My tubby old 27' ChrisCraft Cavalier didn't ahve it, but it did have a
nice wheel,and forward steering was effortless. But my 22 Ft. Monarch
with 350 GM Mercruiser doesn't.

A friends 19 ft tri-hull w/ 250 Gm Mercruiser has power steering, And
I've seen smaller boats like my 17 ' Chris craft with a 3.0 have power
steering?

What's the deal?

It looks to me like a real PITA to install it on mine, even if I spent
the big bucks and bought a factory kit, or got a system from a donor
boat.

On some craft, is it an option? and what is the advantage of power
steering ...if any?