# Flotation Foam



## WhiteDog70810 (May 6, 2008)

Some one posted a very concise explanation of the structural properties vs the densities of different foams a couple years ago, but I cannot find it anymore. I was planning on using plain `ol extruded polystyrene (XPS) for flotation foam instead of pourable foam. I seem to recall that polystyrene served well in this capacity, but I can't remember if it was extruded or expanded. Both are close celled foams, so I should be fine either way... ...right?

Nate


----------



## Brett (Jul 16, 2008)

I remember an article from boatdesign.net

http://boatdesign.net/articles/foam-core/

another from glen-l

http://www.glen-l.com/weblettr/webletters-7/wl55-flotation.html


----------



## DuckNut (Apr 3, 2009)

So many problems with foam, but it is necessary and required.

I am going to give a different perspective on adding flotation.

If you are using it for structural purposes then you have to use the pour foam. With its inherent problems it is still the best for this.

If you just need to add flotation then any foam will work. The key to having it last is to keep it out of the sun. The key to prevent it from absorbing water is to keep it dry. 

You can't keep it dry when enclosed in a space. Picture this: If you were to build a bench seat from side to side and to a height of a few inches off the floor you could add the foam in the cavity and hold it in place with a strap of some sort. 

Doing it this way would allow any water to evaporate off. I have seen a 30 year old boat built this way and the foam was still in perfect condition. It was a little dirty but the standard white styrofoam was still perfect. I have never seen pored in foam that old that was not filled with water.

Determine what you need the foam for and seek alternatives. Keep it dry and you will never touch it again.


----------



## fsae99 (Apr 8, 2010)

What about shrink wrapping the XPS?


----------



## DuckNut (Apr 3, 2009)

You could do that Jim but if any water ever got in, may not ever get out.

I am in the camp that - any foam that is used will be beneficial for it's intended purpose but it has to have air circulating around it to be able to dry out. Seal it in any manner and you seal in the water. Seal it in a compartment of some sort and even if you don't get water in, over the years condensation will happen.

Looking at Nate's build he has plenty of room to cut foam and stuff it in the space above the tubing and then cover it with the gunnel cap and he'll never think about it again.


----------



## cutrunner (Jun 8, 2010)

2 liter coke bottles full of helium ;D


----------



## WhiteDog70810 (May 6, 2008)

Cut,

I just snorted water out my nose when I read that. Not what I was expecting.

Ducknut,

I am with you regarding enclosed spaces and foam. I plan to install some inspection plates and suspend the foam. I've never opened a flotation compartment that has been sealed for years and not smelled mildew/mold, no matter how air tight the compartment was supposed to be. I get real nervous when I see foam poured under the sole.

This foam will serve no structural purpose, but I couldn't remember if it waterlogged badly.

Nate


----------



## DuckNut (Apr 3, 2009)

Rethink your plan slightly. Even with inspection plates you are asking for problems. Once the foam is wet, it will never dry out - no matter how many months you leave it in the garage.

Try to figure a way that it can be placed so that it is not resting on the sole - kinda like I described. If you have to bury it somewhere, then suspend it and make pathways for air to circulate around it.

Completely forget about helium as boring 'ol cut suggested - use nitrous oxide - much more fun.


----------



## cutrunner (Jun 8, 2010)

Nitrous isnt flammable
But if you wanna store it in the come bottle and hook up a nitrous kit it ould be like killing 2 birds with one stone..

Coke bottles dont absorb water either


----------



## Dillusion (May 21, 2012)

> Nitrous isnt flammable
> But if you wanna store it in the come bottle and hook up a nitrous kit it ould be like killing 2 birds with one stone..
> 
> Coke bottles dont absorb water either


Store it in the WHAT bottle? [smiley=1-whoops1.gif]


----------



## cutrunner (Jun 8, 2010)

Ha! Stupid ipad..
The *coke bottle, not the come bottle


----------



## DuckNut (Apr 3, 2009)

Come on you jokers...nitrous oxide is laughing gas. Hence, store it in the bottles for the captain to have some fun.


----------



## WhiteDog70810 (May 6, 2008)

I wasn't clear. I plan to suspend the foam within the floatation compartment so it doesn't touch the sole. The inspection plates are so I can check to see if moisture is collecting at the bottom of the compartment and dry it out if it is. No foam will sit on the floor.

Nate


----------



## firecat1981 (Nov 27, 2007)

I spoke with Jacque from Bateau a while back on the subject of floatation foams and water. They said they have never had issues with the better closed cell pourable foam they sell. it will not soak in water and condensation will not effect it. He said many of his customers are using it in exposed areas with no problems.
If I build another boat I'll use pourable foam for the whole thing instead of polystyrene blocks, it will be easier and add a tiny bit more rigidity.


----------



## DuckNut (Apr 3, 2009)

> He said many of his customers are using it in exposed areas with no problems


 Exactly what I said. But I say sales propaganda on the other statement.


----------



## staiano94 (Jul 24, 2012)

> > Nitrous isnt flammable
> > But if you wanna store it in the come bottle and hook up a nitrous kit it ould be like killing 2 birds with one stone..
> >
> > Coke bottles dont absorb water either
> ...


Thank you! I laughed out loud and REALLY needed it!


----------



## staiano94 (Jul 24, 2012)

> > Nitrous isnt flammable
> > But if you wanna store it in the come bottle and hook up a nitrous kit it ould be like killing 2 birds with one stone..
> >
> > Coke bottles dont absorb water either
> ...


Thank you! I laughed out loud when I read this and I really needed it.


----------



## firecat1981 (Nov 27, 2007)

> Exactly what I said. But I say sales propaganda on the other statement.


I don't mean floated off the sole, look through some of the builds, guys are using it in the bilge area around chases, meaning they are constantly wet, with no issues. I don't see it as propaganda, that implies dishonesty and deception, 2 concepts I wouldn't label those guys at bateau from my dealings with them. 
I don't understand why there couldn't be water proof expandable foam, isn't that how many core materials and transom kits are made now? The main difference in some of them is the density, rather then the chemical cocktail.


----------



## DuckNut (Apr 3, 2009)

I can't think of a single rebuild on here that had foam enclosed in some area that was dry. Please find it and post it.

The foam will last long enough for you to get tired of your boat and sell it to somene else and then it becomes their problem.

I have high regards for the guys at Bateau and would never imply they are deceptive or dishonest. They are simply restating the propaganda the industry tells to them and they are required to pass along because the regulations say your vessel is to float right side up in a catastrophy. They did not invent the stuff. Heck they don't even make their own brand, they are a reseller of someone elses.

Too many years of dealing with that garbage - just giving personal experience. You can use it anywhere you want. I am not telling anyone not to use it but use it in a manner that will not breed problems down the road.


----------



## firecat1981 (Nov 27, 2007)

> I can't think of a single rebuild on here that had foam enclosed in some area that was dry.


Exactly! You keep referring to old school products, the cheap crap many manufacturers used to save on costs. It's a similar argument as old boats with rot issues because the builders used cheap poly resin. Things have changed greatly in modern times. I used it in my last build and I will use it again.

As far as the guys at Bateau just regurgitating propaganda, I think you are very much mistaken on that count. They use and test the products on there personal builds and have 1000's of customers globally. If they have issues with a product they stop selling it and from what I've seen they do there due diligence before offering them.


----------

