For many years I've been told that our SOT kayaks don't need floatation bags or interior foam because the plastic the yaks are made from is less dense than water and it will float itself, even if the kayak hull fills completely with water. I had no doubt that was the case, but still wondered how much floatation would be provided in a real world situation where you are sitting in the kayak with your gear.

Last week before the weather turned nasty again, I took my Hobie OutBack and WS Tarpon 120 to a local lake and situated them in a shallow water area. About 4 feet deep. I opened the hatches and began pouring in water until the hulls were filled. Both kayaks submerged to the level of the waterline, but did not sink to the bottom. So far so good.

Then I sat my gear on board the Hobie. This consists of a plastic box with about 10 or 12 pounds of related fishing and clothing gear. Some of it probably floats, some doesn't. I added a cooler with the usual couple or three drinks and a few snacks. Also, my two 2-pound anchors. At that point, the kayak sank to the bottom, and fairly quickly.

The WS Tarpon was next. Adding the same gear, it also sank, even quicker.

My conclusion is that none of these kayaks will stay afloat if they fill with water when loaded with a fisherman, gear, rods, anchors, etc. In other words, in a true fishing situation, SOT's will drop out from under you and sink to the bottom unless you add a floatation device foam inside the hull. The bouyancy of the plastic itself will keep the yak from sinking like a rock, but only if the yak is empty or nearly so.

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quote:

My conclusion is that none of these kayaks will stay afloat if they fill with water when loaded with a fisherman, gear, rods, anchors, etc.

First, I think that if the kayak is sinking you are not going to be in/on it. Secondly, this is exactly why I have had several people on KFS tell me to put some (2 or 3) Pool Noodles inside the kayak. I haven't done this yet, but I also haven't gotten my own out so far this year. I have used other peoples.

I plan to add Pool Noodles in the next week or so before I go to the coast. There, I will be in shallow water; here or in the Gulf, I will not. I plan to slip several, probably at least 5 to 6, inside the hull to add floatation to the kayak. I'll have to see how much open, unneeded space is there, and I will probably fill that part up. Once done water will not be able to displace lighter material that is already present, thus giving a much better floatation factor to an already light weight boat.

Ray

Cool experiment.........Also instead of foam or bouancy bags inside the hull, you can put in drybags loaded with your gear (extra clothes or stuff) and the air inside the drybags (even if they are filled with stuff) will definitelly prevent the kayak from fully submerging, I almost always carry with me two drybags filled with extra clothes or whatever stuff I might need in the emergency, one in the bow and one in the stern (you could also place them on top of the deck or in a tankwell as long as you tie them down) that will help the kayak to float in case it fills up with water.
Tom

Great test and thanks for sharing your results. How hard was it to get them back up and empty of water again?

IIRC poly density is around ~.92-.95

So your not gettin much bouyancy contribution from a flooded 60# boat. No wonder your gear sunk it.

I have 5 pool noodles stuffed into my Adventure. One small kid one and four large. I also did something that might help others if it's me rescuing someone rather than the other way around. I keep a piece of clothes line strung through each noodle so someone can tie them around themselves with the noodle wrapped around the chest under the arm pits.(if you stash rods inside your yak cut the noodles in half so you can squeeze them in at various places- the clothesline can be slacked off to do this) Stuck some left over reflector tape on them also. Who knows when you can help?



I also carry a bilge pump. And some emergency stuff for stopping leaks. Plus the usual assortment of flares, whistle, and air horn.

Yak designers should consider doing internal compartments so the yak does not flood it's entire length when holed for whatever reason.

Wonder if spray-type expanding foam would work?? Like the kind usually used around the house to fill cracks so cold air doesn't get in?

Other than having to be careful around rudder/control lines (wouldn't want to stick those down and this stuff is STICKY), might try adding some to the inner hull around the seating area.

Tom, thanks for the experiment. You just saved me a lot of work, because I was planning to do the same later this Spring.

I agree that Kayak builders should design in some method of positive buoyancy, whether internal compartments, foam, air bladders, or a combination of techniques.

Casper, I've also thought about spray in foam. I don't think the household kind will work, but I bet the kind already used by boat builders would work, if anyone knows how to get ahold of the stuff. I'm curious how much weight it will add, since my tiny Sport is already nearing max weight.

For now, I guess pool noodles and a bailing sponge will have to do.

Good job Tom!

Beach balls anyone?

quote:

Originally posted by Casper:
Wonder if spray-type expanding foam would work??

STOP RIGHT THERE!! The insulating foam that you mention (most commonly branded as Great Stuf) is NOT suitable for marine use. Its density, for that matter, isn't all that great for flotation.

