Open or Closed Cell Foam in c.1979 Boat

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Nsp
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Open or Closed Cell Foam in c.1979 Boat

Postby Nsp » Tue Jan 08, 2019 9:58 pm

Is the foam used in 1979 to make Boston Whaler SPORT 13 boats open-cell foam or closed-cell foam?

I don't know if my 1979 SPORT 13 hull is heavier [now than when it was made].

jimh
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Tue Jan 08, 2019 10:44 pm

What is the difference between open-cell foam and closed cell-foam?

Is there some way you make foam one way and not the other? I would ilke to get more information from you on these two types of foam, how they are made, and how they differ. Thanks.

As far as has been known and determined by actual chemical analysis of the foam used in a Boston Whaler boat, the foam has been the same type of foam for decades. As far as I can determine, "foam" as in foam made by chemical reactions of two liquids that hardens into a solid medium with entrapped air in small bubbles must consist of small air bubbles suspended in a solid. If you have a solid material that has no closed cells of entrapped air but has a porous nature, you call that a "sponge" not "foam." Since Boston Whaler has been making boats with their Unibond process, to the best of my knowledge, they have always filled the hull with foam and not with sponges.

If you think your Boston Whaler boat hull has entrapped water, see the FAQ for some advice.

Q3: Is There Water In My Hull?
http://continuouswave.com/whaler/reference/FAQ/#Q3

The FAQ answer will give you methods to use to determine if your Boston Whaler boat has entrapped water in the hull.

Mr 88
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby Mr 88 » Thu Jan 10, 2019 9:40 pm

Having Googled open cell foam vs closed cell foam, I see there is a difference ,mostly in density and R value. So there is a difference in the two.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Thu Jan 10, 2019 9:50 pm

What is "R value" of foam? Are you talking about the insulation rating of foam with regard to conduction of heat? That is meaningless in the use of the foam as a medium to fill the space between the hulls of a Boston Whaler boat.

How is density related to "open" or "closed" cellular foam? It would seem to me that foam density is a function of how much air (or other gaseous compound) is trapped in the bubbles in the foam in a particular standard volume. Since the solid cured material that makes the foam weights more than the gaseous compound, the more entrapped bubble volume the lower the density.

But I still don't understand what the terms "open-cell" and "closed-cell" mean, and how you make different kinds of foam. Can you explain that?

Mr 88
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby Mr 88 » Thu Jan 10, 2019 10:13 pm

Just Google it as I did. Many of the aricles go into great detail. All I would be doing is copying and pasting .as I am not expert in this field.

dtmackey
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby dtmackey » Thu Jan 10, 2019 10:26 pm

Mr 88 wrote:Having Googled open cell foam vs closed cell foam, I see there is a difference ,mostly in density and R value. So there is a difference in the two.


Yep, the web is loaded with information on spray foam used in homes and that's where "R" value comes into play. Open and closed cell foams have with very different insulation and property characteristics.

Closed-cell is a lower density foam (2 to 3-lbs-per-cubic-foot) and open-cell even less (0.5 to 0.75-lbs-per-cubic-foot). Since there is no structural strength required in wall insulation between supporting 2 x 4 or 2 x 6 construction, these foams work just fine. Open cell foam is a very poor performing material for strength.

In boats, foam can also be sprayed, poured, or injected into the desired area. The density of the foam can range from 2 to 16-lbs-per-cubic-foot. The foam density is selected depending on the application and strength required.

I'm not aware of open-cell foam ever being used in the marine setting. I have only encountered closed-cell in the boats I've owned or rebuilt over the years.

Two-part polyurethane closed-cell foam strictly for flotation [has a density of 2-lbs-per-cubic-foot]. When strength is required [a foam with a density of 4-lbs-per-cubic-foot] or greater would be used.

The "weight" of foam is based on what one-cubic-foot of fully activated and expanded foam weighs. For comparison, a cubic foot of water weighs 62-lbs.

D-

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Fri Jan 11, 2019 3:38 pm

DT--I deleted all the hash marks or octothorpe characters from you post because they are never used here to mean pound-avoirdupois.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Fri Jan 11, 2019 3:53 pm

The comparison of the density of a typical foam with water is very cogent. What makes a Boston Whaler boat "unsinkable" is not that the foam would float, but that the foam fills up a very considerable interior volume of the boat's hull, and by occupying that space it prevents water from occupying it. When a Boston Whaler boat hull fills up with water, the amount of water that can be held by the empty space below the top of the gunwales is limited; much of that space is filled with foam, which, as mentioned, has a much lower density than water.

