Steps in Building a SCAMP sailboat
Links to all my scamp building pages.
Setting up the Bottom, Bulkheads 4 5 and 6, making Centreboard case
Dynamite Payson had developped a method of butt joining a sheet of plywood by thinning the edges and putting a strip of fiberglass over the joint. The same process is done on the opposite side. I've tested the strength of this method and found that it was sufficiently strong. In my test the wood failed before the joint.
Some people argue that it modifies the rigidity of the plywood but I have not seen this myself in the gradual curves I have needed to make.
This is how I intend to join the plywood parts of my scamp.
The bottom pieces get joined
I sanded both sides of the join, top and bottom, and got ready. Plastic on the table, weights and fiberglass strips and epoxy are all handy. First I wetted the joins with epoxy them added a bit of thickened eposy on the edge of the plywood. I placed the bottom fiberglass strip on the plastic and rolled epoxy on the strip. It was easy to slide the 2 pieces of the bottom on the fiberglass and apply the top strip.
The joint got a plastic covered board and weights.
The next morning the epoxy was set and the joint was solid. I trimmed the extra glass and checked the joint. A couple of bubbles but otherwise everything was fine.
I'll sand it and fair the bottom at least so there is no mark when I paint.
I cut the daggerboard opening, My First Disaster!
After adjusting the width of the centreboard opening to the actual width of my board I went ahead and cut the opening.
I then placed the bottom of the boat onto the building frame and screwed it carefully in position. It bend nicely and looked fine, except for the opening which seemed odd. While checking I realized I had drawn it on the inside of the seat vertical rather than towards the outside so it was in the wrong place. With a sinking feeling I took the bottom off the frame and carried it to the bench to patch it.
After thinning the sides and the patch with the sander I was ready to glue it back in. The piece I had cut out got slathered in thickened epoxy and put back in it's original opening and any gap got filled.
I cut a piece of fiberglass and put it over the patch and covered everything with a board and weights.
I'll repeat the process tomorrow from the other side.
Because this is an area that will be subjected to quite a lot of stress, I will beef up the supports around it to compensate for any weakness of the patch. Harumph...
While I was checking to see the fit of the vertical piece and centreboard case It seemed that the opening was slightly too long by a thickness of plywood. I checked the plans and the length was as drawn but I wonder if there is an error with the plans. To be determined before I cut the new opening.
Coating parts with epoxy is ongoing
I think it's a really good plan to always have a few pieces around ready to take leftover epoxy. This saves on waste.
I made a jig to hold bulkheads upright on curved bottom
I'm waiting for epoxy to set. So I made a jig.
Since I work alone I often use jigs to help clamp parts temporarily.
I made this jig to hold bulkheads onto the angled bottom so I could set them up and measure or attach permanently. It can hold a bulkhead vertically while sitting on the curved angled bottom.
I still had some time so I went and sharpened all my planes. I sat on the front porch and worked quietly. It's very satisfying to sharpen or polish stuff.
Dry Run First Try as Assembly of SCAMP
The bottom is patched and looks solid. I'm now where I was 3 days ago!
After putting the bottom back on the frame I dug up the various bulkheads and assembled them along with the seat verticals.
Since I measured and cut the parts, rather than buying a kit, I wanted to make sure that there were no glaring errors.
Bulkhead 3 was not symmetrical in the top part. I mis-measured one of the points. It was an easy fix to put in a patch. I'm happy that this boat will be painted.
After many stops and starts I was able to assemble the boat bits and found no obvious problems. I still have not added the very front bulkheads and the stem.
I can't explain the discrepancy of the length of the daggerboard case from the plans compared to reality but I think there might be a problem with the plans rather than with my measurements since the inner framework of the boat goes together very nicely. Or maybe I made a mistake. Time will tell.
I marked the position of the centreboard case opening and it's ready to be cut out.
I checked the swing of the centreboard inside the case and there is enough space. I had a moment of sheer panic when I could not fit the inside piece and figured I had marked it incorrectly. It turned out I had not completed the cutting out of the part and I still had one line to do.
The inside parts of the centreboard case got a coat of fibreglass.
For this build I'm testing out a new epoxy called East System. It's made in Canada so it's much less expensive for me. Noah's carry it. So far I like it a lot. It is advertized as non blushing and so far so good. I've run a few tests and checked the panels I've coated and no trace of blush. In spite of this I still sanded the set epoxy before coating it just in case.
One thing I've noticed so far is that it sets smoother than other brands I've tried.
The centreboard case interior get a second coat of epoxy. I seem to do better with several thinner coats than one fat layer.
Today I did a final dry run for the centreboard case. Everything seems to fit ok. The curve of the bottom had to be adjusted slightly (see below) but it fits now. The centreboard has space to rotate and come down. The hull and bulkheads line up well with the case. Time to glue up. Hopefully no surprises.
I've ordered a pound of graphite powder to add to the resin for the next coats of epoxy of the centreboard and the centreboard case. It has the reputation of making the parts less susceptible to abrasion. I don't know if that's true but I'll try and run a couple of tests.
Checked the fit of the stem and modified the curve of the hull.
