Sorry to be a bore chaps, theres been a lot of good advice so far on this matter regarding techniques; things that will bite you in the arse etc, however have you considered a few reference publications?
I've also listed a few questions the lawyers will use to try and take your children's inheritance away with:
Did the pilot study CAP 437 Offshore landing Areas Chapter 9 (Vessels) and/or the International Chamber of shipping Guide to Helo/Ship Ops?.
Who is the owning oil company, have they surveyed the helo deck recently and is the helo insurance cover sufficient ? current rates for offshore vessels fully laden plus environmental damages are astronomical.
Did the pilot contact BHAB for advice ?, they might hold a deck survey of the vessel concerned.
Watch out for the flying avoid North of Alexandria Airport over the Mil Academy/Hospital if you are operating that way.
If you are flying pax, are you offshore equipped/floats/ELTs etc?
I said sorry to be a bore, I'm not a lawyer, just a WAFU trying to keep you out of trouble...........enjoy it....