flotation foam

[BigMac1]

Hi all!!
Newbie here, just bought my first boat 89 Capri, my (winter project). Any who had some rot in the rear of the boat, removed and found that my floatation foam was waterlogged, I have had a family on for a week straight and it is almost dry. My question....if it's dry is it OK to keep or should I remove and add new?

 

[jbcurt00]

It may appear to be dry, but likely isnt if you core sample it all the way down to the hull.

If it has become waterlogged it is no longer closed cell and is no longer going to provide flotation.

Welcome to the iboats dry dock

Dig a little deeper, soft spots and waterlogged foam arent good signs.

Read thru other rebuild topics, lots of good info can be found. Reading will also prep you for whats ahead. Then when you encounter something unexpected on your boat, often you've read about it in someone elses rebuild and know better how to proceed.

Good luck

Pix
Pix
Pix
http://forums.iboats.com/forum/forum-rules-and-guidelines/9938375-photo-upload-tutorial

 

[BigMac1]

yhx, Pretty Much What My Plan was. Sometimes it just makes it easier to hear from someone else.

 

[jbcurt00]

Please try to notice when topics were started and last posted to. After 90days w no posts, inactive posts should remain inactive until whoever started a topic, posts to it again.

Wierdboy's topic is about an aluminum boat, the rigid sheet foam used on his build may not be the best choice for a fiberglass boat like your Capri.

 

[fhhuber]

The main advantage of the 2-part pour-in chemical reaction expanding foams is ease of installation. Mix, pour and watch it fill the space. That makes it wonderful for the boat factory where the labor of dealing with the white styro can be more than the savings by going with the cheaper foam.

Common white Styro (EPS) foam is cheap, but you have to cut the blocks to fit then glue it in place. If the space is large and easily accessed then the white styro is more resistant to becoming water logged to the point that some docks use big unprotected blocks for flotation.
Modern EPP foam is even more resistant to degradation, but costs more.

Its not hard to order a 4 ft X 4 ft X 12 ft block of white styro... (or smaller blocks from a foam cutting service) the issue is cutting the bits you need to fill your spaces and then installing it.

You could even specify the exact block shapes and the foam cutting service will do the cutting for you... but then you added the labor cost back in again.

You might consider a mix of foam types... getting a couple of big styro blocks (the size of a common ice chest) and cutting to fit in large spaces, then use the 2-part pour-in to fill the hard to access and really odd shape spaces.

What is best for your project... depends on the project.

Definitely don't trust old foam that has been waterlogged.

 

[tpenfield]

The 2-part pour-in foam does two things. It provides flotation and adds structural strength. Your boat needs both of those things and the old foam is providing neither at this point.

Foam blocks only provide flotation, yet no strength to the boat.

 

[BigMac1]

Great info guys, thx!
The two part foam you speak of, where can you get?

 

[Scott Danforth]

you can get the 2-part foam the same place you get resin and cloth from. there are dozens of places. I use US composits

 

[gm280]

I totally agree with Scott. The mix and pour works perfectly. It is so easy to do that it is a no brainer. And yes I also use U S Composites as well for the mix and pour foam and polyester resin. Great people there.

You really need to watch what type block foam you decide to use. Some of it is not closed cell and therefore will soak up water in very little time. And that is what you have now. So stay clear of the typical Styrofoam. The Home box type stores, like Lowes and HD, do have closed cell foams that you can use. But then you have to cut each piece and make fit. And then you also loose out on the structural capability of the mix and pour foam. JMHO!

 

[fhhuber]

I'll disagree about the styro not being structural...

something about building a 200 mph 35 lb RC model with foam core wing. capable of 100G maneuvers.

How its installed matters.

 

[gm280]

I'll disagree about the styro not being structural...

something about building a 200 mph 35 lb RC model with foam core wing. capable of 100G maneuvers.

How its installed matters.

I understand what you are trying to say. But honestly a mere 35 lb R/C boat, even with 100G of forces (don't know how that was figured out), does not translate directly across to a full scale hull in the least. I've built R/C planes and boats and used a lot of building techniques as well. But the scale and material if transformed to the full scale hulls would be a totally new materials indeed. Structure on smaller models does not guarantee the same structural abilities in full scale. Two different animals.

When you use mix and pour foam, it fills out the cavity and therefore makes that section stronger then merely cutting foam and placing it in the same area. You just can't get the same filled up cavity regardless how well you fit the foam. That certainly doesn't mean it won't offer floatation, but not to the extra structural support that a totally filled cavity with mix and pour foam can. As mix and pour foam starts to expand, it forces itself into the structure bounds and offers a compression that cut foam doesn't. That IS where the extra structural support comes from, the compression of the form to the confinements of the cavity. JMHO!

