Yanmar Transmission set while sailing?

jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,301
CAL 35 Cruiser #21 moored EVERETT WA
Met a new sailor with a Jeanneau 34.2 and Yanmar engine.

Says the transmission or prop shaft sing/ hum when under power between 1400 & 1600 rpm. Then it stops. When sailing at about 6.2 knots there is a growling sound. It also stops below 6.2 or above 6.5 knots.

Any ideas? What is the recommendation for the transmission when sailing? In gear in neutral? He said he thinks he has a prop and straight shaft with a strut.
 
Davidasailor26

Davidasailor26

.
May 17, 2004
5,709
Beneteau Oceanis 37 Havre de Grace
A noise described as singing reminds me of a thread that I think involved the edges of the blade being too sharp? Can’t explain a growling sound. A freewheeling prop (which is the correct sailing setting for a Yanmar of that vintage, as sail sfbay cited) could make a hum. But the freewheeling hum would usually happen over a wider speed range than just 6.2-6.5.
 
  • Like
Likes: jssailem
D

dlochner

.
Jan 11, 2014
13,030
Sabre 362 113 Fair Haven, NY
What kind of prop is installed?

A fixed blade prop will spin the shaft in neutral. A folding or feathering prop shouldn't , but sometimes it is necessary to put the transmission in gear with the motor off to get the prop to feather and then return it to neutral.

Following the recommendations by the manufacturer is always the best course of action.
 
  • Like
Likes: sail sfbay
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,301
CAL 35 Cruiser #21 moored EVERETT WA
Yes David. I thought is a little strange. I wondered if there might be a shaft issue or the cutlass bearing was at fault. He has asked me to go sailing and I will take him up on it in the near future as being tied to the dock gets boring.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,301
CAL 35 Cruiser #21 moored EVERETT WA
He was unsure. Knows it is a 3 bladed fixed prop.
 
sail sfbay

sail sfbay

.
Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
3 bladed fixed propeller on the Hunter 46.....no big deal to sail in neutral.
 
D

dlochner

.
Jan 11, 2014
13,030
Sabre 362 113 Fair Haven, NY
jssailem said:
He was unsure. Knows it is a 3 bladed fixed prop.
Click to expand
The fixed blade prop will spin when in neutral. The various noises may be a function of the props rpm, hearing the noise could be just a result of the acoustics of the boat. You can't hear them when the motor is running.
 
  • Like
Likes: jssailem
Crusty Ol Salt

Crusty Ol Salt

.
Aug 19, 2021
508
Hunter 280 White House Cove Marina
What kind of shaft seal is he working with. If it is an old school packing gland, they will sing when they are to tight and dry. Smoke too, trust me.

The growling sound could be prop cavitation. Now you take cavitation and the with Davidasailor26 answer that it is the prop singing.... Maybe it is a prop issue on both ends.
 
  • Like
Likes: jssailem
B

Benny17441

.
May 24, 2004
7,175
CC 30 South Florida
Yanmar recommends using Neutral. There are mechanical shaft brakes available to stop the shaft from turning. The hum at certain RPMs is normal and the fact that the growling stops at speeds over 6.5 knots tends to indicate it is not a metal on metal grinding sound. It is likely some prop induced resonance.
 
  • Like
Likes: jssailem
ifmdalvey

ifmdalvey

.
Feb 2, 2010
373
Island Packet 37 Hull #2 Harpswell Me
Neutral or reverse, it all depends upon what gearbox you are fitted with. Some have gear oil and some have ATF. Mine is ATF and reverse is recommended , those with gear oil appear to have neutral recommended . Read your manual.
 
  • Like
Likes: Tally Ho, jssailem and Alan Gomes
You must log in or register to reply here.

Top Bottom