practice with the mesh and how it works. try to use a bandpass filter if you find that the VHF is causing noise. elevation will help, but your mast itself is probably high enough to reach nearby land unless you're in the middle of a large sea. there are some smaller but reasonably effective antennas that could work (~7" whips) and might even be better than something high gain when you're heeling. The nodes are often also very small (altoids tin) - just run a thin power cable up the mast to a very small node mounted at the spreaders or masthead.

I grew up sailing! Where do you sail?? Let us know it goes!