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devout
06-03-2012, 05:24 AM
Morning everyone

I am building a Sam Devlin designed Winter Wren in South Africa. I am busy with the gaff spar and jaws. The plans aren't clear on the jaw dimensions. How much wider than the mast must the jaws be?

http://farm8.staticflickr.com/7240/7326094282_436262249e_z.jpg

These are the Meranti blocks from which I cut the Jaws. The gaff spar is a 8'10" bird's mouth assembly.

http://farm8.staticflickr.com/7236/7326111320_443e17e757_z.jpg

One half of the jaws done

http://farm8.staticflickr.com/7085/7326120124_d3110eee92_z.jpg

The fit around the gaff spar

http://farm8.staticflickr.com/7228/7326086782_540aee7dcc_z.jpg

From the front

So, the question is:

Current width of the jaws are 4 inches as on the pictures. The mast diameter where the gaff sits when raised is 3 inch.Diameter of the mast at widest (base) is 3 inch. I can take about an inch outof it’s width by taking out a table saw blade width from each jaw and off eachside of the spar. What about covering them in leather? Any advice?

And also, have I over-engineered these jaws? I have seenpictures of some flimsy looking ones. I do plan to round up everything a bit more which will make it a bit thinner.


Thanks and regards

Devout

Peerie Maa
06-03-2012, 06:25 AM
Those are probably about right, allowing for some thickish leather. If you do want to reduce the gap a bit, make a tapered cut on the spar, do not take any more off at the end of the jaws, take it all of from the spar end, so as not to weaken the spar any.
Your question about leathering. Were you asking for tips on how to, or whether you should? You most certainly should.

wizbang 13
06-03-2012, 06:36 AM
There is plenty of meat there, but maybe not proportioned how I would have done them. But then I do mine a bit different than most.
I tend to make them longer on the spar. I do not use a "car" , even on my 12ton ocean smasher. So, where the extra thick area for your car will be, it needs to be well clear of binding in the shrouds.
Going upwind, the jaw will almost float on the mast, it is off the wind that they take licks, and usually from levering against the lee shrouds.
Now, for your question, if it clears closely at the bottom of the mast, it will be fine at the top.
I like to round off the inside edges of the jaws. For small boats , I like molding wet leather. Big boats, hardwood strips added to the mast. Not both together.

devout
06-03-2012, 08:45 AM
Thanks for the responses Peerie Maa and Wizbang. Peerie, my question was about whether I should leather them or nor, so you answered that one for me. There is a guy up my street that makes all kinds of leather stuff (mostly furniture) so I'm sure he will be able to give some advice. I'm also going to put in a tumbler.

Wizbang, this is a small boat (21') so I am going to leather the jaws. The mast will also be a bird's mouth, same wood as the spar, (Meranti)

Thanks much for your advice.

Regards
Devout