Looking at your saildrive and rudder, you have a sticky boat around lobster pots and their connected pot warp. But you're not alone, a lot of boats have similar features.

You snagged under sail. That's usually (at least in our boats case) a good thing.

There's only a few ways any boat can snag warp. The idea you didn't see a buoy but only one line sounds familiar. In that case, I suspect the buoy may have been lodged on either your saildrive or your rudder out of view. I assume your keel is also high aspect , if it is, that's a possibility too.

This may sound crazy, but you might take a lobster buoy and a little warp up to the boat next spring and see how it can catch on either the saildrive or the rudder and hull. It may give you some ideas, it can only be a simple bend of warp if you hooked under sail.

Our only hook up point on our boat is a blade on the prop in the aperture. It's rare under sail, but has happened a few times. In our case, it's either hooked port or starboard side and holds the stern to the wind.
First, I go below and twist the coupling, feel the warp, once this even released the loop on the prop.

If it's stuck though, I have to get that loop and the blade it's connected to, on the upwind side of the hull. This has been accomplished by dropping sails and trying to gybe onto the other side. The idea is getting the blade and warp at an angle it will simply fall off. The mizzen can do that sometimes.

But if the buoy is jammed up tight to the blade, as happened one time, this didn't work. That one time my son jumped in and found the buoy against the blade and aperture.

With that event in mind, in the future(I'm not jumping in), I'll assume that if I can't see the buoy, and work with the sails to turn the boat so the loop and buoy has little or no purchase.

I'm thinking that if you find the catches of how the buoy and warp can attach to your potential snags, you too may be able to "unwind" snag. It's only a 180 degree bend of pot warp. You'll want to figure how you're connected below by the direction of the warp streaming aft. You don't go the wrong way, and tie a bowline on your rudder.

And of course if you see two lines, you've got something else. Look for the buoy somewhere nearby. In that case, hooking and pushing the line down would be the first choice. You may have to do it more than once. But that's better than cutting and wondering if you still have warp ready to wrap the prop.

If you wrap it under power, all bets are off. Our boat has low enough freeboard the few times we had to cut, we could pick it up with the boathook and cut, re tie if possible.

Some bad news.

When the economy went south a couple years ago, the lobster market went belly up. It's starting to recover, but the amount of traps on the coast were down, quite noticably in the midcoast this past season.