Brunton autoprop problem help needed

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Pagetslady

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Hi I have fitted a Bruntons Autoprop to my Westerly Corsair which I also fitted a new Beta Marine 35 hp engine. The problem is that when sailing I select astern to stop the prop rotating and feathering the blades. Ok this some times works but some times it does not, when the prop is turning the drag is amazing slows the boat down by at least a knot, it also causes steering problems. I have tried selecting ahead which sometimes this locks it but not always. On my old engine VP 2003 locking it in Astern was fine. Has anybody out there experienced this problem.
Regards Mike.
 
Pagetslady said:
Hi I have fitted a Bruntons Autoprop to my Westerly Corsair which I also fitted a new Beta Marine 35 hp engine. The problem is that when sailing I select astern to stop the prop rotating and feathering the blades. Ok this some times works but some times it does not, when the prop is turning the drag is amazing slows the boat down by at least a knot, it also causes steering problems. I have tried selecting ahead which sometimes this locks it but not always. On my old engine VP 2003 locking it in Astern was fine. Has anybody out there experienced this problem.
Regards Mike.
Click to expand...

On our Jeanneau Sun legende 41 that we owned when back in the UK which had a 4JHE Yanmar 44hp with a Brunton Autoprop we just stopped the engine whilst still in forward gear and moving ahead, I believe this was as Brunton's instructions. It worked fine for us and if on rare occasions it was sticky to engage neutral to restart, then a quick blip of the starter with it still in gear ahead did the trick allowing neutral to be selected and the engine started normally.

I wish we had a Brunton on our current boat in the USA because the fixed 3 blader prop with a 3GM30 Yanmar has much less oomph ahead or astern and considerably more drag. You need a goldmine to buy a Brunton over here:disgust:
 
The Autoprop is "self feathering". When the engine is in neutral, the blades will set themselves into the position to give least drag and this will involve some shaft rotation. If you prevent the shaft from turning, there will be an increase in drag, even though the blades will still self set. I can see not reason for the performance action you report, unless the blade bearings are stiff.
 
Topcat47 said:
The Autoprop is "self feathering". When the engine is in neutral, the blades will set themselves into the position to give least drag and this will involve some shaft rotation. If you prevent the shaft from turning, there will be an increase in drag, even though the blades will still self set. I can see not reason for the performance action you report, unless the blade bearings are stiff.
Click to expand...

No, that's not the case with an Autoprop. The prop must not rotate when sailing without the engine, otherwise you get the symptons described by the OP. Bruntons recommend stopping the engine in astern, but I sometimes, after stopping the engine, I have to move the (combined speed and) gear lever back and forward until it locks. Very occasionally, it frees itself, and the first time it did that, crossing the Sea of the Hebrides, in a F6, I thought something drastic had happened to the rudder.
 
Wow that is great news I was seriously worried about my gearbox, I don't remember reading anything about stopping the engine in gear, I will try that today, I aborted a passage from Fleetwood to the Menai because the steering was acting so strangely Yesterday while sailing over to our one and only local anchorage we had a good blow 25kts apt but the boat just refused to do more than 6kts when it occurred to me perhaps the shaft was turning , went below to find it was running at great speed so put it in forward , off she went steering light and 7 kits no problem. Thanks for all your answers.
Mike
 
NormanS said:
No, that's not the case with an Autoprop. The prop must not rotate when sailing without the engine, otherwise you get the symptons described by the OP. Bruntons recommend stopping the engine in astern, but I sometimes, after stopping the engine, I have to move the (combined speed and) gear lever back and forward until it locks. Very occasionally, it frees itself, and the first time it did that, crossing the Sea of the Hebrides, in a F6, I thought something drastic had happened to the rudder.
Click to expand...
Hi we'll I tried both stopping the engine in gear in astern and forward but it still didn't lock, I did eventually get it to lock but I have noticed that when it is in gear it is possible to rotate the shaft one way but not the other, i didn't have this problem with my VP 2003 with a secondhand Autoprop this has only happened since fitting new engine and prop.
Mike
 
Do you have a hydraulic gearbox ? If not I'm surprised that it turns. I do and have had to find a way of stopping the prop from turning the shaft, there was a recent thread about this - http://www.ybw.com/forums/showthread.php?405241-Ideas-please-for-clamp-to-use-as-a-shaft-brake.

That said, I rebuilt my Autoprop (an H5) a couple of weeks ago and tightened the bearings down more than they had been previously. The instructions are a bit poor on this as they just give a max torque to tighten to which seemed very tight. Upshot is that at the moment the shaft does not rotate when sailing, previously I needed to manually lock it. I cant turn the shaft by hand under sail so I'm sort of assuming the blades now align and are applying sufficient pressure to stop the shaft turning - clearly the dynamic in the system has changed!
 
The problem you've got may simply be one of the blades not feathering, aside from everything else.
The blades should flip effortlessly. If they don't it is probably due to the lubricant in the bearings not facilitating frictionless oscillation.
When next out of the water try flipping the blades and see what happens.
If one or more does not flip easily it is a lubrication problem.
Autoprop provides lubrication nipples you can attach to a grease gun to pump grease in, is my twoppenceworth. Good luck.
 
OK, I must be a bit simple, but when my engine is ticking over, it is out of gear. Does this mean that if you have an auto prop, you have to stop the engine while it is powering the boat? The "stop" cable is connected to the rack of the fuel pump. If I am in gear, this is forward of the tick-over position and the rack would have to move further in order to cut off the fuel. My current installation only stops the engine at the extremity of the stop cable when ticking over. Does it work under power too? I'm not on the boat until later this week so I can't just give it a go.
 
