When I was in the Coast Guard, we had these flexible patches for largish holes that you can deploy from inside the boat. What you have to do is:
1. Get a piece of stiff material that is big enough to cover the breach. (could be plywood
, thin metal sheeting, etc...)
2. Put a piece of canvas
3. Layer a sheet of thin rubber or gasket
material over the canvas
4. Drill a hole in the center of the stack
5. If your stiff material is something like plywood
, you're gonna have to saw it in half and hinge that sucker.
6. Take some strong line and thread it through the holes.
7. Put a big washer on the end and then tie a BIG old stopper knot
8. Fold the whole mess in half, so you've got a sandwich with the stiff material on the outside and all the rubbery goodness nestled within.
9. Keeping a hold of the other end of the line and shove the patch through the hole, all the way outside of the boat.
10. Allow the patch to unfold flat against the hull
, rubber side touching the hull.
11. Pull the line tight and tie it off to something secure.
Now you've bought yourself some time. The amount of water coming inside should be pretty manageable, giving you a little breathing room to figure out a more permanent patch, or limp into port, or wait out the storm or whatever. The rubber and canvas mold
beautifully against the hull and the stiffer material prevents the patch from collapsing into the boat. For training, we had a burn/sink boat and got to actually construct and use these patches in real-time on a sinking vessel. Worked awesome.