Step 1 - Get something over or in the hole, quickly. A sail, cushion, whatever- just slow the flow somehow. No pump that fits on board will cope with a major hull
Step 2 - Start getting the water out so you can reach and stem the leak.
A 10,000 GPH gas powered emergency pump can easily be found for $200 to $350 (CDN/USD). A failed 2" seacock, three feet down, won't keep up with this pump.
A 25,000 GPH model starts at about $500, and will clear the bilge
with a 3" through-hull broken off three to five feet down.
If you have hydraulics and trust your main engine
, similar flow rates can be obtained with an industrial/agricultural pump like a Pacer S-series coupled to a hydraulic motor
. Or if you want a fully independent diesel
pump, couple one of these to a $600 air-cooled 10 hp diesel
Any of these pumps have flow and pressure good enough for effective fire-fighting. They're also great for wash-down, special events
(welcoming foreign boats, etc.), dealing with charterers who anchor
too close, etc.
Yes, you have to add suction and discharge lines to those costs. But it's still pretty cheap
compared to what some folks spend on furling gear
, nav computers
turbines and other useful cruising gear.
(Of course, it's best to keep the hull
intact, the seacocks working, and have watertight bulkheads in the high-risk areas- but the thread's about emergency pumping, i.e. what to do when all that prevention still isn't enough. The priority must be to find and fill the hole, by whatever means necessary- the pump's immediate purpose is to stop the boat from sinking while you do that.)