floatation : air bags vs. foam

Has anyone considered this ? Can air bags be substituted w/ styrofoam like what you might use for dock floats ? I’m trying to cut costs without comprimising safety. Or build a bulkhead that can breath a little for expansion & contraction. Any help will be appreciated

Yeah, flotation foam is fine. It’s not cheap though. If you can find a part of a billet that is being discarded by someone you can carve that up and fit it in your boat.

Blue board
Cut layers of house construction type blue board styrofoam to fit the area. Some people even glue them together, which pretty much insures the plug’s not coming out by accident. If you want, finish it off with an outer layer of anti-fatigue mat minicel. the whole thing wouldn’t cost you more than $10-15 and you’d end up with a lot of left-overs for other nooks or other boats even.


Make your own float bags.
To save costs, I made my own flotation bags. In the long run, I can’t say I saved money- but, I’ve got some swanky bags for the boat that fit it exactly.


pool noodles
Might be a little late in the season but they are darn cheap at Wallyworld. Stuff a bunch in - I may do the same to supplement the pillar in the from of my rec boat.

not sure what kind of watercraft
you are referring to but if it is a kayak made out of fibreglass and is lacking bulkheads, building one is not that difficult.

If that would be your first project with handling resin maybe it’s a bit daunting however I have built bulkheads (replaced cheap foam ones) for various kayaks of friends of mine.

The “breathable” part is a very small hole drilled right in the centre of the perfectly sealing fibreglass bulkhead to allow for air expansion/contraction due to temperature changes.

If your craft is plastic, I have unfortunately no better suggestion suggestions than the ones already mentioned.

Cheap Flotation . . .
Once you decide where in your kayak you want flotation (preferably both front and back), you can take some one inch tape and tape around the outside circumference of the boat to temporarily mark where you want the flotation. Next, take some wire and bend it flush around the boat to make the shape where the tape is marking the circumference there. When you slide the wire off the boat, you will have a wire shape of the cross-section of the boat where you want to put your flotation.

Next, decide how long (how much space, lengthwise) you want each flotation “bulkhead.” Take one of the bunch of swimming pool noodles you just bought (the type with the hexagonal shaped sides is good) and cut one that length. (Both flotation “bulkheads” should be large-enough to float the boat level when it’s swamped with water.)

Lay your wire shape, ends joined together with tape, on a flat surface and place the length of pool noodle straight up inside the perimeter made by the wire. Keep cutting pool noodle lengths the same length as the original and space them in the wire perimeter, one by one, until you have shaped the noodle lengths to define the wire perimeter.

Using Marine Goop, glue all the pool noodles together inside the wire shape. Once the glue is dry, you can take the noodle cluster and slide it into the boat until it is placed even with where you placed the tape. If the taper of the boat is dramatic-enough, you may have to shave one end of the cluster down some to make it fit. The idea is to lightly wedge the noodle cluster into the boat. Depending on your preference, you can use the same glue to adhere it inside the boat, or rely in the wedge pressure to keep it in - but it’s obviously important for it to not float out and away from you if you swamp your boat.

This will give you a flotation “bulkhead” but not really a bulkhead, as it will not block water from entering into that end of the boat. Kind of like foam blocks in many white water boats, it will keep your kayak from sinking without costing you an arm and a leg for flotation bags or constructing an actual foam or fiberglass bulkhead.

For fun, depending on your type of kayak, you can cut shapes into your foam block to fit your bilge pump, water bottles, etc. If you don’t want colorful pool noodles, you can achieve similar results using pipe foam insulation. Make sure your glue does not melt the foam before you commit to the glue.

Good luck . . . have fun with it.

Test the pool noodles
On another forum, I read about a guy who said he tested the flotation of pool noodles in comparison to his SOT. If I recall correctly, he was surprised that they wouldn’t provide nearly enough adequate flotation to properly float the kayak in the case of a hatch/catastrophic failure.

You might try the pool noodle thing, but then give it a real world test by flooding it on purpose. Better to know in a controlled situation than trial by fire.

What about a bag filled with the expanding PU foam? - just a suggestion, probably there are quite a few things wrong with it.

big difference between
expanding and expanded.

I presume you are alluding to the “out of the can” foam?

If so, putting the foam in a confined place in large quantity you might run the risk of cracking and separating the deck/hull joint or cracking the hull.

Depending on foam type and quantity.

However, if you meant a bag filled with pieces of PU foam then I can’t see too much of a problem as long as it fits and stays put.

Cutting and fitting Styrafoam bead block
flotation used to be a high art in the 70s. They often used a “hot wire” consisting of a thick bare wire heated by current.

There were, and are, two kinds of Styrafoam. One is bead block, where many beads are welded together to make dock flotation or canoe flotation. The other is continuous foamed Styrafoam such as is used for the base blocks of flower arrangements, etc. Experience in the 1970s was that bead block was more durable, though the tiny spaces between the beads would soak up water with age. I never saw a successful float block made with “straight” Styrafoam, only bead block.

Bead block floation supported the sides and thwarts of a canoe in a way that flotation bags cannot do. Why did bead blocks die out? One reason is that a single bead block tends to interfere with where paddlers can sit and where they put their gear. As whitewater boating changed from mainly tandem to mainly solo, putting the solo paddler in a balanced center position in the boat meant that the float block was not where it could best float a swamped craft, or one had to have split float blocks. Second, a float block weighs more than an equivalent amount of bag flotation, especially once the float block has absorbed some water after a few years of use.

One alternative to Styrafoam bead block is to use Ethafoam or Minicell (also polyethelene). I made a continuous center pillar with seats for an Old Town Tripper in the 80s, using Ethafoam cadged from packing. It did not weigh less than an equivalent amount of bead block flotation, but it was stronger, more flexible, and degraded from sun and water more slowly. I now use Minicell triple saddles in a similar way. BUT I also use float bags.

Float bags can be positioned optimally for solo canoe use. For tandem paddling, there are some problems, but they can be overcome with ingenuity.

So, while the switch in the 80s from bead block to float bags was perhaps partly a matter of style, there were reasons for it, and I don’t see the trend reversing.