Or my first adventure into boat building - Part Two

By Adam Gray - Gravesend, Kent, England

Part 1
Part 2


After turning over the hull, I went round with the sander giving the hull a general tidy up and keying any areas of epoxy that needed it. I thought this would be maybe a ten minute job, but it ended up taking the best part of one and a half hours! The lesson here is not to just slap on epoxy to fill in holes and so on as you go, but to make sure you do it properly.

While sanding, I identified a number of areas where the hull panels did not align perfectly and I noted that would need fairing. I think this was probably due to the fact that the plywood was only 3.6mm thick. I also had the remaining stitch holes and the gaps in the seams where the stitches had been to fill.

Although the hull was not at the stage where it was fair enough to paint, I decided to epoxy coat the entire hull next. I also applied a layer of glass tape along the centre seam.

Hull Epoxy Coated & Glass Taped

When checking on my coating work the following day, there was a waxy, slightly sticky feel to the epoxy. I thought that either the epoxy had not cured properly yet or it was the dreaded amine blush. So I checked my West epoxy manual and came to the conclusion it was definitely amine blush. As a full sanding was required, I decided to sand off the amine blush.

I thought I would give hand sanding a go. Sanding the outside of the hull is much easier than the inside, because you are working on a convex surface and, as 80 grit cuts through amine blush and epoxy fairly easily, I was able to sand one half of the hull in about an hour and a half. I then gave that half a second fairing.

I repeated the process on the other side of the hull. While doing the fairing, I also applied a couple of pads of filler on the centreline. One of these can just be seen in the picture below. The reason for them is, once sanded flat they will give me two flat surfaces that the centre runner (outer keel) will land on ensuring that it stays level while it is being epoxied in place.

Second Stage Faired

I sanded some more. While sanding I prepared the pads for the keel runner. Next on the build list was fit the keel and bilge runners. All the runners were cut from 9 x 18mm (3/8" x 3/4") Douglas Fir with the keel runner being 1200mm (4') long and the bilge runners 600mm (2') long. Once cut to length I put a radius on the ends.

Before fitting I had to locate them. I first marked the centre of the hull and transferred the centre line 120mm (5") out each side for the bilge runners over their 600mm length. Finally, I marked the width of the bilge runners on the hull in the locations where I will be drilling for temporary screw fixings.

I was now ready to dry fit the runners. The keel runner has only a very gentle curve to it, so it only really needed to be held in place while the epoxy cured. I drilled a single hole through the hull each end at the locations of the two flats and I drilled matching pilot holes into the runner and screwed it in place. The bilge runners have a much greater curvature to them, so I decided to fit two screws each end to spread the bending load over a larger area of the runners.

As I had found putting masking tape around the bulkhead fillets so successful, I did the same again for fixing in the runners. I then epoxyied them in with filleting blend and colloidal silica added. About three quarters of an hour later, I peeled off the masking tape.

Keel and Bilge Runners Fitted

Once the epoxy had gone off, I removed the temporary screws and gave the runners a quick rub down. I now turned my attention to the interior. Because of the simplicity of the design, the interior fit out consists of a seat and a stretcher at gunwale level. To fit the seat I would need to set the boat up level, which I did not want to do at this stage, so I started by dry fitting the stretcher and outwales. The stretcher is a piece of 18 x 25mm (3/4 x 1") Douglas Fir. I marked the cut angles and length straight off the boat, cut it to size and dry fitted with a single screw in each end.

Going back to the boat later, it looked like the stretcher was pinching in the sides slightly, so I decided to dry fit the outwales without the stretcher fitted. As it turned out, I was right. The stretcher was about 3mm (1/8") too short which is not a lot, but it was noticeable.

As the build has been progressing, I have spent a fair amount of time thinking how I was going to fit the outwales. The method I used was a combination of screws and clamps. I used screws only in the buoyancy tanks each end and along the cockpit sides. I used the screws and clamps in a hit and miss sequence. The outwales themselves are more of the 9 x 18mm (3/8" x 3/4") Douglas Fir. In my stock I had two lengths that were perfect for the outwales and they did not need to be cut to length until after dry fitting.

After dry fitting both outwale,s I cut a new stretcher at the correct length. The plans give an indication that the corners of the stretcher are chamfered. I liked the look of this, so it’s out with the router. I removed the outwales, did a dry fit to the stretcher, masked up the glue lines as previously and fitted the stretcher and outwales.

Outwales and Stretcher Fitted

After curing overnight, I removed the clamps & screws. Now that the outwales were fitted, I could finally fit the breasthooks. Before I could fit them, they needed some fettling to get them to fit. I think this was probably due to the outwales changing the hull panel alignment slightly. At the same time, I shortened the length of the breasthooks. I also filled all the temporary screw holes and any other areas that needed filling internally.

