Foam vs. No foam

your right snob, i just got a plow back from last year which I welded all the gussets where they should be, the plow shouldve been taken out of service 3 years ago, after every gusset there is a crack,
exactly snob your spot on, you re-distribute the weight exactly as you would on a trailer, you must understand hydro theory, when in the water you are redistributing weight and it is equal in the water, its hydraulic theory

one would think a 46 foot cougar that does 100 mph hitting 8 ft waves, with 10,000 lbs of engines in the ass end would snap in half, the hull averaged 3/16 across the structure, thin enough to see light thru it. 46 feet long, 8 ft beam, looking out the bow you could see the flex under way, not a drop of foam. normal single stringer design with secondaries...were talking 8 straight hours of brute punishment, to this day i have not seen a boat snap in half.
I look at these cast iron bath tubs (CC's) 19 foot long, built like a tank, if its lucky hitting someones wake is the biggest wave it will ever see in its life.
just comparing apples to apples, I really could see the foam effecting more of the structure in a negative way, glass is designed to flex as proven many times when you put a boat in the water....
in the grand scheme if that 46' footer was foamed i believe it would snap in half because you are eliminamiting the flex, alot of you guy's are engineers, and should possibly see this?
imagine if you had a rigid air plane wing, you look out that window and see it bobbin up and down, it bobs for a reason, so it doesnt snap off the side of the plane
kinda the same theory in a car possibly, you hit a wall in a 68 duece and a qauter your gonna die because of ridgity, now you take a tin can kia with crush zones the car will absorb the sudden stop. so maybe its a double edged sword, flex is definitely considered in a boats design

Seb - I wanna hear the story on how the boat capsized!!!

Damn, Kapla! With all the prop repairs, capsizing your boat, and having to wipe sunscreen off your seats from all the pretty ladies, it's amazing you have any time to ski!

I don't think one can conclude anything other then if you keep your boat chronically soaked, bad sh|t happens. ponderous.


My noodles are doing just fine since '97.

I restored a Glastron Skiflite a few years back (I still don't know why) . The hull was in nice shape, but the floor and stringers were mud. The PO had screwed a sheet of treated 3/4" plywood to the rotten floor with drywall screws that were a little too long. When I removed all the material from this quality repair I found that he had stuffed pool noodles under the floor through some holes he made before he screwed the plywood on top of the rotten floor. The pool noodles were saturated and almost as heavy as concrete. They broke apart under their own weight when handling them. I left a big piece of one out all summer to see what would happen. It only lost a little weight.

KRoundy wrote: Gary, I LOVE that old Merc. Nice shot!

Unfortunately Kevin that old '64 is history.Last winter it started to have starting issues.You have to pull the powerhead to remove the starter.Dad being in his mid 80's just can't work on them anymore or use the pullstart if need be so he took it in and was advised that it was not worth it.That and the fact it was in Florida saltwater now,the wiring was going too.Before I could get it back he had got rid of it.So this spring he found a low hour '03 Mercury 25 up here and he's going to ship it down.

I have an 80hp Mercury with the blue stripe on my dad's 1978 16' boat. Awesome motor.

Anyone ever think of using 2 litre soda bottles? They would last forever, provide flotation, and not hold water if capped. They offer no structural support but noodles can't be much better.

As for the bashing. If it comes from a salesman, it might as well come out of a politition. The crap the reps feed you about how good your product is versus how bad the other guys stuff is usually about 99% bull.

Greg, my point is from a structural standpoint, the foams add little or nothing, you could fill it with concrete, but it's still unneeded.
How many boats are running no foam and no catastrophic failure occurrs?

As Miskier stated these boats are way overdone on structure, specially the old ones, the stringer we are used too see are unthinkable on most other boats.

Yes, there's the CG regs and the sound dampening, but that's a whole different matter. probably a composite hull without any foam would sound very shallow on the chop.

What keeps the boat in shape is the floor/stringer/hull combo, I dont know why foam is being thrown in the structural discussion.

if you had to build a boat
Would you cheap on the floors?
Would you cheap on the stringers?
would you cheap on the hull?
would you foam or not foam? This is the only debatable issue, because i'ts not fundamental to boat building structure.

