Redesigning sailplan

[Guest]

Has anyone plunged into the unknown depths of redesigning their sail arrangements, and could suggest reading which provides enough of the physics to provide a basis for having a stab?

I want to find out whether converting my 28 ft masthead sloop to a cutter rig might offer greater control in high winds & sea (i.e. more sailpower at a lower point). This would have the added bonus that one could put up two sails, sit back and run with the trades.

My instinct would be that the low-power centre concept makes a ketch more seaworthy too.

 

[Twister_Ken]

Bear in mind that with a cutter rig on a shorter boat, the yankee and staysail can end up so close together that they interfere with each other's air flow. Mind you, Northshore seem to get it to work on their Vancouver 27'.

 

[Guest]

Looking at the same issue for a 32'. Best book I have found so far is B Toss, The riggers handbook which is reasonably "in depth" without being a sailmakers text book. It does get complex though and access to copmuter software for looking at centres of effort is definately useful. The other problem pointed out by a survayor is the deck fitting, I have big wooden beams and a sampson post as a start but the average glass deck is going to give no support. Ideally it needs a strut to the stem post. Let me know how you get on?

Roly, Voya Con Dios, Glasson, Lancaster

 

[Fr J Hackett]

The concept is a good one, the use of a staysail and reefed main in strong winds is much more satisfactory than a reefed foresail ( roller reefing assumed). The attatchment point at deck level and at the mast is very important, at deck level all the cutters that I have experience of have a substantial cross beam laminated to the hull, deckhead and or foreward bulkhead for attatchment of the inner forestay. The mast attatchment needs to be supported by running backstays or permanent lower shrouds to counteract the foreward pull that will be exerted by the staysail which in heavy conditions can lead to repetative loading of the mast and possible failure. As a start point the deck fixing point for the inner forestay should be about 40% of J behind the forestay taking it to the mast parallel to the the forestay. The best of sail trim, Charles Mason Adlard Coles ISBN 0-229-11843-7 is interesting.

RAG @ STICK

 

[Guest]

Tension in the mast is I guess a point that will need further thought. Thanks for the book references too.