Foam...water-logged foam...and no foam...Let's talk

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Now THIS is impressive! Great example of foam keeping a boat not just floating, but functioning as normal. There is a TON of foam in there, good foam, and installed very well. Most bench seat aluminum boats have about 15% of how much foam your boat has.

jigngrub said:
A very simple test to see if your boat needs foam, has waterlogged foam, doesn't have enough foam, or has the right amount of foam is to launch your boat with the drain plug out and leave it until it doesn't take on anymore water... anybody got the cojones to do this?

I have done this with my Tracker Pro Deep by accident (launch without the plug in), the foam in my boat is so good that the bilge doesn't even fill completely and water doesn't come up through the deck drain. I have fished all day with the plug out, only to discover my mishap when I pull the boat out of the water on the trailer and water is shooting out of the bilge drain like a garden hose turned on all the way.

My boat is equipped with the closed cell 2 part pourable urethane foam from the factory.
DSC02206.jpg


The 2 part urethane foam can become waterlogged, but it has to be submerged for months for this to happen.
A quote from a urethane supplier:
Common Applications: Our 2LB density marine foam is recommended for void filling in nonstructural applications. This product can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy. This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years. We recommend this product strictly for flotation applications. If looking for a liquid foam for sculpting or casting we recommend using at minimum our 3LB or 4LB density. More questions? [Try our Foam FAQ.]

The blue Dow "Styrofoam" and the pink Owens Corning EPS rigid sheet foam is also closed cell and takes a long time to become waterlogged. The beaded white Styrofoam isn't closed cell and become waterlogged much faster and the beads break down over time.

I would be a very bad scenario to suddenly realize that you really do need the floatation foam that you so stupidly removed from your boat and didn't replace. Especially if you're boating over frigid water or get caught out on the lake in a severe storm.
 
There is a big white elephant sitting on the couch here. It's eating all the popcorn, so it needs to go.


One thing that hasn't been discussed here is corrosion. As a result, there is a right way to install foam, and a bunch of wrong ways. I may have missed it somewhere, but I've yet to see any foam installed the right way on this site - it has been hinted at in this thread, but only just.

The problem with many of the pour in foams is that in a wet environment, and especially a salty wet environment, they can actually become corrosive to the aluminum (though, what isn't corrosive to aluminum, really?). Others, while fairly stable, can still cause crevice corrosion, just by trapping minute amounts of water against the aluminum, with no airflow. Airflow is critical for the longevity of aluminum. With a fresh supply of oxygen, aluminum will constantly 'heal,' or produce a protective layer of aluminum oxide. This is what gives and otherwise worthless metal commercial value. However, if the water becomes trapped, with no airflow, the aluminum begins to pull 02 out of the water, leaving the remaining water more acidic. This acid then starts eating away at the metal, and the cycle continues. Say the water that gets trapped is salt water, and the time frame of this issue is expedited greatly.

Furthermore, most foams will absorb water, to some extent. Some pour in foams form a watertight 'shell' which is fine and dandy until you have to trim bits of foam, or bore holes in it for accessories. Also, I think there was some statement about the foam taking months to absorb water. I know the boat isn't going to be semi submerged for months, but simple bilge water will be absorbed. No boat stays completely dry. Even with bilge pumps and the likes, there will still be some water down there, from the sudden rainstorm, to getting back in the boat after swimming, etc. Over the course of a few year's usage, the foam is going to spend a great deal of time in direct contact with water, and will start to absorb some.

Now that we've pointed out the flaws with the foam, lets discuss the correct way to install it. Pouring into the hull is not a good idea. Ideally, you'd want to build a mold that matches the cavity you are installing in, minus an inch in all directions. Line the mold with plastic, pour the foam, then remove from the mold. Then, completely wrap and seal the foam block with plastic and heavy tape. To install in the cavity, the foam should be resting on 1" furring strips of starboard or UHMW or the likes, to give water adequate room to flow, as well as grant the aluminum the airflow that it needs.
 
I was going to run my foam between the rubs but glued to the bottom of the deck as to avoid direct contact with the bottom of the boat. This should keep it dryer, avoid wicking up water, and allow water to flow to the back of the boat unimpeded.
 
