I wish everyone (myself included) a happy and productive 2017, which for me would entail getting this boat done enough that I can finally splash it and take it around to my home port!
With the exhaust risers welded up and the starboard riser insulated, I bought some high temp epoxy resin with the intention of making a hard shell to cover the insulation. But the more I try to make a hard shell, the less convinced I am that I can pull it off. I welcome any suggestions or comments about how to proceed.
I dissected this riser to see how DeAngelo makes them. It’s just a shiny fiberglass layer over dense blanket insulation. But this riser doesn’t have the sharp mandrel bends that mine does, so wrapping it would have been pretty easy. Then there’s the shiny coating, which appears to be just tinted resin that’s heavily saturated the fiberglass cloth below. The more I think about it, if I wet out fiberglass that much, gravity will take over and it’ll end up dripping onto the floor. All I can come up with is that I’d need to mount the riser in a low speed part rotator that kept moving until the resin set up to get a nice, uniform surface like DeAngelo does. Otherwise, I’d need to use the same approach as we did when we made the cabin top bullet-proof, and do the FRP layer, then top with fairing compound, THEN come back and sand, prime, and paint later. But fairing compound, epoxy primer, and urethane paint aren’t high temp products…that can’t be the right way to do it.
The 1″ ceramic blanket I’m using as primary insulation is outstanding to work with, and the Inferno Wrap is much, much easier to use than any fiberglass strip product I’ve seen. But after thinking about this over the last couple of weeks, I decided that if one layer of ceramic blanket is good, two would be even better. So…off came the Inferno Wrap and out came the scissors.
I wasn’t going for a nice, uniform wrap because I was still planning on doing a fiberglass hard shell at this point. Even without uniform spacing, the Inferno Wrap looks good and holds everything securely. The Inferno Wrap manufacturer recommends the use of straps to permanently hold their product in place.
At the sharp bends, the heavy cloth leaves high ridges at every overlap. At the exhaust flange, I never was able to get it to lay down nicely in full contact with the substrate, even though I spent two whole days trying. Maybe if I overlayed the 1708 with a lighter fabric…
It turns out that the lighter 9 oz fabric lays down even worse around the tight mandrel bends than the 1708. It looked worse with the added layer. So, then I thought maybe I should use the 9 oz fabric as the base layer, and top that with pre-pregged 1708. So I gave that a couple of dry test fits…total failure.
I tried every permutation in wrapping the FRP, but none of them worked. Now I have a bunch of strips of fiberglass fabric with tattered edges from being handled too much, especially the lightweight stuff. I realize that when wetted out, fiberglass fabric can become quite pliable. But these mandrel bends are tight, and I don’t know how to keep everything in place and smooth until the resin cures.
It did occur to me that I could try wetting out the Inferno Wrap with resin and applying it. I also suspect that DeAngelo isn’t using straight fiberglass to get that nice, smooth finish. But then another thought occurred to me: why not just forget the hard shell? Granted, it’s prettier than fabric insulation blankets, and the hard shell would tend to reduce the possibility of corrosion under the somewhat permeable insulation. Plain Inferno Wrap would eventually get dirty, but if it does (and it bothered me) I could just put another layer on over the top. And there’s still that question of how to keep the resin dripping off until it cures.
I’m leaning toward abandoning the hard shell and just using the double ceramic blanket topped with Inferno Wrap, secured with stainless straps. Feel free to make suggestions/comments below.
Next up on our 1969 Chris Craft Roamer 46 Refit: Priming the V-berth Head