floatation chambers

[jclays]

I am thinking of installing 2 floatation chambers in the skiff I am building. A chamber in the bow and stern. Possibily boxing the middle thwart. What type of foam do I use?
Thanks

[Cuyahoga Chuck]

I am thinking of installing 2 floatation chambers in the skiff I am building. A chamber in the bow and stern. Possibily boxing the middle thwart. What type of foam do I use?
Thanks

If the boxes are air tight you don't need anything. Foam just adds weight, and it isn't cheap, for no benefit. Air boxes can be fitted with deck plates so the chamber can be examined for seepage, used for strorage or aired out in the off season.
If, for some reason, you must use foam it should be marine grade closed cell foam that won't soak up water.
The problem with any two-part foam is it is hard to control and can blow a compartment apart if any excess doesn't have sufficient room to expand.

[JimD]

If I were going to fill them with foam I would use pour in place two part. To keep from busting yer boat, pour it before the lid (or thwart) goes on. Trim the excess that expands over the top, and then cover. There is the advantage that the boat won't sink if holed, and the disadvatages already mentioned. I have a few small boats with floation compartments and they are not foam filled. So they would fill with water if holed.

[rbgarr]

Airbags strapped securely and disguised within the thwart boxes are another option.

[Thorne]

I'd seal them well and leave them empty -- otherwise they become a rot magnet. Get commercial plastic screw-on access plates, cheap from Duckworks at $10 -
http://www.duckworksbbs.com/hardware/hatches/sd337155/SD337140all_big.jpg
http://www.duckworksbbs.com/hardware/hatches/sd337140-150-160/index.htm

You can then use them for emergency gear (or other) storage, and if getting holed becomes an issue, fill them with various items like pingpong balls, capped empty plastic soda/water bottles, etc.

Many threads on this topic can be found by searching the forum.

BEFORE YOU SEAL IN THE CENTER THWART - think about oar storage. Unless you always want those oars to be whanging around on top of the thwarts or on the gunwales, the ability to put them on the floorboards may be really important -- particularly if you may ever use an outboard or trolling motor.

[JimConlin]

Another approach is to fashion a piece of styrofoam to fit loosely beneath the thwart, glue it to a piece of plywood that's just smaller than the thwart, clad its exposed face(s) with light plywood or glass and screw the whole assemblage to the underside of the thwart. It can clear the bottom and can be removed for cleaning and painting the interior.


BTW, I like the Beckson deckplates, which are widely distributed.
http://us.st12.yimg.com/us.st.yimg.com/I/yhst-52784242245472_2010_3155287

[ahp]

Always open them up when you are not using the boat.

[videoguy]

If you use foam be sure to leave room for it to expand as you can see in the shots of my dory it can cause a lot of dammage.
http://im1.shutterfly.com/media/47b7cf30b3127ccec2c3d629a62b00000010O00EYs2LVs4cMQ e3nwk/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/
http://im1.shutterfly.com/media/47b7cf30b3127ccec2c38006a62f00000010O00EYs2LVs4cMQ e3nwk/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/
This happend when I left her in the sun under a clear plastic cover for a few days the expanding foam just lifted the deck about 2inches...........Phil

[SawmillBrook]

I did a hybrid of the above I guess and it's worked out quite well.

Putting "nothing" in the chamber gives me the willies. The poster is probably correct, but I duck hunt so my boat is out in the coldest New England has to offer... I didn't like the 2 part foam idea for two reasons:

1) Rot, as explained above, and,
2) I knew that one day I'll need to get into the floatation chambers and race a wire or a cable, etc... and sure enough I did both this past spring when I built a center console.

So, I collected dock (closed cell) foam that I found along the shore and using a band saw I cut 2" by 3" blocks. I placed the blocks into the floatation chambers one at a time. I'll admit it took a while, but I was left with a chamber that allows some air circulation and as I noted above, I was allowed to remove the blocks to access the space.

So, there you have it.

Good luck,

Andrew

[TerryLL]

You can do both. The dory below has decked compartments fore and aft with gasketed hatches for storage, and the thwarts at either end of the centerboard trunk are boxed and filled with block foam. The boxed thwarts have tube limbers so gunk doesn't get trapped inside. But if I had to do it again, I'd have hatches on the boxed thwarts for more storage.

http://i325.photobucket.com/albums/k365/TerryLava/cape_ann2.jpg

[Tom Robb]

Helium....
Much lighter than foam.