Probably the best example of how a Boston Whaler boat can not sink is found in the OUTRAGE 25. It has a relatively deep-V hull, and most of that hull space below the level of the deck is filled with foam. This gives the hull form tremendous reserve buoyancy. The OUTRAGE 25 hull has 9,000-lbs of "Swamped Capacity." That means that even with the hull filled with water to the gunwale tops, you could add 9,000-lbs more weight before the hull would sink, that is, before the weight exceeded the buoyancy of the hull form displacing water.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Fri Jan 11, 2019 6:12 pm

Mr 88 wrote:Just Google it as I did.


I searched GOOGLE.COM for "it" and got 25-million results. I can't read 25-million search results to figure out what you mean. Please be more specific.

It is not up to readers to clarify the terms you are using. If you throw out some terminology, be prepared to explain it. To require that someone else has to explain the words you are using is not a reasonable basis for you to use those term. If YOU don't can't explain them, then don't use them.

I am still waiting to learn from people using terms like "open-cell foam" exactly what that means and how it is different from "closed-cell foam."

And how do you make open-cell foam?

How do you make closed-cell foam?

What is the chemical basis for these to be different?

So far nothing from anyone about this that has used these terms. Is this some sort of secret code word? Please explain. You all presume that there is universal knowledge and common understanding of these terms. They are tossed out there like every reader is expert about them.

Paul A
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby Paul A » Sun Jan 20, 2019 12:33 pm

Another factor may be the "perm rating" or the amount of moisture that gets through or into the material. I have been told Boston Whaler foam is and always has been closed cell which should have a very high "perm rating" but the foam still holds water like a sponge if subjected to prolonged periods or can have condensation build-up with a boat sitting in cold water but high air humidity. The air hits a dew point somewhere in the hull possibly causing water vapor condensation in the foam.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Tue Jan 22, 2019 9:11 am

Paul A wrote:Another factor may be the "perm rating"...

I have to infer that "perm" in your term "perm rating" must mean permeability. Was that what you intended?

Where do you find a definition of "perm rating" and a listing of the "perm rating" of various materials?

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Tue Jan 22, 2019 9:12 am

Paul A wrote:...Boston Whaler...foam...holds water like a sponge if subjected to prolonged periods...


Prolonged periods--of what?

Many years ago I had a sample of foam from a Boston Whaler boat. I immersed the foam in water and held it in the water for weeks. Then I removed the foam sample from the water. The foam was dry and held no water.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Tue Jan 22, 2019 9:13 am

Paul A wrote:...Boston Whaler....foam...can have condensation build-up with a boat sitting in cold water but high air humidity. The air hits a dew point somewhere in the hull possibly causing water vapor condensation in the foam.


How does outside ambient air enter the sealed interior of a Boston Whaler Unibond hull?

In the production process, any sprue holes in the boat are covered with resin and sealed. Exactly how does air enter the sealed Unibond hull interior? And, if air is free to enter the sealed interior by some access point, would not water be able to enter that same access point? I don't believe there is such an access point. The hull and inner liner are sealed, and the only way air or water can enter is by damage or by osmosis through the fiberglass resin layers.

dtmackey
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby dtmackey » Tue Jan 22, 2019 11:09 pm

jimh wrote:
Paul A wrote:...Boston Whaler....foam...can have condensation build-up with a boat sitting in cold water but high air humidity. The air hits a dew point somewhere in the hull possibly causing water vapor condensation in the foam.


How does outside ambient air enter the sealed interior of a Boston Whaler Unibond hull?

In the production process, any sprue holes in the boat are covered with resin and sealed. Exactly how does air enter the sealed Unibond hull interior? And, if air is free to enter the sealed interior by some access point, would not water be able to enter that same access point? I don't believe there is such an access point. The hull and inner liner are sealed, and the only way air or water can enter is by damage or by osmosis through the fiberglass resin layers.


I'm scratching my head on this one as well. Condensation on a hull from cold water on one side and warm humid air on another is one way to get condensation, but a Whaler hull is sealed and not pulling in humid air for this to happen. I'd discount this since altogether.

Whaler hulls I've seen that are waterlogged are due to damage of the outer skin or the brass drain tubes. In the salt the electrolysis eats them up if the boat is in a marina with stray dock current, but even without current, they get thinner over time and fail. Because of this, I put a drain plug in the inner and outer drain tube holes to prevent salt water from entering in the first place and rely on a rule pump in the boat to remove the excess water.

D-

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Wed Jan 23, 2019 1:31 pm

I don't think the fellow (user-id NSP) who posed the initial question has been back to read any of the answers or to answer any of the questions asked of him. NSP introduced the notion there were two types of foams, open cell and closed cell, and that either could be used in a boat by asking his question.

Since no one has offered any explanation about the fundamental difference between open-cell and closed-cell foam in their structure, I don't see how we can keep discussing these two materials. To know they have different densities, different R-values, and now different "perm rating" is perhaps interesting, but it provides no insight into any structural difference between the materials.

