Jib Boom Balance Weight

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Jib Boom Balance Weight

Postby pgfaini » Sun Apr 18, 2010 9:10 pm

Can someone tell me the weight of the internal jib boom balance weight that is being used? I've squeezed an aluminum arrow shaft(#2117)in a vise, to an oval profile that's a close fit in the Goldspar mast stock, and filled a 4" section with lead. The piece weighs about 2oz. I seem to remember 1-1/2oz. being mentioned somewhere, but can't locate the site. I haven't cut or assembled my jib booms yet, so can't cut and try. Just trying to get all the parts ready, and thought while I was casting my rig substitution pig, I'd make up three balance weights. They should fit better than the round slugs I was originally going to cast.


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Postby Capt. Flak » Sun Apr 18, 2010 10:23 pm

Paul, It really depends on the length of boom in front of the stay, how long your offset is from the stay to the jib swivel and how much your jib weighs. A 40 jib will need more weight than a 25 jib.

What I have tried to do is use a small amount of tape to hold the lead on the boom while it is rigged indoors and laying on its side on the floor. You want the boom to be balanced along the center line of the deck. If the clew end of the boom is pointing to the high side, you have too much weight and if it is pointing to the low side, you are too light. After you have roughed in the weight with it just taped to the boom. Go ahead and insert the lead into the boom and test it again. Make sure you use some oil on the lead so that it will slip out of the boom. You don't want to get it stuck at the wrong time.

Once you have the weight right you can use a small screw to hold in place.

Somebody else might have a better way of doing it.

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Postby pgfaini » Sun Apr 18, 2010 10:46 pm

Joe, I thought you use a "standard" weight, and adjust it by sliding it in and out, not by adding or removing weight. Just trying to find out how heavy this is. I guess Mike Zellanack's weights are about right, has anybody weighed them?

Thanks for the explanation of actually doing the balancing, that was going to be my next post. There's a heck of a lot to setting up these boats isn't there.[:0]

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Postby s vernon » Mon Apr 19, 2010 9:38 am

I doubt if this will get much discussion, but I am very sure that I read or saw somewhere that you should not use quite as much weight as Joe says. My recollection is that with the boat lying on its side you should have enough counterweight so the jib boom points at the upper stay that is closer to the floor - points at the upper stay where it attaches to the stay rack.

I guess either way is acceptable with Joe's info being the accepted "internet method", if you read the Victoria page written by Tom Causin and also Lester Gilbert's info.

Someday I am going to painfully (humor) scroll thru the Bob Sterne EC-12 tuning video (VHS) to see if he shows how he does it.

http://www.myrc.org/bobsboatyard/svideos.htm
I thought Bob was out of business. Who knows? That is a great tuning video and the EC-12 is what he is tuning. (I think he leaves you with the impression that we set the outhauls a lot fuller than we really do as the wind comes up.)

I do know that having too much counterweight makes life difficult in very light air. Sailing upwind the jib wants to sit on the upwind side (backwinding) in very light wind.

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Postby s vernon » Tue Apr 20, 2010 9:19 am

I figured there would not be a lot of interest in clarifying this non-issue, but Carl Olbrich wrote "Kahle balances all his weighted jib booms (no sail etc.) to neutral at the attachment point on the jib boom to the jib shroud rack" on a thread called "jib to main downwind" (I believe).

I am not sure what that means or why there is "no sail etc" but maybe that says Reichard balances the boom to point at the upper stay on the rack rather than along the centerline.

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Postby Capt. Flak » Tue Apr 20, 2010 11:42 am

Again, Maybe I am not doing it right, but my jib seems to go wing on wing easily in most cases. Sometimes if the wind is too much it won't get over.

John B cut a short length of boom section (about 4 inches long) and stuck it in a block of wood so that it sticks straight up. Then he just pours the lead in to the top. Once cooled you just tap the boom section on the edge of your work bench and the lead will fall out. Then you clean it up and start cutting it down to the size you need.

Like I said, start out with a little more than you need and keep cutting and filing it down until you have it just right.

A long offset will require less lead. Basically I balance the boom so that when the boat is upright in NO wind. the boom will just stay where it is on center over the deck. If you rock the boat a little, the boom will stay put for a sec and then catch up with the movement.

The idea is to let the wind move the boom and not the weight of the boom move it.


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