Spray Foam and deck fittings?

[Sierra2]

Afternoon all.

 

In my case this question is regarding a GRP cruiser and not an NB (although the question may be relevant to both)...

 

Do or should you leave access to the bolts/nuts for cleats, railings etc on the inside of the boat?.

 

Part of me thinks if the fitting on the outside deck is tight and solid then spray foam insulation on the inside would be the 'final' waterproof sealant to back up the mastic sealant.

 

Of course if the fitting is damaged at a later date and needs replacing, how big a nightmare is it to cut out the area of spray foam to gain access to the nut or bolt holding it?.

 

Boxing off the area needed to get to said nuts/bolts from the inside with plywood I guess would be an option but create a chink in the insulation?. Would making a plug from Cleotex to fit the plywood hole work?

 

What would you do!?

 

Thanks

 

Chaz

[system 4-50]

Cutting foam away is easy.

[Paul's Nulife4-2]

Hi ya,

We'll I would think there are only 2 ways to do this,& Ofcourse there is an argument for both.

When I sprayfoamed under the gunnels on my GRP boat many moons ago.,I made sure all the backing pads for all the deck fittings where replaced,all Deck fittings where re bedded on sickaflex,new big solid washers then spring washers,then the nut.. Then I did sprayfoam the lot.

My thinking wad no sweating or condensation to form on the metal parts of the fixings.

Then when I clad the internal skin I put removable access pads over the fittings,,but these where never needed. All I can say is I had no problems.

Good luck with whatever you decide.

 

Note

Make sure there is a solid core between skins of GRP,if its a sandwich construction.!.

[Sierra2]

Thanks for the advice guys.

 

How does the Stryo (spelling??) Foam you get say your TV out of the box in compare to set (closed cell) Spray Foam?

[Bee]

Spray the lot, closed cell foam shouldn`t soak up water, the other stuff will but for insulation it`s ok but I wonder if it is more flammable and toxic if burnt?

[blackrose]

Thanks for the advice guys.

 

How does the Stryo (spelling??) Foam you get say your TV out of the box in compare to set (closed cell) Spray Foam?

 

Expanded polystyrene (EPS) or Styrofoam comes in several different densities for different applications, but (assuming your question is about the insulation properties), then in general the thermal insulation properties of expanded polyurethane foam (sprayfoam) will exceed those of EPS.

 

Sprayfoam also has other properties such as adhesion to the substrate (in your case GPS) which help to eliminate condensation occuring between the two materials. EPS can't do that unless it's bonded to the substrate.

 

I go along with the others and think that as long as you don't need access you should sprayfoam over the lot. It should help prevent any non-stainless nuts etc corroding. If you do need to get the cleats off one day then it's not difficult to gently cut the foam away with a chisel.

 

Edit: I would also bed the cleats in with marineflex to prevent any water getting under them. Clean-up with a cloth dampened with white spirit before it goes off (several hours). Try not to get it anywhere near the threads underneath as it will make it difficult to remove the nuts from the bolts!

 

http://www.marinemastics.com/marine-flex.html

Edited November 23, 2013 by blackrose

[Sierra2]

Sorry my bad, I wasn't suggesting using TV box packaging to insulate my boat as I already have decided to get a contractor in to spray 'the good stuff'....

 

My badly worded question was how does the finished (set) product compare in terms of feel to it. Can you break it off quite easily like the goods packaging or would you need to score it with a Stanley knife, hammer and chisel etc?

 

I've not seen spray foam up close so I've nothing to relate to it.

 

Chaz

Blackrose: Many thanks, sound advice

[Paul's Nulife4-2]

Think 'chocolate crunchy bar,the honeycomb center bit'

Very easy to saw,cut shape ect. I found a plaster board hand saw the best (screw fix).

Edited November 23, 2013 by Paul's Nulife4-2

[smileypete]

Could always cover around the deck fitting with parcel tape or cling film to make easier to dig out. Or even cut a section off a plastic bottle too and tape/hot melt glue it up to form a ready made access plug.

 

cheers, Pete.

~smpt~

Edited November 23, 2013 by smileypete

[nb Innisfree]

Think of PU foam as an adhesive with bubbles in it.

[blackrose]

Think 'chocolate crunchy bar,the honeycomb center bit'

 

I've never actually tasted it, but you make it sound very appetising indeed!

 

I wouldn't try it while it's still wet though...

Edited November 23, 2013 by blackrose

[Paul's Nulife4-2]

I've never actually tasted it, but you make it sound very appetising indeed!

 

I wouldn't try it while it's still wet though...

Would be very messy,,but would cure a sweet tooth