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jib boom hitting mast

PostPosted: Fri Mar 03, 2006 1:36 am
by cshelden
I'm almost suer I know the answer but before I chop a jib boom i'll ask the obvious i'm sure.
Building my first EC12, have it all done less the sheets being run (ozman winch). As the rig stands the jib boom hits the mast, about 1/4 or so is past the leading edge of the mast. I have the following on my rig:
-internal counter weight
-travler system on the boom
-topping lift

So is the obvious solution to shorten the boom? If so i'll need to retap some holes but that is no biggie.
Is there an accepted length of booms? Mine is 25" i believe, I got it from Mike Z. (excellent products by the way)

Thanks in advance.
Charlie

PostPosted: Fri Mar 03, 2006 2:28 am
by Doug Wotring
Move the Jib attatchment to the boat forward until it does not hit.

PostPosted: Fri Mar 03, 2006 12:42 pm
by cshelden
Thanks Doug,
That is what I did, and the attachment line is angled now back about 30deg, it is as if the boom is being pulled back towards the mast, I wonder if I don't have my forestay to short? I made a jig to hold the boom 2" off the deck, maybe I need to double check my jib rack position on the deck, but i'm sure I put it where it is called for on the plans/ec12.info site.

Charlie

PostPosted: Sun Mar 05, 2006 2:43 pm
by Carl
Charlie,

23.5 inches is the dimension on the layout by Mark Rienhart.

Checking this dimension on a boom from a good builder he uses 23 3/8

From Bow end. Jib forestay attachment point 3.0 inches
jib attachment to deck (on boom) 6.5 inches

Carl

PostPosted: Sun Mar 05, 2006 4:44 pm
by Rick West
Charlie,
The MZ booms are longer than you need. This is normal. Having a short one leave no options. Use the numbers Carl suggests.

One way to confirm before you cut is to lay the jib on the floor and the boom to where it would attached. You want mounting for the topping lift line to be at the very aft end of the boom and the jib forward enough for the leech roach to brush the vertical line.

Then you can mark all your positions on the boom with consideration of what you will have in the boom or in front of it for counterweight.

Use the information on the building site until you have other ideas after sailing. Some have extra holes in their booms from adjustments they have found to like better.

...94 [8D]

PostPosted: Mon Mar 06, 2006 2:00 am
by cshelden
Thanks to all for your tips and suggestions, all is well now. The hazard of working late at night is error. Well seems I had misread or such the # for the forestay attachment on the boom and I had it back nearly 4" from the tip of the boom which was causing my boom to push back past the mast. DOhh! All is well now. Thanks for the tip Rick, I have no idea why I didn't think to do it that was as it is so simple.

Charlie