Solid RIB tubes

[Darbio]

You make some excellent points. Thank you for taking the time to respond.

I’ll take a look at each option and have a search for the calculations. It needs to be safe!

 

[Yellowjacket]

Trying to fill existing tubes that are old and failing is a fundamentally bad idea. Things are going to continue to fall apart and it's just going to get uglier the longer it goes. While this is a RIB that has a real hull bottom, a lot of stiffness comes from the inflation of the tubes, it's the stretching of the tube in the length of the tube that makes them stiff. Even though you're adding something inside the hull, you aren't going to stiffen the hull in the same way as you would if it was inflated. If you use a higher density foam you might get there, but you're really a lot of weight when you do that. The best bet, although it's not cheap is to get new tubes. That probably isn't what you want to hear, but that's the best thing to do.

 

[Darbio]

Trying to fill existing tubes that are old and failing is a fundamentally bad idea. Things are going to continue to fall apart and it's just going to get uglier the longer it goes. While this is a RIB that has a real hull bottom, a lot of stiffness comes from the inflation of the tubes, it's the stretching of the tube in the length of the tube that makes them stiff. Even though you're adding something inside the hull, you aren't going to stiffen the hull in the same way as you would if it was inflated. If you use a higher density foam you might get there, but you're really a lot of weight when you do that. The best bet, although it's not cheap is to get new tubes. That probably isn't what you want to hear, but that's the best thing to do.

Good points and I'm open to all comments. The last thing I want to do is to break it completely...

 

[Rumars]

No need to thank me.
One thing you need to remember, all of the options I talked of are strictly DIY. The materials for a PVC retubing would cost you maybe 200 dollars retail, and a profesional even less. The money is in the worktime and no profesional is going to spend that time on old PVC.
Laminating over XPS is something only surfboard builders do.
Having proper cored frp tubes buildt professionally is going to make a professional retubing job seem cheap.