A few thoughts
Firstly I will mention your concerns as a polite reminder when I have my call with the folks at Humber tomorrow. They are a pretty good bunch with strong moral values. I have to say, from personal observation, that on the downside a lot of shouting when the actual cause is unknown does not help.. this not as a personal rebuke to you but a fact of life.
It is fair to note.
1. The vessel is 6 years old. This may not seem a lot but has to be put against the use that the vessel has been through. You also do not detail as to what you use the boat for.
2. You have not defined the history of the vessel but one would asume that it has had regular inspections or if you bought it second hand you had a survey prior to purchase. Thus are we suggesting a rapid failure as there has been no event for 6 years ?
3. The weed growth on the tubes as in the picture can become an issue as this does attack the outer layer of the hypalon.
4. The Polymarine glue is Ok and in our experience is not quite the same as 2402 but works better in damp conditions ie. our prefernce is 2402 in good conditions but to effect "in the field repairs" Polymarine is better.
5. There needs to be empathy with your situation in being in a distant shore with lesser facilities and above what is required is a solution. I am sure this can be found.
6. Humbers have been supplied even further south that you to the Antartic Survey vessels.
If you want me to call to offer guidance or to find a solution then in the first instance feel free to e-mail.