[gert]

Get some of these:
http://farm4.static.flickr.com/3106/3118482935_1c13e64408.jpg

[jclays]

I like the idea of storage areas that can be sealed air tight. I have a plastic dingy currently that my son uses and the foam is always wet.

[Rob Hazard]

Kayaking shops carry a tough,resilient foam called Minicell for carving custom seats and thigh braces. It comes in sheets and blocks. You could buy some 4" thick pieces and just glue them to the underside of your thwarts, thereby getting positive flotation without boxing anything in. It's soft enough that you won't stub your toe if you kick it.

[rbgarr]

Get some of these:
http://farm4.static.flickr.com/3106/3118482935_1c13e64408.jpg

Manufacturer? Source?

[jclays]

Good point on the oars. You guys have given me alot to think about. Thank you.I'd seal them well and leave them empty -- otherwise they become a rot magnet. Get commercial plastic screw-on access plates, cheap from Duckworks at $10 -
http://www.duckworksbbs.com/hardware/hatches/sd337155/SD337140all_big.jpg
http://www.duckworksbbs.com/hardware/hatches/sd337140-150-160/index.htm

You can then use them for emergency gear (or other) storage, and if getting holed becomes an issue, fill them with various items like pingpong balls, capped empty plastic soda/water bottles, etc.

Many threads on this topic can be found by searching the forum.

BEFORE YOU SEAL IN THE CENTER THWART - think about oar storage. Unless you always want those oars to be whanging around on top of the thwarts or on the gunwales, the ability to put them on the floorboards may be really important -- particularly if you may ever use an outboard or trolling motor.

[ben2go]

Heres what I did and it allowed for water to drain back to the bilge pump.I took 1.5 inch pvc pipe and split it length wise.Then I placed it down inside the flotation chambers, in the center.I cut holes in the sides of the chambers big enough to allow water to flow through the pvc pipe.Then I sealed everything really good with epoxy and f-glass tape.I used 2 inch pvc house insulating foam cut to fit inside the chambers.I didn't seal the lid.I just screwed it down with stainless steel machine screws.The boat can now hold roughly 300 pounds of gear and not sink.It floats a couple inches out of the water.Enough to get to the shallows and bail out.

[FSS172]

Manufacturer? Source? Funny this thread came up today... I just ordered three bags from these folks (Optimist pram parts) this morning for my son's Nutshell:

http://mauriprosailing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=MPS&Category_Code=ODOPTAIRBAG

Been thinking about them ever since seeing those amazing pix of the Optis down in Argentina.... Free shipping for the holidays too...

[Thorne]

Those Opti airbags are really cool! What a great way to have the flotation when you need it, but not have it take up space or add weight when ya don't...

Much difference between the long and short fill tube?
http://mauriprosailing.com/Merchant2/graphics/00000001/Opt_1218_F.jpg

[S B]

Build a good boat. If you are affraid of it, buy a survival suit,and wear it. If your boat fails you, you are better off without it," but hang arround to build another".

[marcellsworth]

I was given some advice (thanks Wade) to use pool noodles inside the flotation chambers. It worked great. They are cheap and easily available. They are closed cell and can be bent into almost any compartment. And much easier than carving foam blocks and such.

Have a great day,
Marc

[FSS172]

Much difference between the long and short fill tube?
http://mauriprosailing.com/Merchant2/graphics/00000001/Opt_1218_F.jpgNo clue. Ordered long tubes.... probably should have called to get more info first... yeah, that would have been smart :o

[JimConlin]

No discussion of this subject is complete until someone suggests ping-pong balls, PET soda bottles and truck inner tubes.

[David G]

j,

We used inflatable bladders tucked aft of a barrier in our aft flotation tank. Similar in our farward compartment. The rest of the chamber stays empty and is available for storage. For your entertainment, here's a link to one evening of boatbuilding with my sons - which involved the flotation.

http://www.duckworksmagazine.com/06/howto/bladders/index.htm


"In this business you either sink or swim, or you don't"

[Thorne]

Jim -

See my earlier posts. I did miss the truck inner tube bit, though...

:D

No discussion of this subject is complete until someone suggests ping-pong balls, PET soda bottles and truck inner tubes.