One thing that has always bugged me is that "Coasters", which would be roughly equivalent to a Pinnace or a Sloop, are dead the moment they enter the tactical grid with no chance to run away from a Caravel or a Galleon, due to their slower tactical speed. In truth, a Sloop or Pinnace would be able to outpace a Galleon or Caravel, primarily due to their more streamlined hull and their ability to sail closer to the wind.
This inaccuracy in the game throws the ages-old tactical doctrine of having the light ships on picket duty to detect enemy fleets into chaos and makwes the class of shp virtually useless.
I am working with someone locally to redevelop the naval aspect of the game, should the BRCS crew allow me to continue.
I'm pretty certain the naval combat rules will be revised to allow for fast sailing speeds to actually mean something, rather than the old 2e assumption that non-oared sailing ships are useless and pathetically slow on the battle map.

I don't think coasters are really the equivalent of sloops, I think they're smaller and less advanced as sailing ships.

IMC I made sloops a revolutionary medium ship ship designed, where cargo space is sacrificed for greater sailing speed (sloops were some of the fastest sailing ships of their day). Imagine taking a caravel or cog, then stretching it out to be longer and narrower, with a 2-3 masts plus a lateen sail in the fore, and this is a decent approximation of a sloop-of-war.

The sloop IMC isn't a feasible ship design until the advancement of naval science, and the invention of gunpowder, make it a practical fast warship. here were the stats I decided upon, incorporating later gunpowder technology (culverins and musket-era, similar to late Renaissance and the age of exploration):

Sloop: Medium Ship w/ Gunpowder 3; Sail 16, Move 2, Cargo 2, Bunks 1
Melee +2, Missile +6 (19-20/x2, Range: 6), Defense 14, Hits 2, Morale +4
Cost: 12 GB

A sloop without cannons would have much weaker missile stats (probably just one ballista and a few squads of archers, so +2 missile would be reasonable).

As you can see, it has the base speed of a coaster, but is far more battle-worthy. A coaster is more like a generic European medieval light cargo vessel, I think.