Floatation of wet foam

DrJudyB · Apr 4, 2018

Jackdaw said:
i Judy. I understand the THEORY, I'd like to hear about why someone personally made the choice. You didn't - your boat will sink if holed! ;^)

I think that a lifraft makes excellent sense off shore. And I also think positive floatation is appropriate for a lot of day sailers and trailer sailers that are highly unlikely to have a life raft on board such a small boat.

Different solutions work in different situations.

Here’s a case In point:my boat. It comes up with some very unusual ways of addressing safety concerns. My boat won’t sink if it gets holed. It has three hulls with watertight sealed compartments, and foam or balsa sandwich construction everywhere. It would prolly need to be holed in 3 or 4 places just to get it awash to the gunnels. All of Ian Farrier’s trimarans are unsinkable, with sealed chambers and foam sandwich construction. They are virtually their own life rafts. They float high and dry and easy to sit on when upside down, according to racers who have flipped them. .

I do wear a PLB and PFD at all times. I’m probably going to buy a spare PLB for my crew when double handing, just in case I can’t find him easily if he goes overboard in adverse conditions. My boat travels a long way in just a couple of seconds at 10-14 kts. It would be easy to lose track of a COB at that speed.

I’ve owned keel boats in the past, that were very heavily ballasted, very stable, and certain not trailerable. I Didnt need positive floatation on those ecause they were very unlikely to swamp even on San Francisco Bay in 40kt

Heavily ballasted boats don’t, IMO, “ need” positive flotation as much. A life raft is a better alternative.

Conversely, I think positive flotation is a desirable feature in a trailerable, lightly ballasted day sailor who isn’t going to take a life raft on such a small boat when sailing on sheltered waters, near shore or inland

I gotta go back to work! I’m staying off the forum!

DrJudyB · Apr 4, 2018

fritz3000g said:
Thanks DrJudyB. Yes I'm sure it's open cell. It's white like a styrofoam cup and little beads break off easily. The Mac25s came with that kind of foam.

I have always considered styrofoam to be closed cell.

Jackdaw · Apr 4, 2018

DrJudyB said:
Here’s a case In point:my boat. It comes up with some very unusual ways of addressing safety concerns. My boat won’t sink if it gets holed. It has three hulls with watertight sealed compartments, and foam or balsa sandwich construction everywhere. It would prolly need to be holed in 3 or 4 places just to get it awash to the gunnels. All of Ian Farrier’s trimarans are unsinkable, with sealed chambers and foam sandwich construction. They are virtually their own life rafts. They float high and dry and easy to sit on when upside down, according to racers who have flipped them. .

Of course! That slipped my mind - the amas being buoyant independent of the main hull.

Scott T-Bird · Apr 4, 2018

fritz3000g said:
I'm a relatively new sailor in terms of years, but I've spent hundreds of hours out on the water, including lots of lessons with more experienced folks. I don't plan to cross any oceans, but I probably will cross Lake Michigan and/or go to the Bahamas one day. My concern is that the Mac25 is pretty thin fiberglass and could be holed more easily than a bluewater boat. Or the swing keel could break away. So I want to be careful and try to keep the positive flotation if I can.

I think it is delusional to think that positive flotation is going to keep you safe in a boat that you already say is fragile to begin with as you contemplate a Lake Michigan or Bahamas crossing. If you think that a $65 budget for safety is going to fly, think again. I don't mean to imply that your entire budget is $65, but if you have to weigh the cost/benefit between $65 and $300 for flotation (which is not going to do you a lick of good in the Lake Michigan water temperature or Gulf Stream turbulance), then what else are you going to compromise?
In this case, don't get silly with vapor barrier properties between closed cell and open cell. It's not going to make any difference. Just throw in the cheap open cell stuff and be done with it. If your boat capsizes or is holed, it won't matter. You won't be hanging on to a swamped boat in the Gulf Stream for long, I think. Your budget and safety considerations are going to have to be a whole lot more extensive.

