My idea of foam replacement

[shadowrider]

I had some dock foam sitting around so I decided to use it in my boat. I made a foam wire cutter and cut custom fit blocks from the "billet" foam. Thought it might be of interest to some. With these blocks I believe I got the most floatation possible.

 

[Friscoboater]

Re: My idea of foam replacement

That dog will hunt. Good idea.

 

[shadowrider]

Re: My idea of foam replacement

Thanks, I had another idea. I riveted the new epoxy coated plywood, down, before sinking the new rivets, I spotfaced the hole with a 3/8 spade bit. Now the rivet sits below the surface slightly, I then epoxied over the rivet head with a syringe loaded with epoxy. Rivets are now sealed out from any water. I applied marine silicone to the shank of each rivet before installing.
I am very happy with the results. May post more pics later.

 

[wa_ssv197]

Re: My idea of foam replacement

Thanks for the idea! I have 4 blocks from our old floating dock that I couldn't figure out what to do with.
I now have a use for them.

 

[MichaelP]

Re: My idea of foam replacement

That's a clean looking installation. I have a bunch of foam blocks that I'm about to cut for my resto. Can you explain how you made your wire cutter?

 

[oops!]

Re: My idea of foam replacement

besides a wire cutter.......the best cutter for foam...is an electric bread knife.

as far as your boat.....that is one way to skin a cat

 

[shadowrider]

Re: My idea of foam replacement

I made the "bow" out of 3/4" pvc pipe scrap which I thought would be long enough, however I would have probably made it longer had scrap been longer. It ended up being about 38 inches. I just inserted a 90 on each end and then a 12" piece in the other end of the 90. I did glue it together, then drilled a 1/4 hole for a 2.5" long 1/4-20 bolt, with a wing nut to take up tension. The pvc pipe is a perfect material for this tool as you can bend the pipe before putting tension on the wire with the wingnuts. When wire is heated with a battery charger, it stretches and can sag, which causes undesirable surface wave or even melting your foam.
I experimented with all kinds of wire, and found 40lb picture hanging wire to work the best. My battery charger cut best at the highest setting which was 12 volt/125 amps. It would cut at the 12volt/15 amp setting but was too slow for my liking. That setting did work good trimming a cut where I lifted the wire off the template. For templates I had some 1/8" X2" wood venitian blind slats. I drilled clearence holes for 3" nails to hold the foam.

 

[ezmobee]

Re: My idea of foam replacement

The white foam will eventually absorb water just like the factory stuff did. Wouldn't be my first choice. The pink or blue sheet foam will not absorb water. (not trying to be a jerk. Your installation work was great)

 

[tpenfield]

Re: My idea of foam replacement

Yup, expanded polystyrene and extruded polystyrene. I used the 'expanded' type on my sailboat, but never put it to the test, if you know what I mean.

I also made a small rowing dinghy out of the extruded foam (homebuilt fiberglass over foam).

It (polystyrene) is a lot more economical than some of the other closed cell foams - like polyurethane foam - but I bet it does not have the longevity.

do you figure that it will 'float your boat'?

 

[shadowrider]

Re: My idea of foam replacement

I considered coating the foam with epoxy, but the added time and expense was not worth it to me. The old foam that was in the boat was white and was dry. I had no leaks in the boat prior and I am not worried about it absorbing water.
The great thing about wire cutting foam is there is no mess, you must deal with toxic smoke, but a fan takes care of that. An electric bread knife, or a saw would make one hell of a mess ( with white foam anyway) and you are limited to cutting the width of the blade, not to mention lack of accuracy. If you measure carefully and make accurate templates, you will have precision foam blocks. One drawback at least for me, was that it was time consuming to do an accurate job. One block took me about 4 hours
( rediculous I know), but I wanted it to turn out right, as I had no extra foam. I even had to glue some scrap blocks together to make some of the blocks.

 

[MichaelP]

Re: My idea of foam replacement

^^^^^^Thanks for the detailed info!!!!!!!! That will be helpfull to alot of us around here.

 

[shadowrider]

Re: My idea of foam replacement

No problem. Good luck with your project.
Seems odd to me that dock foam will absorb water since it is constantly exposed to water during it's intended use.

 

[zopperman]

Re: My idea of foam replacement

I stuffed my sheets btwn my stringers and used a reciprocating saw with a 15" fine tooth blade. It worked but I like the wire idea better.

 

[Yacht Dr.]

Re: My idea of foam replacement

Ok.. got my attention ..

What Dock foam did you use .. do you have a specific make and type or # you can post up so I can research the stuff please ..

I can not suggest or oppose a product without research and talking with there techs for this install.

Very nicely cut out and layed down .. but sometimes its good to remove the chaff from the wheat .. if ya know what Im sayin ..

YD.

 

[shadowrider]

Re: My idea of foam replacement

I dont know what you mean by your last statement. The dock foam was retreived several years ago from a local lake where a storm had mutilated some docks. I have no other information on it.

 

[wa_ssv197]

Re: My idea of foam replacement

Seems odd to me that dock foam will absorb water since it is constantly exposed to water during it's intended use.

Our floating dock was 20 years old and still floating before we decided to build an entirely new dock, so I wouldn't see a problem using it for floatation either.
If it was made for a dock, why would it absorb water? Docks are supposed to float, correct.

 

[ezmobee]

Re: My idea of foam replacement

Because the white foam absorbs water. That's just the way it is. It doesn't lose ALL it's flotation ability so that's why the dock doesn't sink. If this boat isn't leaky and isn't left out uncovered frequently than I'm sure the white foam will be fine. Heck it was OEM in many of our Starcrafts. My point is just that the pink/blue stuff is better because it will not absorb water. The OP had this stuff for free, so fine use it. I just don't want to see the white foam being recommended over the alternatives for flotation.

 

[Mark42]

Re: My idea of foam replacement

Good idea for dock foam. Generally, the floating dock blocks are made from a polyurethane foam, and not the old style Styrofoam (that sucks up water). I read one test where floating dock foam blocks were weighted down and sunk in 100' or so of water for years. Upon retrieval, there was no water permeation to speak of.

So, even though the foam was cut, I would have no worries about using it for the purpose you did. Great idea, and as long as the foam is poly, and not Styrofoam, you are good to go!

 

[shadowrider]

Re: My idea of foam replacement

I was actually going to reuse the old foam, as my intention was to just replace the plywood. The boat was stored outside when I obtained it.
The original foam was dry as a bone, but dirty, and some was moldy where it was in contact with the rotten plywood.
Also, it was a jigsaw puzzle to get it back in. I ended up with 11 blocks instead of like 50 in the original.
I am glad I decided to replace it, and I think we all learned a lot from this posting. Thats what makes this site so fun a and informative. Thanks to all who chimed in.

 

[wa_ssv197]

Re: My idea of foam replacement

Ah, two types of white foam, makes sense now.