And hulls are ticker on the keel because that's where all the unattached resin ends while laminating!!!

Hulls dont need to be rigid, just on certain points, too rigid cracks, some flex points are even good for the structure.
And I suggest checking on the newer CCs before talking on other brands lamination, as they have gotten thinner lately.

TRBenj wrote: 8122pbrainard wrote: One thing to keep in mind is old wet foam does not provide any support and to this day, I've never seen a hull fail do to the lack of the added strength of foam. I gotta disagree with you here, Pete. Soaked or not, foam does lend structural rigidity between the hull and floor. You and I both know that there are many boats running around with rotten stringers, yet somehow they still hold together. Im not sure that would be the case if the only thing holding the boat together were rotten stringers (no foam to keep everything moving together). I dont know about you, but I dont know of any boats that have had their foam removed, then sealed back up with rotten stringers. That seems like a recipe for disaster. A foamless boat (whether the stringers are old or new) is not likely to fail, as the stringers are not likely to be rotten in the first place... so thats not what Im referring to. Like you, Im a no-foam guy because I hate holding water in the structure. I like the fact that foamless structures can drain and breathe- so they should be much less prone to rot. What Im saying above is that if rotten stringers are a foregone conclusion, Id much rather have foam down there holding everything together rather than rotten stringers alone.

Tim,
There are times that you are as ADD as I am!! Please note that in my post, I never mentioned stringer issues. It was simply hull thickness and foam adding to the rigidity of the hull!!

8122pbrainard wrote: One thing to keep in mind is old wet foam does not provide any support and to this day, I've never seen a hull fail do to the lack of the added strength of foam.

I gotta disagree with you here, Pete. Soaked or not, foam does lend structural rigidity between the hull and floor. You and I both know that there are many boats running around with rotten stringers, yet somehow they still hold together. Im not sure that would be the case if the only thing holding the boat together were rotten stringers (no foam to keep everything moving together).

I dont know about you, but I dont know of any boats that have had their foam removed, then sealed back up with rotten stringers. That seems like a recipe for disaster. A foamless boat (whether the stringers are old or new) is not likely to fail, as the stringers are not likely to be rotten in the first place... so thats not what Im referring to.

Like you, Im a no-foam guy because I hate holding water in the structure. I like the fact that foamless structures can drain and breathe- so they should be much less prone to rot. What Im saying above is that if rotten stringers are a foregone conclusion, Id much rather have foam down there holding everything together rather than rotten stringers alone.

Mike,
Don't worry about hating yourself for commenting as this subject has come up many times with many opinions and yes "seat of the pants" engineering!!

I feel the era (year) of the boat hull makes a big difference. Early glass hulls were thicker and certainly did not need the foam. Then, as years past, hulls were made thinner and the added rigidity of the foam was "engineered" into the hull strength.

One thing to keep in mind is old wet foam does not provide any support and to this day, I've never seen a hull fail do to the lack of the added strength of foam.

JoeinNY wrote: Agreed, thicken your skin that was just good old fashioned salesman bashing! The layup in the non foamed areas of my 83 was thicker than in the originally foamed areas This likely had more to do with the proximity to keel, larger span between stringers, relative flatness of the area in question, etc. than the simple fact that the area wasn’t foamed but nonetheless the bilge where I cut through for the paddle wheel was 3x thicker than the area forward between the stringers that I cut through due to carelessness. I dont disagree that the layup on a skiboat is in general considerably more substancial than is required by the loading seen on the hull during normal use.. however I tend to not discount the abnoral situations very quickly. I am not sure that I wouldnt possibly see a rock, log, or worse at some point (hopefully not at speed but it can't be ruled out).   Even a broken or poorly designed trailer or hoist bunk can provide significantly larger point loading than a boat sees in normal use. My position remains that you dont need no rottin, stinkin foam.. but if you simply remove it and dont give any thought to replaceing the benefits it supplies you may (although likely not on most of these boats) someday regret it..

3X thicker at the keel Every boat that I have dealt with as far as the lamination is concerned has never varied that much in such a short span. Generally it has varied by several layers, never multiples of the hull thickness.