: Doesn't the material your using weigh about 12 to 14 ounces per
: square yard ... if so ... how do you end up with a float bag
: that weighs a pound or less?

: The float bags I made out of the Walmart clear vinyl were short to
: fit the bow of my F1 ... and they came out at about 3 pounds
: assembled without the inflation tube.

: Ken Blanton

Ken-
Perhaps I wasn't clear....
I've made flotation bags (bag, elbow, tube, valve) using heat-sealable fabric, AND flotation/gear bags (bag, end closure, tube, elbow, valve) using the heavy-duty grey vinyl.

The heat-sealable material I'm using now weighs about 9oz per square yard. A tapered bag 5 ft long, tapering from 2 ft wide to 1ft (flat, uninflated) uses about 1.7 sq yd of fabric, weighing about 15 oz. . Fittings and tube add about 3 ounces. So a little over a pound, I guess (bag is outside in the boat). A similar-sized commercial bag I have weighs 15 oz with two fill tubes.

A gear bag to fill the same space, made with the heavy-duty grey vinyl weighs about 3 lbs (exactly 1320 grams), complete with the extra fabric for the closure end, and the plastic tube closure, with hose and fittings. and the weight of the adhesive.....
;-)
'Indestructible'=heavy

One way to think about the gear bag is that much less heavy-duty dry bags (eg backpacking stuff sacks instead of dry bags) would be needed for clothes, etc. if everything was going into the vinyl gear bag. So a bit of weight could be saved there.

These particular bags are for my Mariner Express, which has a small hatch forward, so the inflation tube can be short. For a boat like the F1 or my similar strip boat, a longer tube is needed to get back to the cockpit, so that would add a few ounces more.

BTW, the 'irrigation elbow' weighs 11g with the locknuts, the fill valve weighs 4g.