Largest sailing vessel manned by 2 people
world! I am currently running a D&D campaign and am entering an area that doesn't have many set rules and I'd like a reality check. I want to give them a vessel around the size of the ones from Pirates of the Caribbean, but I feel like there has to be a good reason they have large crews that large. That being said, two people did try to steal the Black Pearl at one point so maybe they could get away with 5? Anyway, here are the details.
World
The world is pretty full of magic. Specifically, the country they are in is the largest magical hub within at least 500 miles. The continent they are on is about the size of North America, is kinda round, and has a LOT of islands surrounding it. They are not visible from the mainland and range in size from Hawaii to Australia. Pirates are a pretty big problem in the area they are about to sail through and I need to take that into account. That being said, the crew themselves are pretty well equipped to deal with opponents...
Crew
Two of them are very experienced with being at sea (grew up at sea, was captain of a ship for almost a decade). The rest have never been on a boat, but I'm not going to have any of them get sea sick. All of them have significantly above average strength, dexterity, and intelligence (they're descended from demigods essentially).
My players are about to purchase a boat at a port and I am curious about several things.
1. Can you even buy a boat at a port?
2. 46
What is the largest sea vessel they can physically man with only 5 people? (if possible a specific classification)
3. What about the largest vessel if they had magical help to propel them?
4. About how fast is that boat for long trips (without magical assistance)?
5. Would pirates go after a ship that has no cargo and a small crew more or less than the average ship?
I'm pretty stumped on this because I know nothing about sailing or historic sea travel. An answer to even just one of my questions would be greatly appreciated.
Thanks!
Edit: Technology can go up to the late 1700s, but definitely not past that. Budget is not an obstacle either. Two of the crew members are children of sea gods so we can assume they will always have decent conditions. Additionally, they have a druid among them who is also well versed in dealing with weather so they can predict storms up to a week in advance.
Edit 2: D&D specifics: We're running version 5e. The characters are all level 4, but they have the base stats of a character that is WELL past level 20 (one has a strength of 30). They are all demi-gods but are not well trained in combat. Classes: Barbarian, Warlock, Druid, Ranger, and Paladin. The Barbarian and the Paladin are the ones well versed in sea travel. 46