I guess it depends on two things, real estate and purpose. If you have the real estate why not just install a 20 meter vertical dipole cut for the specific frequency you want to work, say 14300 kHz. WA6CCA (SK) wrote up an article about the benefits of a vertical dipole for single band use. No need for a tuner and if you have the space, you can put one up for 40 meters as well.
But, if you intent is to work all bands then you want a randon length (which by the way is not random) antenna from the stern to the top of the mast. Minimum of 23 feet and tied to an automatic antenna tuner of your choice. Plus you will need a good counterpoise, or saltwater ground, or both.
Click on my webpage link in my signature and go to the bottom of the page. There you will find several links regarding vertical dipole, counterpoise, and sea water grounding.