I don't mean to knock your boat. Sumner is a real sailor and has made the trip to the Bahamas in his boat, so we all know it is feasible in the hands of a sailor. As he indicates (I think), he hasn't made any consideration for the flotation properties, probably because he knows that flotation isn't going to help him in these circumstances. Storage capacity would have to be the over-riding consideration. He has relied on a whole different set of safety considerations and sailing skill to keep his boat safe. If I'm wrong about that, I'll be happy to absorb any flack that Sumner dishes out.

If staying afloat in the inland lakes of Wisconsin is the goal, then by all means, add flotation (so what is your problem with the existing flotation anyway?). Relying on it for safety in more serious circumstances is a fool's proposition in my opinion.

JamesG161 · Apr 4, 2018

fritz3000g said:
waterlogged closed and open cell foam?

@fritz3000g After reading this long thread, I woulds suggest there no such thing as...

Waterlogged Foam

Unless the foam can "ADsorb" water. Which means to bond or ADhere to the foam.

Example:
A dry sponge can ABsorb water in the spaces between the foam cells [that are sealed containing air]. Leave the Waterlogged sponge in a dry space and slowly the water will evaporate, albeit slowly, depending on the Relative Humidity of your drying space.
_______
A possible solution to your original post...
1) Remove the Waterlogged foam and dry it. How to know its dry? Weigh a piece every few days and when that sample's weight stops dropping, it is dry. You may have to rotate the foam pieces to dry faster.
2) To prevent future "Waterlogging", spay coat it with a water sealer. You can test a coated dry sponge to see if the sealer works.
3) Carefully reinstalled foam so that you don't knick off the coating.

_______

I carefully avoided the question whether the foam originally worked or not.

Good luck...
Jim...

PS: That was just one of many possible solutions.

JimInPB · Apr 4, 2018

fritz3000g said:
WRT the question about whether foam can be waterlogged, yes it can. One of the foam blocks in my boat was waterlogged before I dried it out. The rest are pretty dry.

How long did it take to dry? If you put it back in water again, how long will it take to get waterlogged again? If it soaks up water quickly, perhaps this was an incorrect material that a previous owner put in there?????

JimInPB · Apr 4, 2018

fritz3000g said:
The other advantage to this is that if I can fill all the gaps between the foam blocks I'll have more flotation and so can open up some of that space for water storage.

This comment still puzzles me. Are you asking if you can add more foam & then be able to carry more cargo weight than the boat was originally rated for??? Am I misreading this?

Hayden Watson · Apr 4, 2018

fritz3000g said:
Thanks DrJudyB. Yes I'm sure it's open cell. It's white like a Styrofoam cup and little beads break off easily. The Mac25s came with that kind of foam.

Styrofoam is closed cell foam otherwise you could not hold coffee in a cup made from it. It is not the best quality but it does not soak up water like open cell. For foam to be open cell it must allow air into and out of the individual cells of the structure The little beads do not do that. For open cell foam think of a kitchen sponge or sponge foam seat cushions.
To test your foam take a little chunk of it and hold it under water and give it a gentle squeeze. If it is closed cell it might loose some water but for the most part will remain as buoyant as before. If it s open cell, you will get a lot of air bubbles and when you release it will fill with water. Give it a few more squeezes and it will just barley break the surface.

Will Gilmore · Apr 5, 2018

What a lively discussion. The original post was Thursday and half the first page was filed in a few hours. All the rest of the 1st, the whole second page and up to four posts ago was filed yeaterday.
The original question was for a source and recommendations around closed cell foam but much of the thread was about the usefulness or not, in positive buoyancy in a keel boat. I'm sorry it took me so long to get here.

