Free Wheel or Lock the Prop in Gear

[svzosha]

After decades of sailing, I still don't know the answer to this question....so maybe some of you can enlighten me......my boat 14,000 displacement, 4200 ballast, 28' LOD, 26' LWL, 22 HP diesel with LH turning prop: my question.....when under sail do I
1. let the prop free wheel in neutral
2. put the engine in fwd
3. put the engine in reverse
4. doesn't make any difference what I do

your input would be appreciated
Thanks

[Ram]

yanmar says free wheel (neutral) in the sail drive

[Cheechako]

I think with most transmissions put it in reverse. Keeps from wearing out the rear transmission bearing, packing and cutlass bearing. I've heard it is less drag than a rotating prop , but always had trouble logic-ing that out....

[shorebird]

There have been other, rather lengthy threads about this very thing, with no real answers. I initially put my transmission in reverse, as per the advice of half a dozen sailors, but the first time I did it, the transmission would not engage properly, and even locked up and stalled the engine. I now leave it in neutral, as per Yanmar manual, and have had no problems since. The freewheeling prop is kind of annoying though.

[Cheechako]

Most my boats were Hurth gears, worked well in reverse. Saildrives... no idea.

[mitiempo]

Originally Posted by svzosha

After decades of sailing, I still don't know the answer to this question....so maybe some of you can enlighten me......my boat 14,000 displacement, 4200 ballast, 28' LOD, 26' LWL, 22 HP diesel with LH turning prop: my question.....when under sail do I
1. let the prop free wheel in neutral
2. put the engine in fwd
3. put the engine in reverse
4. doesn't make any difference what I do

your input would be appreciated
Thanks

You don't state what engine and transmission - it makes a difference. Yanmar engines with the Kanzaki transmission should be left in neutral to avoid wear of the cone clutches. This is for saildrives as well as conventional shaft drives. This contradicts some older Yanmar manuals and is the subject of this Yanmar advisory: http://www.mainehuntersailing.com/fi..._MSA08-003.pdf

Each manufacturer will have a recommendation for their product.

[senormechanico]

I saw a youtube video, the link for which was posted here a few days ago.
It was for Flexofold props.
The rep stated drag for a fixed prop locked, freewheeling, vs a Flexofold.
Locked was way more drag than freewheeling, and freewheeling was way more than a folded prop.
I don't remember the numbers exactly, something like 80, 25 and 2 lbs at a specified sailing speed.
It was definitely linked here, so a search should find it.

[cal40john]

Well Maine Sail did his own tests and also links test results from Michigan Wheel and MIT. All point in the same direction. I'm convinced even if others aren't.

And yes you don't want to freewheel your prop if you'll destroy your transmission.

http://www.cruisersforum.com/forums/...ng-7815-2.html


John

[Mr B]

Mechanically, its better to free wheel it,

In gear, it is moving the internals of the gear box with out load,
leading to chatter and slap inside the gear box amongst the gears and the bearings, Because they dont have a load on them.

And will in time destroy your gear box,

[senormechanico]

It has always added up for me to have a folder or feathering prop.
Way less drag and less apt to foul on something as well as no transmission or cutlass bearing issues.

Here's that link I mentioned:

http://www.youtube.com/watch?v=BJRMJuw2iU4

[FrankZ]

Yanmar says to free wheel mine so I do. When I get around the crab pots I have been known to slip it in reverse for a moment if I get too close, though with the full keel and prop in an aperture I seriously doubt I will pick up a line.

I did have an issue once doing this when I tried to take it out of gear it stuck. Took some jingling on the shifter to get it to pop back out. We were sailing along at about 6.5 and I suspect it had to do with the force on the prop jamming something up.

I docked without reverse just in case. Talked to Chief Engineer and all is good.

[delmarrey]

the MIT and US Naval Academy studies which were widely quoted were initially focused on ship propellors with the idea that an engine could be shut down to save fuel at sea. It was
later expanded to look at smaller propellers. The conclusion was
somewhat missreported.

The findings of the study indicated that a prop
with more than two blades that was allowed to freewheel produced less
drag but only if the shaft was allowed to spin with minimal friction.
When friction was added to the shaft, drag increased dramatically and
quickly produced more drag than a prop that was locked. This has
implication for people who are considering a water driven generator that
would be powered off of the prop shaft. Locked three blade props produce
the least drag when placed in the 'Mickey Mouse' position (one blade
down and two up).

Two bladed props were found to produce less drag locked than when
allowed to freewheel and produce the least drag in the vertical
position.

As to your transmission, most small transmissions use a small
'splasher' of some kind to provide lubrication. I am not sure that is
true of small Volvos as they have always marched to their own drummer.
In any event, allowing the prop to free wheel takes a toll on the
cutlass bearing, as well as the engine seals, output bearing and
internal bushings. If you care about transmission longevity then locking
the transmission in reverse makes the most sense.

Jeff H 5/4/06

http://www.catamaransite.com/files/propeller.pdf

It seems 3 blade are different then two blade..........
Propeller Drag under sail, Article

Prop Drag Test Movie - YouTube

[MarkSF]

Originally Posted by svzosha

After decades of sailing, I still don't know the answer to this question....so maybe some of you can enlighten me......my boat 14,000 displacement, 4200 ballast, 28' LOD, 26' LWL, 22 HP diesel with LH turning prop: my question.....when under sail do I
1. let the prop free wheel in neutral
2. put the engine in fwd
3. put the engine in reverse
4. doesn't make any difference what I do

your input would be appreciated
Thanks

If you have a Hurth transmission they specifically warn against leaving it in forward, you will cause damage. Therefore it's a good habit to never leave any boat in forward. Reverse or neutral are OK.

[CarinaPDX]

The assumption so far seems to be that the OP has a fixed prop. For feathering props it is usually put into reverse to help the blades feather (which might not happen otherwise). Once feathered it might not make a difference to put it back in neutral, as it won't have much torque trying to turn the prop.

Some transmissions can overheat if allowed to be turned by the prop under sail, because the transmission is normally cooled by the cooling water">engine cooling water. You should definitely check the recommendations for your specific transmission.

[Wotname]

Originally Posted by Mr B

Mechanically, its better to free wheel it,

In gear, it is moving the internals of the gear box with out load,
leading to chatter and slap inside the gear box amongst the gears and the bearings, Because they dont have a load on them.

And will in time destroy your gear box,

Mr B, haven't you got that back to front.
When it is free wheeling (i.e in neutral), it and the shaft and the part of the gearbox is turning as you sail along but when it is in gear, the prop is stalled and shaft and everything in the gearbox doesn't turn at all - unless of course one goes so fast as to develop enough force to turn the engine over (through compression) - which is highly unlikely in the average yacht.