PDA

View Full Version : Expandable and poorable foam



Stuart
20-01-2007, 03:25 PM
As most here would already know Im building my own plate alloy boat. Im up to the stage were I have to put the flotation in. I'm in two minds as to use block polyurathane foam or the poorable which you mix 1 to 1 and poor into the hull. I have used the other poorable foams for many years but Im not up to date on other products.

The resone for wanting to use poorable foam is it will swell into all the areas I cant get sheet foam into. Their will be no cavities left from pooring the foam in as to laying it in. If any one knows a good polyurathane poorable foam that wont suck up water please let me know.

Stu

FNQCairns
20-01-2007, 04:41 PM
FGI sell a quality foam for that purpose, closed cell and relativly light for volume, here lies the catch the lighter the 2 pac closed cell polyurethane foam the more potentially absorbent it is over time.

Are you planing to lay viscreen or something down before you pour? and then package. I would not like poured in place foam in contact with my aluminium hull.

There is no good answer I think just degree's, I will be sticking with the crappy bilge pump clogging, fuel sensitive, styrofoam in mine.

cheers fnq

leezor
20-01-2007, 04:49 PM
Hi Stu,
My last boat was a 6mt platey and the foam had been poured into plastic bags and then placed into the hull cavities. I did notice that the areas where the foam had leaked from the bags it stuck like the preverbial to the alloy and tended to hold water.
At one point I had to have some welding done to a crack which appeared, the foam bags made it an easy job. Because the bags had moulded to the shape of the cavity it was a simple matter of putting them back in after the weld had been done.
Not sure this is the norm, but it seemed to be a good idea.

Cheers, Lee

tigermullet
20-01-2007, 05:12 PM
I agree with FNQ about not liking poured in place foam in contact with aluminium. But then I am paranoid about anything coming into contact with the hull (or anywhere else for that matter) unless it is guaranteed to be absolutely inert. For any future welding repair it would be a very good idea to be able to remove the foam.

Stuart
20-01-2007, 05:17 PM
I wont do the poorable thing then, maybe pool noodles or sheet foam wrapped in black plastic, do you think this system would be better?

Stu

dfox
20-01-2007, 05:55 PM
Stu- im not sure on what the best solution is for floatation in your case, but stay clear of the poor in foam. I wont go into details as its a long story but the bad experiences ive had with so called top of the range foam is extensive ...foxy

Stuart
20-01-2007, 07:50 PM
I hear ya mate. I will ring a few palces up on Monday and find out the best solution.

Stu

FNQCairns
21-01-2007, 11:12 AM
Hi Stewart, dont know what you are working with, sealed deck etc. But consider either placing viscreen down pouring then pulling and packaging the foam (pulling the edges up over the top and tapeing up) them place this into an industrial plastic bag seal real well and re-insert.

With the foam even closed cell absorbs water over time, the closed cell weight of foam all (I would assume)of the manufacturers use is the light 2 pac, weight and price savings as the reason, this stuff will make it past warrenty and that is usually all that matters.

You, like me, want better and we can get it, use and pay for a heavy weight 2 pc polyurethane closed cell foam, google will fill you in on what's around, then as above pour and package x 2 (or subsitute the viscreen for leesors system) and check every 5 years for rubbing or water ingress.

Noodles etc simply do not have the packing surface area to be considered as floatation, neither does anything else (that I know of) but inner tubes, air, or foam.

cheers fnq

Roughasguts
21-01-2007, 11:32 AM
How about left over wine cask bladders, there pretty strong and blow up with air and seal very well. Don't know about filling all the nooks and crannys but might be worth a shot.

saurian
21-01-2007, 01:07 PM
Stuart , I would definately not pour foam into the hull.
I have seen numerous plateys with double or triple wrapped 200 um or thicker plastic taped ends like fnq mentioned.
I have seen plateys with screw down decks to enable a yearly inspection of the foam and its wrapping and to allow a good wash of the hull.
Lots of expandable foams are copper based so are not suitable for being placed against alloy.( galvionic scale )
I have had builders refuse to place foam in new hulls because of this corrosion problem. Jbs, Riptide, Fisher build bouancy chambers.
I used 1.25 & 2lt coke bottles on my last platey.
They where washed lids done up as tight as hand allows and stuffed throughout the hull. I had a crash bulkhead and main rear deck area all stuffed with them. I put more inspection openings in to allow me to get at the hard to get to spots.
Most people thought it was weird , to say the least.
But I needed the security of knowing that if s... hit the fan I at least had a floating hulk to hang onto or sit on while defending the crocs and sharks off.
Iused the basic theory that 1 metric ton needs 1 cubic metre of flotation.
So I used 2 wool pack bails of bottles all stuffed into a 6.2 m platey.
I think you could probably buy new bottles if you are in a more civilized area
than I was at the time.
Hope this gives you food for thought even if it might seem a tad strange.
Ta.