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Advice and Guidance Needed
Posted: Sat Jun 03, 2017 11:07 pm
by csnco
Would exhausting a 3" x 4" engine, operating non-condensing, through a bronze thru-hull fitting above the waterline likely overheat the immediately surrounding region in a GRP hull?
All thoughts appreciated.
Re: Advice and Guidance Needed
Posted: Sun Jun 04, 2017 8:08 am
by RGSP
The maximum operating temperature for polyester resin is often given as 70C, with a glass transition temperature of 80C, and your exhaust may be well above that. As a short term thing it might be OK, but I'd avoid it myself if possible.
Re: Advice and Guidance Needed
Posted: Mon Jun 05, 2017 2:47 am
by cyberbadger
Have you looked at internal crumbustion engine exhaust thru hulls? If you are not restricting the steam exhaust those can definitely handle the heat.
You could alternatively just wrap the steam exhaust pipe with some ceramic fiber and use some wood/brass trim to hide the insulation. You wouldn't need that much to insulate it enough that it will keep the fiberglass from melt damage.
As far as the exact numbers, it depends on the resin/epoxy/plastic formulation in question whether it will be damaged without thermal shielding.
-CB
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Re: Advice and Guidance Needed
Posted: Mon Jun 05, 2017 3:28 am
by Lopez Mike
I.C. exhaust is almost always mixed with cooling water and is probably a bunch cooler than steam exhaust. On the other hand, by the time the steam gets to the through hull it is likely to have cooled down so far that it won't be any threat to the F.R.P.
Sure you don't want to send it up the stack and get some draft?