There are always some really amusing ideas making their way into a "cruising forum" and a bidet on board is one for a good laugh.
Like Bobconnie succinctly put it - where are you going to get the water from to run such a "fountain?" According to the statistics websites, each person in the USA uses about 152 gallon PER DAY (575L). That's more than the total water tankage on a lot of sailboats.
Cruising is an exercise in minimalist water consumption
- even if you have a watermaker
. Sink taps are opened only a little bit and quickly shut off and not left running while washing
And where are you going to put the thing - in the main salon
? The heads in sailboats are very tightly packed with minimal room to maneuver and just barely enough room for the marine
MSD (Throne) to fit between wall and sink counter.
And when you look carefully at the average sailboat head compartment you will notice that there already is a handheld sprayer mounted in the shower. It is there so you can save water by directing water only on the body areas that need wetting or rinsing - and that includes your "tush."