Ongoing C19 questions...

Power Boats only. Please include the boat type in your question.
TomTom
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Re: Ongoing C19 questions...

Post by TomTom »

Are you just going to make limber holes and the fill the compartments with PU foam? If you are putting limber holes have you considered instead putting foam blocks - as in foam that has been expanded at the factory in a controlled environment. I am told these are much more closed cell and less likely to absorb moisture.

joe2700
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Re: Ongoing C19 questions...

Post by joe2700 »

Dan_Smullen wrote: Wed Sep 09, 2020 1:35 pm Using foam is the most prudent, I believe.

Water, at some quantity, in the compartment is inevitable. Anything that ever gets in there, even condensation, I would like gone.

Foam and limber holes it is! Limber holes in the stringers forward of every frame to drain toward the bilge, frames drain in the center to the transom.

Thank you, Gentlemen! 8)
If you are fully foaming I don't know why you need limber holes. The foam would just fill them up no?

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Re: Ongoing C19 questions...

Post by Dan_Smullen »

TomTom wrote: Wed Sep 09, 2020 4:23 pm Are you just going to make limber holes and the fill the compartments with PU foam? If you are putting limber holes have you considered instead putting foam blocks - as in foam that has been expanded at the factory in a controlled environment. I am told these are much more closed cell and less likely to absorb moisture.
This is an option too. The same was suggested by a guy I know locally, but didn't know that the cellular structure could be better. Probably cheaper too.
joe2700 wrote: Wed Sep 09, 2020 4:41 pm

If you are fully foaming I don't know why you need limber holes. The foam would just fill them up no?
I was reading today about preventing this by laying a piece of rope in the cavity, then pouring foam over top of it, then pulling it out to leave a channel for water to follow. Seems like it could work. :doh:

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Re: Ongoing C19 questions...

Post by Fuzz »

To foam or not can be a tough one. There are good points either way you go. On some boats I think the foam is needed to help stiffen the hull. On others not so much. If you foam and limber hole and want a drain channel you could make the channel with sand. After foaming just wash the sand out. The foam sticks to every thing really well so getting rope back out might be tough.

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Re: Ongoing C19 questions...

Post by Dan_Smullen »

Fuzz wrote: Wed Sep 09, 2020 7:31 pm The foam sticks to every thing really well so getting rope back out might be tough.
Pull too hard and she might inflate.

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Re: Ongoing C19 questions...

Post by TomTom »

Dan_Smullen wrote: Wed Sep 09, 2020 5:42 pm

This is an option too. The same was suggested by a guy I know locally, but didn't know that the cellular structure could be better. Probably cheaper too.
I went through all your permutations. I ended up calling Resichem in South Africa and speaking to one of their technicians. Basically when you pour PU foam in an uncontrolled environment it is very hard to monitor the degree of expansion and consistency. Basically even a “closed cell foam” can be not very closed cell depending on how it is poured. Generally the outer layer that pushes against a surface becomes quite closed, but if you break this skin, the cells inside are not as well closed. So for example tearing a rope out of the limber holes would leave a less sealed surface.

The guy suggested to me that boat manufacturers in SA much preferred buying the factory expanded Foams and they were also able as a company to much better “guarantee” how closed cell they were.

I do not like the idea of large empty compartments in boats - as personally I believe that they leave lots of space for expansion and contraction of air to delaminate your floor from the stringers/ frames.

I ended up pouring foam and doing my best to ensure that each and every compartment is fully sealed and is a separate entity from its neighbour.

If I was going the limber hole route I would buy factory expanded foam and fit it. Firstly - because it has been poured in a controlled environment and you know what you are getting. Secondly, because it won’t expand and stick to the sides of the compartment, if any water were to get it, it would be able to trickle down to the bottom and out of the limber holes without sitting on the foam and getting absorbed into the “not as closed cell as you thought” foam...

Another option - which I thought was very smart was Matt Gent filled his boat with those round balls that you find in kids bouncy castles....

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Re: Ongoing C19 questions...

Post by Jaysen »

Ok.. here's a thought... line the compartment with 3mil plastic. use packing tape to seal the seams on the inside (doesn't need to be pretty... it is in a sealed compartment). Pour the foam in in small pours separated by a few minutes. once the compartment is close to full let it sit a long time. Carefully trim the top. Now remove the ENTIRE THING by lifting the plastic out. cover the top with 3mil plastic and seal ALL SEAMS with waterproof tape. Tape over any holes you find in the plastic too.

I see a few gotchas with that plan. might want to put a spacer of some sort between the plastic and the frame/stringers/hull (flexible cutting board or other material) to make removal and reinsertion easier. But I think this will give the best options as you will have sealed the foam in a bag and also filled the water tight compartment.

Just a thought.
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VT_Jeff
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Re: Ongoing C19 questions...

Post by VT_Jeff »

I was going to use empty water bottles but have decided to use minicell foam, which is used a lot in the whitewater world for flotation and outfitting, and which I have a lot of since we pulled up a floor made of the stuff recently. I've seen too many photos of expanding foam being excavated to be comfortable with it.
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Re: Ongoing C19 questions...

Post by OneWayTraffic »

Don't overthink it.

Pick a method and go with it. My plan is empty compartments below deck level, inspection ports and may do breather holes. Block foam in some of those compartments, glued in place with water channels around. Limber holes where needed. Then more block foam above deck level to give at least basic flotation. Hatches on side compartments, not totally watertight perhaps but enough to keep the boat upright while I bail it.

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Re: Ongoing C19 questions...

Post by Dan_Smullen »

Lots of good points, guys. I’d be lost without this forum as a sounding board, knowledge base and last minute gut check. Th al y’all.

I contacted a vendor of bulk expanded polystyrene marine floatation. Mainly hides under floating docks. They’ll cut pieces to spec. Quick pricing on a chunk, 12” square and 60” long is $25. Seems reasonable to me even after that number goes up with to cover custom sizing. If this is suitable material I can fill the bulk of the volume with blocks, filling around edges as needed with pour foam.

Regardless, limber holes are drilled at the bottom edge of stringer, forward of every station. Exposed edges have been sealed.

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