Question about propeller installation

"I've done a ton of work o

"I've done a ton of work on outboards. Was installing a prop for a guy (a new Solas Alcup). Anyhow, he was reading the instruction sheet while watching what I was doing. One of the instructions said "Install propeller and make sure it is recessed into gearbox". I've always taken that for granted, but he asked WHY? I don't really know the answer - told him I assumed it ensured that the water would flow over the unit better and it would protect the prop shaft from picking up junk (fishing line, weeds etc) but would try and find out. Read everything I could, but couldn't find an answer. Would like to open it up here - hopefully someone knows. Thanks"

i would say ventilating if it

i would say ventilating if it was not because of the exhaust gases from through prop exhaust

You'd be surprised how lit

You'd be surprised how little turbulence it takes to make a prop cavitate and not work. The prop and housing above it must NOT interrupt the water flow or...rrRRRRRR!!

Jeff

"Ok, thanks for the responses

"Ok, thanks for the responses - figured it was something along those lines, just couldn't find any thing really explaining it."