Anchored and prop keeps turning in current.

[Pmcsurf1]

We're anchored in Matanzas inlet south of St Augustine. One of our favorite spots but the current here is really ripping. Woke up this morning to the sound of a small boat running in the distance but the sound never went away or stopped. After some investigation I realized the prop is turning in the current. Can't stop it. Our boat has a ZF 80 gear and placing the shifter in forward or reverse does nothing. Hydrolic actuated I guess. Never been a problem but just really loud this morning. Full moon probably has something to do with it also.
Anyone ever experience this also? Any "practical" solutions?

 

[PM]

Boy, I would really hesitate to put any type of clamp in place. If you forget to remove it you will have a problem. Might stop turning with a couple wraps of line around the shaft.

pete

 

[psneeld]

Normal.

Lots of options for shaft brakes. Any strong ones, place the start key on them or placard at start helm about brake.

Or...do the key, placard thing, but just use light weight twine with a loop and place over a shift coupling nut. Even if you forget, its enough to prevent turning but will snap immediately if put in gear.

 

[Pmcsurf1]

My understanding is that it does not harm the shaft gear. Other than noise there should be no problem. Right?

 

[ranger58sb]

Can't stop it. Our boat has a ZF 80 gear and placing the shifter in forward or reverse does nothing. Hydrolic actuated I guess.

If you have the engine running and put the gear in either forward or reverse... then stop the engine... does the gear stay in either forward or reverse?

Not sure that would make much difference, though...

-Chris

 

[High Wire]

Look in the transmission manual for caution of the need to lock shaft when towing or otherwise output spinning without engine running. If the manual says no problem then you are good. Still I would lay my hands on the transmission case and feel for hot spots.

 

[psneeld]

My understanding is that it does not harm the shaft gear. Other than noise there should be no problem. Right?

The rpm with a few knots of current and bearing drag should be so as to not harm anything if a couple of days.

Especially is slow enough you can count the revolutions.

Stopped is better, but often isn't worried about.

I would still check the manual or find out from the manufacturer so you know for future trips.

 

[oscar]

1 Vice Grips.
2 Check Lists.

To expand on the latter.... A lifetime of aviation using checklists that were "written in blood". I have a "before start" "after start" "before shutdown" and "before leaving ship". I have a laminator and if there's changes/additions I mark them with a sharpie, then redo the checklist. It has saved my butt more than once.

 

[rslifkin]

If you have the engine running and put the gear in either forward or reverse... then stop the engine... does the gear stay in either forward or reverse?

Not sure that would make much difference, though...

-Chris

Most likely it'll go to neutral when the engine stops turning and hydraulic pressure drops off. Nothing to hold the clutch plates together at that point.

 

[Stout]

Have had this happen at a couple of spots on the lower Columbia River during the spring runoff. Last year at Beacon Rock state park dock it started and was spinning enough that the noise was bothersome. I used a rubber strap wrench to stop and hold it, and wire tied the keys to the wrench. Have used the same method twice now.

 

[Comodave]

Maybe a chain wrench?

 

[Ski in NC]

Put a small zip tie on one of the bolts and looped to something nearby. It will hold the shaft still, not much force there. Crank engine and put in gear, pops the zip tie, no harm done.

Slow windmilling in current won't hurt a gear, but the noise can be obnoxious.

 

[cafesport]

Our props spin in anything over two knots, which also lets us know if we have problems with our cutlass bearings. We have shaft brakes and we routinely use them in similar situations, not because the transmission will overheat, because it won’t, but primarily due to the sounds which irritate our dog. If you don’t have a shaft brake, you could always rig one sailor style with a pair of 2x4’s rope and or hose clamps. As previously mentioned don’t forget to hang the start key on the contraption you create.

 

[DNT99611]

Had twin disk trannies in my old boat. Kept in a river three months a year when not fishing. Shaft would spin something like 18 hours a day for 3 months. Never a problem nor did I hear of it being a problem for the other 400 boats doing like wise.

 

[Pmcsurf1]

Look in the transmission manual for caution of the need to lock shaft when towing or otherwise output spinning without engine running. If the manual says no problem then you are good. Still I would lay my hands on the transmission case and feel for hot spots.

Good point about heat. Thanks

 

[Pmcsurf1]

Put a small zip tie on one of the bolts and looped to something nearby. It will hold the shaft still, not much force there. Crank engine and put in gear, pops the zip tie, no harm done.

Slow windmilling in current won't hurt a gear, but the noise can be obnoxious.

Agreed. The noise is the problem. Albeit not a major one.

 

[Pmcsurf1]

Had twin disk trannies in my old boat. Kept in a river three months a year when not fishing. Shaft would spin something like 18 hours a day for 3 months. Never a problem nor did I hear of it being a problem for the other 400 boats doing like wise.

Thanks, good to know.

