Double Mainsheet System

[thinwater]

Originally Posted by Al Oliva

Thank you,
I understand the point you are making and I think it is an easy way to put all the work on the windward sheet. However, what I don't understand is how to move the boom to windward in light air. The windward sheet would need to be overtightened to move the boom and would defeat the mainsail shape. The main would be overtightened for the light air conditions.
Ak

Not if you slack off the leeward sheet. Think it through and you will realize it can give the same result as a traveler. You are positioning the end of the boom in a two dimensional space using a triangle. Many options.

[citlab]

Originally Posted by Al Oliva

Thank you,
I understand the point you are making and I think it is an easy way to put all the work on the windward sheet. However, what I don't understand is how to move the boom to windward in light air. The windward sheet would need to be overtightened to move the boom and would defeat the mainsail shape. The main would be overtightened for the light air conditions.
Ak

Do you have a topping lift or a rod kick that can push the boom up?

[Snore]

Originally Posted by Joh.Ghurt

Maybe I'm a little stupid rigth now, but why not simply tie a knot (eg a double 8-knot) where the double line leaves the aftermost block and goes down to the blocks on the coach roof? Then the two sides will be isolated from each other and you have a double main sheet. Tie it very closely to the block.

If that works satisfactory, you can get rid of the aftermost block on the boom with a shackle, cut the sheet in half and and tie / splice both new sheet-ends onto it.

To me this construction looks a little as if it was offered in the "stupid cruiser" mode and with a simple modification make it a regular 2-sheet main control which is just as good as a traveller.

My concern would be point loading. The existing system distributes the force into two blocks (points) on the boom.

Putting all the stress onto one, could lead to boom failure.

[psk125]

Originally Posted by Snore

My concern would be point loading. The existing system distributes the force into two blocks (points) on the boom.

Putting all the stress onto one, could lead to boom failure.

The changes suggested for the sheeting do not shift the pressure all onto one block on the boom. Tying off one side of the sheet shifts the pressure onto the other side. Looking at the photo supplied by the OP, each side goes through two sets of blocks on the boom to spread the load. Tying off one side does put all the pressure onto the two blocks that are being used, but the total pressure on the boom remains the same. Since the four blocks are mounted together in pairs, the pressure points on the boom do not actually move.