Hi, Michail:
When I visited Britannic on the Ballard expedition in 1995, there were surprisingly few fishing nets around the wreck. Yes, there was the one that is still on the rudder and perhaps three or four others scattered around the wreck. All were fairly small, however, and could easily be avoided. They posed no threat to an ROV. Unless the situation at the wreck has changed considerably over the last six and a half years, I don't really see nets being any obstacle to using an ROV on site like Ballard did.
You wrote: "...many of the entrances are obstructed by debris."
That's true, but most of the debris we saw blocking the entrances was all "soft" organic material that could be easily cleared away. There are plenty of openings on the wreck -- both in the superstructure and the hull -- through which an ROV could easily pass if it were small enough in order to explore the interior of the wreck. The problem with the ROV that Ballard used is that it was too large. If someone wants to take the ROVs Cameron used on Titanic, I'd bet they could get some spectacular footage inside the ship. Look at what Cameron brought back from over 12,000 feet.
"If a ROV gets trapped it would very difficult to bring it back to the surface."
That's actually a fairly common misconception. If you were talking about Titanic, that would be true, but even there, Cameron was able to retrieve the ROV that became trapped inside the ship. It took a while, but they finally got it. During the
Lusitania expedition in 1993, the ROV Jason became entangled in fishing nets, and a diver was simply sent down to cut it free. The same could be done on Britannic if the ROV became trapped because she is only 400 feet down.
I would really like to see Cameron take an interest in visiting Britannic and
Lusitania because he seems to be the only one who visits wrecks with a clear idea of what needs to be done. Everyone else seems to plod and poke but doesn't really accomplish much. And no matter how difficult, Cameron doesn't usually stop until he gets what he wants.
Eric Sauder