Anyone used plywood alternatives with a deck/stringer rebuild?

[jigngrub]

Once again jig u spoke before u comprehended what I was saying all I was saying is we all talk about spending hundreds of dollars water proofing our decks, and then use something that is known to hold water under it, your answer is don't let the foam get wet, and I agree, but yet we water proof the heck out of everything expecting it to be wet, I've got as much right to my opinion as anyone does, you fill yours with 2 part foam I'll fill mine with sheet foam I'm sure we'll both be fine. Can I borrow the big rivet gun by the way

No, urethane foam can be exposed to water for months at a time without absorbing a drop... something you and others on this site can't comprehend.

From a well known urethane foam distributor:

[SIZE=-1]14. Is this foam water resistant?[/SIZE]

[SIZE=-1]Yes, but with the following caveat. The foams that we sell are considered closed-cell, which means that each cell that makes up the foam structure is completely closed off from surrounding cells which prevents it from acting like a sponge. It is completely safe for this foam to be in contact with water for hours/days/weeks and even months with no adverse effects. However, it should never be submerged in contact with water permanently. Over a period of years the water contact can begin to soften the foam and cause it to lose its closed-cell status. This foam is designed primarily to be used as an insurance policy in case of damage/holes that could cause a vessel to lose buoyancy. Pinhole sized openings would essentially have no effect on the foam since the amount of exposure is so minimal but you should always make repairs as soon as possible to keep the foam effectiveness as good as possible. This will be the case with all after market closed-cell polyurethane foams and even manufacturer installed foams.[/SIZE]

You can borrow the rivet guns any time.

 

[hadaveha]

A foam distributor saying his foam won't exorbe water, imagine that those junk emails saying I can make 1000 bucks a hour must be true allso. I swear you can lead a horse to water but u can't make him drink the foam soaked it all up

 

[tpenfield]

A foam distributor saying his foam won't exorbe water, imagine that those junk emails saying I can make 1000 bucks a hour must be true allso. I swear you can lead a horse to water but u can't make him drink the foam soaked it all up

I think you mean absorb . . . (sorry, just had to)

Sharing my thoughts on the wood/foam debate, to throw gasoline on the fire . . .

The water absorption thing with closed cell foam is interesting and maybe not fully understood . . . However, I did get a first hand view of water absorption in urethane foam when I repaired the bulkhead and fuel tank bay on my current boat. Here is a picture of what I found as I cut out the bulkhead and dug into the foam surrounding the fuel tank.

The water migrated into the foam forming a vein or perhaps you could call it a river. It was very isolated to that darkened area you see in the picture. The areas around it were dry.

Later on in the project, I had traced the source of the 'river' up along the starboard side to a low point in the foam where water could collect. There is no telling exactly how long it took the water to migrate this far into the foam, but the boat was 17 years of age when this picture was taken.

Essentially, water 'migrates' into closed cell foam at a very slow rate (years) by filling the voids between the closed cells and also aided by freezing to break down the wall of the cells. You can submerge closed cell foam in water for extended periods of time and have negligible/no absorption, as I have done when testing out various foam for use in my boats over the years. By contrast, wood more readily absorbs water and allows it to travel great distances throughout a boat's structure in a much more even and rapid fashion.

That is why we hear folks on the forum and elsewhere emphasize maintenance (i.e. keeping the boat dry) in context of wood core structures. Because the wood 'wants' to absorb water, whereas the foam would rather not and has to be persuaded.

 

[jigngrub]

That is why we hear folks on the forum and elsewhere emphasize maintenance (i.e. keeping the boat dry) in context of wood core structures. Because the wood 'wants' to absorb water, whereas the foam would rather not and has to be persuaded.

Persuaded is too nice of a word, but I like it. To me a better word would be forced, the foam has to be forced to absorb water.

This is a pic of the foam in my '97 Tracker taken in 2011, 14 yr. old foam. Bone dry and light as a feather:

I know the foam was dry and light as a feather because the section outlined in red had somehow dislodged and was laying in there loose, when I picked it up to examine it it was as dry and light as the day it was installed. So I glued it back in place with some 5200 and didn't think anything more about it. I bought this boat brand new and tried to take as good of care of it as I could by keeping it trailered and covered when not in use and the bilge plug removed. I've been caught in several rain storms with it, launched with the bilge plug out, and turned the garden hose on it on the inside to scrub it out regularly and none of this had any effect on the foam.

I guess if you've only owned old rotten boats and never owned a brand new boat and taken good care of it, or bought a used boat that has been well taken care of you won't understand the virtues of urethane foam... but take it from someone with first hand experience, it takes a lot of abuse and neglect to saturate urethane foam and it's not something that happens quickly.

 

[tpenfield]

Yea, foam get blamed for water issues . . . but if the foam were not there, the water would still be. Wood is a better 'sponge' than closed cell foam.

 

[Scott Danforth]

if you want to make your own seacast, simply take 1 gallon of non-waxed urethane resin, 1 gallon of urethane body filler and mix the two. then using the creme hardener from the body filler, add the hardener and recycled GRP chips, mix thoroughly and pour

for the chips, take all the mold trimmings from your fiberglass manufacturing operation and run it thru your patented GRP reclamation grinder (or any other industrial tool of destruction to grind up and chip the GRP to small chips the size of nickles and dimes. add to that up to 35% post consumer GRP (old boat hulls that people payed you to take). if you want, this is where you can add smurff berries that sphelps wants.

voila - DIY seacast.

I make my own version of PB by taking 1 part tiger hair reinforced urethane body filler and 1 part resin. mix the two, and apply using a plastic disposable pastry bag. sure, it costs a bit more than chopped fibers and cabosil, etc. however I can sneeze on it without using PPE and I still wont blow glass fibers in the air to inhale. it is also pourable.

as for foam, it took years of neglect to get water to the foam. it also took years of contact with water for the foam to break down. however add a couple of freeze/thaw cycles and the breakdown process accelerates.

 

[83mulligan]

The whole key to foam, in my personal, very unprofessional experience and from years of reading on this site is to install drainage channels so that the water cannot accumulate and contact the foam for long periods (months). In both of my boats that I have torn apart the only place there was waterlogged foam was in areas where the water could pool for long periods of time against the foam.

 

[hadaveha]

Scott on the DIY sea cast with the cream hardner what kind of work time do u think you would have.

 

[Scott Danforth]

just like seacast, between 3 and 10 minutes depending on temperature before it starts to kick.

 

[jigngrub]

You could do the same thing with an epoxy resin and add the hardener last after everything else was mixed in and get a 20 min. pot life/work time. Plus it would be epoxy and not polyester!

 

[hadaveha]

Could u not use fiberglass hair instead of boat chips u could make it extra thick with hair or more runny could you not

 

[sphelps]

Work time on Seacast is around 20 min or so .. Add up the cost ofall your ingredients to make up a gallon and compair that to the real stuff .

 

[kcassells]

Does anyone have any noted applications worth sharing? Like stringers, bulkheads or full transoms with the homemade recipes?

 

[zool]

Does anyone have any noted applications worth sharing? Like stringers, bulkheads or full transoms with the homemade recipes?

I made a nice hockey puck, just inverse the epoxy mix ratio, then go look for your beer

 

[kcassells]

Zool....Love ya again lol... Best laugh I had in a week or two. Still laughing as I'm typing. Thanks I needed that....still chucklin.:lol:
I remember shooting those pucks on the ole basketball court and man they flew and hurt. Especially if it was a lifter.
TX!