I was considering the possibility mermaids might make use of sailing ships similar to the USS Monitor, but with sails and supposedly wood.
Now, the mermaids wouldn't mind the ship being filled with water, in fact they'd prefer it. Water is heavy: you don't want your ship filled with water. The air in the ship also has a lot to do with it not sinking.
Please review and criticize my idea for a mermaid’s boat.
To the point
My curiosity is about ship designs they could utilize. One idea I had was what if you took out the back/stern (or most of it) of a ship? It would fill with water, but the weight of the water inside of it shouldn't create drag when the ship moves forward? If you tried to move it backwards, of course, that would go poorly, and this may also affect turning speed.
You would need some way to maintain buoyancy, and keep the sails above water and level enough. Also, depending on the size of the hole in the back, you'll want to make sure nothing in the ship falls out that you don't want to fall out.
This idea may well be useless, but I hope that it can inspire some mermaid ship design of interest. Thank you.
1: The Air Decks. Size may not be representative of the real thing. It would be filled with air to keep the ship buoyant and the sail/rigging above the waves. It would also be used as dry storage. The air decks also extend out further than the Submerged Decks, I thought this may be necessary for the ship's buoyancy. There's also the question whether extra buoyant materials should be added to the vessel to counteract the water.
2: The Submerged Decks. Water flows in through the opening in the stern, and it is not closed off so it can freely flow out when the boat moves forward. Note that a grating is likely placed here, so that it isn't easy to fall out by mistake. Mermaids hang around here with cargo that doesn't mind being wet.
3: The sails. The question of how mermaids will handle rigging comes to mind, but that's for another time.
4: The sea. It needs to not totally wash over the air decks. This creates some issues. If you have sensitive cargo in the dry decks, you don't want seawater getting in. Which implies the water doesn't get that high, or there are no windows, which will make things quite dark. You could have lanterns for lighting, but that comes with dangers. You could try to have lighting come down from the top deck with some grates, so that as long as the waves aren't crashing over your boat things will remain pretty dry. Sealing off certain cargo rooms so no water can get into them is also a possibility.
5: I was considering the type of opening you would have in the stern. You'd want it elevated above the keel I'd expect. For one thing you would want to make sure the rudder is adequately supported. How a rudder would work on a strange ship like this is questionable.