Sailing With A Fixed Prop

[Dockhead]

I have never had a fixed prop on a sailboat. I have had Brunton Autoprops on all the boats I've had with inboard propulsion so going back to the '90's.


Now I'm stuck in Kalmar, Sweden after a long passage from Helsinki with a drive system problem. My Autoprop has a stiff blade which I stupidly didn't stop to fix last April when my boat was last lifted -being in a hurry to get on my way to the Baltic.


Now that stupidity is going to cost me -- the stiff blade finally caused a vibration which destroyed my cutless bearing and no doubt damaged my shaft.


I'm hoping to get lifted tomorrow to see for sure. It ain't going to be cheap to fix. Assuming the best case -- that the shaft can be repaired and a new cutless bearing can be found and fitted quickly -- I might be in a position where I will need to fit my spare prop in order to get the boat back in the water and get back in my way.


It occurred to me that I have no idea what to do with a fixed prop. If I lock it I supposed the the boat will hardly sail -- it's big beast of a prop. Also, I doubt that my transmission would even lock a fixed prop. I have a Yanmar 4JH3 HTE with a Kanzaki mechanical cone clutch transmission -- not hydraulic. Can I just let it spin? Will it hurt the gearbox to do that? I realize it will be noisy.

[De.windhoos]

Originally Posted by Dockhead

I have never had a fixed prop on a sailboat. I have had Brunton Autoprops on all the boats I've had with inboard propulsion so going back to the '90's.


Now I'm stuck in Kalmar, Sweden after a long passage from Helsinki with a drive system problem. My Autoprop has a stiff blade which I stupidly didn't stop to fix last April when my boat was last lifted -being in a hurry to get on my way to the Baltic.


Now that stupidity is going to cost me -- the stiff blade finally caused a vibration which destroyed my cutless bearing and no doubt damaged my shaft.


I'm hoping to get lifted tomorrow to see for sure. It ain't going to be cheap to fix. Assuming the best case -- that the shaft can be repaired and a new cutless bearing can be found and fitted quickly -- I might be in a position where I will need to fit my spare prop in order to get the boat back in the water and get back in my way.


It occurred to me that I have no idea what to do with a fixed prop. If I lock it I supposed the the boat will hardly sail -- it's big beast of a prop. Also, I doubt that my transmission would even lock a fixed prop. I have a Yanmar 4JH3 HTE with a Kanzaki mechanical cone clutch transmission -- not hydraulic. Can I just let it spin? Will it hurt the gearbox to do that? I realize it will be noisy.

if it's a standard Yanmar transmission, you can let it spin, actually, Yanmar has stated in one of their service anouncements that you should sail with the transmission in neutral. I've got a yanmar 3YM30 and once tried to sail with the transmission engaged. the problem I encountered is that I could get it out of gear above 3 knts.

The noise really isn't that bad.

[Pete7]

Years ago we surfed our way home from Weymouth on a Nic 55. As we ran down the wave with the engine in gear, the perkins would fire up just at the worst moment. The skipper was convinced the boat sailed faster with the engine in gear and we didn't know any better. After the third scary rush down the wave face he was persuaded to try it in reverse and the problem of bump starting ceased much to our relief. Arriving in Gosport the skipper couldn't then get the gearbox into neutral

Not much you can do about the cutlass bearing but you remember I had to dress my shaft after some plonker drilled into it, so if the damage isn't too bad you may get away with dressing it as a temporary fix until you get home. Files and emery paper will be needed going down as fine as you can get, say 1000 grit which should give a smooth satin finish.

Pete

[FlyingScot]

There are Yanmar service bulletins stating that you have to sail in neutral. I'm not sure if this applies to your particular model. For sure on 3YM30/SD20 combination that I have. Good luck. We just swapped to folding props. After one short outing I wouldn't want to go the other way.

[Calif.Ted]

The only place I could find the TSB from Yanmar regarding sailing in neutral is on the Ericson owners website, hope the link works. Run in Neutral, it's my SOP, the gear whirling at 5 knots and above is annoying but beats mucking up the trans.http://www.ericsonyachts.org/infoexc...8&d=1269282236

[Calif.Ted]

Here's the transcript in case that link doesn't work.



dvisory Number: MSA08-003 A

: DATE February 8, 2008 rs and OEMs TO: All Marine Distri butors, Deale Sailing SUBJECT: Gear in Neutral While ODELS: All Sailboat Engines M


We continue to get questions regarding the correct gear position while sailing with the engine OFF. This advisory is issued as a reminder; Yanmar requires that if sailing with the engine OFF (not running) the transmission shifter must be in the neutral position or internal damage to the gear or sail-drive will result. This damage will not be covered by Yanmar’s Limited Warranty. Please instruct customers and dealers who deliver the sailboat to the customer, of the correct (Neutral) position for the marine gear while ailing. s

If the customer desires that the propeller shaft not spin while sailing, either a folding propeller, shaft break, or other suitable device may be used. However, Yanmar accepts no responsibility for the selection, installation, or operation of such devices. Please also refer to Marine service advisory “MSA07-001_Yanmar Sail Drive Propeller Selection” for dditional information. a


If you have any questions regarding this advisory please contact a Customer Support epresentative at (770) 877- 9894. R



MSA08-003 Page 1 of 1 February 8, 2008

[JPA Cate]

Hi, Dockhead,

Best wishes for a speedy repair. You'll lose sailing speed, it's like towing a bucket, but you'll be able to finish delivering your boat to where you want it.

