Adding Foam Emergency Flotation To Sailboat

Article By Shorty

I am a bit of a nutball when it comes to emergency floatation. The coast guard requires all power boats to have enough floatation to "keep the hull floating and give the passengers something to hold onto while waiting for rescue", but interestingly they do not require floatation for sailboats. It is popular among blue water cruisers to have full floatation, so that if the boat is holed and fills up with water, it can still be sailed. I agree with the blue water guys, because there are plenty of logs, shipping containers, oil drums etc that are out floating free that could easily crack open my hull. In 2005, one report stated that 450 shipping containers were lost that year alone - and they can stay afloat for years, just below the surface. With a little time, most holes can be jury rig repaired on the water - which will allow you to bail and continue your trip.

There are many types of floatation that you can put in your boat. I have been using 2 part expanding urethane foam for structural purposes, such as making supports under cockpits. It is very simple to use, you just mix equal amounts of part A and B, stir in a small cup and pour it where you want it. Then in 5 minutes, the stuff expands quickly then hardens. Have to be careful to only use it in small quantities, if you put too much in, it will expand too much and break apart your boat. This foam was advertised as "expanding rigid urethane foam is a closed cell, pourable foam, which will resist the absorption of water." And I recognize the foam, have seen it in many boats.

Just to make sure it is closed cell, and will resist water, I did some experimenting. I made a couple of little globs, some were complete globs, and others were gobs that I cut in half. I then took them and submerged them in a small plastic container filled with water. Pushing the lid on made water squirt out the lip, so I knew the foam pieces were submerged under water. Came back the next day, opened the lid and guess what? The pour foam had sucked up a bunch of water!!! Each little piece was just like a sponge, I was so angry !!! Well, time to move onto plan B, so I did the same experiment with a couple of other types of foam. I had some sheet construction foam and that held up to the water, was still fine after a month. Popcorn packing chips were another good one.

Some other floatation choices are empty soda bottles, truck tire innertubes, other inflatable stuff etc. I really wanted a foam type thing that I could stuff in every spare crevace of the boat, so I could get the maximum amount of emergency floatation. The packing chip popcorn / peanuts seemed like a good option, so I did some experimentation to see exactly how much float power they had.

I took some packing chips and put them in a plastic bag with holes in it, that way the air would not add to the floatation. Another plastic bag tied to it, and I started to load it up with lead weights. I added and removed weights till I found a balance point where the foam was just under the surface of the water.

Water weighs 62 lbs per cubic foot, and these chips seemed to be able to float 40 lbs per cubic foot. That sounds pretty good to me.

The next step is to figure a way to encapsulate them packing chips, because if I holed the boat, I didn't want my floatation material to float away. So I got some cheap nylon fabric and started sewing pillows of chips.

If you leave the pillow a bit on the baggy side, you can work it back and forth into smaller holes. Here is the cavity between the liner and the bow. It was filled with small cut pieces of pour foam, and the white foam. There was also a flashlight sealed up in there (see the pic above), wonder when it got in there?

My boat is supposed to weigh 1350 lbs. Of that, I think 400 is supposed to be in ballast. One boat manufacturer told me that you don't have to support the entire weight of the boat, only need to support the weight of the ballast plus 40% of the fiberglass weight, because of the density of fiberglass.

1350 total weight of boat
- 400 lbs of ballast & metal parts
950 lbs of fiberglass
* .4
380 lbs of floatation needed for fibglass part of boat
+ 400 lbs of ballast & metal parts in boat
780 lbs total float needed

I buy popcorn in 11.5 cubic foot bags
11.5 cubic feet
* 40 lbs
460 lbs float power per bag of chips

780 lbs total float needed
/ 460 lbs per bag
1.7 bags of foam packing chips needed.

Or, if I wanted to support the entire 1350 lbs, I would need to stuff 2.9 bags of packing chips into my boat, or even more if I wanted to support the crew weight also. Lucky for me there is a ton of cavity space around the boat and I think I should be able to stuff about 4-5 bags of packing chips in the hull. Some time in the future, after I have stuffed all the floatation in that I can, I'll take the boat out and pull the plug, see how much she sinks and try to sail her around. Will make for a fun experiment.