Since you have two shows dealing with ships, one is a funny ship show with romance and comedy, and another a pirate anime show filled with action, let's compare what these two shows have in common.

The Love Boat is, of course, set on the Princess liner, where romance take place, and One Piece is set on the Going Merry and the Thousand Sunny, where action takes place.

Let's look at the characters from both shows:

Captain Stubing = your captain
Adam "Doc" Bricker = your ship's doctor
Burl "Gopher" Smith = your ship's purser
Isaac Washington = your bartender
Julie McCoy = your cruise director
Vicki Stubing = the captain's daughter

Monkey D. Luffy = your ship's captain
Tony Tony Chopper = your ship's doctor
Roronoa Zoro = your pirate bounty hunter
Usopp = your sniper and liar
Sanji = your cook
Nami = your ship's navigator and thief
Nico Robin = your archeologist
Franky = your shipwright
Brook = your ship's musician
Portgas D. Ace = Luffy's brother

See the cast comparison? What if the Love Boat crew and the Straw Hats swap ships for a day? The Princess crew would board celebs in either the run-down Going Merry or the new Thousand Sunny and would experience action against Luffy's enemies from MarineFord, Enies Lobby, Galley-La Company, etc., while the Straw Hats would live up the glamour of being in the biggest cruise with celebrities of the Love Boat episodes. In addition to the Straw Hats' adventures on the Princess, Usopp plays the director who lies to the guests on going to the wrong destinations and the others have their own agendas to get treasure while the guests disagree about their wrong ports of call, Sanji's lack of bartending skills but big on his cuisine at the Baratie, Chopper fools around with Doc's medical stuff to make Rumble Balls, Zoro using Usopp's wrong destinations to capture bounties, and Luffy's experience on piloting the Princess. While the Love Boat crew experience the Going Merry/Thousand Sunny, Doc has to learn about Chopper's complex art of first aid than Doc is used to, Isaac must learn Sanji's cooking and a little bar, Julie doesn't have a clue about directing in the One Piece world, the celebs on board won't even know the places the One Piece world has to offer, Gopher's only way to preserve the valuables is being a bounty hunter which he refuses to be at all, and most of all, the Marines would find out about the Love Boat crew, and later have bounties for the crew and the guests! Later on, the both crews will find out that the swap is tough and want to go back to their own ways.

It'll be a wacky adventure for both crews. What do you think?