View Full Version : Setting up a jig for an SSS

06-27-2006, 04:29 PM
Finally getting my 20' SSS project going. Got a large amount of warehouse space lined up to build it, have plywod on order. I am now going to have to build a jig. Origionally, I planned to use a composite bottom plan that did not need a jig. Now I am going back to the origional plans and will build the strongback out of a straight 2x10x16. For any builders of SImmons skiffs, or anyone else experienceed in setting up a jig, what is a good way to go about setting this up? I was thinking about some modified sawhorses, maybe using the make-your-own sawhorse brackets. Would these be to unstable? Any advice helps.


Tom Robb
06-27-2006, 04:39 PM
Solid, stable, and level is handy.

06-28-2006, 01:23 AM
Saw horses tied together down low with stretchers would work.You need to put rat runs on the undersides to tie the frames together and diagonally brace these to something to keep the frames level.The problem I had was finding a straight 2x. You are better off buying a TJI- engineered ply web/solid wood(wood I-beam) member like they use for floor joists in modern construction or building one if you dont have something substantial to brace the jig "string straight" to.This will make a continuous stongback to fasten your jig board to. I had to make my own uprights because I couldn't find straight lumber. I then had to concrete these into the ground so that I could brace the jig perfectly straight.Next time I will buy or build a engineered timber to set the jig on.

Tom Robb
06-28-2006, 08:53 AM
The wood I-beam idea isn't a bad one. A friend in upstate NY works at an aircraft museum where they're restoring a trashed B26 WWII medium bomber. They're rebuilding the wings on a large table undergirded by wood I-beams that ensure a reasonable degree of flatness - an important reference in the wing jig.
Someone here once complained about the inconvenience and back pain when the jig is either too low or too high off the floor. Harbor Freight sells a motorcycle jacking platform that would move the jig up & down as convenient.

06-28-2006, 11:53 AM
Why all the concern about a perfectly flat jig? How 'bout a sorta flat ladder frame with a very taught, as in stretched with a turn buckle, 1/16" steel cable as a centerline. Orient the molds to the cable, not the jig.

Tom Robb
06-28-2006, 12:35 PM
Because the flimsy base will move.

06-28-2006, 01:31 PM
For the current project, i used engineered i-beam joists to make a 26' long box beam. Top and bottom are of 1/2" plywood. It has been 100% stable. Sometimes it's on dollies so the boat can be moved around.

Robert W. Long
06-28-2006, 02:05 PM
For Jim Conlin:
I am very interested in your box beam. I'm ready to build the jig for a caledonia yawl. Could you describe more about how your box beam is built? Is it a solid box that the molds are set on? thanks, Robert.

06-29-2006, 12:36 PM
Tom, I use a pair of 2x8s 'tacked' to the concrete floor with dabs of construction adhesive. Cross beams at each station. Not flimsy at all.

I'm starting to set up the molds and frames for my Coyote II launch today. I'll post a couple of pics asap.

Tom Robb
06-29-2006, 12:47 PM
Level, or at least flat is nice for the same reason a level foundation for your house is a good thing. It saves having to constantly adjust for the out of level, out of plumb base. If I tacked 2x's to my concrete floor, the base would be both wavy and too low for my aching back.
Do as you please. I'm just claiming that a good foundation, as with most things in life, is a good place to start.

06-29-2006, 01:22 PM
For Jim Conlin:
I am very interested in your box beam. <SNIP>.
It's an open-ended box. The sides are 10" I-beam joists and the top and bottom are 1/2" ply, secured with construction adhesive and drywall screws. When building one, take extra care that the top has no twist.
Station molds and other such things get screwed to it.
On occasion, i've positioned the molds such that the stem hung over the end of the box.

Bruce Hooke
06-29-2006, 02:03 PM
It is really nice if you can anchor the whole works to the floor because then you can build off the inherent stablity of the floor rather than having to make the whole thing rigid enough so that if it gets moved it won't go out of true as it bends to match the inevitable variations in the floor.

While flat beams are really nice, my inclination would be to go for reasonably flat but use a taught wire as the ultimate reference. It partly depends on the boat. For a boat with a lot of frames that you have made with a precisely postioned cross piece that will reference to the beams on the ladder frame, getting those beams dead straight and level might well be worth the effort. On the other hand, if the situation is such that you are going to have to shift the frames around in space anyway to get them in the right position, you just need a solid frame to which to anchor them when they are in the right position and it matters less if those beams are dead straight and level.

06-29-2006, 02:40 PM
I'd love to have a solid wood floor with the space to walk around the victim, but i don't. In my cramped shop, the setup must be moveable and the very stable box beam is my solution. I jack and shim it level if it's going to matter. Certainly when first erecting molds, I go through the full levelling and taut wire high mass.

The ability to change the height or tilt of the setup has not been useful with larger boats, but very useful with dinghies and canoes.