Kaimusailing

The attempt to make a dinghy using cheap insulation foam sheets has turned into a disaster. The foam sheets are coated with a film of aluminum on both sides and when it is removed, the foam sheet starts to warp. The attempt to use wood lath to make frames to keep the foam in line turned out to be as much work as making the enclosed foam filled seats in the original plywood dinghy. I was making the job harder rather than easier.
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I found that the local Lowes home improvement store now carried the polycyanoacrylic insulation foam, brand name R-MAX III, so we didn’t have to go very far for more of it. I will attempt again but change the technique to only remove the aluminum skin in a small area at a time, for instance, removing a narrow strip along the edges of the panels when they are taped together with glass, or, taking off a 1 foot wide swath and glassing it right away.
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Once I made the decision to abandon the foam dinghy build it didn’t take me long to chop it up with a sheet rock knife. I also used the knife on the blue inflatable that I had been trying vainly to hold air. I cut off all the hypalon, then used the multitool with a scraper blade to scrape off the scraps that were still glued onto the fiberglass RIB.
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I continued, using a piece of scrap foam insulation that was a full 8 feet long and wide enough to use as a dinghy side. It took some time to mark it up, a little bit at a time, and tape it to the RIB. Eventually the piece of insulation matched the edge of the rigid bottom and a fair line was drawn, the gunwale. After the piece was cut out it was used as a pattern to cut out a mirror image for the other side of the dinghy. The ends where the side of the dinghy would meet the transom and where the front edge of the two sides would meet to form the bow were left unmarked and uncut. I’m not sure at this point if I am going to make a whole new transom (I had already cut out a transom for the abandoned dinghy) or make filler pieces to fill in the round spaces where the inflatable tubes met the transom. The transom has some damage to it.
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After a few days I decided to remove the wood core from the transom and replace it with new plywood, and then feather the edges of the glass sheathing, trim any flanges flush with the face of the transom, and then glass the whole thing after gluing the plywood into the transom. The main problem was getting at the old plywood which was like mush in some areas.
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I returned the next day with a 1/2“ chisel, drill with long 1/2“ bit, angle grinder with chainsaw blade, and the multitool with the scraper blade. The glass sheathing on the transom was kind of flimsy when it was separated from the wood. The wood was drilled, chiseled, scraped, and removed in any way possible. It looked like I couldn’t remove all of it, but the small remaining bit at the bottom of the transom would be soaked with epoxy, hopefully strengthening it.
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I used a 2‘X4' project panel from Lowes to make the new wood core for the transom. While working on the transom the boat fell off its sawhorses and the foam split right across the sides of the hull from about amidships to the stern. This foam has no strength at all. It can be repaired when the hull is glassed.
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The wood core was epoxied into the fiberglass faces of the transom. After it set up I taped the ends of the foam sides to the edges of the transom on the outside with Gorilla silicone tape. Then I prepared two thin glass strips, one in each corner of the transom, to attach the foam to the inside face of the transom, and glassed them in. After they set up I glassed the outside corners.
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The foam had big longitudinal cracks in it where it failed when the dinghy fell off the sawhorses. Also the foam was irregular and didn’t form a fair curve as it bends around the sides of the dinghy. I used cheap pine laths to stiffen the foam. I planned to have two stringers on each side, one stringer was actually a gunwale and is mounted on the outboard edge at the top of the side, the other is a stringer that supports the seat(s) and is located inboard on each side about 8 inches above the sole of the dinghy. I placed stringers inboard at both positions with lath cut to length pushing outwards to force the stringers into a fair curve and touching the foam. Now additional outboard stringers were screwed through the foam into the inboard stringers. When the inboard and outboard stringers were tightly fastened together the foam insulation now had a fair curve. The edges of the foam where it had cracked didn’t line up exactly, so I tapped screws into the inboard stringers at spots where they had to be pulled in toward each other and tied 80 lb. test monofilament line to the screws and drew the sides toward each other to line up the edges of the crack(s).
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During this time I received a Windows 7 laptop for 74 dollars and set it up to use with my boat design programs, which mostly run on Windows or DOS. I had to buy a new battery for it at $14, but otherwise it runs and looks like a new laptop, but of course obsolete, according to the experts. Steamfitter Bill brought his computer down and we installed OpenCPN and over a terabyte of nautical charts.
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I have received some flak about not posting frequently enough, but I can point to Jack van Ommen who last posted on October 15th of last year. C’mon Jack.
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The photo is of the inside of the dinghy project showing the temporary stringers and braces and the foam insulation that is so hard to work with.