Volvo 350 or 570 gets cold

[tank]

Hi all
The motor warms up at

Hi all
The motor warms up at the dock but when moving it gets cold I mean she gos from 180 to under 100!
only thing I can think of is the stat is stuck
open? would it get that cold?
Thanks

 

[sandkicker]

IS the engine raw water cooled

IS the engine raw water cooled or closed cooling system?