When our boat sunk(grounding) due to an opening, say equivalent to 2-3", one of these wouldn't have kept us afloat.
Our Coast Guard loaned us one of these gas emergency pumps for our 6 mile run to a travelift. But if our temporary patch-repair let go, that loaner emergency pump would have gone down with our boat, for a second time. The ingress pressure and flow from below the waterline is alarming.