Interesting. Perhaps because it can become saturated. My hot tub cover (styrofoam) got waterlogged and was super heavy and only 4 years old. I guess the stuff will eventually absorb moisture. Sounds like that's what happened to your boat.
I just got caught up in "mission creep" while setting out to repaint the dinghy's gunwhales.
I managed to break my hot knife in the process, but it was useful while it lasted. I bent it so much that the leads bent and connected shorting it out. Finished the job with the pruning saw and chesils. Just have some corners to clean out and to sand down the whole area. Someone mentioned the idea of placing a protective wrap/cover against the hull before pouring the new foam mixture in to facilitate the removal of the new stuff down the line when it, too, needs to be replaced. Does anybody have a suggestion of what to use? The foam mixture generates heat as it expands. So, I am thinking a simple thick plastic garbage bag would not survive that process and would itself trap moisture should my new sealant begin to leak going forward at some point. I was wondering about gardening cloth. It lets moisture escape but is fairly rugged. Open to suggestions. 
The PVC pipe runs from a drain hole in the "cockpit" through the transom so water can be drained while washing the boat or upon trailering the boat with rain/bilge water to get rid of. It has a bronze screw-in plug for sailing/motoring. It needs to be carefully sealed around it's through-hull/cockpit openings, too. I'm adding an old pic of the boat rigged for sailing. these work pics are so grimy; I want to show how nice she looks when "shipshape!"
Ordered. Thanks. Got a wedding for a grandson this weekend, so give me a couple of weeks for follow-up. Just so happens, he's the same kid standing at the bow of Laddie II in the pic. He's 28 now!OverEasy wrote: ↑Sun Jun 22, 2025 12:53 am Hi Herschel!
I’ve used polypropylene sheeting, like the mid/heavy drop cloth type.
It worked well for fiberglass work area protection too as ‘generally’ the fiberglass doesn’t stick to it ….
Has stood up to the heat generally well.
I’ve gotten it at Home Depot, Lowe’s and paint stores.
Hope this helps…
Pretty boat she was, gorgeous she will be!
Best Regards,
Over Easy
Cheers, Herschel
We are inching forward. Got the grandson hitched very nicely last weekend in Seattle. Beautiful couple. They will do well. BUT...we contracted COVID apparently at the reception, and upon returning to Orlando early Monday morning came down with symptoms a day later. Our PCP got us on the meds to help, but it is still a formidable experience. As for the dinghy foam extraction, that is complete. I have all the materials I think I need for the replacement foam and a plan to implement...as soon as I get some energy. The more I approach even this simple "practice project" I am becoming more aware that I am doing these projects mostly for the next families that will enjoy these boats. Maybe my own sons or grandchildren; maybe someone else. Yes, I'll have some fun with them a few more years, but I want to do a good job so that those families will be well served. And safe, and have nice boats to be proud of and want to be maintained well.OverEasy wrote: ↑Sun Jun 29, 2025 8:28 am Hi Herschel!
How goes it?
The temperatures up here in South Carolina have been tough as of late in the 90s with equal measure of humidity!
I can only image what you’re contending with where you are at!
I copied your idea of the pop up shade for working on the trailer refurbishment.
It makes a difference!
If I was to be doing this on a regular basis I’d need one of those big directional swamp coolers!
How is it working with paint & fiberglass with the temperature and humidity you are experiencing?
Hope all goes well for you!
Best Regards,
Over Easy
Sometime this summer i need to trailer my Mac and have the yearly/100-hour service done on my 2013 50 Yamaha. It only has 364 hours. That's a two-day evolution for me and the Admiral; i think my son will help this time, though. Should go easier. 
And Good Luck with your project; you will likely be ahead of me on that. Pass on lessons learned. I don't see getting to the Mac until October/November time frame. 
