Re: Pumps do not do what you think
my boat, 40' 9tons relatively shallow bilge, has a pisser (800gph rule) for the minor drips and drabs and occasional wash down of the cabin sole. set about 6" above that is a 2400gph electronic (with a siren alarm thatll wake the dead) mostly in case the pisser fails and a deck hatch is left open during monsoon season. then theres the beast - 8000gph rule - i picked up at a marine swapmeet brand new for $75. its not on auto, you have to throw that switch intentionally. ive got a huge manual whale i can work vertically from the cockpit and a y-valve on the head pump so it can be pressed into service if need be. they all discharge to the COCKPIT and not a throughhull , where ive got more than enough drainage out the transom above the waterline. if your cockpit drains arent up to that kind of flow then thats where you put a scared crew with a bucket. and youve got a visual warning that your pumping when you are at the helm.
next, im essentially double-hulled from the bow to midships about 6" above the waterline as all the v-bearth, settee, and stowage lockers have secure latches and gasketed lids. this isnt as hard to do as one might think, and itll at least dramatically slow or even stop and compartmentalize flooding from a collision until a repair or patch can be well thought out.
lastly, carry several sizes and shapes of 1/2" ply pre-drilled around the perimeters and some truss head self drilling sheet metal screws, and a cordless drill. think it through and when youve calmed down some splooch on some sealant and just drive the screws into the hull.
and of coarse tapered plugs at all the seacocks.