Adrian Tchaikovsky

I took a physics class in college! Immense momentum, lots of sloshing unless lots of baffles, huge debris field if breached

It's the sloshing that concerns me - or at least the fluid movement of the water under acceleration. The water is for the crew to live in.

How much acceleration are you wanting? Rapid changes of direction or long burns? Big diff in feasibility and slosh.

Are you planning on some lobster kinden? Would be so tasty in a soup. Captain named Thermador? Just a thought. Keep up the good work

Have you not got to The Sea Watch yet then? :)

I'm getting there

Assuming super-strong hull to support the mass of pressurized water, you’d probably need lots of slosh plates to prevent slopping under accn

consensus so far is that no air spaces = no slosh in that sense. it's all water.

Yep. But: Rotations, especially swift ones, may be different: communicating a spin around an axis to a static mass of water will take time

True that.

I suppose the main concern is that water is really heavy and would put a lot of stress on the ship compared to air.

Like if you were at the "bottom" of the water and the ship accelerates it would be as if you were in that depth of water on earth.

Even with breathing apparatus (I think) the water would kill a human because of pressure. Can fish die if pressure gets too great?

Many marine creatures are able to adapt to varying pressures by matching internal pressure - presumably limits to how quick you could change

So I think that would be a bit of a thing. It would perhaps be a bit like making your ears pop. A voluntary change.

Oh also if you rotated using gyros you'd have to be careful about the flows of water round the ship. It could easily cause currents right?

Another question. Do these creatures breath air? If not, would you need such a tough ship? Water is easier to contain right?

they breathe oxygenated water (i.e. they're earth-style marine life)