Weve had a few, the rigid part is foam filled and they can plane without any tubes fitted at all.
We were rescued off a Welsh Island while diving by a club members small rib, we had 12 people in it with all their bottles and weight belts.
It was powering along through three foot waves with the whole rib under water and only the outboard intake at the top of the cover just clear.
Derek was his name, he shouted for us to throw all the equipment out.
No one did , I had to stop my mates bag floating out the back.
He was a crane driver at the docks and was crushed by a manager joy riding a new container loader, huge payout but never recovered properly.
Took up golf.