J-prop 63 AC!

[snwl]

Question for machinists or. lubricating propeller owners. I have a J-prop 63 AC (Adjustable Pitch Feathering Propeller) installed on the boat. Three years ago, when lifting, I normally lubricated the propeller so that excess grease came out on the rear flange. Lubricate with blue grease Kent. In the bonaca (calm sea) at 2100 RPM I achieved 7 kn. During the last lift, I re-lubricated the mentioned propeller by mounting a zinc protector up earlier (so the excess grease could not "escape out of the system"). Now at 2100 RPM I reach 3.6 kn. Now my question. Is it possible that there is too much grease in the system and consequently the blades do not reach the desired slope? So the propeller "grinds" the water more beneath it because it does not reach the proper "pitch". I didn’t change the pitch.

Thanks for the help.

[rene460]

Hi Snwl,

I have a feathering prop, also with adjustable pitch, and also at each lift, pump more grease in until any water which has leaked in during service is all displaced by fresh grease.  While pumping in the grease I turn the blades both ways by hand, and again after the greasing.   Mine is a different brand, Autostream, which has several differences compared with the one in the video, but similar in principle.  However, I have not noticed any change in the range of blade rotation before and after.  (I note that the pitch appeared to be changed by one or two divisions on the scale in that video, but I don’t know if that was your boat.)

Once back in the water, I note the rpm needed for the 5 knot speed in the channel, and when out of the channel, I gently push the throttle to wide open, and note the engine rpm and boat speed that is achieved.

This test checks the performance of the hull, propellor and engine against previous tests, and was recommended by the Yanmar mechanic when I first installed the propellor.

If the pitch had changed, the propellor would present a different load to the engine.  Probably harder to detect at low speed, but at wide open throttle, if I don’t get the previous max rpm, the propellor load has increased, indicating higher pitch if pitch has changed, while if I get to rated engine rpm before wide open throttle, that would indicate less pitch than at the previous tests.  Yanmar recommend about 10% over the rated engine speed at wide open throttle for the propellor selection to fully absorb the available engine power.  If you reach 10% over rated rpm before full throttle, don’t go any higher rpm, hence gently pushing the throttle, so you can stop before going overspeed.

In my experience, that slow speed you are experiencing is more likely to mean some sort of propellor fouling, such as some of the plastic sling protectors during relaunching, or a a plastic bag or some weed.  It does not take much.  The wide open throttle test is very useful in this regard.  If there is even quite a small amount of fouling of the propellor, the engine will not reach anything like rated speed at wide open throttle, and boat speed will be slow, as you will just not be getting the thrust you would get from a clean propellor working efficiently.  I usually notice that as the hull fouls a bit through the year, the engine speed required to achieve that 5 knots in the channel creeps up.  

I don’t know if diving is practical for you, but a quick check of the propellor and test if it appears to move through the normal range by hand might yield useful information.

rene460

[snwl]

Thanks for the reply. The video doesn’t show my boat but I pasted the link because it also has a J-prop. I was dive under the boat and there's nothing on the propeller. Like I said I also didn’t change the pitch from the propeller. I put the boat back in the water in April with a new antifouling paint. As I said before, I only changed the fact that I installed the zinc protector on the propeller before and only then started lubricating the propeller. Is it possible that there is too much grease in the system?

[bereboot]

I had a perhaps similar "problem" on my previous boat with a max prop.
When i greased the propellor untill all the water was out, then i had to move the propellor by hand in the forward and the backward position. In the beginning the blades didn't turn free. It was only after repeating this session 10 or 20 times, that the propellor behaved "normally" and got to the desired angles.

[lunah]

Hoi,
Ik ben Steven en nieuw op het forum
Ik heb het zelfde probleem nu
Na het smeren komt hij niet meer op snelheid
Voordien 2000 toeren 5,7 kn
Nu 2000 toeren 3,5 kn
Is het bij u opgelost en hoe

[Don Reaves]

May 31, 2022 8:40:45 GMT lunah said:

Hoi,
Ik ben Steven en nieuw op het forum
Ik heb het zelfde probleem nu
Na het smeren komt hij niet meer op snelheid
Voordien 2000 toeren 5,7 kn
Nu 2000 toeren 3,5 kn
Is het bij u opgelost en hoe

Using Google translate:

Hi,
I'm Steven and new to the forum
I have the same problem now
After greasing, he no longer gets up to speed
Before 2000 rpm 5.7 kn
Now 2000 rpm 3.5 kn
Has it been resolved for you and how?

[rene460]

Hi Steven, welcome to the forum, you will find many friendly like minded folk here, and a wealth of timeless information in the old posts.

Based on my experience, that difference in speed is a good indicator that something is not quite right.  The wide open throttle rpm is a good test to indicate if it is something fouling the propellor or a pitch issue, however, only assuming that you know the wide open throttle rpm from previous tests.  Be cautious in applying wide open throttle, as if it is a pitch error, the engine might overspeed.  If you get to the specified max rpm before wide open throttle, that is a sure indicator that the propellor blades are not rotating to the intended pitch.  No need to open throttle further.

I don’t have much to add to the previous posts in this thread.  The response by bereboat is particularly interesting. but as you are already back in the water, hard to do if you can’t dive for any reason.  It may be possible to achieve the same result by trying a few forward and reverse cycles too rotate the blades back and forth to see if they will settle better onto the stop, which you will see in gradually increasing speed at 2000 rpm.  Don’t have to do anything rapidly, just change gear in neutral and gentle rpm increase, then back to neutral then reverse and increase the rpm a few times, and see if you start getting some improvement.

If you have a go-pro or something similar, a mounting on a stick over the side in clear water is a good way to inspect for any debris on the propellor.  Be on the lookout for something caught on the hull or rudder also, as hull fouling can also significantly reduce boat speed at the same rpm.  Easy to check with a Go-pro on a stick.

I always greased my propellor in the same way described above without issue and worked the blades back and forth until I could feel the hard stop at the correct pitch.  In my case the anode and grease provision was original with the propellor.  I do expect that it is something simple and I hope you can resolve it soon.

rene460

PS one other thought - did you remove the propellor to fit that anode?  Or fit the grease nipple with the propellor in place on the shaft?  If the propellor was removed, it is very easy to get the gears not properly aligned which results in a severe pitch error.  But this is only an issue if the propellor was removed.

[snwl]

I apologize for not reporting back on how I handled the matter. If I want to change the pitch on my J-prop I have to remove the zinc protector first. So I dived under the boat, removed the zinc protector, and blindly changed the pitch. The test on the water at 1600 RPM showed me a speed of 6.7kn - significantly too much. Re-dive under the boat and slightly reduce the pitch and now the matter works OK. 2100 RPM - calm sea - speed 7 kn. :-)