Pouring foam - need advise

[thedeeg918]

I am about to order foam mix. I know how much I need, but unsure about what density.
I understand that 2 pound is the most common. When reading the descriptions of the other foams , it said that 4 pound is good for under decks and adds to structure.
Even tho it costs a bit more, would it be better that the 2 # ?
The stringers are very low... maybe 3" on the sides and 4"+ in the middle , at least for the most of it. The boat is 16" catamaran.

 

[jigngrub]

Re: Pouring foam - need advise

4# would be better, it'll give you a more solid build.

 

[jetdoctr]

Re: Pouring foam - need advise

how thick is the deck material? if its like mine with 3/4" flooring (and 3" stringers) you prob could get away with 2# unless you plan on beating the **** outa it. but if its a thinner floor then the 4# might be a better way to go

 

[ShellBack89]

Re: Pouring foam - need advise

I used 2# ordered from Areomarine products. 5 gal each for both part A & B. I have enough left over for another boat.

 

[chriscraft254]

Re: Pouring foam - need advise

The 4 pound will give you a better density, so less water intrusion is it gets wet. Something to consider I think.

 

[thedeeg918]

Re: Pouring foam - need advise

I had planned to go with 1/2" for the floor. Had considered go 3/4" for better stiffness but I thought it would be to heavy for that size of boat.
So if I stick with 1/2" floor and 4# foam, that will make a good solid structure for the boat ?

 

[tfret]

Re: Pouring foam - need advise

I don't think there is technically a right or wrong answer. I think 2 lb is what is typical from the factories. 4 lb will weigh twice as much, if you are trying to keep it light that may be a consideration. I put 2 lb in my ski boat with a 1/2" deck. It feels solid as a brick.

 

[Cadwelder]

Re: Pouring foam - need advise

I use the 2 lb for all my restores....just be sure to mix it really well before you pour it. It'll expand much better with a good mix...

 

[tfret]

Re: Pouring foam - need advise

Also, the warmer the stuff is the better it works. I placed my cans in the direct sun on my drive way in order to preheat the stuff. You get better expansion that way. Mix it good for about 20 seconds then pour it. I never tried to do more than about a quart at a time. That way I new I could get it mixed well. I also screwed one of my hole plugs onto a short peice of 4x4 board and used that to plug the hole after the pour. That way the stuff keeps swelling under the deck and doesn't puke out the pour hole wasting a bunch of good foam. Wear latex gloves. The stuff sticks to everything and is hard to get off.

 

[oops!]

Re: Pouring foam - need advise

I use the 2 lb for all my restores....just be sure to mix it really well before you pour it. It'll expand much better with a good mix...

2 is all you need.
remember, with 4 lb, the walls of the cells are thicker, and the cells them selves are smaller. this will give you more anti crush stregnth. but it is more than you will use.
4 lb is twice the product in a cu foot than 2 lb.

however....we are not building a tank here. we want light and strong...

a half inch deck with 2 lb foam glass and stringers is a really strong cross section.
im going to venture a guess, that a cross section of hull would stop a .22 round easy.

i have seen hulls with 2 lb foam that have hit stumps at 50 mph and still floated away.
a really heavy duty steering wheel bent like it was in a head on collision . (blue water....they are like volvos) big chunks of glass hanging off them. foam and stringers hanging out for all to see.
and still floated away....the only blood on the vessel was where the driver hit the windsheild frame.
have he, and his passengers walked off the boat.

what more does a boater want?

 

[oops!]

Re: Pouring foam - need advise

I use the 2 lb for all my restores....just be sure to mix it really well before you pour it. It'll expand much better with a good mix...

Also, the warmer the stuff is the better it works. I placed my cans in the direct sun on my drive way in order to preheat the stuff. You get better expansion that way. Mix it good for about 20 seconds then pour it. I never tried to do more than about a quart at a time. .

mixing of any two or more ingredents is crutial to a strong product.

the better you mix them......the better the product.

swishing with a stick will rarely do the job.

 

[thedeeg918]

Re: Pouring foam - need advise

Thank you for the advise.
Well, I guess if a boat can take that kinda hit become mangled and actually float away... then I see no more debate about it. 2# it is.
I just bought the wood for the floor and stringer today.

Is it the correct procedure to completely install the structural ... glass it in solid and everything. Then cut holes and pour the foam, then plug holes?

 

[oops!]

