Floatation chambers Air or foam

C

clinton andrus

Active member
Hello gents got a question on floatation chambers.

I'm wanting to do sealed air floatation chambers instead of filling them with foam. Is there some kind of test my boat has to pass at time of inspection to use this method of floatation.

I googled it and did some reading but to be honest it made me even more confused trying to understand it all.

Any help would be useful gents.
 
Air shouldn't escape as long as the watertight compartment is intact.

Air also gives off more pounds of bouncy then the two part foam do's as well.

It also save's a few pounds of weight maybe not much but five pounds is still five pounds when you have to get out and push the boat off the bottom.

I'm sold on doing it this way, I'm just looking for some advice on if there is a certain test that my boat must pass or is there a particular way it has to be built into the boat for it to be legal.

I googled and read up on it but it leavet me even more confussed about how to go about it.
 
How is the expansion/contraction of the air with temperature swings handled with a sealed air chamber? Is there a vent that is only closed when actually on the water?
 
How is the expansion/contraction of the air with temperature swings handled with a sealed air chamber? Is there a vent that is only closed when actually on the water?
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That is a problem in wooden boats that has been seen here. There have been a couple cases (not more) of sealed compartments blowing out.
 
How is the expansion/contraction of the air with temperature swings handled with a sealed air chamber? Is there a vent that is only closed when actually on the water?
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Yes I was going to install tempress 6 inch screw lock deck plates in each chamber that way when the boat is on the water it will be sealed and when it's parked the covers are removed and that will allow the chambers to vent.
 
I spoke to ldwf today and they said that the state only care's if it's a produced boat hull meaning buying it from a builder and that since it's a home built boat I was not required by the state to use foam floatation. But that said I could have it listed as a commercial hull with no flotation.

I respond to them saying I don't want it to not have floatation but to use air chambers as floatation, so they gave me the number to the inspection devision to ask how to go about doing that but was unable to get a hold of them at this time.

So I went to the uscg website and looked up the reg's for backyard builders and it say's air chambers can't be built into the hull but air chambers are legal.

What I'm not understanding is how do I go about useing the chambers that are designed into the bluebill already to be legally used as a air chamber.

And is there a test it has to pass when it gets inspected?

I think it was on here that I seen pics of someone doing it this way, useing air chambers with screw in deck plates to allow it to vent and to use to inspect the voids for moisture build up.

I think it was Eric that had done this but not sure will have to go back throw past post again to try to find it again.
 
There is a floatation test that the USCG administers, that's more for commercial builders though and you can only conduct it at their facility in Maryland. I know that the USCG wants you to have level floatation, meaning that if the boat is swamped it will float level with the water and not turn over. That's why the floatation chambers on Devlin designs are in the bow and stern, to help it float evenly, and there are 2 in the stern to offset the weight of your motor.

Honestly if it were me I would just fill them with foam and be done with it, pour foam weighs next to nothing. You could even cut blocks of 2" insulation foam and stuff your chamber with it, then you will have floatation and not have to worry about venting the chambers. Just my .02 cents though.
 
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Thanks for the reply Cody.

I had just gotton off the phone with ldwf inspection devision and they gave me the needed info I was looking for.

No special test is needed for me to use air floation is what I was told by them.

The foam weights 2 pounds per square foot, now my math maybe off some and I will beable to get a exact messurement when it's built up and at a point where I can calculate the exact square inches of space in the chambers but my rough math puts the total weight of foam in all chambers close to 20 pounds.

I can save that weight by useing air chambers that's a huge weight savings when having to push the boat around while standing in a foot to 6 inch inches of water with mud up to my hips.
 
What I'm not understanding is how do I go about useing the chambers that are designed into the bluebill already to be legally used as a air chamber.
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Is this Devlin's Bluebill? If so, the matrials list in the study plans i have lists "(2) 1 qt kits, makes 1 gallon total" Jamestown Distributors has a 2 quart foam kit and lists the weight as 9.4 lbs/gallon (resin), 10.2 lbs/gallon (activator). Assuming the 2 quart kit means 1 qt of resin and 1 quart activator, we would have a total weight of 4.9 lbs for the amount of foam called out in the Bluebill materials list.
 
Yes sir that is correct and mine would need that amount if it was being built to plans, I am changing most of the measurements that are listed on the plans.

My boat will be longer, wider in the rear, plus have a normal transom not the pods, and I'm adding height to the side panels, so the amounts that the chambers can hold will increase over what the plans call for.
 
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Gotcha. Just as a point of reference, the Scaup 16 calls for "(1) gal kit, makes 2 gallons total" of foam in the materials list. If that means 1 gallon resin and one of activator that would give a total weight of 19.6 lbs. your close to 20 lb estimate may not be to far off then. good luck.
 
The total weight savings is yet to be figured, when I have the boat built to the point that I can pull exact messurements and calculate the exact square foot area of each chamber I will know how much foam it would take to fill them and in turn know the weight for that amount of foam.

The specs on the foam is 2 pounds per square foot and provides 60.4 pounds of floatation per square foot.

Air has no weight and gives off 62.4 pounds of floatation per square foot.

Just a ruff quess right now my finger math say's between 12 and 15 pounds foam weight total.

If it indeed comes out to that much that's a good weight
savings by going to a air chamber instead of foam, anywhere I can save on weight just makes it that much better come duck season when I'm trying to push a boat out of the brush or grass so I can leave and I'm in mud that reaches my hips in some places.

I want to thank everyone for replying
 
Everyone is thinking this.... but not saying it... BAD IDEA.

Might as well save weight and not take PFDs as well. If you have any sealing failure, or don't screw the hatch. Or the more probable...Start using those compartments for storage.

$60 and 20 pounds... and it is there.
 
Each cubic foot weighs 2 pounds. Do it right and put the foam in. If your chambers are air tight then the foam will always stay dry. If they become unsealed for some reason the boat will still float. This my personal opinion so do what you wish. It's not my life at risk. Also the Coast Guard will tell you that foam will provide more buoyancy then just air in a chamber.

Tom
 
I believe Mr. Ayers builds boats for a living, may want to listen to him.
Also if your running and hit lets say a stump, if you breach a boat with an air chamber vs. a foam floation chamber boat which boat would you want to be on?
 
Clinton,

Totally get it. Every vessel has it's purpose and agree with you, air will work just fine.

Just remain cautious. The White Star Line was pretty confident their air chambers wouldn't allow the Titanic to sink. A tragedy of errors for sure, but something to consider when operating a hull with air chamber flotation.

Look forward to the pictures!

Rob F
 
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