Water proofing urethane

[Lulu]

I have a question, "What sealant is used to waterproof polyurethane?" I'm cleaning up the fish hold making ready for a possible focus on tuna in 2016. I need to waterproof some patches to the fishhold's insulation which I'm told is sprayed on urethane foam. It appears the original waterproofing material is some type of latex or rubber compound, but I have not found anyone who knows for sure. Does anyone remember how steel boats were insulated back in the 70-80's?

[JKD]

I can't help you directly because I have forgotten what the product was called, but you must have a few private outfits that spray urethane insulation down in your area. Most of them are pretty up-front with how they seal the products they apply for insulation. I know there a few different types of urethane - and some do not react favorably to epoxy or fiberglass resins.

In 1997 I ran down to Bellingham and stripped the entire fish hold in the steel troller I owned at the time. The foam in the hold was saturated because I had used the vessel for crabbing. The sub-contractor came in and sprayed the hold surfaces with a urethane foam and shaved it to the thicknesses we needed for freezing and holding the catch. I don't know the name of the product, but just before they applied fiberglass resin and filament "skin" with a "chopper gun", they sprayed a layer/coat of clear "stabilizer" on the raw foam to prevent a reaction between the urethane and the fiberglass resin. They did a beautiful job.

I'll try to remember to ask our local fiberglass guy if he has any recommendations.

[Lulu]

JKD, thanks for the response. I'm going to try a few boat builders. I talked with Whal Marine when researching the paints to use on the bottom after sand blasting. They were really helpful. I'm beating they'll know what I'm talking about.

[JKD]

Lulu - Wahl does some retrofitting on boats so they may/should know exactly what you need.

[Breadline]

I think what you want to look at are the polyurea coatings, truck bed liner is one example, but there are many forumlations out there. They are generally spray applied, cure super quick, and are waterproof. I believe that the coastguard RIB sponsons are polyurea over foam of some kind, tough stuff. I have nrver personally used the stuff, but wished I had looked into it when I built my holds last year

[Lulu]

In the process of making the fix. Wahl Marine referred me to Versaflex, a manufacture of urethane and polyurethane products. I was not able to find anyone that knew about applications back in the 70s. But, Versaflex was able to provide a best guess to what might work today. Its better than tearing everything out and starting over from a time and cost perspectives.

I'm repainting bind boards and building a few replacements that were broken last crab season. I hope to have all the metal in the fish hold cleaned, prepped, and painted with new epoxy this week. Somewhere between these projects I'll experiment with a small, easy to access, spot of urethane that needs water proofing. If it works, I'll finish water proofing all the patches and hopefully have a brand new fish hold ready for a load of tuna by late next week.

I'll let you know how it goes and the products I used after I know they work.

[Lulu]

OK, after hours of research and phone calls, I found a product that seems to work thanks to Bob at Walh Marine's referral. VersaFlex manufactures a number of polyurethane products for use in a wide variety of applications. The product I tried is a patch product called VF HM/45. It comes in 1 and 5 gallon kits, has a pot life of about 5 minutes (which means you have to mix small batches and work fast). When it's cured it looks like Tool Dip. It does a nice job of filling holes in the urethane , but you have to work it in with a brush. The one gallon kit (A and B) was $110. I could have sprayed the entire fish hold had I used a sprayer instead of a brush. VersaFlex will pigment any color you want or send you the pigment for you to mix. I had them mix whatever was easy; which ended up being a light grey. It's the fish hold, who cares what color it is?

There is a second product called Tack Coat ($55). It comes in 1 gallon containers. Highly recommended to wear a respiratory when using this stuff because it is a powerful solvent. It's general purpose is to clean and soften the urethane before applying the HM/45. And it works.

The problem was this stuff is it is so toxic it has to ship on a pallet. It cost about the same to ship as the cost of the products. I did save some money by will calling to the Fed Express distribution center. VersaFlex doesn't have regional distribution centers. Everything is shipped from Kansas City.