Seal Flybridge Deck Hatch

[UrsusMaritimus]

Good day,
My Hershine Sundeck 42 has a large hatch in the flybridge floor meant to be removed if engines needed to be lifted out. Over the last few years I have had much frustration with trying to seal this hatch. At this point I am considering a layer or two of fibreglass over the entire seam.

I have two questions for the group. First, does anyone see an issue with this, aside from the fact that it would need to be cut if the hatch needed to be removed. Second, is there any issue with fibreglassing over top of the Sikaflex that is down inside the seam. Obviously, I know I have to grind the deck to bare glass for the fibreglass to adhere, but do I need to dig out the sealant from the seam first?

Once this is completed the plan is to apply EVA Foam flooring (which is what was there previously).

Thanks!

 

[Comodave]

I guess it would be ok. I would take very careful measurements before you glass it so if needed to cut it open you will be able to make the cuts in the right places. I would grind a shallow valley for the fiberglass to lay in so you don’t have a hump when you are done. Then I would lay in a layer of 1708 and a second layer a bit wider. I don’t see why you would need to remove the caulk before glassing.

 

[UrsusMaritimus]

Thanks Comodave I can still access the backside of it from the salon just by removing some moulding, so that’s an upside should I need to cut it open later. Agreed on the method for laying in the glass… and I didn’t think there was an issue with the caulk, just wondered if the hive mind thought differently.

 

[Jaep]

I would think it would be easier to unbolt the hatch. Thoroughly clean both surfaces. Tape off, use dow corning 795 or caulk with a large temperature expansion. Could use a combination of butyl tape also. Do not excessively tighten and blow out the sealant. Let dry for days if it is thick. Kind of same as a window installation. If being walked on. You can place small blocks of pvc inboard of caulk to take the load and minimize flex. Wrap a ring of butyl around head of mounting bolts under washers.

 

[Comodave]

While I am a big fan of butyl tape, just used a bunch yesterday, in this case if he ever wants to open the hatch the butyl will be a mess. I believe it would be easier to cut the fiberglass and then grind of the residue before reglassing it.

 

[SIBERNUT]

If you're gonna put eva foam deck over it, why bother? Fair it & put the deck on

 

[UrsusMaritimus]

If you're gonna put eva foam deck over it, why bother? Fair it & put the deck on

It was faired in before, with EVA foam over and the fairing cracked and leaked.

 

[SIBERNUT]

I thought that decking was waterproof....

 

[Long Island Boater]

I’m surprised anything gets past the Sikaflex, but I’d go with 4200 /5200 before going through the process of grinding and fiberglassing. Another product I have used in areas where there’s expansion and contraction or movement is West System G-flex.

WEST SYSTEM G/flex Epoxy Resin and Hardener Kit​

$34.82In StockSee

 

[kapnd]

I’d redo the sealing with 5200, it won’t leak if done correctly.
Lay a piece of thin SS cable in the bottom so that it can be used to rip through the sealant if the need ever arises to remove the hatch later.

 

[ABfish]

I'm scared of 5200; it's incredibly tenacious and generally intended for permanent installations. The 3M 4200 would be a better sealant for something that might be removed in the future.

 

[Comodave]

I only use 5200 for things like through hulls and transducers.

 

[SIBERNUT]

I like the embed wire idea, but id use
piano wire

 

[kapnd]

I don’t understand all the hate that 5200 gets.
It’s a truly excellent sealer, and, contrary to popular belief, can be removed with a bit of diligence. Worth it, IMO, especially in situations where a leak could be disastrous!

 

[SteveK]

I don’t understand all the hate that 5200 gets.
It’s a truly excellent sealer, and, contrary to popular belief, can be removed with a bit of diligence. Worth it, IMO, especially in situations where a leak could be disastrous!

Never having used it, let me be the one to ask you about "a bit of diligence" needed to remove it without harm to other components.

 

[Comodave]

It is a royal PITA to remove. Yes it can be removed but it is a lot of work and can damage the gelcoat or fiberglass. It has so much strength that it can rip the gelcoat off. I only use it where I need the extra strength.

 

[kapnd]

I’ve removed my fair share of it, mostly from replacing thru-hull fittings and transducers.
Haven’t experienced it lifting gelcoat.
I usually try to cut it loose first, using a knife, wire, or razor, or whatever the situation demands, then carefully scrape the remainder off the surfaces.
Heat helps loosen it up, and WD40 helps cutting tools move through it.

 

[Comodave]

I believe the PSI strength of 5200 is more than most gelcoats. I am not saying that you will rip off the gelcoat but rather that it can happen.