Gaff jaw clearance

[John Di Dio]

How much clearance should be allowed between the mast and gaff & boom jaws?

I'm building Ruell Parker's San Juan Sharpie if anyone is familiar with that boat.

Masts are 6" diameter. What should the distance between the inside faces of the jaws be after the leather padding is applied? Is the same clearance appropriate for both boom and gaff?

[Andrew Craig-Bennett]

Too much is better than too little! 50% over mast diameter would be good. Only drawback to having say 100% is that the jaws do a fine job of catching any halyard going!

[Smacksman]

And it helps to round off the jaws so that the gaff can rotate a bit axially.

[T.KAMILA]

Can someone confirm that. At fifty percent to a hundred percent over the mast diameter rotation doesn’t sound like it would be a problem. Just seems like a lot of clearance. I need to get this correct because I’m assembling my gaff at this time. The other question I have is are the gaff jaws riveted and glued to the spar or just riveted without glue?

Tom

[John Di Dio]

Tom-
That seemed like a lot of clearance to me too, but I certainly don't know much about the subject. If you make a full scale sketch of the mast & gaff jaws viewed as if you were looking straight down the length of the boom or gaff you can see that the amount of rotation you can get increases rapidly as you start to add clearance and as clearance is increased you get smaller increments of additional rotation (hope that makes sense).

I think the deal is that if the clearance is too small the jaws tend to bind on the mast when the gaff rotates on it's axis. When it binds it doesn't swing back & forth or come down easily.

As far as how the jaws are attached to the boom--I plan to through bolt mine with 1/2" stainless steel all-thread rod and epoxy the joints between jaws & spars

[Ed Nye]

The boom doesn't need that much. An inch of clearance on each side will work fine. For the Gaff 50% is not to much. Anything under 40% and the jaws may bind and break. Attach the gaff jaws with rivets, glue and anything else you can think of. They get a lot of racking stress.
Ed

[ 05-15-2002, 03:32 PM: Message edited by: Ed Nye ]