From FX Update's zones.cfg file:
;Modified by TheDarkWraith
[DistressFlareWarship]
Multiplier=1.000000
Flotability=0.000000
Critic Flotation=0.300000
Armor Level=-1
HitPoints=130
Destructible=No
Critical=No
Effect1=
Command_room_crewman_splinter_explosion_escort, 40
Effect2=Distress_Flare_Red, 75
FloodingTime=59.999996
CargoType=None
[DistressFlareMerchant]
Multiplier=1.000000
Flotability=0.000000
Critic Flotation=0.300000
Armor Level=-1
HitPoints=65
Destructible=No
Critical=No
Effect1=
Command_room_crewman_splinter_explosion_merchant, 40
Effect2=Distress_Flare_Red, 75
FloodingTime=59.999996
CargoType=None
Those effects when triggered will throw bodies, debris, lifejackets, and some other items and they will float on the water and some emit blood pools on the water. Morbid yes but really cool
The units in the game need to have these zones specified in their .zon file in order for these to be seen. FX_Update includes them on some of the ships.