An interesting boat : matinbleu (free standing "wing sails" goélette)

[Eric Sponberg]

Shearwater was designed and built by Richard Black and I believe her freestanding carbon fibre masts were designed for Richard by Eric Sponberg around 1980. She has two-ply wing sails which wrap around the mast. I bought her from a friend on Orcas Island in 1999 and use her for daysailing. She is stored in the winter on her trailer. She is great fun to sail.
This year I am undertaking a refit and considering improvements. Her sails are about 5.5 oz and two ply means 11 oz. As a result of their weight they have hardly worn in 30 years. My question is what weight of sail cloth is appropriate for two ply sails? Can I go for 3 oz as the fabric is two ply?
I would also change from the older triangular profile to the current blunt ended sail profile.
Thanks for any suggestions.

Boy, I remember when Richard was building Shearwater. Yes, these are the first free-standing masts I ever designed. Richard would be pleased to know where the boat ended up. He lives in Sevilla, Spain, now, and is quite the celebrity Flamenco guitarist. I send him an email with a link to this page.

I am not sure that you should go much lighter on the sail fabric--maybe if the sailmaker has something around 4 oz. or so, that might be OK. This is one of the drawbacks of double-ply sails--they are twice the weight and twice the cost, and they really don't give you twice the performance that a single-ply sail can give you.

If my "blunt ended" profile you mean a sail with a higher roach, remember that you have to support a roach with battens, and that adds weight, cost, complexity, and the opportunity for more chafe to the sails. At some point, you might want to consider adding sailtracks to the mast and going with single-ply sails. Freedom did that back in the early 1980s. I did the design conversion for a Freedom 40 about a year ago that should be getting accomplished right about now.

Thanks for the update on Shearwater--I'll let Richard know.

Eric

 

[Gulf Islander]

Comment on Shearwater - cat ketch

Hi Eric

Richard Black is obviously a man of many talents! Becoming a Flamenco guitarist is quite a career change from engineer and designer. Shearwater was a very innovative boat and has achieved its design objectives and provided a lot of enjoyment. The fact it is intact is a testament to this. The current rig does work well but I am finding it harder to manage as I age.

Thanks for your reply and your suggestion for a design solution to the drawbacks of two-ply sails. I will step back and take a broader perspective on the question of a refit and what I hope to achieve. This is a light-wind area and windward performance in light airs is not a strong point for Shearwater compared to off the wind performance in heavier airs. I have a conventional boom set up now which would facilitate a conversion. The two-ply sail does deal with mast turbulance which is a major benefit. I would like to be able to rotate the mast to preserve the current advantage I have. I think this is possible but not simple or inexpensive.

Thanks again for your comments.

John

 

[Tanton]

Maybe you might want to try the " Sock Sail" as described on the following blog.
www.tantonyachtdesign.blogspot.com

 

[Gulf Islander]

sock sail

Thanks for the comment
I will track "sock sail" down.