Before committing to starting the assembly I wanted to check the stem and sure enough it has a problem. Or rather my bottom has a problem. My fair curve is too curvey in the front. The stem is essentially flat but I have a slight curve on my frame. I checked measurements for the form and there is really not much of anything to change. I fiddled and modified the front part a little and was able to flatten up the bottom so the stem fits a bit better. I still have about half a centimetre of curve but that's what thickened epoxy and big fillets are for. The rest of the curve is dead on I think, because the seat verticals, which I cut according to the plan, fit perfectly against the bottom.
I expect that the front of the first planks will be tricky to fit on because of this but I'll face this later. I might have to recut the front piece of the plank to adjust the fit but I hope not.
Milled Carlings and Centreboard ends and cut Channels
Milled some lumber today to make the long support carlings on which the side deck will sit. I had 2 very nice Douglas fir boards. They are only 10 feet long but I'll join them. They milled out at slightly over 3/4 inches thick so that will work. It's a bit confusing, plans are in metric and instruction booklet is in imperial measurements.
Several years ago I bought this planer. I wasn't sure I would use it very much but it has been really nice to have around.I don't have a jointer and I'm afraid of them. My father was missing several fingers as a result of a jointer accident. I use the planer to flatten boards.
By hot gluing a crooked board onto a stiff carrier board I can flatten it quite well. I use the same method of gluing the board to a carrier board and passing it through the table saw to get a good edge.
I also cut the end pieces for the centreboard case. I have 2 long pieces for each end and 4 spacers.
Now that I have the lumber dimensioned for the carlings I can cut the slots out of the various bulkheads. I had marked the rough position but not cut them.
I used the pull saw and a chisel to cut the channels that help position the carlings.
Instead of a through channel, the first and last bulkhead have indents which support the carlings. Chisels worked well to cut these.
Unlike kit builders, I don't have very good benchmarks to line up the various parts so I wanted to be able to keep the bulkheads lined up with the carlings. If I can keep everything square and symmetrical I'll be happy.
Gluing up the Centreboard Case, finally!
After temporarily clamping the parts together and checking the alignment, I drilled some pilot holes and marked the parts.
I had roughed up the epoxy before hand so it was a simple job to smear the sides and panels and put them together using temporary screws. I have several spacers inside the case to keep the distance even but the wood is not warped and they are not doing much.
After a final check for mistakes, I scraped off any glue that squeezed out. I let the assembly set up for a couple of hours and removed my temporary screws. I did not want them to get glued in. I don't have stainless screws yet.
After cutting out the centreboard opening I had a dry run of the various components. Although everything goes together quite well I had an annoying 3-4 mm discrepancy. Things were just a little off. After checking the square, level, alignments and anything else I could think of, I moved the bulkhead placement back by a few mm. This fixed almost all my discrepancies.
This means I adjusted the position of the centreboard, again... but I think this is right.
I must have marked the bulkhead placement wrong. It annoys me that I cannot find the mistake though.
In order to put the seat top on to check for alignment I had to cut the centreboard side that had been left oversize.
My trusty Japanese dozuki pull saw worked well.
With all the other parts clamped in position and checked for square and level I finally took the plunge and glued bulkhead 4 in position.
I now have 2 pieces that are correctly placed. The bottom and this one bulkhead. These will serve as reference for the rest. I think the basic framework will go together quite fast now.
I have all my drafting lines on the parts. Most important are the centre lines and the lines at every 300mm. These are very useful to position parts.
Working alone imposes a slower pace. I'm really good at clamping things together rather than requiring extra hands.
I've come back to the frame after drilling the pivot holes, and checked them, they are ok. The whole framework and side pieces and doublers are now ready to glue. I think that is tomorrow's job. I'm tired and I'm very stupid when I'm tired. I will also do some filetting. It's going to be a busy day.
Bulkheads 4, 6, and 7 have been glued. It was easy to position them by putting the seat top on and checking the alignment.
Since Bulkhead 5 is split by the Centreboard Case, I wanted the rest in place before fitting this bulkhead. I had to trim a small amount but otherwise it was perfect.
Because the size of the centreboard case varies depending on the final size of the centreboard, I needed to wait till the centreboard thickness and exact position was finalized before putting bulkhead 5 in place. It was a quick job to mark it's position. Before I glue it in I will cut the centreboard case doublers and drill the pivot hole. The doublers are used to re-inforce the spot were the pivot supports the centreboard.
Drilling the centreboard pivot holes.
I used the drill press to make pivot holes for the centreboard, first on the case, then on the doubler.
The holes are slightly undersized and I will need to enlarge them. I will do that when I have the bronze bushings and pivot bolt. I will enlarge the holes by drill. I'm more confident to just enlarge existing holes than to drill perfectly square holes by hand.
Doublers fit and are drilled. Everything seems to line up nicely.
The first part of the SCAMP build is now complete
Benchmark day. The centreboard case and middle bulkheads are glued, tidied up and coated with at least one coat of epoxy.
Everything is square and level that should be, except for bulkhead 6 which somehow managed to get out of true and is at a slight angle from the centerline. 2 mm off. Annoying but not very important I think.
The hull planks will at least have a symmetrical framework to tie up to.
I have to do some fillets but that is not hard. I'm happy.
There is something very exciting when a pile of parts starts to look like a boat.
Next step is the Stem, bulkheads 1 - 3 and mast trunk
If you decide to build a boat be careful. These tools can be dangerous. If you don't know how to safely handle something find out. There are lots of forums out there.
This web site reflects my personal ideas and doesn't represent anyone else's point of view. I don't claim to be an expert in anything, just someone muddling along.