Quite a bit of work has been done over the past week or so, but I don't have a lot to show for it. I have begun fiberglassing the insides of the side and topsides panels of the hull. The bilge (bottom) panels are not 'glassed at this time, partly because it would be much too difficult to force them into the proper shape. There are other reasons which will be easier to demonstrate as the boat comes together.
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| Upper Panels Final Coat |
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| Upper Panels Fiberglassed |
On the right are the same two panels after applying two more coats of epoxy. I only have room to do two panels at a time.
Not much difference between the two pics, except you can see how much glossier the epoxy is after the finish coats. That will all be sanded down to a uniform dull finish. Any shiny areas will help to detect low spots. The sanding is kind of a balancing act for me. I want to get the surface as smooth and flat as possible, but at the same time I don't want to sand down into the fiberglass weave--or worse, down to the wood! I'm amazed I was able to get the entire length of the panels into the shots. They are about 15 1/2' long.
This is probably all I will be able to do for a while. Unless plans change, Jan and I are headed for L.A. a week from today and will probably return in a little under a week. I'm keeping the garage at about 55-60 degrees, which means the epoxy will take approximately 7 days to fully cure using a medium hardener mix. Obviously, I don't want to leave the heater running while we are gone. We're expecting some warmer weather this week, so I'm hoping the heater won't have to run all that much while we are here. I'm feeling guilty enough as it is. I have added insulation to the garage door, and it seals very well around the edges, so that helps. I just wish the garage itself was insulated. If I ever start another boat project I will probably do that first. I was thinking of building a small tent of clear plastic sheeting over the whole thing, but decided that would be too dangerous.
Hi, haven't begun building my pocketship yet but am trying to read all the blogs and info I can! I've read that you can apply a second coat of epoxy as soon as the first coat "sets" (no longer sticky, but still can dent it with a fingernail). That way you don't need to wait until a full cure and you don't have to sand the surface between coats. Have you tried that strategy and have you found it to be effective?
ReplyDeleteYes I have tried that strategy and found it to be effective. I do it differently now though. I have printed out a table from MAS Epoxies that gives Pot Life, "Thin-Film Set" time, and Full Cure time for a variety of temperatures. I apply subsequent coats after Thin-Film Set and long before Full Cure. Pretty easy in cooler weather. For example, with the garage at around 59 degrees and using medium hardener, I can apply my next coat after 6 hours, but I still have 7 days before full cure. I think it's chancy to wait too long though, so I try to apply the next coat within 24 to 48 hours. When it gets hot, say 95 degrees, then with slow hardener I can apply the next coat after 2 1/2 hours. Full cure occurs at 2.5 days, so I always get the next coat on within 24 hours. If you wait too long, you do have to sand it to get mechanical bonding. If you apply the second coat in time then you get chemical bonding, which I believe is better. Does that help?
DeleteHF caged Lamps does it for me. Leave overnight aimed at area to cure. Also use slow cure West epoxy.
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Yes, I've used that method in the past. Problem is, with 16-foot boards it would be a little hard to heat evenly down the whole length, so I'm happy with the way I'm doing it. Also the electric heater is safe and has a thermostat so I can set the temp where I want it.
DeleteI'm not sure where my brain was when I replied to your first comment--maybe still loopy from epoxy fumes? Anyway, with MAS epoxies, you can apply the second coat as soon as surface tack is achieved. They say on their website that if a bit of cotton from a cotton ball sticks, then you can recoat with no sanding. If you can press with your thumb and leave a thumbprint, but there is no tack, then you need to scuff sand. Best chemical bond is achieved when there is still some tack, though, and no sanding--so try to recoat while there is still tack. With West System resins they say it should still be rubbery but not sticky. So it depends on the resin brand, e.g., MAS is "100% solid (no solvents)." One of the most important things is to do your fill coat the same day, because you should not sand the first "wetting out" coat or it will weaken the glass fibers. Two good resources are: The epoxy company's website and "Epoxy Basics" by Russell Brown.
DeleteThanks for your help! Of all the things I'm worried about building this boat, Epoxy is probably the biggest. Seems like a very finicky system with little room for error, and I have no previous experience. I've read enough horror stories of epoxy-gone-wrong and don't want to mess anything up! So thanks.
ReplyDeleteMy plans arrived Monday and I officially kicked off construction... cross your fingers, hope it goes well :)
Just be sure to read and re-read the instructions and plans. The Pocketship manual does not include as much "hand-holding" as some of the others so refer to the forum (Pocketship.net) often and write directly to CLC when you have to. From what I have read, MAS is the easiest to deal with, and no solvents so little or no odor. The book I mentioned is based on West System, but most principles are the same (except for when they say you should recoat). If you wait too long don't worry, you can always sand and recoat, just a lot more work. Also, if you wait way too long you will get a mechanical bond only, no chemical bond. It's best to be sure this does not happen to parts that will have structural parts, like bulkheads, attached to them. Also, take a look at some of the blogs by users posted there.
DeleteThat last sentence should have ended with " . . . posted on the forum." Some of the most helpful photos are by Jeff Hatch at http://www.flickr.com/photos/35243545@N02/ . No commentary, but there are tons of pictures that show a lot of detail. The photos start with the latest ones, so scroll down to see how he did things from the beginning.
DeleteGood morning from Arizona! Can't get it in my head that the edges of the transom are not glued to the bottom and side panels. Is that true? The manual indicates only temporary screws, then the fillets. Is that correct? Thanks
ReplyDeleteCorrect. In the beginning the transom is held in place by temporary screws and fillets. The fillets make for very strong joints, but later fiberglass is added to inside and out (and perhaps fiberglass tape--don't remember), further strengthening the joints. The screws are left in place until it is time to apply the fiberglass on the outside.
DeleteCorrect, the transom is held in place with temporary screws and fillets. The fillets are very strong, but later fiberglass cloth and epoxy are applied both inside and out, further strengthening the joints. There may be fiberglass tape also, I don't remember. The screws are left in until time to fiberglass the outside.
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