My little trailer sailer is suppose to have positive buoyancy but it is old and I don't trust it. There are big waves out there, any sized sailboat could get swamped. I was at the helm when our family's 56 footer was completely underwater for about 3 seconds. Only my shoulders and the masts sticking up above the swamping wave. Wanting positive buoyancy is completely understandable. The problem with displacement buoyancy (foam blocks intended to displace water filling space inside the hull) is it takes up space, storage, and adds weight, much of it above the center of balance. Thus, by some small degree, your boat becomes a little easier to swamp. However, I think it is often worth it. I wouldn't add flotation because of fears the keel could fall off. A sailboat that loses her keel is hardly a boat anymore and there is no gunnel right-side-up to keep the sea out so bailing isn't a thing. However, a hole is worth having flotation for. Consider that your boat is far better equipped with supplies, and possibly mobility plus radio, etc. If your boat can be your life raft, awesome.
It is interesting to think about. If you consider nearly all the material of and on the boat were neutral to negative in buoyancy, the volume of air that will keep it afloat is equal to the volume of air inside the boat from the waterline down. Replacing that volume with foam will add weight so you will need to fill that space with more foam that extends above the waterline to equal the flotation value of the air. That is just to achieve approximately neutral buoancy. Fortunately, some of the material onboard is also positive in buoyancy, coolers, life jackets, cushions and mattresses, if they are not water logged, wood, very small rocks, ducks

Beaded Styrofoam gets waterlogged. It it's slow, you would have days, maybe weeks, if it started dry. If you couldn't bail yourself out by then or return to rescue the boat before it sank, you are in pretty bad shape regardless of the floatiness of your boat. However, I am interested in doing similar things to Dragonfly. I want to attach closed cell foam mattresses and seat cushions to her with mechanical fasteners to aid in keeping her afloat should she become swamped. I have been considering the idea of a cabin airbag that could inflate to fill some of the cabin space and keep water out until repairs or rescue or port is reached. Maybe even an inflatable rubrail encircling the boat. I want Dragonfly to be capable of crossing an ocean. I'm not going to do it, but it is cool to think about, maybe I would some day.
I support the OP's concerns.

- Will (Dragonfly)

Scott T-Bird · Apr 5, 2018

Hayden Watson said:
Styrofoam is closed cell foam otherwise you could not hold coffee in a cup made from it.

Yes, excellent point for clarification! Re-reading the original post, it seems that fritz hopes to increase storage by creating more efficient flotation via a more expensive closed cell polyurethane product and he is wondering if it is worth the substitution. There also seems to be some question about the effectiveness of waterlogged flotation. I'm still not sure I get what that is all about.
1. I've learned from experience with my ski boat that spray foam underneath the floorboards does get waterlogged and that is not good. If the flotation is already waterlogged, get rid of it and replace with dry material. It's not going to dry out on its own if you can't remove it and place it in an open, dry environment for a long time. It's not worth the effort.
2. The higher quality closed cell foam is made denser so that it improves insulation value. That doesn't seem to be what fritz is looking for so it doesn't make sense to go that route. It's just going to add weight and there probably isn't any gain in flotation. It may even be a negative, given the higher density.
3. Styrofoam, which is apparently what exists in the boat and is what fritz seems to want to use IS a closed cell polyurethane, that is cheap and light weight. It's not good for insulation because it is not high density closed cell, but who cares? It does work well for flotation. Will it absorb water in the voids quicker than a more expensive spray foam that is closed cell? Maybe, but probably not worth the additional weight and expense.

If the purpose is to provide flotation only, the Styrofoam is probably the best product for the job. It's not easy to work with ... the blocks are not shaped efficiently and shaping the blocks will make a huge mess. I like somebody's idea of stuffing pool noodles in inaccessible spaces. So fit shapeable and compressible materials in the gaps that are left by the Styrofoam blocks. I'd not worry about the waterlogging possibility. The material is not intended to be soaked, so it should be maintained dry. When you really need it for flotation, you should be rescued long before waterlogging becomes an issue.

Sumner · Apr 5, 2018

fritz3000g said:
... One of the foam blocks in my boat was waterlogged before I dried it out. The rest are pretty dry.

I'm wondering why/how are the foam blocks getting waterlogged?

