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ratbag
25-05-11, 23:08
hi all
when sailing , should i be in neutral or reverse ? bav 36 volvo sail drive non folding prop , i think i read in the manual that i should be in neutral , however i have always put her into reverse from when i learned to sail
thanks

Stu Jackson
25-05-11, 23:23
It depends on the transmission you have, not the engine. Read the manual for the transmission.

trapezeartist
25-05-11, 23:27
Personally, I don't think it makes much difference. I put it in reverse when cruising (for quiet) and leave it in neutral when racing (for a teensy weensy bit more speed).

Tranona
25-05-11, 23:34
hi all
when sailing , should i be in neutral or reverse ? bav 36 volvo sail drive non folding prop , i think i read in the manual that i should be in neutral , however i have always put her into reverse from when i learned to sail
thanks

You are correct. Volvo recommend leaving saildrives in neutral. However many people ignore that as they can't stand the noise. It does sometimes make it difficult to get out of gear before restarting but you can usually start in gear.

My saildrive failed after 3000 hours (30 years of normal use) but don't think it was because it was locked regularly in reverse.

prv
25-05-11, 23:36
Personally, I don't think it makes much difference.

As Stu says, it depends on your transmission. The one on my 2GM20 will jam if I put it in reverse and then have a good fast sail. It's a known issue with a tech note published by Yanmar saying to leave it in neutral. I had it jam several times before realising the problem.

Pete

ratbag
25-05-11, 23:50
thanks guys, that makes sense now , the noise/vibration is what troubled me

Tranona
25-05-11, 23:54
thanks guys, that makes sense now , the noise/vibration is what troubled me

A folding or feathering prop solves that - at a price. You get better sailing performance and often better motoring performance as a bonus.

Neil_Y
26-05-11, 07:48
Personally, I don't think it makes much difference. I put it in reverse when cruising (for quiet) and leave it in neutral when racing (for a teensy weensy bit more speed).

My Volvo sail drive gear selector jammed up completely, stuck in reverse which made me sweat a little as I was approaching an unknown harbour thinking I only had reverse. Thinking it was the lever/mechanics with all the sliding combined throttle/gear I dismantled the lever outside the harbour hove to (in a Bav) only to find it was the gearbox.

The gearbox manual was quite clear...leave in neutral
I'd just lost a blade of the folding prop so had the spare fixed bladed prop on!

cdogg
26-05-11, 13:17
hi all
when sailing , should i be in neutral or reverse ? bav 36 volvo sail drive non folding prop , i think i read in the manual that i should be in neutral , however i have always put her into reverse from when i learned to sail
thanks

Hi,
You might find the attached of interest

cdogg
26-05-11, 13:25
Sorry tried to upload as pdf attachment wouldn't load as pdf. so please excuse text only copy.

Note last para.

Halo
26-05-11, 13:33
Its easy really
1. If you can afford it fit a folding or preferably feathering prop
2. Pending 1. above sail in neutral as it is faster and better for drive chain
3. If you cannot stand the noise from 2. above sail in reverse and take consequences - adverse effects seem to take time or never show
Martin

nimbusgb
26-05-11, 13:35
As Stu says, it depends on your transmission. The one on my 2GM20 will jam if I put it in reverse and then have a good fast sail. It's a known issue with a tech note published by Yanmar saying to leave it in neutral. I had it jam several times before realising the problem.

Pete

Didn't read the manual then :) :) :)

fireball
26-05-11, 13:54
Manuals are only there to refer to when everything else has gone wrong ....

didn't you know that?!

tidclacy
26-05-11, 14:14
As Stu says, it depends on your transmission. The one on my 2GM20 will jam if I put it in reverse and then have a good fast sail. It's a known issue with a tech note published by Yanmar saying to leave it in neutral. I had it jam several times before realising the problem.

Pete

Does the same apply to my 3gm30f and where can I access the tech note from Yanmar or can you send me copy?

prv
26-05-11, 14:22
Didn't read the manual then :) :) :)

I did - both user's manual and workshop manual, the latter several times. It's always possible I may have missed it, but I don't think so.

Pete

prv
26-05-11, 14:24
Does the same apply to my 3gm30f and where can I access the tech note from Yanmar or can you send me copy?

Don't know if it applies to the 3GM - presumably it might if they use the same or similar gearbox.

The yanmar PDF is on my home computer; I'll try to remember to send it tonight.

