Well, if you wanted an 'as the arrow flies' speed boost, we could have some fun with this tool.
The buff is simple. The longer you use the tool, the faster you go.
Now for debuff thoughts.
Start by making the helm very sluggish and unresponsive. You would have to fight your ship to make just the wheel turn. The ship would still have the same turning abilities, but you could not spin the helm quickly.
Tool locks throttle to full speed. This lasts for (n) amount of time after deactivated. Tool is also locked, disabling all other tools for same (n) time.
Reduce angular drag substantially. If you do start turning, your ship won't want to stop. Add that to the sluggish helm, and you could end up spinning out of control at high speeds (though this might benefit the Galleon).
Armor or bare hull and balloon would take constant damage once you reach a certain speed due to wind shear. Damage increases the faster you go. Barrier wind effect from map edge would also come at this speed, shaking the entire ship.
Make the ship take more damage from all sources.
Basically, you implode when hitting another ship, terrain, or a bird. NOT for ramming.