Depends on where the leak is, if it's right at the exhaust
like it sounds like, then you could be sucking water
back against the hot exhaust valve and that could wreak havoc.
All exhaust and intake systems for that matter have some reverse flow, it's called reversion.
It could also believe it or not wear a slot into the head
or the heat exchanger side which would mean you might have to buy those parts
, the leak could also suddenly get much worse right at the worst moment.
None of this is guaranteed, just things that could happen, it's also likely that nothing bad would happen, but it's prudent to not push your luck in my opinion, and that is just an opinion of course
If your an hour or so away from a maintenance
or whatever and have SeaTow or Boat US, I think they will tow you there.
On edit, sorry I don't know your location, I assumed US, but of course that may be wrong