 

[Arc]

2 pieces of oak with wing nuts . Clamp the shaft

 

[rgano]

If your shaft seal has a cooling line running to it from the engine's seawater cooling circuit, that cooling water is not getting there with the engine off. Likely not an issue at a couple of knots, but you can assure yourself all is well by placing your hand on the seal to check for heat. Another reason to lock the shaft if being towed a long way.

 

[kchace]

Since we moor in a river with a 9 foot tide, there is usually a pretty good current and both of our props will turn in the current. We have Velvet Drives so no problem for the drive, but the sound is a bit annoying in the middle of the night.

I use 2 bungee cords with the ends hooked on a coupler bolt and then attached together in the middle. If I forget to take them off, it just breaks the bungee cord and no other harm done. (I’ve only forgotten once so far)

I would not use anything too solid because if you forget to remove it a lot of damage could be done.

Ken

 

[ProMaritime]

Lucky you are not anchored in the Straight of Gibraltar, current there can run 6-7 knots at times during tide changes. Of course its fairly shallow there so if you anchor there you can troll without burning any fuel.

 

[CarlF]

The force that's turning the shaft is probably less than 5 pounds. If a friction "lock" that can hold 5 lbs is accidently left on, an engine that outputs thousands of pounds isn't going to care.

Line it with something that won't heat up if it's left on - like felt. Metal could score the shaft.

 

[McDan]

We're anchored in Matanzas inlet south of St Augustine. One of our favorite spots but the current here is really ripping. Woke up this morning to the sound of a small boat running in the distance but the sound never went away or stopped. After some investigation I realized the prop is turning in the current. Can't stop it. Our boat has a ZF 80 gear and placing the shifter in forward or reverse does nothing. Hydrolic actuated I guess. Never been a problem but just really loud this morning. Full moon probably has something to do with it also.
Anyone ever experience this also? Any "practical" solutions?

The noise is the worrisome thing; do you have a drip-less thru-hull on the shaft? Those are water cooled by engine raw water so when the engine is off there’s no cooling water to it. If not, is the stuffing box too tight? Could the noise be the cutlass?
The trans likely needs oil pressure (engine running) to shift into gear, and why risk your trans anyway?
Could you use an anchoring tactic, like hooking up to the side of the channel or tying off to position a bit cross-current? Locking devices are a hassle and induce strain on multiple items.

 

[Comodave]

We had dripless stuffing boxes in a previous boat. They didn’t need cooling water from the engine at slow speeds.

 

[greatpapabear]

1 Vice Grips.
2 Check Lists.

To expand on the latter.... A lifetime of aviation using checklists that were "written in blood". I have a "before start" "after start" "before shutdown" and "before leaving ship". I have a laminator and if there's changes/additions I mark them with a sharpie, then redo the checklist. It has saved my butt more than once.

Snap! Before start / Taxy / Before T/O / etc, etc. Check lists work a treat especially if we've not been boating for some time.

re the turning shaft, see what the gear box manufacturer says. My TwinDisc doesn't like more than 4 hours free-wheeling.

 

[Hippocampus]

Dumb question. If it’s only mild current why not just place the shift in reverse and look to see if that’s sufficient to prevent it from turning? Could do that before resorting to more serious interventions. Of course if there’s even a small risk of that not being sufficient don’t do that.

 

[Flatswing]

I have ZF transmissions that freewheel with engine off. Manual says ok to run on one engine and let the other freewheel which I do from time to time. I toyed with the idea of plumbing crossovers from PSS engine seawater feeds but At trawler speeds, laser gun never shows any increased temp at the PSS when freewheeling at 7 knots so didn’t bother.
So your not doing any damage at anchor. If the noise bothers you enough use a pin easily breakable method like twine or zip ties. Do not use a pipe wrench. Perhaps a light rubber strap wrench but you will have to use zip ties to keep the strap in place in the handle

 

[Shay]

Shafts turning in current.

My previous DeFever had ZF transmissions and the manual states that free willing is ok. In a deep hull boat at less than planing speed the water pressure will keep the shaft seal lubricated and cool. We used to run offshore passages on one engine quite often without any problem.

I also experienced the shafts turning in the current while at anchor. This will not damage any of the boat systems but I didn't like the sound so I would hang a tag over both engine keys reminding me the shafts are tied. Then use a 1/4" line with a small loop on both ends to hold the shafts from turning. I would hang the loop over a bolt on the engine to shaft coupling and allow the line to wrap a couple turns around the shaft. One end of the line was wraped around the port shaft and the other was warped around the starboard shaft. I was able to stop the turning using gloves and my hands. The 1/4" line is weak and will brake I needed to start an engine in an emergency.

 

[woodscrew]

That happened to me in a tideway in Georgia. I have a single screw, 30” prop, and a big barn door rudder. After some worrying I simply turned the rudder hard over. It broke the flow and stopped the windmilling prop. Current was easily 1.5 knots.

 

[FF]

PLAN B might be to locate a special wound shaft alternator that has some output at low RPM and use the electric to charge the house batts.