Swing rig easier on winch?

MultiHulls General Discussions (MultiHull/MultiOne)
1

Is Swing rig easier on winch load, IF so how much easier 10% 15 %???

2

Hi Jim,
hope having understood your question.
In my opinion the variation is proportional to the ratio between the ‘servo drum’ diameter of the winch and the length of arm of the ‘servo arm’.

This of course is simple theory since the real useful power available from a servo under load is about 50% of what specified at no load in data sheets.
As consequence, the servo arm shall be more powerful to produce the same torque of a servo drum.
Longer the arm less torque available or more power servo required.

ClaudioD

3

Thanks for the useful information.
My question is on a swing rig, does the Jib help balance the rig so the winch needs less torque?

4

According to this article by Eric Rosenbaum what you say is correct.

5

Common knowledge and practice says yes, though I have not ever seen any real data on this. However, to address the implication of your question, the winch is one place that you never want to skimp. An under powered winch is never fast. It is the source of endless frustration and sucks the fun right out of your sailing. The extra grams from an appropriate to slightly over sized winch are well worth it.

Back to your question, though. Typically a conventional rig is set up so that the last tug of sheet at close hauled closes the leeches. This requires a great deal of force, and I would venture to guess where most winches burn out. A swing rig, particularly with a sheeting post (so that the actual sheeting point is above the deck at boom level) does not do this, so it requires a lot less force.

6

Swing rigs use about half the power of regular rigs. Same boat, one swing, one conventional, the swing rig used lots less battery, maybe 1/3 the mah.

Think about it this way, on a swing rig the CE is only slightly behind the mast, so if you do a moment diagram, to pull the sail in you have the sheet force X the distance from the mast, that equals the force on the sail X the distance of the CE from the mast. On a conventional rig you do that with both sails and the force on the sails are much further from the pivot. You probably have almost twice the force with the conventional rig.

7

Thanks guys, I will have to do some experiments.