Maybe it's possible and it's just not clear how to do it?

I have a tanker ship, and I've set up a port where 2 inserters will place coal directly into the rear "cockpit" area. They can't get any closer to the ship (trying to place 1 square closer gives the red collision box). I've made sure that they line up with the small yellow rectangle (visible on mouse hover), at the back of the green connector (visible on mouse hover). The boat/waterway is perfectly horizontal at this location.

The fuel is empty, but the inserters do nothing.

Help.

Sigh.

Nevermind. They were ghost inserters.

ugh.

Nevermind, I was wrong again. It seems that the inserters are getting destroyed. Perhaps the ship is colliding with them or something

Yeah, i caught the inserters before they disappeared. they're all mangled, so they were destroyed. I'm on an island with no insects, so it wasn't them. When the boat visits, I check while the boat is still there or after it leaves and the inserters are destroyed.

I was able to workaround it by using long-handed inserters

Can you post a screenshot of your port? Is there a turn right before the ship enters the station?

Yes, there is a turn before the port.

I was able to revert to port to (more or less) the way it was before my workaround, and I caught the ship blowing up the inserters.

Screenshot: https://imgur.com/a/1LY8cfW

Is this a bug?

If this is the way you want the mod to work, it should be documented, because this was completely unexpected to me.

I'm not sure the circumstances where a "train" should be able to damage fixed objects, but ships are weird because they have wider collision boxes than the rails. They are big things so they can hit stuff if they get too close. It would be weirder if they could clip through everything without issue...

I just checked how it works in my base. I'm not sure from your screenshot, but you may be able to move them one more tile away from the ship? Or it could be that I just got really lucky with where my inserters and curve are placed. I stood in between the inserters and got killed by the ship. See https://imgur.com/a/ccy4VCF

Ok. I don't know. I ended up straightening the "rail" a little and using long-arm inserters.