3R hull

I’m thinking of building a 3R type hull. I like the classic looking overhanging bow and stern. The other people I sail with sail Mistrals and I would like to stay competetive with them. I would also like to use my US1M rig if possible. Could anyone give me an idea of what waterline length I should use? I first thought that a one meter LWL would be obvious but then I started wondering about the overhang advantage(if there is one). Maybe there is someone that actually sails with ODOM’s or US!M that could give me a clue?


Glad to hear you?re interested in the 3R class. With respect to the USOM rig, you are going to have to have a really short lwl to use it, because of how much sail area a usom carries. If we assume your usom rig has 750 square inches of sail area, you would only be allowed a maximum lwl or 28 inches under the class rules (no free roach area); this is to short in my opinion. I would personally recommend something in the 30 to 38 inch range?. The formula to calculate lwl based on sail area is 3*7000/SA=LWL.

What are the wind and wave conditions like in the area you sail? A short lwl may be possible if you don?t have big waves.

Here are two shots of my 3Rshowing the overhand affect in action. She has a 35 inch lwl and 45 inch loa. I couldn?t find any good shots, but I have had her using all of her length on more than one occasion. My next one will have a narrower bow to take better advantage of the overhangs.

As there is only three boats in my area I am not too concerned about following the rules for 3R. What I am interested in at the moment is building a hull with overhangs that can possibly use my US1M rig and be competetive with a Mistral. There would be no joy in building a boat that was not competetive with the other boats in the area. Winning all the time is almost as bad as losing all the time. Note that I said almost. I can always build a proper 3R rig if the opportunity arises. How would your 3R do in a race with a Mistral? Where do I find more info on 3R’s? I looked at the AMYA site and couldn’t find anything. What is the formula? Where we sail is flat water with winds rarely exceding US1M “a” rig. I know I’m not really trying to build a 3R, I just thought that you would be the people that would know the effect of overhangs and how to juggle waterline lengths to arrive at a given speed. Maybe I’m asking the immprobable. Might I find that the two boats would only go the same speed in one set of conditions? suppose I might just build a 3R for fun sailing. Any ideas or advice would be appreciated.


I currently sail by myself, because the nearest club is about 3 hours away, but I plan on trying to start a club in the spring. Thus I can only speak from the theoretical. Consider a power to weight ratio. My boat is 5.5 lbs and has 600 sq. inches of sail.

600/5.5 =109 sq. inches of sail per lb.

No lets consider a 7 lb. Mistral with 750 sq. inches of sail area.

750/7=107 sq. inches of sail per lb.

Thus a 3R would theoretically have a better power to weight ratio. I personally feel that a properly designed 3R will be competitive against a Mistral.

Here is my page about the class http://www.shermanyachts.com/informational/3r_class/

The class forum can be found here http://www.ayerpuzzles.com/cgi-bin/yabb/YaBB.cgi

We have articles coming out in the next two issues of MY. MY boat is on the cover of the next issue.

The formula is 3>=LWL*SA/7000

Since the water at your lake is flat, then you ?should? be able to get away with a short lwl and long overhangs, thus allowing you have more sail area under the 3R rule. The problem with overhangs in big waves is hobby horsing.

I would personally recommend a 32? lwl and 40-45? loa, and 5 to 6 lbs ready to sail. Please feel frees to let me know if you have any questions at all and I will be happy to answer them.