Well, for those that prefer a bit more history, here's a historical unit of the Romanian navy. A shrimpboat, but she did sink (and assist in sinking) several Russian subs!
What about an actual shrimpin’ boat? Make it grey so everyone can use it.
Humorous, but seriously, I don't see how this is worth a card on first blush:
Cost: 1 Speed: 1 A/V/H: 1/1/1 (Generous - most small boats could be sunk with slightly more than harsh language) No weapon lines
No Sea Control: This unit can't claim objectives Very Slow: This unit can't move during the first turn of the game. (or some other speed SA to reflect a speed lower than 1) Shallow Draft: This unit can enter sectors that contain islands or shoals
?
Brigs is good...maybe he can come up with something. Perhaps a swarm of these that represents a hazard to navigation (which they can be in real life).