I sunk my brand new ski a few months ago, and guys here helped a lot. Here are the steps again:
1. Do it as soon as possible
2. Remove plugs and turn ski upside down.
3. drain all the water
4. disconnect tank and empty and clean completely from the bad fuel left.
4. crank the motor upside down a few times without spar plugs upside down.. a lot more water will come out
5. Spray some starter fluid in the cylinders, dry out and clean plugs, worm them up and put them back hot.
6. crank engine again, it should start right up if motor is all good. If it doesnt work the first time, pull out the plugs, spray some more starter fluid clean make them hot and try again. If engine does not give a single sign of life then you have a problem

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7. with flush system running water through it, run the motor for a while and keep spraying fogging oil in the carbs just as much as you don't stall it.
8. Drive ski back to lake or ocean ASAP with full tank. Run the whole tank with really hard riding to burn out everything else left in the motor.
9. Put bilge pumps and don't repeat the same mistake

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P.S. forgot to mention, when you try to crank the motor for the first time, help it with little starting fluid spray directly in the carbs while cranking. The whole task require 2-3 enthusiastic friends for moral and physical help