Sealing Screw Fasteners on Deck; Free Water in Fuel Tank Cavity

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
rnln
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Joined: Mon Aug 23, 2021 6:15 pm

Sealing Screw Fasteners on Deck; Free Water in Fuel Tank Cavity

Postby rnln » Tue Oct 05, 2021 3:11 am

Q1: [To seal screw fasteners on the center deck area of a Boston Whaler boat that covers the fuel tank area] what sort of sealant is recommended?

Q2: is 3M4200 recommended [as a sealant for screw fasteners on the center deck area of a Boston Whaler boat that covers the fuel tank area]?

Q3: in a Boston Whaler boat that is rocking, [can water that accumulates in the fuel tank cavity splash upwards and penetrate between the fiberglass laminate layer of the deck and the wood reinforcement backing]?

[Moderator's comment: separated from another thread on a tangential topic.]

jimh
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Re: Sealing Screw Fasteners on Deck; Free Water in Fuel Tank Cavity

Postby jimh » Tue Oct 05, 2021 8:03 am

rnln wrote:Q1: [To seal screw fasteners on the center deck area of a Boston Whaler boat that covers the fuel tank area] what sort of sealant is recommended? what sort of sealant is recommended?

BoatLife brand caulk is often mentioned as a good sealant. If a silicon-based caulk is used, the silicon should be of the type that does not leach acetic acid when curing.

rnln wrote:Q2: is 3M4200 recommended [as a sealant for screw fasteners on the center deck area of a Boston Whaler boat that covers the fuel tank area]?

The product 3M4200 is a very strong adhesive. Using 3M4200 as a caulk or sealant is not recommended, unless you also want its strong adhesive properties to glue together the two surfaces involved. For a metal screw fastener that may need to be removed in the future, using a strong adhesive may create future difficulties. Also, the time to full cure for 3M4200 can be a week.

rnln wrote:Q3: in a Boston Whaler boat that is rocking, [can water that accumulates atop the fuel tank in the fuel tank cavity splash upwards and penetrate between the fiberglass laminate layer of the deck and the wood reinforcement backing]?

I have never seen any water accumulate on top of the fuel tank on my Boston Whaler boat in any volume that could produce a slashing. If enough free water exists on the top of a fuel tank that a worry about it splashing around is created, a much bigger problem exists than concern it might get into the wood backing of the deck. You should probably start bailing.

rnln
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Joined: Mon Aug 23, 2021 6:15 pm

Re: Sealing Screw Fasteners on Deck; Free Water in Fuel Tank Cavity

Postby rnln » Tue Oct 05, 2021 9:19 pm

Thanks JimH