question that started this thread that we were dealing with a conventional fixed keel boat; and given a particular keel, how would you design a boat around it that was as fast as possible to windward.

2. I do not doubt that an open 60 could plane at 50 degrees TWA. At 20 degrees heel the boat would likely have a fairly narrow waterline with one high aspect assymetrical daggerboard and one rudder in the water, both nearly veritical. This would give excellent lift/drag ratios and the overall effect would be similar to a cat lifting a hull. The righting moment from the water ballast or canting keel would be huge. To be truly "planing to windward", I think you would have to show that you were indeed planing in the direction that gave you the highest VMG to windward. I have heard that Open 60's point notoriously low, so it sounds as if you were doing it.

[SailDesign]

Shu,
We are talking about a sub-20,000lb 60, with 7500 lbs of water ballast, and a 95' stick, using non-overlapping headsails that can be sheeted inside the shrouds (hence can point far better than those that can only sheet to the shrouds. Draft was 14 feet, and twin ruddered.
However, this sub-thread was really born of someone stating baldly that wide, light boats can't plane to windward. They can, but there are those who refuse to believe it. 'Nuff said.
Let's instead get back to the original question - what kind of hull to stick on that keel found on the beach. ;-)
Steve