Breasthook Fitted

I started to look at how I was going to fit the decks. My aim was to fit them without using any mechanical fasteners, so I had to work out a method of holding them in place while the epoxy set. Initially, I thought I could clamp the deck using the outwale, but the deck and outwale were too far out of alignment. So I tried making up a short beam with legs down at the positions of the ends of the deck at the bulkhead. I then used a ratchet strap wrapped around the hull to push the deck edges down, but I found that the deck edges between the bow and the bulkhead did not lie on the correct alignment. The deck had a convex curve between the bow and the bulkhead. I made up two runners that had a curve along the bottom that matched the curve of the deck between the bow and bulkhead. I fixed these to a spreader and again used the ratchet strap to push the deck down. This worked much better, but the deck was still not sitting down properly. After much fiddling, cutting of wedges and so on, I came to the conclusion that the bulkheads had too big a radius to the top of them.

As the bulkheads were fixed, I needed to come up with a method of trimming them down. The decks were still to have a radius, so I marked what I thought would be a suitable reduced curve. I then ran a sharp knife along the line to cut through the outer lamination of ply to prevent splitting. A majority of the waste ply was then cut away in small sections. To finish off I got out my favourite sanding tool, which is my belt sander. Although capable of removing a lot of material very quickly, belt sanders can be used for delicate removal if handled carefully. Sanding the top edge of the bulkhead, I was easily able to get the plywood down to the line.

New Bulkhead Top Radius

A further dry fit of the deck panel was a success with the edge of the deck laying perfectly along the gunwale line. I found that by using a top beam that was over length, I was able to revert to using clamps rather than the ratchet strap. It was much easier and quicker. After a number of trial fittings, I was happy with the fit of the bow deck, so I taped the edges of the clamping frame to epoxy proof them and the deck was then fitted.

Bow Deck Epoxied in Place

On removing the clamping frame the following morning, the bow deck looked perfect. The stern deck was then fitted.

Finally, my attention turned to the seat. This is the last piece of boat construction required and to do the fitting I needed to set the boat up level in both directions.

The plan shows the top of the seat at 40mm (1.5") above datum, but, rather than working out how much to subtract, I just set it 40mm off the inside of the hull. To get the level of the seat, I placed my sprit level at the position of one end of the seat and measured down to the hull. I subtracted 40mm and then put a mark on the hull each side at that level. Once I had the marks, I extended lines from them along the hull by using the bubble on my set square. Finally, I marked the position of the front and back of the seat on the lines.

Seat Marked Out

The seat is simply a flat piece of ply the width of the hull supported front and back with two lengths of 9 x 18mm (3/8" x 3/4") Douglas Fir. I had an idea to modify the seat slightly, but as I would still need the stringers front and back they were the first items to make. Firstly, I measured the length overall and cut two pieces of fir to suit. Then by a process of marking and cutting, bit by bit, the stringers were shaped to the hull. Both the stringers meet the hull close to a chine, so they both needed a double angle cut each end plus the hull narrows across the width, so the ends also needed to be cut at an angle in plan. The idea I had to modify the seat was to reduce its width and to give it some shape in order to make it more comfortable.

Seat Support Stringers Ready to Install

Next, I install them. To ensure the stringer tops were parallel, I placed a batten across the top and then weighted the whole lot down with a battery from my battery drill. The seat itself is a rectangle of 3.6mm ply 220mm (8.5") x 150mm (6"). I cut this out, put a small radius on the top edge and rounded off the corners. After dry fitting, I mixed up some epoxy and fitted it. To hold the seat matching the curve on the stringers, I clamped a strong back across the middle at the lowest point.

Fitting Seat

I had now finished the construction of the canoe itself, yet there was still a lot of sanding, trimming and tidying up to do before I could coat the entire hull with epoxy and then paint, but this was never the less a major milestone.

Construction Complete

It was now time to prepare for final epoxy coating. The first thing I did was to sand the inner edges of the decks back flush with the bulkheads and then smooth out the rest of the deck edges. Once I had this done, I methodically worked around the interior and outwales picking up all the areas that needed attention. Once I was happy with the decks and interior, I gave them a coat of epoxy.

Deck and Interior Epoxy Coated

Of course, once the epoxy had gone off, there were the inevitable signs of amine blush, but I had expected this though. My intention was to leave it until I had the external hull epoxy coated. I turned the boat upside down and did the small amount of preparation work that was required. I then broke out the epoxy and went for it.

