Wrecks encountered in the ocean cannot be hammered. Attempting to hammer them causes the characters to try to sail closer to it, even if they are as close as possible. I was using a Cargo Boat at the time.
I suspect the issue is with the size scale, based on the variants I'm seeing in their script file. I didn't attempt to try this yet, but I believe only "mast" variant can be hammered.
Find a wreck of "midship" type. Pick the limpets. Make sure boat has empty lantern slot (due to another bug). Attempt to hammer the wreck. Expected: wreck is hammered. Actual: The character sails towards the wreck, never reaching it.