The weather is clear a perfect 20 knots and you are making great time.
A crew member decides to go below for a soda and reports that their is 6" of water above the sole.
The first thing you do is check the taste of the water and it is salt water.
If there's that much water I don't need to taste it to know the situation isn't good!
START THE ENGINE. If, like I intend to do, you've put a Y valve and a hose into the bilge you can start pumping the boat out.
Depending on the number in crew issue a PAN PAN (VHF and SSB)while someone tears the boat apart looking for a leak (the broken speedo/depth sounder, torn hose, etc.)
If still sailing, TACK. MAYBE you can get the cause of the leak out of the water or at least lessen the pressure.
Shorten sail so you can heave to or at least sail more comfortably.
If you still haven't found the leak assess how long you have and prepare to abandon. Send out the MAYDAY. Use your Epirb AND your Sat phone. Call your Epirb contact to let them know you are indeed sinking (the CG will call them) and then call the nearest CG rescure station (you DID preprogram the # for the Coasties, right?)
As an alternate lets say you heard a large bang on the hull and noticed the water a few minutes later. How would this changed situation affect your actions?
Another alternative would be the loud bang during a gale with about 35 to 50 knots.
Someone looks below to assess extent of damage while someone shortens sail and gets the boat under control w/ minimal movement
If in the loud gale scenario, TACK immediately. It could have been a fitting on the windward side. (you would not believe how loud something is that fails even on a small boat!)
How about the same to issues above but in the middle of long island sound about 10 miles from land?
Pretty much the same as the first scenario w/ the benefit that you can me a little less concerned about abandoning the craft.
Definitely send a PAN PAN on the VHF. Turn the boat towards the nearest piece of shallow water. MAYBE you can find a shoal to drive her up on as a last resort and minimize the damage if you can't find/stop the leak.
I'm sure I'm leaving out a few things I would have thought of but figured I would just jump in as that's pretty much what you have to do in this situation.
Best thing is to discuss these scenarios ahead of time w/ your crew and come up w/ all the different variables/answers.
I play the "WHAT IF" game lots of times and not just w/ sailing.