Re: Pouring foam - need advise

make sure you get lots of gloves.....and wear really old clothes.

foaming is a really messy messy job.

you will likely need to change gloves each time you mix.

you can also use small plastic bags as an insert to a mixing bucket.....otherwise you will go thru a bazillion buckets.....and there aint no re using old ones....lol

 

[Woodonglass]

Re: Pouring foam - need advise

Thank you for the advise.
Well, I guess if a boat can take that kinda hit become mangled and actually float away... then I see no more debate about it. 2# it is.
I just bought the wood for the floor and stringer today.

Is it the correct procedure to completely install the structural ... glass it in solid and everything. Then cut holes and pour the foam, then plug holes?

Yep, That's how I'd do it.

 

[Yacht Dr.]

Re: Pouring foam - need advise

This is a 16' power cat .. 60 HP ? Not a blow/sail cat ... right ?

Hmm.. I'd go with the 4 lb mix myself if its a power cat.

Yea..if it was a blow cat then 2 lb it.

YD.

 

[thedeeg918]

Re: Pouring foam - need advise

Hehe, ya, I could see the bucket issue for sure. Plastic bags are a good idea. I do have quite the variety of buckets and such.

Yes. It is a 60hp , not a sail.
So you think 4 lb would be better Yacht Doc?
I still havent placed an order for my foam yet, figured I would do it monday.

 

[Woodonglass]

Re: Pouring foam - need advise

To each his own, but the 2lb is plenty IMHO, since your stringers are no more than 4" in depth. If they were taller then I'd agree with the 4lb.

 

[Yacht Dr.]

Re: Pouring foam - need advise

Hehe, ya, I could see the bucket issue for sure. Plastic bags are a good idea. I do have quite the variety of buckets and such.

Yes. It is a 60hp , not a sail.
So you think 4 lb would be better Yacht Doc?
I still havent placed an order for my foam yet, figured I would do it monday.

I would get some disposable paper 1 qt cups.
Mark your measure cups A and B .

Put a few strips of duct tape around the hole to catch any drips from the foam pour ( I put like 6 strips wide over and beyond the hole and then cut out the hole with a razor blade ). That way when you put your hole plug back in when the foam is still wet you dont have the mess. Just take a hacksaw blade and zip off your over flow and peel up the tape .

For me I would feel better with 4 lb for rigidity. May not need it .. but slappin on the wakes and bouncin down the highway on your trailer .. well you understand.

 

[thedeeg918]

Re: Pouring foam - need advise

Hehe. I am torn between the decision. I agree with both of you. I do believe that 2# would be just fine. However the 4# would give me better rigidity. I have a tendency to over engineer anything that I do.. ( its the German in me ) =)

If I could find 2# locally then I would use it, but if I have to order it then I will probably go 4#.

Woodonglass, do you know of anyone locally , other than LaFaver , that I could buy this material at?
They are out of part B .

 

[fngboater]

Re: Pouring foam - need advise

make sure you get lots of gloves.....and wear really old clothes.

foaming is a really messy messy job.

you will likely need to change gloves each time you mix.

you can also use small plastic bags as an insert to a mixing bucket.....otherwise you will go thru a bazillion buckets.....and there aint no re using old ones....lol

now im not tryin to bash you oops but.......i did a pretty good job today on my foam.... i was able to reuse all of my buckets...i used three 3m quart mixing cups for a total of 10...no...12 pours(two of those were very small pours to touch up where i started) it was probably about 5 min between each pour so i was able to keep my cups in a rotation and clean up the oldest one before each pour. the 3m cups are nice because you can see how much liquid you have in them so mixing both parts equally is easy. i maybe went thru 3 pairs of gloves and didnt get any on my clothes at all. i didnt even spill anywhere on the boat i did manage however to get a small dab on my cheek:facepalm:...must have been a bug.

i had very little waste

the best advice i can give you Thedeeg... is take your time...start out by making a small batches. my first ever batch of foam was 8oz of each part. which doesnt seem like much but wow does that stuff expand..it worked out just short of filling the cavity between ribs. which was good, no waste. i was able to adjust for the other side which is the same size.

my method which worked perfect... pour foam, lay plastic sheeting over cavity ,no wrinkles, ( heck you could even spray glue plastic to some ply wood so there are no wrinkles in it and you only have to deal with one thing.) put some 1/2 ply over that and stand on it.....now heres the trick.......drum roll..........if you kind of bounce around and stomp on the ply to make it flex it will help the foam disperse very evenly around the cavity. i only weigh about a buck fifty and i was basically kind of bouncing on my toes . do that for about 5 min and you should be able to remove the ply and then peel the plastic off for a nice smooth surface. if the plastic is sticking then wait another couple of minutes. once it gets pretty solid you good to go .