Prop question

billyo · Post by **billyo** » Oct 27th, '10, 17:53

It appears that all the help i got from everyone is going to get me out of a jam.but during this dilemma we realize we need to get the correct props for the long haul. I don't know squat about props as my knowledge is in greenhouses (orlandogreenhouse.com) The props on the boat that seemed fine were 3-Blade bronze 18X19. The motors are Yanmar MODEL / HP: 4LHA-STE / 226 hp. TRANSMISSION: ZF HSW630 1.6:1 ratio My question is what should i be looking for in a prop? Pitch,cupping etc.

In Memory Walter K · Post by **In Memory Walter K** » Oct 27th, '10, 18:35

You may be inundated with advice but rule of thumb is :
If you know what your engine's WOT is rated at (this is key), take your boat out (warmed up) and nail your throttles to their max position. Look at your tach. Does what your tach says match your engine's rating? If they match, you are properly propped.
If your rpm's are higher than the rating add pitch, adding 1" of pitch will bring you back 100 rpm.
If your rpm's are under the rating, remove an inch of pitch at the rate of 100 rpm's per 1 inch of pitch.
Since you are talking about Yanmars (higher rpm running engines) this may not be an issue. If your fishing demands slooow trolling, at idle are you running slow enough? If OK, fine. If you need to go slower at idle rpm, remove an inch of pitch and add cupping. Tell your prop shop what you are trying to do. Usually cupping will give you back your speed etc., at cruise (higher end of the rpm scale) but let you run slower at the bottom end of the scale.
I have found this formula works whether bronze or Nibral props are used. Hope this helps. Walter

Bertramp · Post by **Bertramp** » Oct 27th, '10, 20:06

There are prop shops here in town (Ft Lauderdale) that should be able to set u up right and maybe even take my spares and make them a "good" set of spares for you.
Try F&J prop 954-377-0119

Marlin · Post by **Marlin** » Oct 27th, '10, 20:21

find a good prop shop, that is there business and they should stand behind there recommendation, u dont want to repitch a wheel 2 many times ,they fracture

Bertramp · Post by **Bertramp** » Oct 28th, '10, 06:50

Marlin ....
I am meeting BillyO's Capt this AM and giving him what was my spare set of props. I have an extra set, because of the ones you gave me. What comes around goes around ..... great to be in a place where help and everything else is given so freely.
all the best my "Bertram brothers"

bertram31.com

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