I'm not aware of any in our boat having any water in them and I've had a number out doing mods. They were all replaced. I've opened up more room in a couple cases like above the galley, in the coaming at the bow, by cutting up some of the pieces into smaller pieces so that they can fit back into the openings better.

I would recommend changing out the standing rigging before a trip to the Bahamas if you are going past Bimini. I like the comment a friend of mine made about going to the Bahamas (past Bimini)..... the further you go the further you are going out to the end of a long limb. Going in a small boat isn't for everyone although a lot of people use to do it. A little off topic but I've written up some things to think about before attempting it, especially if others are going to be involved...

http://1fatgmc.com/boat/mac-1/2015 Bahamas/Things to Consider-1.html

One other suggestion that isn't related to the foam and you might be aware of it. That is if you haven't dropped the swing keel and inspected the pivot hole and the pivot pin I for sure would do that. It is something that has failed on 25's ending up with the keel going to the bottom and the boat becoming more or less useless.

Good luck with your Mac and have fun with the boat,

Sumner
================================================================================
1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...
Mac Trips to Utah, Idaho, Wyoming, Canada, Florida, Bahamas

JamesG161 · Apr 5, 2018

fritz3000g said:
I should probably test how long it takes to saturate when submerged.

For water to permeate into the non- sealed void areas, it has to enter from the outside.

The time that takes is depends on the surface of the Foam Block exposed to water. Less surface, more time.
Even if you don't fully coat your foam blocks with something like this...

https://www.homedepot.com/p/Rust-Oleum-Stops-Rust-11-oz-LeakSeal-Clear-Spray-265495/203165633

You will add a big time delay. Plus, if you get only spray the top and sides, little water will enter your foam spaces, if at all.

Think of taking your empty foam cup , turning it upside down and then try to sink it.

As water tries to enter the voids, air must be pushed out.

Jim...

PS: ALL rigid foam is closed cell. No such thing as OPEN CELL foam. There may be permeable space around the cells, but little of it.

BobbyFunn · Apr 5, 2018

fritz3000g said:
polystyrene

This material is nasty when burning. If used in the hull try to seal so that it does not have easy acces to a heat source or air.

In narragansett ri there are ww2 cannon bunkers we used to play in. Some goofball would usually add styrofoam garbage in the campfire inside and within seconds the entire room was black and breathing was impossible.

DrJudyB · Apr 5, 2018

fritz3000g said:
https://www.austech.com.au/news/extruded-v-s-expanded-polystyrene-1
Expanded polystyrene (the white kind we make cups out of) is open celled and so more likely to absorb water than extruded polystyrene (the pink or blue stuff). My boat came with expanded polystyrene blocks (8" x 10" x 12") in the bow and stern.

I respectfully disagree. Expanded polystyene (like coffee cups made of beads of closed cell foam are stuck together in a mold to form a shape) and extruded polystyrene (blue board or pink board) are both closed cell foam. Both foams trap air in closed cells. Both are rigid, non-flexible foam.

Expanded polystrene has interstitial spaces between the round beads. Water may seep into the block of foam via the interstitial spaces and replace the air that was previously there. But water doesn't penetrate the round beads themselves unless you crush them and break the cell walls.

I tried to find "Open cell polystyene" and "open cell styrofoam" for sale on the internet. I couldn't find any. I'm pretty darn sure that "open cell polystene" isn't commercially available.

JimInPB · Apr 5, 2018

Judy's research leaves me with a new question. When the foam blocks are waterlogged, how much weight do they gain? Is the amount of the weight gain anywhere near the weight of water for the same displacement? Or is it only a small portion? If the foam only gains something like 5% of water weight, then you may not be so bad off with what you have, despite 5% of water weight probably being many times the weight of the dry foam.

timebandit · Apr 5, 2018

My original foam was starting to crumble and mildew so I took it out and washed it with a mild bleach and dish soap and allowed it to dry. It got painted with white house paint and allowed to dry, I think the paint keeps it from soaking up water.