@thekranch
If you'd rather keep your treasure, then don't try to fight in a 1v4 or 1v3 situation with a half crewed ship against a fully crewed one. Get better at leading them into a disadvantage. For instance, you, in your sloop, will outpace brigantines and galleons alike while sailing directly into the wind. You will be free to drop off of the ship and attempt a board as many times as you like, with gunpowder kegs or simply your own weapons, in attempts to hijack, distract, delay or even sink the crew. When doing events, keep your head on a swivel and keep your ship stocked up. Planks are essential, followed by cannonballs and fruit. A good supply of gunpowder kegs, cursed cannonballs, and cooked meat wouldn't hurt either. Past that, when a larger ship approaches, take note of the situation - location, orientation, nearby skeleton ships, kraken possibilities, onboard resources, your skill and readiness, the incoming ship's appearance - all of it can help. You can tell a lot about a ship by what liveries it has equipped, whether their sails are turned, and what they have in their crow's nest. Should you decide to fight, use your superior maneuverability to keep out of the other ship's line of fire while keeping them in yours, listen and watch for boarders and defend the biggest choke point you have: the ladders. You can keep yourself afloat better than any other ship, are a smaller target, and a faster turner. You can also recover from just about anything, be it a keg, cursed cannonball barrage, normal cannonball barrage, ram, land formation, anchor drop, anything. Should you run, keep in mind the maneuverability of a sloop, and the water displacement. Being chased by a brigantine? Run some circles between parts of islands, or charge one and turn away quickly. You'll turn long before they will, and they'll run aground. Being chased by a galleon? Find a good sanbar (uncharted islands work great for this) or some particularly thin rocks to go by, and watch as the galleon, with its wider and taller hull, hits something and gets caught. Being solo doesn't mean you're defenceless, though you're also playing what has been designated by the developers themselves as the 'hard mode' of the game.