If all the water in the oceans was replaced with gravy, what type of seafaring vessel would most ably handle the gelatinous sludge through which it would now have to travel?
IANA Marine engineer…
Boat and ship design already has to take into account the viscosity of water - this would just make it a more extreme design criterion.
All displacement vessels would be worse off, but probably more so at the flatter, blunter end of the hull shape spectrum.
Hovercraft, largely unaffected.
Planing hulls less affected than displacement, but still impacted by viscous drag (some might not be able to sustain planing speed)
Hydrofoils largely unaffected, except that they might need tougher engineering of pylons, etc.
All bets are off on day 2, when the gravy has formed a thick skin. Except for hovercraft.
Mmmmm, eels with gravy.
What about ships in curry sauce?
If it’s onion gravy, then I’d recommend an airboat, to prevent prop tangles.
“Somali pirates attempted to board an American freighter in the Gulf of Tapioca today. They were repelled when the crew of the freighter opened fire with whipped cream cannons, and sank the pirates boat with a maraschino cherry bomb.”
a gravy boat.
:smack:
Applause.
An ice breaker. Or possibly a biscuit cutter.
Part of the Gravy Navy, no doubt.
CheeseDonkey, time to cut back on the drugs, dude. 
Why not an Amphirol or other screw-drive based design?
I believe ships take on seawater to use (after desalinizing it) as steam in the turbines, for those that use steam turbines.
Dunno if seawater is taken on board and desalinized to use for other purposes. (Cooling the engines? Drinking water? Air conditioning via chilled water?)
The wake that the ship leaves would be wavy gravy.
If you run most boat engines without them being immersed in water, you can seriously damage the engine- they use it for coolant. Can’t imagine that working with gravy.
I don’t know, but I want beaches of mashed potatoes and islands of dumplings.
No, no, no! He probably hasn’t even peaked yet! 
I’m beginning to roux reading this thread.
I used to have a gravy boat, now I’m on the gravy train.