For serious offshore, you want to stay warm and dry. For hands, forget the Gill and WM "cold weather sailing gloves". If it gets really wet, you'll be wringing water out of them 10 miinutes into a watch. For one trip, it's also not worth buying heavy duty goretex boots. Go to your local REI and get Seal Skin gloves and socks. They are waterPROOF, and work. I use them at night in Maine much more than my $300 DuBarry's. Size the socks so you can put another pair of socks beneath, and they'll be OK with a pair of Keens. Rubber boots are cheap and OK, but your feet will sweat. The Seal Skins really work.
Climbing/skiing/Biking shell layers are NOT the same as offshore FWG. I know. I thought I was going to freeze to death in Maine in July in my Arc'teryx ice climbing shell gear. If there is any way to swing it, at least get an offshore jacket with a high fleece-lined collar, wrist seals and hood. I love my Musto, but it is pricy as the dickens. My son has had very good luck with a much less expensive Gill. I think layering under a goretex bib or pants that are meant for skiing would be sufficient.
If you are going offshore, be sure the host has an extra inflatable PFD/harness and tether, or get your own.