[RWilson2526]

can you span your gunwhales with a heavy piece of lumber and hook a come-along into the sender hole and pull it out that way.

Theoretically aluminum doesnt spark when you cut it with a grinder so I guess you could go at it if you had to but I would probably fill it with a few inches of water first at least just to be sure.

I would try to pull it out first with a come along because once you start cutting it you will still have to get the bottom out which might be even harder without something to grab on to.