Topcat47 said:
OK, I must be a bit simple, but when my engine is ticking over, it is out of gear. Does this mean that if you have an auto prop, you have to stop the engine while it is powering the boat? The "stop" cable is connected to the rack of the fuel pump. If I am in gear, this is forward of the tick-over position and the rack would have to move further in order to cut off the fuel. My current installation only stops the engine at the extremity of the stop cable when ticking over. Does it work under power too? I'm not on the boat until later this week so I can't just give it a go.
Click to expand...

You don't need to have any significant revs. Just throttle back and pull the stop lever. The important thing is to have the gear engaged.
 
I've had an Autoprop for 22 years.
It's always in FORWARD when sailing.
Just put the single lever control to tickover in forward and then stop the engine by it's stop button.

The drag, if it's allowed to rotate is considerable.
The OP was misinformed when told to stop in reverse - Bruntons were a trifle vague about which gear to use, but I put that down to the fact that mine was one of the earliest and their experience was limited.
 
Topcat47 said:
The Autoprop is "self feathering". When the engine is in neutral, the blades will set themselves into the position to give least drag and this will involve some shaft rotation. If you prevent the shaft from turning, there will be an increase in drag, even though the blades will still self set. I can see not reason for the performance action you report, unless the blade bearings are stiff.
Click to expand...

I'm afraid you're wrong. Mine, unless locked, has always started to rotate @ about 30% of hull speed. It's rather more effective for slowing a boat than a bucket over the back.
 
I suspect it may be a function of the gearbox installed in the boat. I have a Yanmar 3GM30F, can't remember the precise gearbox code. My Autoprop rotates when the gear is neutral. In forward it continues to rotate but stops in reverse. I have never stopped the engine with it already in reverse, selecting gear when sailing, usually when I am reminded by the noise of the shaft turning. It is then not possible to reselect neutral without starting the engine first, but doing so has done it no harm in 12 years or so.
 
Viv, as always, is right.
Some gearboxes stop the shaft in forward, some in reverse and some never and need a brake. So EVERBODY is right.
Which makes a change! (If we can agree on that).
 
vyv_cox said:
I suspect it may be a function of the gearbox installed in the boat. I have a Yanmar 3GM30F, can't remember the precise gearbox code. My Autoprop rotates when the gear is neutral. In forward it continues to rotate but stops in reverse. I have never stopped the engine with it already in reverse, selecting gear when sailing, usually when I am reminded by the noise of the shaft turning. It is then not possible to reselect neutral without starting the engine first, but doing so has done it no harm in 12 years or so.
Click to expand...

Interesting, on both the 2GM (which had a double cone clutch box) and the 3YM (with a similar box), I've used forward to lock the Autoprop. In fact my box spends most of its time (except when alongside) in forward gear. No problem in getting out of gear without starting the engine. On the 2GM reverse had little effect on preventing the prop rotating.
In fact one would expect reverse, with its wider gearing, to be a more effective brake, except that what stops the crankshaft rotating is the compression stroke on one of the cylinders. My box is 2.21 in forward and 3.06 in reverse.
 
vyv_cox said:
I suspect it may be a function of the gearbox installed in the boat. I have a Yanmar 3GM30F, can't remember the precise gearbox code. My Autoprop rotates when the gear is neutral. In forward it continues to rotate but stops in reverse. I have never stopped the engine with it already in reverse, selecting gear when sailing, usually when I am reminded by the noise of the shaft turning. It is then not possible to reselect neutral without starting the engine first, but doing so has done it no harm in 12 years or so.
Click to expand...
Hi I am beginning to wonder if there is a problem with my gearbox. I am sure that when I first installed the new Beta 35 in my boat it did lock but only in forward which was the opposite to my old VP 2003. but now it will lock but i never know if it is locked or not and if it is I am not sure why. I have tried stopping the engine while in both forward and astern with no effect at all.
I have always wondered why even on the VP when gearbox is locked it is possible to turn the shaft one way but not the other, my gearbox and engine have now done 180 hrs so it is still new. I will look up the details of my gearbox and ask the manufactures or maybe call beta. thanks for your reply any further suggestions very welcome.
Regards Mike.
 
We ran some trials yesterday. With the Autoprop rotating the tiller was horrible, vibrating and pulling badly, really unpleasant to sail. Once the prop was locked and feathering she went back to her usual silky self and noticeably quicker.

Ultimately you could install a shaft lock. I think Bruntons sell them and there have been tales that some engine makers recommend that you never lock the shaft using the gearbox, so there are clearly benefits. For a cheap and nasty alternative a mole wrench with round jaws would do it:nonchalance:
 
vyv_cox said:
We ran some trials yesterday. With the Autoprop rotating the tiller was horrible, vibrating and pulling badly, really unpleasant to sail. Once the prop was locked and feathering she went back to her usual silky self and noticeably quicker.

Ultimately you could install a shaft lock. I think Bruntons sell them and there have been tales that some engine makers recommend that you never lock the shaft using the gearbox, so there are clearly benefits. For a cheap and nasty alternative a mole wrench with round jaws would do it:nonchalance:
Click to expand...
Thank you VyV exactly what I experienced, I have spoken to Beta Marina and they are contacting the gearbox people lets hope they come up with something helpful I do not want to have to go below to lock it when out sailing. I have had a wining noise from the gearbox when hot and they are looking into that too, although they blame it on the prop or misalignment of shaft.
Regards Mike.
 
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