You can't tune boat engines out of water. There are two main reasons. First, if you set it for a good idle on shore, it'll be way too lean when you try opening up the throttle on the water. Second, running the engine at high RPMs on shore is a sure way to destroy the rod. So, you have to set them so they're slobbering rich on shore and just keep blipping the throttle until you launch. Once it's on the water you'll have a better idea whether it's lean or rich. Bogging down and dying shortly after launch is most often a sign that it's too lean. A rich engine usually stays running, but just not too quick.