Attaching Boom Jaws

[Stu Fyfe]

Ok, here's today's question. What's the best way (in your opinions) to attach new jaws to a boom. The oak jaws on Redwing, a 22 ft gaff sloop, are starting to show rot and have stress cracks in them. I need to replace them and was considering laminating ash for the slight upcurve. How should I attach the jaws? Would thru bolts work or should I put a long rods through the boom and cap them off like rivets? What do you think?

[Chadd Hamilton]

Well, Stu, thru-bolting/riveting seems to be the best way to attach the jaws to the boom. I think Rossell's "Building Small Boats" shows this in detail and I have seen this fastening on several other gaff booms.

If you were to use thru-bolts, you'll want to counter sink for the nut and file the bolt flush as to prevent any chaffing or snagging.

$.02

[Stu Fyfe]

Thanks Chadd. I'm gonna try to find Rossell's "Building Small Boats" through the library system and check it out as a resource. Anybody else have 2 cents on this?

[mmd]

While through-bolting would possibly be easier to accomplish, I think that the bronze rod peened over washers has several advantages: It will not require countersinking which removes material and therefore weakens the jaws; it won't loosen over time; and it has that all-important "proper salty look".

[Art Read]

MMD? Bronze only? Copper would certainly be easier to peen, no?

[Wooden Boat Fittings]

I'd be happy using copper myself, but Michael's method is undoubtedly the right one. Moreover, if you used roves instead of flat washers, then the peening would put the joint under considerable prestress, which would be a Very Good Thing.

Mike

[Bayboat]

Bronze is preferable, but copper is OK. If you use copper, the rod should be a tight fit in the hole, to avoid bending while you're peening the ends. Copper roves are a good idea.

[Stu Fyfe]

Here's what I've decided to do. I picked up some ash which I'll laminate and bend upwards for the gaff jaws. I ordered some 1/4 bronze rod, bronze washers, copper nails and copper roves from Jamestown. I'll put the rods through the jaws and cap them off with the washers. I'm gonna use the copper nails through the laminates on the upturned jaw openings as a way to hold the shape and the laminates together. They'll be capped off with the copper roves. I've got the old set of jaws to use as a jig for the laminated sections. I originally planned on using white oak, but I couldn't find any that fit the need. So ash will do. The ash might even hold the epoxy better.
Thanks for everybody's advice.
Stu

[mmd]

Stu. Sorry to take so long to to get back to this - I missed Art's question to me. The reason for bronze rather than copper is the very same reason Art wanted to use it - it is so soft. The boom jaws are relatively highly stressed 'thwartships, and will cause the washer to work against the peening. Copper is soft enough that it will eventually work loose, causing sloppiness and possible failure. Bronze is harder to peen, but will be much stronger.

Ash is a fine wood for this use. It laminates well, finishes nicely, is strong, and looks good.

Good luck with the project.

[Dave Fleming]

I too would recommened against Copper. Unless you are very sure of the alloy and its composition.
A good grade of Silicon Bronze would be my choice.
Copper will 'work harden' as you peen it and develope stress cracks, can be seen with the eye, and therefore weaken the peened head.
You gonna leather wrap the jaws or put wear strips on the mast area?

[Stu Fyfe]

I've leathered the jaws in the past and will once again. I do get some abrasion on the mast, but not enough to wear away at the wood. So I uaually just apply a few coats of varnish every year to keep the wood from weathering too much. With two reef points, I ve accepted the fact that wear and tear will happen at three places on the mast.
Stu

[Ian G Wright]

Originally posted by Stu Fyfe:
I ve accepted the fact that wear and tear will happen at three places on the mast.
StuGrease with Tallow, lots of it, and avoid the wear.

IanW.