Funny is I have a 1989 25hp evinrude with a 10.3 X 12p wot rpm 4500. 21.3 mph across lake. Topper Trapper 15.5 650 lbs one person. My engine power is 4500 to 5500rpm . I ordered a solas Amita 10.8 x 10p the evinrude dealer expects it to gain 1000 rpm. I watch on the RUclips This old outboard and with the 13 spline propeller and 25hp he was testing with a 9p and 10p 9"prop with the 25 evinrude 27mph with crazy fast get and using the 10p. Both engines are in 89 88 year range.
I have a Tohatsu 40 hp 3-cylinder 2-stroke since it is a boat 460 meters deep semi-vy with 3 people plus day fishing things it does not go beyond 5200 rpm, propeller 10 1/4 14........ .should I take a step down? could you change x a propeller 11 1/8 13? I appreciate information! thank you
if you go down from 14 to 13 (-7.5%) ,your rpm will increase +7.5% from 5200 to 5600. if you go down from 14 to 12 (-15%) ,your rpm will increase +15% from 5200 to 6100. Check your engine's power-rpm curve. If there's not much HP difference between 5200rpm and 6100rpm, don't buy a new propeller.
Is it fair to say that we can work out the approximate flow rate from the pitch and RPM? Putting aside the hub diameter for the moment: pi * r^2 * pitch * rpm = cubic inches per minute? (and of course cubic mm if doing metric mm measurements)
@@JustMeBlindFreddy elevation…. I live and boat at 5-9000 ft above sea level. If you live on a coast that is sea level. The density of water changes as you gain elevation changing the WOT rpm.
Wait a minute .. Where did you get this first 15 number ? How did you calculate it ? Measured ? Measure on what ? How did you get a 20 ? Ddid you bent the hub ? I need help to understand it , Can anybody. educate me on this please , Thank you
To the point , no bla bla. Thanks.
To gain hole shot or increase your RPMs, decrease your pitch.
To gain top speed or decrease your RPMs, increase your pitch.
Finally it makes sense!
Thank you sir well explained 🍻
so just keep buying props till your happy?
I understand buddy 🫱🏾🫲🏿
Pretty much sums it up.
Great information!
I got 3.0 Merc with 14.5x19 prop, damaged it, got 14.5x21 prop for 60$ locally, I assume I won't be damaging my engine?
Funny is I have a 1989 25hp evinrude with a 10.3 X 12p wot rpm 4500. 21.3 mph across lake. Topper Trapper 15.5 650 lbs one person. My engine power is 4500 to 5500rpm . I ordered a solas Amita 10.8 x 10p the evinrude dealer expects it to gain 1000 rpm. I watch on the RUclips This old outboard and with the 13 spline propeller and 25hp he was testing with a 9p and 10p 9"prop with the 25 evinrude 27mph with crazy fast get and using the 10p. Both engines are in 89 88 year range.
Thanks Sir
I have a Tohatsu 40 hp 3-cylinder 2-stroke since it is a boat 460 meters deep semi-vy with 3 people plus day fishing things it does not go beyond 5200 rpm, propeller 10 1/4 14........ .should I take a step down? could you change x a propeller 11 1/8 13? I appreciate information! thank you
if you go down from 14 to 13 (-7.5%) ,your rpm will increase +7.5% from 5200 to 5600.
if you go down from 14 to 12 (-15%) ,your rpm will increase +15% from 5200 to 6100.
Check your engine's power-rpm curve. If there's not much HP difference between 5200rpm and 6100rpm, don't buy a new propeller.
I have a 60hp merc that the rpm only hits 4100 rpm wot the prop is 10.5 x 13 what would be a good prop?
Depends on hull type (planing or semi-planing) , boat weight , number of passengers, engine model (ct or standard gearcase)...
Are you sure it is a 10.5x13 by the way... not 13x10.5 ?
Is it fair to say that we can work out the approximate flow rate from the pitch and RPM? Putting aside the hub diameter for the moment:
pi * r^2 * pitch * rpm = cubic inches per minute?
(and of course cubic mm if doing metric mm measurements)
To bad most people decrease pitch to gain top speed...
Does elevation impact how you choose a propeller? I was told the higher your elevation the higher pitch you need. Is that not correct?
If you mean above sea level that sounds more like an airplane thing
@@JustMeBlindFreddy elevation…. I live and boat at 5-9000 ft above sea level. If you live on a coast that is sea level. The density of water changes as you gain elevation changing the WOT rpm.
Wait a minute .. Where did you get this first 15 number ? How did you calculate it ? Measured ?
Measure on what ? How did you get a 20 ? Ddid you bent the hub ?
I need help to understand it , Can anybody. educate me on this please , Thank you