Others may have done this successfully to but I was very apprehensive before hand.
I needed a sea water
supply for my new deck
wash and my boat
was not due to come out for 6 months so I enlisted help from two of my adult children
and chose a nice quiet spot with a clear sandy bottom in about 1.5 metres of water
It was mid summer so temps were ok. I used a 40mm hole saw in a cordless drill protected by an ice cream lid with all parts
ready to go. I was down in the bilge
with my son who was in the water below and daughter was at the side door for communication and emergency
Son had the fitting with thread tape to insert from underneath and I had the valve cock.
We told the crew on the adjacent boat
who immediately got out their deck
chairs to “watch a boat sink” 😂
All went very well and we celebrated with drinks afterwards with cheers from the spectators next door.
I would definitely repeat the exercise if I had to as we all went through many dry-runs before the real thing.
Hope this is easy to understand for anyone thinking of a similar task.