Thanks John. I'm not shouting as such because I honestly don't expect to get anything out of it, it would be a rare company in this day and age that contributed anything significant to a six year old product however little use it has had, unless maybe I was the original owner which I am not. The essence of my email to them was indicating that I believe there is a problem with the design, that the failure seemed extremely premature and if it was a known issue that I would appreciate their advice in sorting it out on the basis that they must have developed some sort of "fix" for this problem on other boats that had seen much more use than the 50 hours a year mine has seen.
There are all sorts of questions that could be asked e.g. why they use those sorts of seams when it seems from Ribraff's post to be a fairly common weakness; why they don't fit wear patches as standard when I have looked at several other RIBs since and all have them, and so on. All these things point to a slightly iffy design which is a bit odd given their 45 years experience which must surely have taught them what works and what does not, long before my RIB was built, and the additional cost of fitting those wear patches would have been peanuts in the context of what the original owner paid. But I am really not seeking to do them down as a company, far more interested in getting my boat fixed and back in the water where it belongs
In answer to your questions
1) Both myself and as far as I know the two previous owners have used the boat for leisure use only, in my case just cruising around but I have not had it very long, the others I think used it for a bit of diving but no serious or commercial type use as far as I am aware. The total hours run on the (original) motor of 303hrs in 6 years is testament to pretty light use I think, 50 hours a year or about an hour a week is not a lot and I don't know what is reasonable but I would have thought you should expect 1000 hours plus with no structural tube problems in this sort of use. A guy I know here has used a 6.0m Destroyer for 12 years in his commercial diving business with no such problems, not sure of the hours run but I am sure it will be a lot more than mine.
2) It was a rapid failure in that it developed a slow leak then went bang when I pumped it up to try and find the slow leak. Looking at the fault suggests that it has been developing for some time until it weakened the tube to the point of failure. I am fairly certain there was no slow leak when I purchased it a month or so ago and since then I have done about 15 hours. There are no facilities for getting anybody to survey it here prior to purchase, and of the two people I know that do know something about boats, one was a close friend of the person selling it and the other was trying to sell me his own boat so I am afraid that through necessity the only inspection was my own. There is no regulation at all here, of privately owned boats of this size.
3) noted - unfortunately it is a "weedy" environment in the harbour here but having said that it has been stored out of the water for most of its life I think. There are no signs of any deterioration of the fabric apart from along these seams.
4) Noted - thanks - the conditions I am going to have to repair it under are less than ideal so that is very useful to know, I will find out where this came from and order some more.
5) I am sure I can bodge it one way or another, how long it will last is perhaps a different matter, but a significant issue from my point of view is that I spent quite a bit more than I originally intended in order to get a Humber because of their good reputation for no-nonsense well designed durable boats. Despite buying a fairly lightly used example I didn't seem to end up with one!
6) I was aware of the BAS use prior to buying it as I did a bit of research into the brand before buying; it was another reason I decided to go with Humber because I figured BAS would have tried and broken anything that was not robust.
If the worst comes to the worst I already have a quote for a complete re-tube from a trade member off this forum and the cost would not kill me but I just don't think it should be necessary to do that on something this age and as my first foray into boats it would not be a happy start.
Any assistance you could give would be very very gratefully received.