Because I have only used a melter with cats (the water flow is between the hulls) I have never faced the issue. An interesting question.
Generally 4-6 knots (7-10 feet per second) is the threshold, depending on the paint. That's a lot of flow, so unless it is quite close, I doubt it.
The other thing you should do is put the melter on a thermostat so that it only runs when the temperature is below ~ 28F (when ice will form). This saves
power, reduces clogging of the prop (you will catch plastic bags and sticks), reduces wear on the melter, and potentially, saves paint.
Honestly, in Deale, you don't need it. Been there 20 over years.