When we tore the decks off my boat, all we found was waterlogged foam, and we're wanting to replace it. I'm looking at Lowes and homes depot and you guys were talking about a some kind of Closed Cell foam? Can someone send me a link to a sheet of this foam from either Lowes website or Home depot website? Thanks
 
They will know what you mean when you talk to someone at the pro desk there or that handles the dept. it is extruded/closed cell insulation.
 
Crevice corrosion is exactly what happened on my boat hull. I did have a few fittings that I thought were the culprits, but come to think of it all the corrosion was right were the seats were. I put bedliner down to prevent this from causing more damage. I'm willing to bet is was the foam that caused the corrosion, since the seats had damage too, and guess what they were filled with foam. Things that make you go hmmmmmmm.
 
I had an issue with crevice corrosion on the fuel tanks in my jetboat.

When I first built the boat with the 2 stroke engine, the tanks were set on top of a sheet of extruded styrofoam, and then I used the expanding foam in the cans to blow around the tanks.

Well, 6 years later, when I went to replace the 2 stroke engine with the 4 stroke high output, I had to pull the tanks, so I could weld, cut and modify my hull. Low and behold, there was surface pitting on the tanks from crevice corrosion caused by being in contact with the foam, particularly on the bottom side of the tanks. Also, the blown foam was waterlogged (I know, the stuff in the cans isn't closed cell...live and learn)

A few areas on the tanks looked really questionable, so I TIG welded those areas, to burn off the corrosion, and lay in some new filler metal, then I pressure tested to make sure everything was good.

So, when I re-installed the new tanks, I welded some aluminum channel to the hull of my boat, and used 5200 to glue strips of rubber to the top of those channels, and I have them positioned so that they are only in contact with the mounting bracket on the ends of the tanks, that way, the tanks are elevated off the floor by an inch, and they're not in contact with anything that can cause any further corrosion.

Now you know why I have an aversion to putting any foam in the transom of my boat around my fuel tanks!
 
bassboy1 said:
There is a big white elephant sitting on the couch here. It's eating all the popcorn, so it needs to go.


One thing that hasn't been discussed here is corrosion. As a result, there is a right way to install foam, and a bunch of wrong ways. I may have missed it somewhere, but I've yet to see any foam installed the right way on this site - it has been hinted at in this thread, but only just.

The problem with many of the pour in foams is that in a wet environment, and especially a salty wet environment, they can actually become corrosive to the aluminum (though, what isn't corrosive to aluminum, really?). Others, while fairly stable, can still cause crevice corrosion, just by trapping minute amounts of water against the aluminum, with no airflow. Airflow is critical for the longevity of aluminum. With a fresh supply of oxygen, aluminum will constantly 'heal,' or produce a protective layer of aluminum oxide. This is what gives and otherwise worthless metal commercial value. However, if the water becomes trapped, with no airflow, the aluminum begins to pull 02 out of the water, leaving the remaining water more acidic. This acid then starts eating away at the metal, and the cycle continues. Say the water that gets trapped is salt water, and the time frame of this issue is expedited greatly.

Furthermore, most foams will absorb water, to some extent. Some pour in foams form a watertight 'shell' which is fine and dandy until you have to trim bits of foam, or bore holes in it for accessories. Also, I think there was some statement about the foam taking months to absorb water. I know the boat isn't going to be semi submerged for months, but simple bilge water will be absorbed. No boat stays completely dry. Even with bilge pumps and the likes, there will still be some water down there, from the sudden rainstorm, to getting back in the boat after swimming, etc. Over the course of a few year's usage, the foam is going to spend a great deal of time in direct contact with water, and will start to absorb some.

Now that we've pointed out the flaws with the foam, lets discuss the correct way to install it. Pouring into the hull is not a good idea. Ideally, you'd want to build a mold that matches the cavity you are installing in, minus an inch in all directions. Line the mold with plastic, pour the foam, then remove from the mold. Then, completely wrap and seal the foam block with plastic and heavy tape. To install in the cavity, the foam should be resting on 1" furring strips of starboard or UHMW or the likes, to give water adequate room to flow, as well as grant the aluminum the airflow that it needs.

