I've been doing the Party Barge quests for some time now -- not religiously every day, but as often as I have time, and there seems to be some rewards that are much more likely to be received than others. I'm not a spreadsheet person, so I haven't got actual scientific data charts or anything, but my personal observations are as follows:

High Level pirates are likely to receive either a Level 70 Musketeer or Witchdoctor No Auction totem, sometimes a Musketeer Level 70 ring, or the Polarian ship armor.

Mid Level pirates are likely to receive either a Level 45 Buccaneer or Swashbuckler No Auction totem, or the Polarian ship armor or Level 38 Polarian wheel.

Lower Level pirates (12-21) are likely to receive a Level 1 No Auction item or a LEVEL 65 Polarian wheel(??).

This seems like a very odd distribution of rewards. If anyone else has been doing the Party Barge quests and has received other items, I'd very much like to see if there is more variety.

Further analysis of rewards has yielded the result that, other than the occasional ship equipment that can be used by any pirate of the appropriate level:

Privateers can receive no items for their class at any level.

Swashbucklers can only receive Level 1 items, if they have a lower-level pirate doing the quests.

Buccaneers can only receive Level 45 items, if they have mid-level pirate doing the quests.

Musketeers can receive either Level 1 or Level 70 items, from the appropriate level.

Witchdoctors can receive either Level 45 or Level 70 items from the appropriate level.

http://www.pirate101central.com/forums/showthread.php?61265-Guide-to-the-Party-Barge-Quests&p=304355#post304355

Please, if anyone can dispute this information, feel free to do so.