prop lost curve

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jeffdjpeat

Petty Officer 2nd Class
Joined
Mar 25, 2009
Messages
125
i just bought a boat 15 foot marvac, with a 60hp merc. the former owner had the old prop stating it had lost its pitch or curve in the blades. this may not me the right place to ask this question, or maybe it is a merc issue, but could this be caused by excessive pulling, or pushing? if so which one? i am just trying to find out if the boat was run hard, or what could have caused this issue. the motor is a 1986. the boat is a fiberglass 15 foot bowrider.
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: prop lost curve

Never heard of loosing pitch but I have seen props that were run in the mud go the other way till the engine would not turn them.
 
J

jeffdjpeat

Petty Officer 2nd Class
Joined
Mar 25, 2009
Messages
125
Re: prop lost curve

thats the same thing the mechanic told the former owner when he replaced it. but after doing so he gained about 8mp/h. weird, i figured it may have been from waterskiing, or hauling around 8 people.
 
Randybeall

Randybeall

Petty Officer 1st Class
Joined
May 2, 2008
Messages
319
Re: prop lost curve

You could take the old prop to a good prop shop and have them tell you about it. They should be able to measure the pitch and tell you if it lost anything. That may not be worth doing, some places charge as much as you can buy a new prop for now. Labor is expensive, rightfully so if the technician is good at what he does.
 
dbkerley

dbkerley

Chief Petty Officer
Joined
Apr 6, 2009
Messages
443
Re: prop lost curve

More often is the hub getting weak and allowing the prop to slip excessively. A good prop shop can diagnose all the ills. The first indication of a prop problem is a motor that won't run full rpm or overspeeds.
 
bowman316

bowman316

Lieutenant Commander
Joined
Oct 21, 2008
Messages
1,822
Re: prop lost curve

are you talking about a cupped prop?
just where there is a cup in the interior section of the blade?
because that is just in the design of the prop.
 
S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: prop lost curve

Aluminum props especially do wear from regular use; faster in silty water. They can lose diameter, edges can become blunted, shape can change mostly along the curved edge.If cupped it can become flattened.Harder materials wear longer.
 
J

jeffdjpeat

Petty Officer 2nd Class
Joined
Mar 25, 2009
Messages
125
Re: prop lost curve

im not sure exactly what happened, the prop was just a standard replacement Merc prop for a 1986 60hp. maybe it was a defective prop i dont know, but the 3 blades seemed to have lost their "cup" they almost appear like straight peices on the hub, hardly any curve to them at all. im not worried i have a new prop, and all is well, just wanted to understand why.
 
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