rrb Posted October 15, 2003 Report Share Posted October 15, 2003 As mentioned in my previous posts, I'm constructing a minicup from plans on the stevenson projects site. The plans, coming from popular science 25 years ago, call for styrofoam to use inside the compartments to prevent them from filling with water in the event of a leak. I am wondering if there are any sprayable foams that are waterproof and could be used to accomplish this same goal. I figure with styrofoam you either have the tiny balls that could trap water between them or you have large blocks that would be very difficult to fill as much of the compartment as possible. I assume that with a spray foam I could get it to fill the compartment in as much of a form fitting manner as possible. Any suggestions, thoughts? Quote Link to comment Share on other sites More sharing options...
Barry Pyeatt Posted October 15, 2003 Report Share Posted October 15, 2003 Anything that will prevent water from entering the chamber will suffice. That could be ping pong balls, an inflatable bladder, a good seal around all the seams, plastic milk cartons, the packaging bladders that you inflate yourself or foam. The challenge with most of the expandable spray foams is that if submerged, they will absorb water, if a leak develops in the chamber the foam can absorb the water and become ineffective. If you line the chamber with a waterproof membrane and then fill that with the foam it will keep the water from entering the chamber and causing problems with the foam, kind of a double wall theory. Any closed cell foam will work, blue board in strips, blocks or broken up into small chunks. The advantage to foam is that if there is an impact that penetrates the hull the foam still works, a bladder will deflate, multiple bladders will probably not. Open cell foam (white styrofoam) is useless. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 15, 2003 Report Share Posted October 15, 2003 This is great stuff for your job. The spray cans will break the bank. This stuff is waterproof and will give you an huge amount of boyancy. Follow the instructions carefully. It does not have much working time. Stir it for around 20 seconds and get it in the place that it will be, like now. DO it in small pours. You can make flaot chambers out of milk jugs as a mould, and then remove it after the cure. If you would like, I can share some working properites with you, if you go that route. It can be bought online or in many marine stores, if avaliable in your area. Oyster. A 1 to 1 mix liquid urethane foam with 2 pounds per cubic foot density, which is not affected by solvents or gasoline. Bonds to wood, metal or fiberglass and foams wherever it is poured. Provides extra flotation in boats and sound proofs and insulates hulls, walls, floors, seats, decks or any cavity. Great for those otherwise inaccessible places. Can be used to mold anything. (Do not use below 70 Quote Link to comment Share on other sites More sharing options...
Barry Pyeatt Posted October 15, 2003 Report Share Posted October 15, 2003 I should have added the Urethand foam to the list, Oyster is correct. This was generally not available in smaller quatities until recently. This will work well. One of the concerns with anything that you seal up is that you have good tight seams on all the joints. Finish and Caulk everything and be certain that the area is completly dry before pouring the urethane foam into the cavity. Any water/moisture trapped inside can cause potential rotting problems. Quote Link to comment Share on other sites More sharing options...
rrb Posted October 16, 2003 Author Report Share Posted October 16, 2003 Oyster thanks for the suggestion that sounds like what I was really looking for. do you know anything about the quantity of foam produced per can? A rought estimate of the volume of the compartments in the minicup is around say 15 cubic feet (very rough guess at this point no real math done.) what quantity of the poly-u-foam would I need for this project? If purchased could i just pour that into the compartments and allow it to foam to fill them? Quote Link to comment Share on other sites More sharing options...
Guest Posted October 16, 2003 Report Share Posted October 16, 2003 The specs show around 2.5 cu ft. But I do believe you could get more out of the two quart kit. But it can be bought in one gallon kits, and five gallon kits pretty reasonable. Now here me out on this one. I have mixed the chunked up blueboard in small lots into a mix of the pour foam to stretch my dollar, with great success. We mix the foam and then pour into the cavity with the blue board already in it. Stir the mix a little so you can get the foam to the bottom areas, for sticking it rigid to the hull parts. Be extremely careful to avoid the mix geting on your skin. You will wear it for a while. We use long sticks to stir the mix, to keep it away from our bodies. It will turn a dark brown on mixing, and then a yellow color will appear, upon ready. Get it out of the pot at that time. In large mixes we use a paint paddle type stirrer in a drill motor, to mix it completely. Its not as bad as it sounds. We also will seal the areas, as in the foward lockers, and then pour through a hole saw hole. Be very careful not to mix to much. It will expand and has been known to blow out sections in a hull. But this is not an issue, if you do small batches, till you get the hang of it. Many people will express concern, for later down the road, for access to the hull for any repairs. What we do to help this matter, is we seal the glass, or epoxy coating with a primer, or even a gel coat mix, with little sanding, to allow for release in bulk sections, upon the need to work on the area. The foam sticks to the primer or coating, and stays in place, becuase of being formed inn place, and then will pop out with a little bit of pursuation. I have pictues of this, if needed to show a job I am doing now, with just the same issue. Quote Link to comment Share on other sites More sharing options...
Konrad in Lincoln Posted October 20, 2003 Report Share Posted October 20, 2003 Personally, I'd just use emtpy milk jugs (if they'll fit). They're basically free, and I like free. Quote Link to comment Share on other sites More sharing options...
Tom Holder Posted October 20, 2003 Report Share Posted October 20, 2003 How about various sizes of plastic pop bottles or water bottles? With 3L, 2L, 1L, 600ml, 500ml etc. sizes, you would be able to maximize the availible space. Hot glue the caps on maybe just in case. If the rattling bothers you, hold them in place with a quick squirt of expanding foam. In a pinch, you can shove a few of them in your pants and shirtsleeves in case of a turnover far from land. Place the kids on your stomach and they can paddle you to safety. Wear a pointed hat to help break the waves . . . Quote Link to comment Share on other sites More sharing options...
Guest Posted October 20, 2003 Report Share Posted October 20, 2003 In a pinch, good life preservers, and float rings work correctly. When I need, like really need flotation, I want to know I have positive flotation. The worse thing a person can do is to start swimming from a sunken boat, that is at least a wash in the water. Any rescue is greatly increased, when you stay with a small craft, or objects from a larger craft, that have broken away from the large vessel. If you have any doubt that your small vessel will not float, then you don't need to be in it. Is your life not worth even a hundred dollars of flotation for this job? A boat is a hole in the water that you pour money. Why pour your life in it, never to be found again, for going it the cheap way. Don't scrimp ,when in doubt on foam. Quote Link to comment Share on other sites More sharing options...
rrb Posted October 20, 2003 Author Report Share Posted October 20, 2003 I am going to agree with oyster on the fact that it is ridiculous to cut corners on a situation where your life may be at stake. When I fly I always remind myself that its better to safe/late/stuck on the ground than dead, that the only option you have is taking off-- once you've done that landing is inevitable, and that if you die because of weather remember that your funeral will be on a nice day. that being said, I have no problem with examining cheaper alternatives on this boat since at best it will be used on a small lake nearby and always with a life jacket (i've heard the horror stories of people getting knocked out by a boom and drowning.) however I am worried about losing face, which is why I was thinking that the pourable foam would be a good option. I don't want to have to explain to my friends why I spent so much time on a boat that takes on water and gets swamped after a little sailing. I don't anticipate more leaks (I'm about to do the second round of leak testing now that I've reinforced seams), however would like the foam as a redundant safety (face saving) feature. i like safety otherwise some very fun things wouldn't make any sense. Quote Link to comment Share on other sites More sharing options...
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