Steps in Building a SCAMP sailboat
Links to all my scamp building pages.
Making the Scamp Centerboard Pivot
I had left the centreboard to work on the hull and the centreboard case but now it's time to work on the details of how the board pivots down and how the up-haul line is attached.
I had marked the pivoting position. This gets drilled out and bronze bushings get inserted and epoxied in place. The actual pivot pin is a half inch stainless steel bolt cut to size. It extends a short way out of the centreboard case and is held in place by a screwed in piece of wood.
The bronze bushings are 3/4 inch OD and 1/2 ID and the bolt fits in snugly but not tightly. The first step is to cut them to size. 2 pieces get glued into the centreboard and the 2 remaining bushings go in the case. I used a hacksaw. It worked very well and was quick to cut. I started by holding it in my wood vice but the bushing kept moving so I moved to a metalworker's vice and it held much better.
After sanding the cut edge to remove cut marks and burr, I also cut a few shallow cuts on the side of the bushing to give the epoxy something to hang on to.
I used the drill press to make the hole in the centreboard. I had a nice oversize forstner bit and it cut a very tidy hole.
The hole is oversize to allow a generous coating of thickened epoxy. I might sand it slightly larger.
It is pretty much flush and by the time I have a couple more coats of epoxy on the board it might be just slightly under the surface. I'm planning to finish the board and the inside of the case with a coating of graphite-epoxy.
I glued the bushing in place using epoxy thickened with silica only. I usually add some wood flour too but I think the silica alone is stronger.
The only thing I fretted about was getting the bushings straight. I eventually used a rod supported by a very square piece of wood to hold the bushing in place while the epoxy set. Epoxy squeezed out just a little.
Preparing the bolt which supports the centreboard.
I prepared some plywood pieces that will be used to support the bolt and keep it in place against the centreboard case. I'll be gluing the bolt to the holder and will put a top piece on the bolt head just to make absolutely sure it does not come loose and move back. Dropping the centreboard while underway would not be a very funny exercise.
The bolt / pivot is removable to allow the centreboard to be removed if necessary. Once side of the support can be permanently glued and sealed. The other side needs to be screwed only.
I debated whether I should have the removable side facing the hull or facing the inside. I decided on the inside was the least likely to cause trouble. If it leaks at all it will be in the water ballast compartment, not in the hopefully watertight side compartment.
I am putting an o ring to help keep the seal waterproof. I got it in the automotive section of Canadian Tire. It took me a while to figure out how to cut an even groove. Eventually I used a router bit in the drill press and screwed the wood on the drill press table and turned it slowly while the bit cut the groove. I set the depth gauge on the press.
Everything needs several coats of epoxy.
The parts of the bolt holder have been epoxyied and glued up. It's essentially ready to be installed. I'll add some waterproofing goop to help keep the assembly waterproof. In the past I've used 3M 4200 but although it is sold as not permanent, it is almost impossible to remove anything stuck down with it. I'll decide later.
I cut the hexagonal hole for the bolt head with a chisel, just for fun really. It took no time at all to do.
Drilling the centreboard case holes
I've been putting off drilling the centreboard case. I'm not that confident that I can drill both sides perfectly square and lined up. I drilled a smaller hole already before I glued it up (and kept it lined up) but I'm not a brilliant driller for thick things.
I think I will get one of these drill jigs that are a sort of substitute for drill presses for places what are too big for the drill press. Lee Valley has one in their Christmas Catalogue. :) If I had a plunge router that would do but mine is fixed base.
I'm thinking that the little jig will also work to help drill the pintle / gudgeons on the transom and the ring in the front of the boat.
Using the guide to drill the pivot holes
I ordered the Milescraft 1318 AccuDrill Mate from Lee Valley but it is also available from Amazon .com. That's where the link goes.
I had quarter inch holes already I had used to line up the sides of the case. I put a metal rod in the hole and lined up the drill guide on that. (I actually used a screwdriver which was exactly a quarter inch.)
I actually screwed the guide to the centreboard side. I'm using a short forstner bit to make a cleaner hole. It's too short to go through so I drilled from both sides. It worked just fine even though the jig wobbled some. Screwing the jig down helped control the jig. My holes are lined up and square.
My holes are now drilled. I can get the bushings installed and go on to make the filling hole for the water ballast.
I aligned the bushing by using one of my spacer blocks with a hole in it. These are the spacers that I used to keep the centreboard case sides spaced properly. I just used the drill press to make a nice clean hole. I put a dowel through the hole and this will keep the bushing centered and square so I can glue everything up. I had oiled the dowel really well so it would not stick and I went when everything was gelled but not absolutely set and removed the dowel.
The filling hole is drilled and the doubler is cut and ready for some epoxy. I tried to use the portable drill guide but the space bit was crooked and everything wobbled too much. I drilled by hand. There is some tear out that will need to be filled when I work on the bottom of the hull.
Dowel is removed and bushing is nicely centered in the opening. The inner block (covered in packing tape) kept the epoxy from running into the inside of the centreboard case. There is no cleanup to do on the inside. Some sanding and filling of screw holes to be done on the doubler.
I'm now about to close the side lockers and have glued and screwed the pivot pin cover.
This web site reflects my personal ideas and doesn't represent anyone else's point of view. I record the process I have followed and the result. I am not saying that it is the right or best way.