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fretz

replacing wet foam in an 84 2020

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Hope you all have had a great summer boating! We got allot of use out of our classic robalo and hopefully stretch the season well into october. However it is time to work up the to-do list for next year.

 

Last winter i replaced the aft floor and re-did the scuppers. Part of the project was removing all of the wet foam and re-pouring new flotation foam. We couldnt be happier with the results.

 

With the law of unintended consequences always at play the boat now floats noticeably higher in the transom. So the logical solution is to continue cutting up the floor and replacing the soggy foam.

 

My question for all of you is...

 

How structural is that foam between the hull and deck?

 

If i cut up the inside of the forward fish well and remove it is there any support for the hull besides the foam sandwiched between the 2 skins?

 

  • the plan is to cut the glass
  • grind the cut so that i can tabb it back in before i remove
  • remove the floor
  • remove the foam
  • let sit for a few months with a dehumidifier
  • glass the floor back in place
  • Pour new foam through a few holes
  • plug the holes

 

Im not worried about the "cosmetics" in the forward fishwells and the entire floor will be covered with new non skid or something like raptor deck.

 

I just want a better idea of what is going on between the hull and deck. If there is a specific density foam or something that i can inject with lower expansion properties please let me know.

 

Thanks!

 

Chris

 

 

 

 

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2 lb foam is what is used below decks on boats. What structural support it provides for the decks is really secondary since it's primary purpose is floatation. It does provide sound deadening and does help support the deck a little. Bottom line, removing the foam should not have impact structural support.

 

So you plan on tabbing the deck on the top side only? I would lay up some flat tabs out of fiberglass cloth, then attach them to the bottom of the remaining deck with a thickened cabosil/resin mix and pull tight with sheet rock screws. Once set, remove the screws. When it is time to re-install the deck, it will sit on the tabs and then you can glass the joint back together from the topside and not have to fight working around the tabs.

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Thanks for the tab suggestion.

 

I knew something would have to be done but figured the solution would present itself at the time.

 

So you dont think the foam is structural like a boston whaler?

 

Im concerned that i will have voids when i go to re-pour it

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No, it is nothing like a whaler. I would love to know the hull thickness on a whaler compared to that of a Robalo. I do know for a fact the glass in the hull bottom 12 inches forward of the transom is about 1/2" thick. These hulls are strong enough with the frames and stringers that the foam does contribute to the overall strength. Once the deck is in place and glassed to the coamings, you now have a ridgid grid system below deck surrounded by a box beam (hull and deck structure). This results in a very strong hull.

 

Regarding potential voids when re-pouring the foam...I would foam the open areas below deck prior to installing the deck. You can do multiple small pours to fill in the areas until the expanded foam is slightly above the floor level. Once it is hard, use a hand saw to trim it flat so it is just below the bottom of the deck. Brush a coat of fiberglass resin over the cut foam to seal the exposed cell structure, then install the deck.

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