Milky substance in Oil?

We just bought a boat, it has a mercruiser inboard and when my husband went to check the oil it was milky, the boat was on the lake for 2 years in Florida Weather uncovered, my husband wants to put either diesel or kerosene to clean the water out. Now he is not sure which one. I think both options sound ridiculous, but he says it would help it clean the water out so he could refill with oil to see if the head gasket is cracked. Are his methods correct or is there a better way to do this? Thank you for all answers in advance.
Jody

The correct way is to change the oil and filter until no water is in the oil. That is of course if there is nothing wrong witht the motor, IE; cracked block or manifolds.......

So purchase a case of inexpensive motor oil and three inexpensive oil filters and change the oil and filter once and run motor to operating temp ( approximately for 30 to 45 minutes)(of course with water attached to keep everything cool and lubricated in the cooling system and water pump impellor).

Change oil and filter again and repeat this at least three times.

After the third time replace with high quality filter and correct oil (mercs spec is 25w-40w that they sell or a good quality 15w/20w-50w oil synthetic or regular.

That is what is done............

If the milk does not go away then........Huston we have a problem........

.... or if the engine overheats at any time in this process.
Also, this would be a good time to invest in an oil changer, i.e., a special pump/container for draining oil via the dipstick tube. There are manual ones and electric ones.