Alpo

Fittings are screw and nut type and will seal well to the fabric, with perhaps a little glue or a rubber gasket. I’ve used those for attaching inflation tubes. Problem is more likely between fitting and crossbraces as it’s not easy to find exactly matching sizes. And perhaps if your fabric is on the thin and flexible side then the hole in the…[Read more]

I’d propose a different construction, though it’s a bit of a heretic idea to make holes in the hull…

Use longer aluminum crossbars and make them go through the whole hull, using plastic boat thru-fittings:
https://www.amazon.co.uk/through-hull-boat-fittings/s?k=through+hull+boat+fittings
I’d imagine if you cut off the unnecessary length in the…[Read more]

“I wonder if aiming a drinking straw at the valve opening and blowing through it would also work.”

It does. I started with various everyday objects. Ballpoint pen barrel was quite ok. The structure above just helps to aim in the middle.

Forgot about the 3D-model: you need to drill the nozzle open to 3-4mm (1/8 – 1/6″).  Print has a rough…[Read more]

STL-files of the nozzles if someone is interested in printing:
https://drive.google.com/file/d/1JENGRPHTo1_nk3GdEx0I47fs0Hq4R9VT/view?usp=drive_link

The rods connecting the two nozzle parts are cut from the most common 2mm (14 gauge) bicycle spoke. And superglued into the holes of the 3D model

15 years ago in Lapland (it’s a catamaran with rigid narrow skeleton):

I think catamaran is a good idea and especially if you can make it work with an inflatable frame. One thing to consider: the two bow waves of the hulls can merge to a higher one between the frames and add drag plus get you wet. It helps to toe in the hulls a bit, so that bows…[Read more]

I might have exaggerated the edge shape. you can see the effect in real life in some Thermarest Neoair photos. In your use, the large side pontoons will be more rigid than the mattress and will force the edge to be straight. So I don’t think you need to make changes to the original plan. More baffles and curved edge would just mean more work (and…[Read more]

Howdy,

This is a bit late but yes, I think your measures are good, just note that:
– The width will vary a bit due to baffles bulging. It will be quite a narrow mattress but you know if that’s ok for you.
– end ‘chambers’ will be a bit smaller than the rest if you don’t give them 5cm extra fabric due to the missing baffle fabric