As I proffered earlier, a material with open cells that can absorb water is usually called a sponge. And, as already noted, Boston Whaler does not use sponge material inside their hulls.

If there is no explanation of the structural difference between the two materials to be offered, I can't see much use in further discussion of their R-values or their densities, as in the application to Boston Whaler boats, I doubt that R-value or density is of much concern, at least not in regard to density because the density of just about any polyurethane foam is going be much lower than water. I am certain that for use in Boston Whaler boat fabrication, the principal characteristics desired are low cost, rigidity and resistance to deformation, low permeability to water, insolubility in water.

As I mentioned earlier, I have some actual samples of the foam used in Boston Whaler boats, and I have immersed that foam underwater for long periods. The foam holds no water when removed from the water; it gains no weight. The foam is also quite rigid. It resists deformation quite well. Of course, with enough force, it can be deformed, as can any material.

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GoldenDaze
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby GoldenDaze » Tue Jan 29, 2019 9:54 am

Regarding open- and closed-cell foam, here's a quote from the Wikipedia article on "foam" at https://en.wikipedia.org/wiki/Foam: "Solid foams can be closed-cell or open-cell. In closed-cell foam, the gas forms discrete pockets, each completely surrounded by the solid material. In open-cell foam, gas pockets connect to each other. A bath sponge is an example of an open-cell foam: water easily flows through the entire structure, displacing the air. A camping mat is an example of a closed-cell foam: gas pockets are sealed from each other so the mat cannot soak up water."

And here's a short article on open-celled foams: https://en.wikipedia.org/wiki/Reticulated_foam

A few key quotes:
"Reticulated foams are extremely open foams i.e. there are few, if any, intact bubbles or cell windows."
"Producing reticulated polyurethane foam is a two step procedure: a conventional closed-cell polyurethane foam is produced, then the faces (or "windows") of the cells are removed. [...] [E]ither filling the closed-cell foam with a combustible gas like hydrogen and igniting it under controlled conditions, or exposing the foam to a sodium hydroxide solution will remove the faces and leave the edges."

One application I'd never heard of is using open-cell foam as a fuel tank filler to reduce slosh and prevent vapor explosion.

-Bob
2003 160 Dauntless Golden Daze

jimh
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Tue Jan 29, 2019 10:37 am

Bob--thanks for the cite to Wikipedia. As I mentioned earlier, Boston Whaler Unibond hulls are filled with foam, not with sponges. I don't know where the notion arose that Boston Whaler uses sponges in their Unibond hulls, but apparently this misinformation is out there somewhere.

I can't believe the OP has not returned to the thread. Perhaps he started it just to create confusion.

ECU1984
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Re: Open or Closed Cell Foam in c.1979 Boat

Postby ECU1984 » Wed Jan 30, 2019 8:53 pm

Traditionally open celled [materials] will absorb water and get heavy.

Closed cell foam doesn't absorb water and is what you want in a boat floor.

The above is what I have always been told and has been my experience.

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Re: Open or Closed Cell Foam in c.1979 Boat

Postby jimh » Wed Jan 30, 2019 9:54 pm

Yes, I have the same experience. When I use an open-cell material to soak up water--a sponge--it gets heavier because the water flows into the many connected open passages in the sponge. I cannot imagine that anyone has ever tried to make a boat using a material that acts like a sponge to fill the space between the inner and outer hull.

The solid cured material containing entrapped air bubbles that was once a foaming liquid that is found inside a Boston Whaler boat has closed cells and does not hold water. It is no longer "foam." It is a rigid solid material that has reasonably good mechanical resistance to deformation as long as a force is not applied over a small area.

If you expose this solid cured material inside a Boston Whaler boat to a stream of very high-pressure water, as might occur if there is damage to the outer hull of the boat and the boat is operated at high speeds so the sea can beat on the material, you can damage the material and compress the material, causing the entrapped air bubbles to be collapsed and become open and connected to other collapsed cells. When that occurs, the solid cured material no longer contains closed cells of entrapped air. If the material continues to be immersed in water and subjected to continued exposure to high-pressure water, water can begin to infiltrate the material and occupy those areas that were once closed cells of entrapped air but have been broken down.

If is also possible that in the operation of the boat the hull could encounter very high pressures acting on the hull, such as might occur when the hull slams into a wave or when the hull is on a trailer and there is a very big jolt from a bump on the highway. In an instance like those it is possible that forces applied to the hull might exceed the material strength of the laminate layer and cured internal closed-cell material, cause perhaps some compression of the internal cured closed-cell material and possibly collapsing some of the closed air bubbles in the material. If at some time in the future water is admitted to the sealed interior of the hull, it could be held in those areas where the closed cells were damaged and collapsed.