The trader 3 is arguably the best trader-class boat in the game, with it's very high 750 health, and 6 krew slots, it may be able to withstand attack. The 6000 cargo is one of the best aspects of this ship, as it is the most cargo available on a single boat in the game.
The trader 3 is the biggest ship of the trader series, but in other regards, is identical to them. It has a curved front and a straight back, with sails 1/3 of the boat away from the back.
The trader 3 is excellent for trading because of it's 6000 cargo space. Additionally, it has 6 krew space, costs 30,000, and is only available in Jamaica.
With the Trader 3
Avoiding conflict is the best strategy for the trader 3, as with all trading ships. It is a large, easy to hit target and can therefore be killed easily. So you should all hostile ships, and run safe trading routes such as Labrador-Brazil. The trader 3 may be able to defend itself because of the large krew, but it is unwise to take this risk.
Against the Trader 3
Basically any boat can overpower the trader 3, unless it's krew is expert. With a small boat, high damage/range build, and skill, you should be able to kill the trader 3 with ease.