Sooo, did you launch your boat without the plug in to see how much water it would take on?

Crevice corrosion can occur anywhere on aluminum where water sets for a period of time. In between your transom wood and the outer skin, under wet carpet, and under wet leaves is one of the worst places... you get the tannic acid and the oxygen depleted water.

Water doesn't have to be saltwater to cause corrosion on aluminum, fresh water will corrode aluminum if it sets long enough. Throw in some acidic rain and it corrodes even faster.

BUT! an aluminum boat with proper drainage in the bilge (like mine), that is properly cared for and maintained will not have corrosion problems. Keep your boat covered or garage kept when not in use, and good repair with no leaks and it doesn't matter how much or what kind of floatation foam you have... you'll never have any corrosion problems. I keep my boat covered when not in use and I pull the drain plug after every outing to make sure the bilge is dry and I have no leaks.

It is people that neglect their boats and leave them exposed to the elements that have problems with saturated foam and corrosion... and it's their own fault!
 
Sooo, did you launch your boat without the plug in to see how much water it would take on?

Never in that post did I say my boats don't have flotation foam. I only mentioned the downfalls of incorrectly installed foam, and the correct method of installation. Though entirely irrelevant, I will note that I have launched nearly every boat I've ever owned without the plug (though never intentionally), and never lost a single one.

Crevice corrosion can occur anywhere on aluminum where water sets for a period of time. In between your transom wood

Hence why in past posts, I often harp against wood transoms, or wood anywhere. That, along with carpeted trailer bunks. But, this post was discussing flotation foam, not wood transoms, so I didn't discuss that.

Water doesn't have to be saltwater to cause corrosion on aluminum

Don't believe I said it did have to be saltwater. I'm fairly sure I didn't. I just said that would expedite the process.

BUT! an aluminum boat with proper drainage in the bilge (like mine), that is properly cared for and maintained will not have corrosion problems. Keep your boat covered or garage kept when not in use, and good repair with no leaks and it doesn't matter how much or what kind of floatation foam you have... you'll never have any corrosion problems. I keep my boat covered when not in use and I pull the drain plug after every outing to make sure the bilge is dry and I have no leaks.

Yes, that is nice, but at the end of the day, we are talking about boats here. They are used in some of the harshest environments in the world, and while it is nice to keep them in a climate controlled garage, that is not going to be the case for many of us. As a result, someone with a boat like yours can keep the boat indoors, clean, dry, and rarely used, and never see corrosion problems. Or, someone can keep the boat outside, moored at a dock all summer, let it fill up with snow, etc, etc, and with a slightly different flotation foam installation methods, can have the same results. I'd personally rather everything be tougher than train wheels, and if the boat happens to get pampered, it will not hurt a thing - merely outlast the owner. On the flip side, if the boat is built with shortcuts, and it for some reason, gets abused, there will be problems.

I'm not saying that a boat like yours is going to corrode apart, and develop pin holes by the end of the week. Based on the original post in this thread, it seemed the poster was looking for a civil discussion to bring up facts pertaining to flotation foam, which is a somewhat heavily debated subject on this forum. The intention of my first post was solely to point out some of the corrosion issues that the foam can cause, in a marine environment, which to the best of my knowledge, does not include garages, covers and sponge drying. The next portion of my post was to provide the method in which is potential problem can be avoided from the get go. No portion of my post was directed at any one person, or any one boat - just a broad generalization into the best ways of completing a task, and furthering this educational discussion.



This next part has absolutely nothing to do with my previous posts, but instead contains my educated opinion on flotation foam vs. other methods of flotation. Please note that I'm not implying that one should forgo flotation, but instead that there may be better ways to skin the same cat.

My personal opinion of flotation foam is not very high. I'm much more comfortable with seal welded, pressure tested airspaces. However, on boats under 20', this becomes problematic. It's not practical on riveted boats, for obvious reasons. It even can pose construction issues on smaller welded boats.
Furthermore, on boats under 20', the USCG does not allow flotation airspaces to be integral with the hull. So, while on a 21' boat, it is perfectly acceptable to weld in and pressure test the deck, on a 19' boat, air spaces have to be entirely separate 'tanks.' The problem here is that the regulations are all inclusive, covering a wide array of boat designs and materials. Therefore, the regulations are adjusted for size alone, ignoring many other [more] important variables.
Therefore, flotation foam is a necessary evil on small boats. With a few simple steps, it is able to be a non issue.
 
I never heard of crevise corrosion, so had to look it up.

Crevice corrosion: https://en.wikipedia.org/wiki/Crevice_corrosion
galvanic corrosion: two connected metals + single environment
crevice corrosion: one metal part + two connected environments


The acid part doesn't make sense to me, ie Pulling O2 out of water shouldn't create an acid. Acid generally needs more O2 plus another element, sulfur, nitrogen, clorine, or phospherous. Where is that coming from?

Sulfuric acid: H2SO4
Nitric acid: HNO3
Hydrochloric acid: HCL
Phosphoric acid: H3PO4

I think you might be refering more to aluminum pitting corrosion.

So we should paint the inside to make sure water is not touching raw aluminum?
 
Poultice corrosion, a form of crevice corrosion. This is the term I've always used, but I'd say it is pretty similar to wikipedia's version of pitting corrosion.
https://corrosion-doctors.org/Forms-crevice/Poultice.htm

As far as the water becoming acidic, free hydrogen molecules can decrease the pH. The constantly forming aluminum oxide is created using Aluminum and oxygen molecules, leaving free hydrogen molecules in the water. Furthermore, decaying organic matter (plankton, etc. that would normally be found in lakewater) will also consume oxygen, leaving the stagnant water slightly acidic.

https://imnh.isu.edu/digitalatlas/hydr/basics/main/chmtxt.htm
 
Have you experienced this in a boat? I'd like to see some pictures if possible. Wouldn't paint make an effective barrier to prevent this process from occuring? ie little or no contact with the water.
 
Jdholmes said:
They will know what you mean when you talk to someone at the pro desk there or that handles the dept. it is extruded/closed cell insulation.

Yeah, We went to Lowes the other day, and YBC ((Your building Centers.)) And they had no idea what we were talking about.. But we went to A Marine, and they said to buy Water resistant, Foam, and wrap it in the plastic and tape it, with the taped side facing up towards the underside of the deck, So we're going to do that.
 
FuzzyGrub said:
Have you experienced this in a boat? I'd like to see some pictures if possible. Wouldn't paint make an effective barrier to prevent this process from occuring? ie little or no contact with the water.

Yes I've seen this. Fortunately, every time I've seen it in person, the boats were used in freshwater, so the damage was much less extensive. I've seen pictures from certain builders that I know, and trust, of what the outcome is like in saltwater, and it isn't pretty.

My uneducated opinion on the paint is that yes, it very well could prevent this from occurring. That being said, I've never had any first hand experience with paint under foam, so I will not say for sure. Furthermore, painting aluminum is also a subject for which I've got very little experience with, so I'm certainly the wrong person to ask in that regard.
 
Getting back to the subject:

Foam it can save your life and keep your boat from going to the bottom.

Waterlogged Foam isn't the foams fault and it isn't the boats fault, it is the boat owners fault for permitting water intrusion and neglecting their boat.

No Foam is a very foolish mistake and may cost you your boat, or your life, or both.

Keeping your boat covered and protected from the elements while it's not in use will greatly extend the life of your boat.

Not protecting your boat from the elements will/can cause water intrusion damage, freeze thaw damage, and UV damage... and all will age your boat quickly requiring much more work and maintenance.
 
jigngrub said:
Getting back to the subject:

Foam it can save your life and keep your boat from going to the bottom.

Waterlogged Foam isn't the foams fault and it isn't the boats fault, it is the boat owners fault for permitting water intrusion and neglecting their boat.

No Foam is a very foolish mistake and may cost you your boat, or your life, or both.
.

Calling people fools isn't nice. :)
 

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