 

[BigMac1]

Ok, I've decided to use foam peanuts...kidding.
I am going to use the two part, how far will a gallon of both part a and part b go on average? I have about 4ft down either side to the Transom. I just tonight removed probably 60lbs of waterlogged foam back to where it was dry, holy crappy I couldn't believe it pulling it out!!
Btw kudos to all responding to my post you all seem to have it locked in and I look forward to learning from all of you.

 

[fhhuber]

Depends on the 2-part mix you get... 4 cu ft/gallon is average but there are other formulas for denser or less dense foam

 

[fhhuber]

As for the G loads on the RC models... Eagletree.com has one that reads to 38G. I haven't found a commercially available one for 100G We use math and the radius of the loop and measured airspeed to calculate G forces higher than the instrument can deal with.

http://www.eagletreesystems.com/index.php?route=product/product&path=64&product_id=62

There are commercial shipping "label" G meters (to detect how bad the packages were mishandled) that will burst a glass vial at a calibrated shock load and we pop the 100G ones regularly.

 

[jbcurt00]

Lets try to remember this is a people size boat forum, and try to stay relevant to boat building.

Pour in foam for boats is measured as pounds per cubic foot. Most rebuilds use 2lb foam and a cubic foot of it, which weighs 2lbs, will support about 60lbs +/-.

Measure the area you want to foam fill, estimate whether X cubic feet at 60lbs per CF will support the boat and motor, and order the amount of foam needed.

2lb is sufficient
4lb is available as is 3lb and several other specs, up to 12 or 16lb, cant remember which was the max typically available

 

[Woodonglass]

Ok, I've decided to use foam peanuts...kidding.
I am going to use the two part, how far will a gallon of both part a and part b go on average? I have about 4ft down either side to the Transom. I just tonight removed probably 60lbs of waterlogged foam back to where it was dry, holy crappy I couldn't believe it pulling it out!!
Btw kudos to all responding to my post you all seem to have it locked in and I look forward to learning from all of you.

Hey don't discount those Peanuts, we've seen it all!!! Coke bottles, ping pong balls, Noodles...You name it, it's been suggested and or tried!!!!:crazy:
The 2# foam is most commonly used for boat flotation. The amount it fills has a lot of variables, Temps, Humidity, Technique. They ALL come into play. As to the amount needed. All things being considered, 2lbs of 2# foam will fill approx. 2 cubic ft of space.

As to the structural benefits...The pour in foam, unlike the cut and place foam, will actually "Bond" to the substructure as it cures. It IS a resinous material and in its resin form it attaches to the wood, forms a bond and then expands and cures. If you've ever removed it you KNOW how well it can and will adhere to the surfaces it comes in contact with. (Try to avoid getting any of it on you when you do the pour) This Bonding of the foam to the substrate WILL enhance the overall structural strength of the Stringer/Bulkhead substructure of the boat binding everything together and thus making it a more homogeneous unit. Cut and Place foam will not have this added benefit.

 

[BigMac1]

Will this 2 part level itself and should I put deck replacement down immediately after or let it set up?

 

[fhhuber]

Generally its recommended to not close up the void you are filling with foam until the expansion is done.

The foams expand with some amount of pressure and if you got a little too much of the stuff in you will have it expand the deck out of place.

Not quite the same stuff... you can get a can of the polyurethane expanding foam in a can and check how it behaves. These are NOT flotation foam, but will give you an idea of how the foams expand. Spraying this stuff into a nearly closed structure can apply internal pressure that destroys the structure.

 

[JASinIL2006]

There are at least a couple of ways to add the foam. I think the most common way is to put in the decking, cut some 2" holes using a hole saw, pour in the foam, and then replace the plugs and fiberglass them in. (That's how I did it.) It's pretty easy, and the foam adheres to the deck and the hull, making everything quite rigid and solid.

Some folks have put in temporary decking, then pulled that and installed permanent decking after the foam cures, and some (I think) have poured the foam without any decking and then shaved the top of the foam level. (There is some concern, though, that by shaving the top of the foam, you may disrupt the closed cell structure and open a path for moisture to get into the foam.)

Foam will level somewhat, but not very well. The nice thing about pouring it in after the attaching the deck is that it will fill every nook and cranny below decks. You just have to make sure you have enough holes to add the liquid before it foams, and you may want some relief holes in case you pour too much in.

Hope this helps....

 

[Woodonglass]

Will this 2 part level itself and should I put deck replacement down immediately after or let it set up?

The attached link might be considered the "Bible" for pouring a foam deck here on the forum. This member did a GREAT job in all aspects of his boat restoration. Studying his thread will give you a LOT of good insight. As stated there's more than 1 way to skin a cat but if you want to ensure that the cavity has been filled and the foam has adhered to all surfaces then having the deck on is the best way IMHO. You MUST take careful measurements and mix the resin accordingly, allow for a bit of foam "Blowout" and then do the necessary "Plug" repairs but this will allow you to have the most solid and best filled structure. Again Just and Old Dumb Okies opinion and worth every penney you paid for it.:bounce::thumb: