Do you have pressure relief valves fitted? It could be the increase in pressure causing it. Then again it could be a problem with certain tubes caused by a certain tube maker - NOT Paul Tilley or Henshaws of course.....
Sounds a bit dodgy to me. I have black tubes (made by Henshaws) which contract and expand loads on a hot day (don't have release valves). No problems there. What colour are the tubes?
In that case I suspect that the tubes were made by a company who "apparently" had a problem with a batch of glue. If that is the case maybe he should correct the damage? That is if he was paid for the tubes in the first place - the people in Guernsey who built the boats were nothing short of scum......
Codprawn, You would be very supprised who made the tubes, but lets not go there,
just wandered if any body had the same problems and some ideas on it, rib going back to guerney any how to have a few changes.