It simply work better!

You will often hear someone on HF say: "someone's tuning up right next to us" when what they are hearing is the carrier of an AM station. 'Ancient Modulation' puts half the available power in a carrier, a continuous wave which would move your 's' meter even when no one is talking. The voice is mixed with the radio frequency resulting in two sidebands of audio frequency. The other half of the power is divided between these two.

Single sideband results when the carrier and one sideband are suppressed so that all the power goes into one effective voice pattern. You could think of it as the voice 'keying' the radio frequency. Much more effective. Roughly speaking, the resulting speech is four times stronger.

When the Drake receivers came on the market in the early 60's, they were considered to be 'very sensitive.' They really weren't. It's just that no one had ever heard a voice at the edge of strength coming through Q-5. It was the double sideband they were hearing so well.

Re: gnd plane. The sea is a ground plane and could be passive. Many sailors find that loading the backstay with a tuner and using the vessel's grounding system is an effective multi-band approach for HF and up. Ground planes do not have to be attached to work. They are only really needed with quarter wave resonators such as a 'hustler' on the rail. But if you get into it, you'll find that you will be part of the ground plane, whatever you do. There's good, better and best. Many antenna lovers envy your 'salty sea."

I urge you to get some help loading a backstay. Safety first.