Turn - Turn - Turn

[Lenny and Louise]

Then Again is located on Hayden Island, Portland, in the Columbia River. She is in a berth in a marina facing upstream into a current that ranges from three to over five knots, depending upon what is being released at the Bonneville Damn. Over the weekend, I realized that the propeller shaft sometimes turns in response to the current. This is a new phenomenon, and I always approach machinery with the twin questions, “What changed and why?”

But more important than the philosophical questions is this: How do I make it stop?

It rotates after the engine has been run. If I stop it by applying friction to the shaft (as with the sole of a shoe) it tends to stay stopped. But I do not know if it starts again after I leave and stops before I return. Someone suggested shutting the engine off while still in gear, and I have done this with no appreciable result. (Nor did I expect this to have much effect, given the hydraulic transmission and so on.)

Others have suggested that this is normal and shows that the boat is well built with good shaft alignment, proper action of the cutlass bearing and so on. Nonetheless, I am worried that as far as the cutlass bearing, the shaft, and the bearings in the reduction gear are concerned, I am going ahead at 3 to 5 knots around the clock. That amounts to a lot of hours. And I don’t know what the effect is on the gears in the transmission.

Then Again is R25SC, new in August 2001, with the Volvo D3-150 engine. There are about 68 hours on the clock.

How do the rest of you good folks stop your shaft when moored or anchored in a current?

 

[Gin]

I know Lenny meant his tug was new in August 2013 . . .

We were with Lenny and Louise, with our boat docketed near theirs, when Lenny discovered his propeller/shaft spinning with the current. Our boat, new in May 2013 (and with about 20 less hours on the clock) had no spin whatsoever in the prop/shaft. So we look forward with interest to answers to Lenny's post. What would explain the difference in the spin of our prop/shafts? Should one of us be concerned and, if so, which one?

Gini & Colleen

 

[trailertrawlerkismet]

The turning of a prop while a boat is docked, engine off and with current running against it is a common occurrence, one we've had happen on several boats over many years. What many have done is put a block of wood between the shaft and shaft housing area, kind of a wedge if you will, to keep the shaft from turning. If you do this make sure to put a sticky note on the dash to remind yourself to release the wood block before you start and engage the engine/transmission.

I think the concern for a prop rotating continuously without the engine/transmission running would be a lack or reduction of proper lubrication for all parts concerned. I don't know this to be true but either way a wood wedge will solve the prop rotation and prevent any concerns....as long as the wedge is removed before the transmission is engaged.

What do others think about this?

Jim

 

[Lenny and Louise]

Thanks, Gini, for correcting my typing. The boat was new in Aug 2013. I did not know i needed to read and write to own a tug.

Thanks, Jim, for the suggestion about a wedge.

Any other ideas?

 

[Don Cardinal]

Lenny,
Have you tried turning the helm wheel hard to port or starboard to see if this would slow the flow past the prop? Not sure how it will affect the pull on your dock lines. A chalk mark on the shaft or coupling may tell you if the shaft has turned over time.
The currents can vary within the same marina due to acceleration of the water around other boats, docks, etc.
Check with Cook Engine on the island to see if they have any ideas. They are on the same channel and currents as you. They are also the Yanmar and Volvo dealer for the area.
Good Luck
Hope to see you on the river soon.
Don.

 

[Fly-fish]

I will be interested in what you learn. Your posting just alerted me to what I may too be experiencing at our dock in Camas. We face downstream and always have the Columbia current to deal with from Bonneville dam. In fact, depending on the current and tide, we may have some unusual eddies in the dock area which might impact the "gracefulness" of my docking!
Though I have not seen this prop rotation yet, I will look at the shaft next visit to see if it is rotating at dock too.
Please keep us informed of what you learn.
Thanks,
Mike

 

[daviduphoff]

Lenny-
We had a Bayliner that I spent about half my nights on a few years ago. We kept it down a ways at McCuddys (where Island Cafe is). It had twin screws. When there was a lot of rain or they were really letting water out of Bonniville one would turn. The other nothing. Same engine, same props, same everything. I was told don't worry about it. As Don suggested, call Cook and talk to Ruth.

 

[Lenny and Louise]

Upon further review –

This is a real study in inertia. If the shaft stops, it tends to stay stopped. However, if the engine is run, even in neutral, the shaft will begin to slowly rotate. If I touch it in reverse, when I go back to neutral shaft will begin to turn in forward direction (as expected, since bow is into current in my berth.) I suspect that a little warmth in the transmission makes every thing turn easier.

I can stop the turning with a nudge from my foot. However I suspect it may start and stop intermittently when I am not there to watch. I have this aversion to things starting and stopping on their own, and I have an aversion to machinery rotating when it is not necessary. No real harm, probably, but no reason for the extra (albeit minimal) wear on bearings either.

I took Jim’s advice and fit a wedge (lightly) against coupling. I cut it from a piece of 2x6, leaving it deliberately very long. It is easy to reach to put it in and take it out and is very visible when opening engine hatch. I have a warning sign hanging on the engine battery switch. The rule is:

When starting, check engine, pull wedge, store sign with wedge, turn on battery.
When stopping, turn off battery, fit sign, fit wedge.

 

[wefings]

The packing might be warm after running [its water lubricated] hence the "spin" and when it cools it stops ????
Just a thought .....
Marc