Wood plugs of different sizes gauged to your thru-hulls. Keep them in sealable bags, and lash the bags to the appropriate thru-hulls. Unbagged, they can swell to a greater width, rendering them useless.
A "crash mat" can be a rubber mat with sturdy grommets that can be "fothered" on the outside of the hull, as can a sail in a pinch. A type of this device...and I've forgotten the name, but it's for a pretty bad hole, looks like a four sided umbrella: you poke it out of the hole (against the incoming torrent, presumably) and open it...it seals against the side of the boat.
I suspect that would work best if you were holed at the waterline, say, hitting a reef on a heeled tack. You could try to heel to the other tack, get the hole above the waterline, and give it a try, hopefully allowing a crippled and pumping-filled motor to the nearest lift or even to deliberately beach it.
Plenty of the older cruising books have tips on this sort of thing. Google will likely help.