Pete

Allan
26-05-11, 14:30
When this was discussed on here before someone put in a link to a report that said a locked prop offered less resistance than one left to turn. It seems to go against common sense but seemed like a comprehensive report.
Allan

vyv_cox
26-05-11, 14:51
When this was discussed on here before someone put in a link to a report that said a locked prop offered less resistance than one left to turn. It seems to go against common sense but seemed like a comprehensive report.
Allan

No, it's the other way around. Less resistance with the prop turning. See http://strathprints.strath.ac.uk/5670/1/strathprints005670.pdf which was also summarised in PBO.

Yanmar and Volvo gearboxes have been reported as jamming in reverse gear. My 3GM does it but the solution is easy. Start the engine with it still in gear, when it will immediately go into neutral. I believe Volvo have suggested that the starter motor be turned over without starting the engine (?) but I start mine.

Bav34
26-05-11, 15:02
Agree that the Volvo saildrive manual says leave in neutral but we have always put it in reverse with no adverse effect.

Whilst I have all your attention :) ... my prop is a LH one i.e. when looked at from astern it rotates anti-clockwise when in fwd.

Which way does it turn when sailing and left in neutral?

Always wondered.

cmedsailor
26-05-11, 15:32
thanks guys, that makes sense now , the noise/vibration is what troubled me

To be honest I though that only shaft drives make noise and vibrate!

upthesolent
26-05-11, 15:41
I truly cannot abide the whine (it reminds me of wind blowing through rigging on a cold winters day) and so put my Volvo S/D in reverse despite the manual advising me neutral.

No problems after 6 seasons and never sticks in reverse either.

ratbag
26-05-11, 20:32
Sorry tried to upload as pdf attachment wouldn't load as pdf. so please excuse text only copy.

Note last para.

thanks for the info guys :)

Beadle
26-05-11, 21:11
Not sure whether your reason for asking is possible risk to engine/transmission or which position has least drag

I cant help about engine transmission but the definitive answer (Ithink) is here


Jig Drag = 12 pounds with no prop mounted. Measured at WOT. (wide open throttle)

Locked Prop Drag: 45-50 pounds: 50 -12 = 38 pounds of actual propeller drag when locking the propeller in reverse under sail.

Freewheeling Prop Drag: 20-25 pounds: 25 - 12 = 13 pounds of actual propeller drag when freewheeling the propeller under sail.

The locked propeller drag is 2.92 times more drag or a 292% increase in drag over a freewheeling propeller when you remove the test jig from the equation!!!!

As I said earlier, the test results are not even close. There's no need to worry about the .001's or a few pounds of drag here or there or even the rather "unscientific" method I used in this test. If a sailor cares to find an additional knot of boat speed in light winds, he must free wheel his propeller under sail.

Despite the MIT study, the University of Strathclyde Ocean Engineering white paper, the Yachting Monthly data and my own research, which all basically show the same thing, that a fixed prop caused more drag, there are still a few die hard types arguing the helicopter blade theory.

For full details of the testing go to http://www.catamaransite.com/propeller_drag_test.html.

From past experience this subject usually ends with a "bar room brawl" so I'm ducking out now.

Crabber24
26-05-11, 21:13
Whilst I have all your attention :) ... my prop is a LH one i.e. when looked at from astern it rotates anti-clockwise when in fwd.

Which way does it turn when sailing and left in neutral?

Always wondered.

The same direction, anti-clockwise.

KAL
26-05-11, 22:02
Since nearly being entangled in a submarine's antenna (like, well scary!!) while sailing through the Minquiers, with the prop in reverse for peace's sake, I have always sailed with the prop in neutral. The noise is nothing compared to the realisation that a sub will be able to hear and avoid me.

I know they're there and it's a bit creepy, but as long as my keel doesn't end up playing host to their antenna cable, I'm happy.

Less drag as well!

vikinglish
26-05-11, 22:03
I also cant abide the whine and some vibration that my volvo penta saildrive (bav 37) makes when left in neutral and so always lock in reverse... no problems in 5 years and many sailed miles from uk to med and back. Id rather a few more pounds of drag but be able to enjoy a tranquil sail!

KAL
26-05-11, 22:14
thanks for the info guys :)

OK - I give up. How DO you put the smilies into the main body of the post? I can't work it out...