Frankly, the pool noodles sound like a versatile, elegant, and inexpensive way to go. My family raced APBA Offshore for a few years and I remember that ping-pong balls were tried in a few of the big catamarans to provide lightweight emergency flotation; for a 'yak, I'd keep the balls in ziploc bags.

There are quite a few types of pour-in-place foam for marine use-- in this case you'd want the lowest density you can get. Personally, I wouldn't affix this goop to MY 'yak... I've worked with these foams for years (both for packaging and boatbuilding) and it doesn't seem like the best solution for a roto-molded poly kayak. If you insist on using a foam, keep a plastic trash bag between the foam and the hull. Be forewarned: the stuff can generate a lot of heat... possibly enough heat from a large volume of mix to screw up the hull.

The best weight/air/cost balance you're likely to find are the air pillows commonly used in packaging. Order darn near anything from amazon.com and you've got enough to displace at least 20 pounds of water.

Yep--I have been carrying 6 large pool noodles in my Outback hold for several years now. Also carry four in my (wife's) Sport. Didn't know if they would do any good, but I figured, what the heck, it's cheap insurance. Thanks, Tom for the real-time experiment--makes me think that mebbe I'm on the right track after all with those noodles!

quote:

Originally posted by New2Yak:
I bet the kind already used by boat builders would work, if anyone knows how to get ahold of the stuff. I'm curious how much weight it will add, since my tiny Sport is already nearing max weight.

The pour-in-place foams are available at most marine supply houses, commercial fishing shops, West Marine, etc. Most of my boatbuilding supplies come from a company out of Florida called Fiberglass Coatings, but there are plenty of others out there.

You are most likely to find "2 pound" flotation foam, which means that each cubic foot of cured foam will weigh two pounds. In reality the material never expands as well into tight corners, so a beginner can double that estimate per cubic foot. There are lighter densities but they require more advanced mixing techniques and cost a lot more. To know how much weight you're adding to the hull, just weigh the cans before mixing and you'll be pretty close to the final weight.

Again, keep in mind that (just like 2-part epoxies) the curing process generates HEAT. If you are mixing a lot of the stuff and minimize the surface area, you could produce enough heat to morph your kayak's hull. If you wouldn't expose your boat to a low heat gun for 5 minutes, don't try the foam.

If I remember correctly my Malibu Extreme seemed to be lined with foam on the inside to help keep it afloat in emergencies. It was a thin coat, but covered the whole inside.

quote:

Originally posted by New2Yak:
Casper, I've also thought about spray in foam. I don't think the household kind will work, but I bet the kind already used by boat builders would work, if anyone knows how to get ahold of the stuff. I'm curious how much weight it will add, since my tiny Sport is already nearing max weight.

I used expanding foam in my power boat last year when I replaced the 100 gallon fuel tank. I used the foam for support under a shelf I built to support the tank. It also serves to fill up a volume so that water cannot get in and as a secondary type thing it adds floatation to the boat. The original design by the manufacturer was a typical "cheap" way to do things, so I improved the process when I replaced the tank.

I got the foam at;

http://www.uscomposites.com/foam.html

You can get a variety of densities. I don't think the heavier foams (classed by how much it weighs per cubic foot) are not the type you would want for floatation.

Thanks for pointing that out. You never know what could happen. I would like to see the same test with pool noodle.

This was a great test. Thanks. Since it is 12 degrees here today, would you mind heading out with the noodles? And maybe a beach ball.
I'll be your best friend!

My Kaskazi Dorado came with a bulkhead built into the bow and stern, so it's unsinkable as is, unless the hull has been compromised. I wonder why poly-yak manufacturers don't do that too? Or, what would it take to install your own bulkhead?

And I second The Riddler's suggestion Tom. Do the same test and see how many pool noodles it'll take to float a yak with gear and all. I doubt that one or two of them will do it, but you never know unless you try it.

Heritage had forwad and rear bulkheads in the Sea Dart and the Expedition (I'm not sure about the other models) They used to make them out of mini-cell foam, but later models got the cheaper foam.

They were only sealed on the bottom and sides but the foam itself provided good floatation

The pool noodles seem like such a simple solution I don't see why you would want to use foam. It seems to me that the foam would just make a simple job much more difficult.

And, messy!

Ray

Ok maybe I'm just too much of an imperialist yankee consumer, but if I'm in water too deep to walk to the shore & my boat sinks, screw the gear I'm going to save myself. Then I'll think about the boat.
Casper... the Great Stuff works to fill holes pretty well, I used it on my Ventura to fill in a spot on the keel that was worn through. Works great no water in the boat. As far as floatation see above.

Sure puts a different spin on discussing PFDs, no? I still like the idea of dry bags for extra gear (like a change of clothes) providing floatation. In some of the safety discussions I read on West Coast sites, they talk about floatation devices coming out of the hatches and floating away - better secure the noodles or whatever you use.