Exterior Hull Epoxy Coated

The next morning there it was: amine blush. So I now had a canoe that was fully epoxy sealed and covered in amine blush! I decided to wash the amine blush off this time with soapy water as there was no danger of soaking anything that shouldn’t get wet. Once free of blush, the epoxy needed to be sanded down flat for painting. This was done wet with wet and dry paper, which is a considerably more pleasant process than dry sanding. After drying off the hull, I masked off the outwale and applied the first coat of two coats of primer

The primer then needed to be flatted off. This was done wet with a fine grade of wet and dry paper. Then on went four coats of undercoat with wet and dry sanding between coats.

The process for the top coat was a repeated for the undercoat. After three coats of paint, I had a finish that, although I was not entirely happy with, was passable. At this point I decided to leave the hull as it was and turn my attentions to the decks & interior. The first thing I needed to do was to complete the sanding down of the epoxy to key the surface. I was not concerned with getting a super smooth finish to the interior. As on the model, the decks and outwales are to have a varnished finish. I also decided to varnish the stretcher and the seat. After masking off the areas to be varnished, I applied the two coat of primer to the interior. This was followed by a coat of undercoat. For the top coat I added a small amount of blue to the white to give me a light blue. I figured this would be easier on the eye in bright sunlight and would go with the hull colour. I now only had the varnishing to do. After completing the varnishing, I looked again at the hull and I was still not happy. I wet and dried sanded it down again and recoated. The finish came out better this time, so I could now pronounce the canoe finished!



Firstly, I had fun. Even in the middle of the sanding down, and with no other jobs outstanding that could be done as a break, it was still fun (in a masochistic sort of way).There will definitely be a second build.

There is no question in my mind that I did overbuild the canoe. I could have built it little cheaper and a lot quicker by not epoxy coating, by not being so bothered about the finish and by not using Douglas Fir (cheap DIY store pine instead) and so on, but that was not the reason for building.

As a test run for the next build, I think I achieved everything I wanted to and on the plus side the canoe will hopefully be around for a fair few years. My grandchildren (if there are any) may even get to use it.

Although it is my only build so far, but, with my experience maintaining other boats, I think that the small size of the canoe made achieving certain operations more difficult than on a larger build. Any operation that required force on the light weight of the canoe, meant it needed to be held down or strapped down. Working on the interior was difficult with the lack of space, especially when sanding down the hull panels. On the plus side, moving it around and swapping between the inside and the outside was no problem at all.

I would highly recommend building a small cheap boat such as this before going onto a larger second build. It is said that you should build your first boat second and having built this boat I can fully appreciate what is meant. I know that the experiences gained and lessons learned will make the next build cheaper (less waste of materials), quicker (relatively) and with a better/more easily achieved finish.

Main Lessons Learned

1. Only layout one panel of a pair - use the first panel as a template for the second. Obvious I know, but less so in this case because all the panels came out of less than a single sheet of ply.

1. All pencil marks on the panels should be on the side that will be painted when finished or use a soft pencil that can be easily rubbed out.
2. When taping seams, use the minimum amount of epoxy possible and allow time for the epoxy to soak into the glass tape - take your time and plenty of care.
3. When filleting joints, place the masking tape slightly further out than actually required (2-3mm) to make sure the fillet runs out properly.
4. Do not just touch in holes etc. with any left over epoxy as you go. Make sure you take the time to do it properly and if not discard the excess epoxy.
5. Although gluing the panels together and removing the stitches prior to glass taping is a good idea, I think I would modify the method:-
6.1 The stitching would be done as normal.
6.2 I would then glue the panels together as I have done this time, but I would use either a syringe or polythene bag with the corner cut off to a suitable size to fill between the panels only.
6.3 I would not worry about epoxy starvation as the seams will have further epoxy added with the glass tape and all that is required is to initially glue the panels together
6.4 This would then:-
a. Reduce the amount of epoxy spread out on the panels to a minimum.
b. Reduce the amount of epoxy wasted.
c. Almost completely get rid of the need to scrape/sand down.
d. Leave the inside of the hull clean apart from a bit of squeeze through.
e. Possibly aid in giving the glass tape a smooth radius between panels.
7. When drilling clearance holes, keep the hole as small as possible to help prevent squeeze through of epoxy.
8. When stitching thin plywood panels, I would consider closing up the stitch hole centres from 150mm to 100mm or even 75mm where necessary to better hold the panel edges aligned. This would help reduce the amount of filling required.
9. Ensure that you mix the epoxy and hardener for the full length of time recommended by the manufacturer (2 minuets for the WEST system). I timed my mixing and had no problems with epoxy not curing properly.
10. Although I was happy using the WEST epoxy system, I will try the MAS epoxy system next time as it is claimed to be amine blush free plus it has other features that would appear to make it more user friendly.
11. Wet sand epoxy, paint and any non porous surfaces whenever possible. Wet sanding gives no dust with the residue being held in the water. The sand paper cutting surface does not clog up and remains sharper for longer.

The End.



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