Just seen this, been off here for a while so although late in coming, the information is as follows;
The DSRV was designed and built by Dennis Cater, formerly of Eden Models. If the dive unit has an anchor moulding stuck to the top of the dive unit then it's one of my kits as I produced them for a while, otherwise it will bear a small badge which says 'EDEN' It is not a scale model of any particular boat but was simply built as a DSRV lookalike and provided the builder with a basic submersible craft which he could expand with his own additional details such as working lights, railings, colours and markings etc. It uses a dive unit which is more or less identical to that fitted to the Akula model. It was a very good working boat, highly visible of course and very maneouverable
It has not been produced for some time now and it was/is my intention to resurrect it but only after I have made a few design changes, the biggest problem being time so there will be little or no movement on this until I can get at it. There are no drawings or plans for it, instructions were a bit sparse and the whole construction of this boat is more or less in my head rather than on paper.
The 'Extreme' was a venture which didn't really take off. Dennis and Nick colluded on this one and what resulted was a kind of Akula based boat with no tower and additional large fins. I believe there may only be a couple of these things out there, one of them being the one in the picture. One was definately built as a dynamic diver, I'm not sure about the one shown here. Again, as I bought the business from Dennis, this all came with it but we agreed at the outset to leave the only remaining complete 'Extreme' boat with Nick.. and here it is.
As for the other sub in the picture, I this was Nicks steam turbine boat.. and of course it worked! Beyond that there is nothing I can add.
I hope this helps fill in with a bit of history.
Chris