I do not have the manuals to hand, but on the 747 2/3/400 do vaguely recall something in one of them about 'Extended over water operations are not recommended with gear extended'. It's about ditching with the gear down I believe. I had an occasion on a 747 when unable to retract, and had a good distance to go over water, so had to look it up. Quite what 'Extended' over water means is of course open to debate.
