Polyurethane Foam

That's what I thought.

 

what is the best foam, (two component) in USA, are there any products that does not absorbe water or humidity,,,, and does not expand....

 

Bart01

We do use foam panels in our pleasure boats. The panels we are using are closed cell, cross-linked polymer foam panels for coring structure and noise reduction. They are producted by Baltek. There are several grades and sizes based on application usage. Hope this helps in some small way.

Kengrome:
Thank you for your entire post. Thank you for your knowledge. Flotational foam as well as structural foam does not effect draft or displacement in a positive manner. As you stated the foam does become water logged with time, and simply adds weight in intitial construction of the boat. Two part spray foam flotation adds 1.043kg per cu ft. which = 27.40kg of swamped bouyancy. Therefore, it increases displacement and draft. Carolina Skiff has shallow draft because the hull depth/length/beam are designed to match the light deadrise to create the shallow draft.

Anyone who wishes to argue this point can easily check out the up right level floatation standards set forth by NMMA for small craft. Along with this, is also the basic flotation catagory for larger craft that does not require up right and level, but does require swamping flotation.

Now, that is my take on it. That and 35 cents will get you a cheap cup of coffee.

Regards,

Christopher Smith
Caravelle Powerboats, Inc.

 

Foam is ancient stuff....

On my latest build I used a Ceramic Thermal Insulation paint on the inside of the hull- this stuff is a spin-off from NASA space program. It is applied thickly on the inside of the hull and the beauty is that you can still see the whole of the hull, no water can be trapped as is the case with foam. And it is white in colour
Because of its granular (ceramic beads) composition, it is best to be applied by roller and brush - destroyed 3 spray guns (2.4mm nozzles) trying to spray it on.

I tested this paint; used two identical plates - painted one with just epoxy paints and one with the additional Ceramic Thermal Insulating paint. Put them side to side and heated equally from the back with a gas flame. When the plain painted one was too hot to touch, the Ceramic one was still cool to the touch

Not so cool is the price though..damn expensive but much cheaper than foam and less messy.

 

Yer not family to Bart Simpson are ye

I use cross-linked, closed cell, expanded Polyethylene foam. Have a look here

http://www.sondor.co.za/index.php

I use the SPX33, 33kg/m^3. This stuff is unbelievable. It absorbs 0 water, I have off-cut pieces that has been laying in the sun > 6 years, and there is no deteriation (beside where the cat sharpened its nails). You can saw it, grind it, mill it, laser cut it, file it, knife it or work with it any way you want.

Depending on the thickness, it forms fairly well. >30mm becomes difficult to make sharp bends.

This is not a structural foam. It is flexable. However, when you have glassed the inner and outer it becomes very stiff, the foam acting as a huge rubber mounting that gives very little if any. I used 20mm sheets.

It has very good heat insulation. The fiberglass bonds very well to it, if you try to seperate the foam and the fiberglas the foam shears off.

The little tri I built was made using this, it is unsinkable, and I used it in my power boat as well.

I have a collection of other foams as well. The PU pour foam I threw away, it is useless, unless you go to a lot of troubles sealing it in which case wood would work equally well and also have a much better structural strength, but be heavier.

The traditional foam they use for boats is also ok, but the price, good grief. Even so, it breaks under force and I cannot say it has any specific properties that impresses me. I have four thinish sheets here I got from someone, but I won't be using it on my boat.

In my opinion, and having worked with it, nothing beats the Polyethylene foam. Whichever boat I ever build gets this stuff.

 

Eh Wynand, are you bragging with your money again ?

You know I'm not into heavy metal like you guys. I know steel boats are successfull, but I will never be able to sleep on such a boat. I can hear it rusting

 

Fiberglass is not waterproof. Gell coat absorbs water too, is very heavy and does not add to the strength of the boat. Even if the gell coat is not chipped, water still seeps through.
Especially when you ride in choppy water and the hull gets slammed a bit you can expect to grain a cup to a liter or so water from the hull. This is why the guys pull their drain plugs as soon as the boat comes out the water.

No, the drain plugs have good rubber seals. The fiberglass is not waterproof.

Because the gell coat is thick, it hides scrapes, small chips and sometimes even gauges in the hull, ie the hull always looks better than what it really does

I prefer paint, and the paint I use is the same stuff they use on cars - 2k.
Spray it on and it is easy to fix up unless you go and mix some weird unrepeatable colors.

 

I have to get about a ton of water in my boat before I notice it... so the water leaking is not really a problem. All the coast guard is interested in is why you're playing chicken with a cargo ship...

 

up unless you go and mix some weird unrepeatable colors.[/QUOTE]

Fanie have you seen the pics of my boat. Try repete that color

 

He he Butch, if it's that wild then you could use any color I guess eh

BTW, where ARE the pics of your boat ? I haven't seen any...

 

F.....off Fanie I plasterd the pics all over the place you cant miss them .Its the vrot wooden boat painted with a red/binne po...pienk type color . It is exterior PVA can you belive what some people do to save a buck

 

The one that looks like it's up on a koppie between the trees ? Link man link. I look at so many boat's I could have sworn your's was painted blue like the sea to blend in more naturally...

 

Does it smell...

 

Yup Like Po.. and booz

 

thats why your suppossed to paint all exposed foam.....read the directions and yes this foam is widly being used in the powerboat industry..