Sunday, October 21, 2012

Building A Canoe: Steps VIII, IX, X

Part VIII - Fiberglass The Outside
After cleaning up the outside, the next step is to seal the wood with epoxy before starting the fiberglassing. I'm using West System's 105 resin and 206 slow hardener. For this size project, Gil Gilpatrick says you would need two containers of the "Group B" units, which is about a gallon container of the 105 resin. I really like West System's measuring pumps, which makes accurate dispensing so easy. The directions say that slow hardener shouldn't be used if temperatures go below 60 degrees (the directions warn about it possibly not curing at all), so it was fine for September, but I switched to the fast hardener, 205, for fiberglassing the inside, which I did in October. Actually, I found that 206 still works with night temperatures going down into the forties, it just takes longer. Anyway, the sealing process is the easiest part of the whole project, it just took a few minutes to mix up the epoxy and spread in out in a thin film over the hull.

After lightly sanding the surface, I reinforced the stems, as Gil recommends, with two layers of fiberglass on the bottom part of the stem and one layer on the front section. This is good practice for learning how to work with epoxying fiberglass. My work wasn't perfect but it can be sanded smooth enough and another layer or two of fiberglass goes over it anyway.
 Reinforced Stem
I should have taken a picture of the fiberglass before epoxying the hull. There are actually two layers on the bottom, one being an (American) football shape, the other covering the entire outside. I found the process of wetting out the fiberglass with the epoxy and getting it smooth to be very stressful because of the importance of finishing before it starts to harden. It is probably best done with two people, preferably with at least one person knowing what they are doing, but, all the same, it was doable. The biggest problem I had was in rapping the fiberglass around the stem. I ended up with a bit of a mess, partly because of inexperience but also because, when I read Gil's instructions I didn't turn the page and look at his picture, which would have clarified exactly what to do. Oh well, I figured I could clean it up with my Festool sander when it hardened, which I did. Problem solved.

It ended up taking about 3.5 hours (with a temperature of 77 degrees at 1:00 when I started) to wet-out the fiberglass (with epoxy squeegee cards) and by the time I was done, the first part had set up too much to be manipulated any more. I should have gone over the first part with a roller when I was halfway done, so the job wasn't as smooth as I would have liked.  
 Fiberglass Outside
After cleaning up the purely amerature, but passable, epoxy job, spreading out a second coat of epoxy was easy. Gil says that a third coat may be needed to fill all the fiberglass fibers, and mine were definitely not all filled, but other people I've talked with recommending using as little epoxy as possible because it adds too much weight and just looks bad the more there is. Better to clean it up and add many coats of varnish after the second layer of epoxy, so that's what I'm doing. 
 After Two Coats of Epoxy
Part IX - Clean Up The Inside
In turning the canoe over, I finally had to deal with cleaning up the inside -- not a particularly appealing task given the difficulties I had created for myself.
Start Cleaning Inside
Here is a better view of the hundreds of dowels (approximately 1500) I had sticking through the hull. I trimmed them with my dozuki (Japanese pull saw) before pulling out my Festool sander/grinder again. Because it was impossible to trim them flush, it was difficult to keep the remaining dowels from tearing up the sanding pads. Eventually, I managed to get it reasonably smooth with 40 grit paper before switching to 60 grit. After 60 grit, I started filling gaps with epoxy again, and then cleaned that up with 80 grit paper. I went over it with 120 paper before going back and rubbing it out with 100 grit by hand.
The hardest part was cleaning out the stems. I had to use chisels and coarse paper to get it reasonably clean. As long as no one is inspecting it with a flashlight, it should be good.
Unfortunately, the canoe flattened out as it rested on the saw horses without the forms. I added some support but it really didn't help much.
Part X - Fiberglass The Inside
So I put it on the ground before sealing with a first coat of epoxy. Again, pretty darn easy process. I used one of those cheap disposable Chinese brushes to get epoxy in the stems.
 Inside Sealed with Epoxy
I had to sign it before epoxying the inside and debated how to date it. I'm not sure that I'll finish this year but didn't want to pre-date it either. I decided to be optimistic and sign it 2012.

I decided I'd better pull the sides together before fiberglassing the inside for fear it would be too difficult to do after the fact. I used the forms to be sure I got the dimensions right.
I was fairly nervous about fiberglassing the inside. Gil's description made it seem pretty difficult and he ends the discussion with what I preceived to be hallow words of encouragement -- "You can do it!" I took this to mean, "I can't do it and it will look shitty" and thought it might make sense to do it in two sections that overlapped. My neighbor, who hadn't built a canoe but has plenty of fiberglass experience thought this was a good idea, but luckily I ran into a friend, who has built a canoe, the day I was going to do it and he talked me out of it -- just one piece, one time. 
It went smoother than I expected and only took 2 hours. The inside stems where much easier than the outside because Gil recommended just cutting the fiberglass short and not worrying about getting it in there.
I thought it looked pretty good when I was done and I had time to go over it several times before it set up but, unfortunately, the next morning I noticed a lot of ridges in the fiberglass. I guess I didn't pull the fabric tight enough as I was wetting it out. Oh well, again, this is what the Festool sander is for (and no, they aren't paying me to say this but I certainly wouldn't mind if they did). Of course, sanding it smooth really thinned out, or totally removed, the fiberglass in some small areas, but I'm thinking that on the inside it isn't going to make much of a difference.
Unsightly Fiberglass Ridges  
And here it is after the second coat of epoxy. It has settled a bit again. Though the width should be a little less than 35 inches, and it is about 38 here, I should be able to pull it back into shape when I add the yoke and seats. 
Fiberglassing Done!

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