Motor Sailing

[typhoontye]

Question regarding motor sailing. I get a lot of racket from the V drive area when I get much assist at all from the sails while motor sailing. I know that we should never ‘drive the prop’ while motor sailing, but often I have to really go to high revs to make the racket go away. Then I am doing seven plus knots, the motor is likely at 2300 RPM, and I don’t like it. Cut the motor and I am sailing three knots or less. So not too much sail assist. The noise is hard to describe but it it disturbing. It often cannot be heard unless I lift the cabin sole access panel. Maybe I am looking too hard for trouble?

The noise is simply a mechanical rattling racket, with a staccato rythym. Goes away if sail assist is eliminated or engine power is increased a lot. It could be related to my prop, a folding model (flex-o-fold). The prop is clean. Any experience with this? My V-drive is relatively new (4 years) and obviously I don’t want to damage it.

David
Blue Moon

[fred panna]

check the shaft going to v drive for play

[john stevenson]

If it weren’t for the fact that this only happens when motor-sailing I would have thought a failed damper plate. Must be related to over driving the prop, even if only a little bit. If the shaft is secure and reasonable well-aligned it might be the prop. Not familiar with that brand, but maybe one blade does not get fully deployed under those conditions. When was the last time it was greased?

[typhoontye]

Thanks for the responses, John and Fred. Confirms my thoughts thus far. I plan to change out the U-joints on the shaft leading to the V Drive as step one. Cheap and easy. Step two is to check alignment of the V drive, then the transmission to the drive shaft flange. A fellow I met with a P-365 while we were cruising in the Bahamas said he changed out his U joints, even though they seemed fine, and it made a measurable difference in overall smoothness. Didn’t address the motor sailing issue specifically, but perhaps it would help. I also didn’t mention that I changed out the engine some months ago, and didn’t really do any specific alignment, except visually. My thinking being, the U joints really should accommodate any partial mis-alignment. Possibly faulty reasoning. Adapter plate? Maybe. I changed out the plate on the old engine, but I don’t think I transferred it over to the new one. Bad on me if I didn’t.

Regarding the prop greasing, mine is a folder, not a featherer. No greasing on the folder. And the blades are geared to one another, so they should be at an equal state of deployment at all times.

Interestingly, Gori makes a two speed folder, so you can increase pitch on the blades when motor sailing. A nice feature if it works, which I presume it does.

David

[Rich Harris]

David,
Alignment is critical. The yokes of the u-joints must be parallel to run smooth. I’ve attached a drawing of a jeep alignment set up but U-joints are U-joins no matter where they are installed. Line “A” and “B” need to be parallel throughout their rotation or you will induce noise and rapid wear eventually letting the smoke out of the U-joints.
The only way you can get away with misalignment is if you use a constant velocity (CV) joint which is what is used on front wheel drive cars. I would bet a paycheck that your noise is a result of misalignment since you mentioned you changed out the engine.
Rich Harris
Gambit

Attachments:

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   driveshaft-alignment.png
   

[RichCarter]

David,
I would think that if you had an engine alignment problem, you’d have vibration at all power settings. Checking it is pretty easy however if you have a Walter alignment key. It’s a small bronze casting that looks almost like a bottle-opener.

I have a folding prop and have no issues motor sailing. My prop is a 3-blade Slipstream with blades that are geared together so they can’t open or close out of sequence. I get impatient sometimes in light wind and turn the engine on at low speed just to make-way. Anything less than 5-kts is unacceptable when I’m trying to get somewhere. I notice no vibration and the engine purrs. The folding prop makes a huge difference in light-air. It’s well worth the expense for me.

Rich

[typhoontye]

Thanks for the tips. I have instructions from Walter V drives on alignment. I think it references the bronze alignment tool, but also describes a process to do the job without the tool. Supposed to rain this week, so looks like that is what I will be working on.

Had never heard about the importance of the U joint axis’ being parallel. I guess in an automotive application that is engineered into the design.

Encouraging to hear that Rich is able to motor sail with his folder without problems

David

[Warren Stringer]

David,

I sail with a three blade Gori. The overdrive does work and cuts engine rpm and fuel consumption by about 20% at cruising speed. But to engage it you have to power astern at about a knot, then shift into forward. You won’t get it if you simply start powering while you are sailing forward. Also, if your prop is pitched correctly, You will get no benefit and will overload the engine at full throttle.

Warren Stringer
s/v Adagio, # 149
Deltaville, VA

[typhoontye]

The Gori overdrive concept sounds like a winner for motorsailing. Lower RPM for a given speed when sail is assisting power. Theoretically you won’t overload the engine since the sail is providing some motive force. And likewise, maybe you won’t drive the prop since each turn of the prop is taking a bigger bite of water. But if I’m reading Warren’s description of the process right, it doesn’t sound very practical in a lot of scenarios. If I’m sailing along, the wind drops, and I elect to motorsail, it sounds like I would need to drop sail, motor backwards to get the prop in overdrive, raise sails again, and proceed. Am I interpreting this right?

David

[Warren Stringer]

David,

Full disclosure – I’ve never actually done this with the sails up. But since you would be doing this in light winds, I would think you could just go head to wind, power in reverse to get a little sternway, then shift into forward and resume course. Maybe rolling up the jib would help, but you could just let the main and mizzen luff. I’ll try it next time I’m out, unfortunately, thunderstorms predicted on the Chesapeake this weekend.

Warren

[typhoontye]

Thanks for the clarification, Warren.

I think I have resolved the problem. I took four actions, and any one or combination of actions may have fixed it. Don’t know. In any case, I went out today in 15 knot winds, set the genoa alone, and ran the motor, in gear, at various RPMs, down to idle and up to 1800 or so (motor sailing). The racket from the V-drive area that I experienced previously was not present at any combination of sail or motor power settings.

Here’s what I did:
1. Aligned the prop shaft to the V drive (at the mating flanges). Standard process, worked it until I could not fit any feeler gauge of over .003 inch between the flanges at any point of the circumference.
2. Replaced the U joint on the jack shaft with a new one.
3. Checked the alignment of the engine/transmission to the jack shaft. I used the process from the Walter V drive owners manual. Basically, measure from the spool adapter face to some point on the U joint bores, and compare four measurements taken after rotating the assembly through 360 degrees, 90 degrees of rotation per measurement. They must not vary by more than .125 inches. I didn’t have to move the engine, as mine came in at .090 inches.
4. Adjusted the ‘AH’ distance. This is the dimension that the splined end of the jack shaft inserts into the V drive. It should be 3 3/16″ for the RV26. Mine was closer to 3 11/16″, way out of spec. Easy to check this. With the jack shaft uninstalled, measure the proper insertion depth with a ruler, and mark the splined end of the shaft accordingly or wrap it with tape. Then assemble the jack shaft to the transmission and V drive, and the tape (or mark) should be aligned right there at the edge of the insertion point. If it’s inserted to far, your tape or mark will be buried in the V drive. Its easy to adjust the jackshaft length…couple of clamp fasteners.

Anyway, thanks for the comments and advice, and I’m hopeful this is a lasting fix.

David
Blue Moon

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