Hi, I have come across this thread and have been following it with interest.
As you can see from my details I too have a crompton, it seems to be quite an old one, perhaps one of his first?
I also have my concerns about the level of the transom. I was told the transom was rated for 250hp, (can't remember where I got that from). I originally had a Evinrude 225 on the back but after that died I went to the 200 Optimax. It sits very low in the water and I often have the bilge pump on emptying the engine bay thinghy.
I have attached a couple of pics of the old tub with the original tubes on, (they were in a sorry state). I had a retube a couple of year ago with Humber. I think a chap in Devon has the templates for the tubes and he comes very highly recommended on here but I was not keen on the distancees involved. The prices were comparable to Humber and they were much closer. Ergo humber got the job.
I love the old tub, admittedley I hardly get the chance to use her but when I do get her out and she behaves; wow what a machine!!
The under floor tank in mine is 200 litres. It is fibreglass construction and I am constanty paranoid about it leaking.
Non the less, although she is rough and ready, I love it and would recommend a Crompton to anyone.
Silent but deaf-lee