brian whatcott wrote:
mememememe! wrote:
Hi,

i'm wondering if someone could give some advice on what prop i should use

i have a 15ft fibreglass runabout with a 70 hp 3 cyl evinrude motor
with trim tilt

i have a propco-19p prop that i would like to use on it , i'm guessing
its a 19 in pitch prop

would this be sufficient for decent holeshot and reasonable top end ?

i cant really find alot of info in goog le.com

its not a heavy boat


thanks


Like airplane props, boat props specify diameter, # of blades and pitch.
Diameter and blade count are a function of shaft HP X prop shaft speed.
Pitch varies with desired boat speed of operation and prop shaft speed
Boat speed depends on hull shape - principally if it can hop onto the
plane.

It's sometimes easier to refer to a guide (of similar types) and try two
or three props to bracket the desired result.....

Brian W

Here's one rough datapoint: on a 16 ft trihull which planes easily,
(but bangs in chop....) the 85HP Johnson (which is really too heavy for
the boat), has a three blade 14 diam 12 in pitch (guessed not read off
the prop...) does 33 mph....

Brian W