flotation chamber

[Westport Jeff]

I am about to add flotation chambers to my skiff. I have seen them with and without vent holes.

The boat is built out of marine plywood with cloth and epoxy coating.

What are the pros and cons of each method? Does it matter what type of Styrofoam I use?

Thanks in advance.

[Brian Palmer]

Sealed air chambers with an access hatch for ventilation when the boat is in storage and inspection are a good way to go.

Styrofoam blocks that can be removed while the boat is in storage are also good.

Inflatable flotation bags strapped in place are also good.

Foam blocks sealed in place and expanding foam filled compartments are generally not good because they can trap moisture and provide a location for rot to start.

Brian

[Thorne]

Ditto above. Better to use something easier to remove through the screw plate hole, like sealed 1-liter soft drink bottles, fun noodles, etc.

Lots of previous threads on this topic. Do a search for "flotation" of this forum via the Search tool, or by Google's Advanced Search tool with www.woodenboat.com spec'd as the URL.

[Ray Frechette Jr]

Personally I see little reason to add anything to a air tight floatation air chamber other than an inspection poort to allow pressure to equalize and to allow air circulation when not in use.

I fail to perceive the benefit to soda bottles and the like.

[Thorne]

It all depends on the usage of the boat, but the recommendations for the sealed bottles, bags of pingpong balls, or fun noodles cover two potential situations -

1. Puncture of the chamber.

2. Hatch left open or failing, as these chambers can also double as waterproof storage areas for gear, but may not be closed or closed properly.

[Ray Frechette Jr]

Yeah, I understand that, for myself I usualy incorporate multiple chambers anyway. IE on CoreSounds I build there are 6 sealed air chambers. Tow under each seat top and one in bow and one in lazaret.

Having seat tops go from bulkhead ot bulkhead by itself prevents downflooding into the cockpit when capsized as seats have suffcient floatation to hold entire hull out of water.

As to closing down hatches and doing so properly, that is part of boater education and proper seamanship as is not overloading floatation compartments.

[SawmillBrook]

I researched this question when I built my boat. I ended up doing exactly what Brian (above) mentioned. I found closed cell foam around the shoreline of our bay here in RI. I cut them closed cell foam up into small blocks and then placed them into the chamber(s). I used a screw-in deck plate which I would inspect from time to time to make certain that there isn't any moisture build up - which would infer a leak.

I built the boat 5 years ago, and just this year I had to remove some blocks to add a hull - through as I added a helm to my boat... if I had used the liquid foam I would not have been able to do this.

In sum, blocks of closed cell foam is the way to go from many perspectives.

Good luck

[TerryLL]

There are two other good reasons to add foam blocks or some other flotation material inside chambers:

1. The chambers need not be completely sealed. Air vents and drain holes can be incorporated into the chambers and left open at all times to vent hot air and condensation.
2. The inspection hatch can be loosely fitted, avoiding the need for gaskets, o-rings, and the like.