Stork_III
26-05-11, 22:27
OK - I give up. How DO you put the smilies into the main body of the post? I can't work it out...
When you reply use Go Advanced button, smilie are there.If not showing Go to User CP, under Edit Options enable Standard Editor-Extra formatting Control.

cmedsailor
27-05-11, 07:24
[QUOTE=

Jig Drag = 12 pounds with no prop mounted. Measured at WOT. (wide open throttle)

Locked Prop Drag: 45-50 pounds: 50 -12 = 38 pounds of actual propeller drag when locking the propeller in reverse under sail.

Freewheeling Prop Drag: 20-25 pounds: 25 - 12 = 13 pounds of actual propeller drag when freewheeling the propeller under sail.

.[/QUOTE]

Very interesting article but have I understood this correct? The drag of a freewheeling 3-blade fixed propeller (13 pounds) is nearly the same as if no prop was mounted (12 pounds)? Is this possible? Why then do I keep that 2-blade mixer on my boat?

prv
27-05-11, 09:14
Very interesting article but have I understood this correct? The drag of a freewheeling 3-blade fixed propeller (13 pounds) is nearly the same as if no prop was mounted (12 pounds)?

No, you haven't understood it right. The 13 pounds is after subtracting the 12 for the jig. The text you quoted gives the initially-measured figure of 25 pounds.

Pete

prv
27-05-11, 09:20
where can I access the tech note from Yanmar or can you send me copy?

Here: http://www.verdonet.org.uk/stuff/Gear%20N%20while%20sailing.pdf

Pete

eyesec
27-05-11, 12:52
Never knew there are so many car drivers, not `sailors' here. At sea, nothing goes in `reverse' it is always referred to as astern.

vyv_cox
27-05-11, 12:58
Never knew there are so many car drivers, not `sailors' here. At sea, nothing goes in `reverse' it is always referred to as astern.

No, you are wrong. Gearboxes have reversing gear, not 'astern' gear. Check Volvo, Yanmar and Bukh workshop manuals to verify.

eyesec
27-05-11, 13:26
The manual says - obviously written by non seagoing engineers for non seamen. Ever seen a telegraph aboard a ship (not the newspaper) on the bridge and duplicated in the engine room they are segmented into ahead and astern. Old fashioned perhaps, but would you call the stern of a ship/boat the back end?

vyv_cox
27-05-11, 14:08
The ship moves ahead and astern. The shaft rotates forwards or in reverse.

cmedsailor
27-05-11, 14:27
I have an MS10L reverse gear (with Volvo Penta engine) which I believe is in fact a ZF reverse gear. The following is from the ZF repair manual:

"3.5 Sailing or moving in tow
Rotation of the propeller while the boat is sailing, being towed, or anchored in a river, as well as operation of the engine with the propeller stopped (for charging the battery), will have no detrimental effects in the gearbox.

IMPORTANT
When the boat is sailing (engine stopped), the gear lever must be in zero position. Never put the gear lever in the position corresponding to the direction of travel of the boat.

Locking the propeller shaft by an additional brake is not required: use the gear level position opposite your direction of travel for this purpose"

Now, what do you understand from the above? For me it sounds that, either neutral or reverse, as long as you don't leave the lever in the forward position it will be OK.

vyv_cox
27-05-11, 14:44
Does putting it in forward stop the prop rotation? On many gearboxes it has no effect. From my understanding of your manual, maybe it would if sailing backwards? Something for experimentation, perhaps. ;)

Captn D
27-05-11, 14:55
As a matter of interest, the manual for the Brunton Autoprop recommends, in order to best set the blades for sailing, one should stop the engine whilst in fwd gear and leave it there.

eyesec
27-05-11, 15:26
The ship moves ahead and astern. The shaft rotates forwards or in reverse.

vyv cox, lifes too short. Safe sailing.

vyv_cox
27-05-11, 17:59
vyv cox, lifes too short. Safe sailing.

Pretty good for someone with 11 posts to his name who comes on here telling everybody they 'are so many car drivers, not `sailors'.

2Tizwoz
27-05-11, 18:12
Folding propeller, S-drive. When switching from engine
operated running to sailing the propeller rotation is stopped by
engaging reverse gear. When sailing maintain the control
lever in the reverse position.

Fixed propeller. When sailing the control lever should be in
the neutral or reverse position. During long sailing trps with
the lever in the neutral position, the engine should be run for
some time every tenth hour in order to ensure lubrication in
the drive or reverse gear.

foeu
27-05-11, 19:28
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