Ann

[Wotname]

Originally Posted by Dockhead

I have never had a fixed prop on a sailboat. I have had Brunton Autoprops on all the boats I've had with inboard propulsion so going back to the '90's................

It occurred to me that I have no idea what to do with a fixed prop. If I lock it I supposed the the boat will hardly sail -- it's big beast of a prop. Also, I doubt that my transmission would even lock a fixed prop. I have a Yanmar 4JH3 HTE with a Kanzaki mechanical cone clutch transmission -- not hydraulic. Can I just let it spin? Will it hurt the gearbox to do that? I realize it will be noisy.

I have only had fixed props on my sail boats going back to the '80's and and they sailed just fine.

Unlocked they are a little noisy but like most constant things in life, you get used to it. The pitch of the sound becomes a like a second log so you hear how fast you are going!

Locked is quiet but does increase drag which is annoying in light airs. Of course once you approach hull speed, it doesn't matter anymore - the additional drag is inconsequential.

As others have already posted do not lock the prop with the transmission if you have a Kanzaki cone clutch however an external shaft lock is OK of course if you remember to unlock it before starting.

Are you sure you have cone clutch? My 4JH3-HTE states the engine has a box with mechanical multi disc wet clutch (a Kanzaki KBW 21). The Kanzaki KM4A box (with a cone clutch) was only fitted to the 4JH3-HTBE engine.

[wingssail]

We have used Martec folding propellors for 33 years (now on third one). They cost less than $1000 fob calif. and can be shipped fairly quickly.

They will free-wheel if the blades are open but shifting to reverse on our Yanmar 3JH with the cone clutch transmission has been no problem and stops the prop from spinning. We have 6500 hours on the eng/transmission. The blades fold and there is no torque on the shaft from the propeller trying to spin. It is also quiet, and definitely low drag. You could probably get a prop shipped to you by the time your other work is completed.

[Wotname]

Originally Posted by Wotname

........

Are you sure you have cone clutch? My 4JH3-HTE states the engine has a box with mechanical multi disc wet clutch (a Kanzaki KBW 21). The Kanzaki KM4A box (with a cone clutch) was only fitted to the 4JH3-HTBE engine.

Opps... that should have read "My 4JH3-HTE service manual states ..."

[SwellGuy]

You must have seen this thread a thousand times already!

Read your manual. Every transmission is different. Some are damaged by freewheeling, some are damaged by not freewheeling.

Some posters will claim they know what you should do before they even know your transmission model number, they don't!

[GILow]

The fixed prop speed hit will probably only be noticed in light airs. On a boat like the OPs, once hull speed is reached I bet it would be very hard to feel the difference.

Regardless of whether the transmission can be damaged by freewheeling or not, I for one hate the noise so I simply put a loop in some 5 mm line, snag it around a bolt on the transmission coupling flange and tie the other end of the line to something strong.

This stops the freewheeling, but the important bit is, if you forget it is there, it will easily snap if you start the engine and put it in gear. (I actually have a small length of the same line that I tie to the engine key when I am using this system to remind me I need to undo it)

[Uncle Bob]

A gentleman with the exact same boat as mine fitted an autoprop and his comment was that he couldn't believe the difference to the sailing, and was very happy with the extra knot as well.
My guess is you will hear a little more noise from the fixed prop rotating and you will also suffer a slight loss of speed, but you will be sailing!

[Wotname]

Originally Posted by GILow

.........I simply put a loop in some 5 mm line, snag it around a bolt on the transmission coupling flange and tie the other end of the line to something strong.
.......

Oh, I do like this method - simple and safe - just adjust the size of line to suit engine / prop size.

[accomplice]

We had a VP-104 variprofile feathering prop. We lost a blade offshore and had to finish the passage without mechanical propulsion. I looked into getting it fixed but was told parts for the VP-104 were no longer made. They offered me a deep discount on a DF-140, but I declined. Instead I replaced with a fixed blade.

In moderate air and above there is no noticeable difference in performance. In very light air there might be some difference (0.25kt) , but in very light air we're probably supplying some diesel assist anyways. In effect, it may raise by a knot or two the wind speed at which we will power up the diesel, but it has no effect on our passage times.

In the process of switching out the prop we went for a slightly steeper pitch (not by design, long story). The effect of this was that motorsailing at low engine speed is now significantly more efficient.

I understand I changed two variables. I've only traveled ~5,000nm on the new prop, but I'm happy with the decision. Not only is it one fewer things to break on the boat, but our passage times are the same and we end up using same or less fuel.

In a boat that races, the extra 0.25kt in light air makes a lot of sense. In a cruising boat, I find the fixed prop works well for us.