One of the biggest problems I have with naval combat in Sea of Thieves is how often the actual ship combat gets bypassed completely.
A single player can board your ship, drop the anchor, kill the whole crew, and basically decide the fight without their ship needing to land a single cannon shot. At that point, it feels less like a naval battle and more like every fight comes down to who boards first.
I think boarding should still be possible, but it should require more commitment or more skill.
My suggestion would be to add retractable ladders. The crew could choose to raise the ladders, which would prevent normal ladder boarding. If the ladders are raised, boarding should only be possible in two ways:
By bringing your ship directly next to the enemy ship and jumping across.
By hitting a proper deck shot.
This would keep boarding as an important part of the game, but it would make naval combat matter more. Players would need to actually pressure the enemy ship with cannons, positioning, and good shots instead of just sending one person to grab the ladder and end the fight.
There would also be a downside to raising the ladders. If one of your own crewmates falls into the water, they would not be able to climb back up and would have to wait for the mermaid. So it would be a real tactical choice for the crew, not just a free defensive option.
I think this would make ship battles feel more like actual naval combat while still keeping boarding in the game for players who can create the right opportunity.
