Partial loss of propulsion

[Johny London]

When I moved the boat a few days ago, it seemed very slow for the rpm. Infact I stopped and put it into reverse, then forward again and it seemed somewhat better. Made it to the next spot and today checked the weed hatch expecting to find the cause. Clean as a whistle.

Whilst the engine is currently overdue its next service, I haven't done that many miles lately. I've checked the gearbox oil, clean as a whistle and filled to the second line (prm150). The only thing I can think of is the bauden cables that control the clutch? Is there a way to check? Or adjustment procedure? Or am I barking up the wrong tree.

Another possibly related thing is the amount of water in the bilge these days - usually a good two minutes worth of pump to get it clear and the stern gland drips regulary though I obviously use the grease thing. I did slightly tighten the two nuts but that seemed to make things worse.

Two steps forward, one step back.

[Paul C]

Probably something on the prop that cleared when you put it into reverse etc. Its an effective way to clear the prop if its not too much stuff. Failing that, could just be that you went through a shallow section - which will feel (and be) slower for a given prop RPM. Failing that, some kind of gearbox issue but without some kind of tacho on the propshaft it would be difficult to properly detect a partial slippage, given the amount of variance between engine rpm and boat speed (due to varying depths of canal etc).

[mross]

To reassure yourself that it is not a matter of cable adjustment, you could disconnect the cable at the gearbox and engage ahead by hand, at the gearbox.  Then move the lever into 'ahead' and see if the cable lines up with the lever on the gearbox.  You could try this underway and see if speed picks up but I would try it alongside.

[Mrs Tawny Owl]

It's Autumn, the most likely cause is leaves round the prop which drop off when you go into reverse for a while.

Deceptive because when you go down the weed hatch all the evidence has disappeared!

When Richard brought the boat back after we bought her this caused him no end of problems. We'd never been boating in November before, and in some locks he just couldn't get any forward movement, he'd bow haul her out, but when he checked the weed hatch the prop was clear, and then she'd be fine until the next lock, which was where the leaves had been piled up in the wind.

A couple of years ago we followed a hire boat through Braunston Tunnel. It was getting slower and slower and throwing out black smoke. when we caught up with them at the next lock they'd had to go into reverse to stop so all was fine again.

we did tell them what the cause of the slowing down was. They hadn't been boating that time of year before either.

Sue

 

[howardang]

Another vote for leaves on the prop. A quick burst of backwards throws them off and away you go again.

Howard

 

[Lily Rose]

Another vote for leaves. We´ve just left the Ashby after a week and I´ve had to clear leaves many times. This happens frequently in autumn, hardly ever at other times.

If you spot lots of floating leaves then that´s an indicator of wbat is likely to happen soon.

The things that tell me a spot of reverse is needed...

The boat starts going slower with the same RPM.

The exhaust and/or engine noise changes.

The visible prop wash, which on my boat barely disturbs the water surface but -what there is of it - comes out in a straight line, changes. There's more of it, it makes more noise and it is more irregular in direction.

I usually, if possible, wait until I'm in a clear bit of water tgen give a short burst of reverse while the boat is still moving forward. If you watch the water while you do this, and see leaves swirling about, then you have seen and removed the culprit. Until the next time. At this time of year, particularly with windy conditions blowing lots of leaves down, that may be sooner than you´d like!

 

[nb Innisfree]

I found that leaves fell off the prop without reverse, as soon as the boat came to a halt. I think just the water flow caused by  movement was enough to keep them attached. 

[junior]

Wondered how long it would take for the first one of these.

LEAVES!

[tree monkey]

Messy buggers,  cut em all down 

[Mrs Tawny Owl]

That's your job

[Ray T]

Just now, tree monkey said:

Messy buggers,  cut em all down 

 

Just now, Mrs Tawny Owl said:

That's your job

The train operating companies wouldn't have excuses for delayed trains in Autumn then. 

[Johny London]

1 hour ago, Lily Rose said:

The exhaust and/or engine noise changes.

The visible prop wash, which on my boat barely disturbs the water surface but -what there is of it - comes out in a straight line, changes. There's more of it, it makes more noise and it is more irregular in direction.

That's very reasuring to hear it is most likely leaves Yes the above two things happened as well - the prop wash was going out at an angle, and more visible than usual.

I'll try mross alignment check though, because I still felt I had reduced power after I'd moored, but it was a bit windy and rainy and I had to turn the boat which was a right faff.

thanks everyone

Edited October 23, 2017 by Johny London

[Ex Brummie]

It's worth checking the oil level in the gearbox, if it is low, it can cause intermittent loss of drive.

[zenataomm]

46 minutes ago, Ex Brummie said:

It's worth checking the oil level in the gearbox, if it is low, it can cause intermittent loss of drive.

True, however if you read the OP ..........

[Johny London]

20 hours ago, mross said:

To reassure yourself that it is not a matter of cable adjustment, you could disconnect the cable at the gearbox and engage ahead by hand, at the gearbox.  Then move the lever into 'ahead' and see if the cable lines up with the lever on the gearbox.  You could try this underway and see if speed picks up but I would try it alongside.

Just did this check. The cable pulls the gearbox lever up to nearly, but not quite, top centre ie close to 12 o clock. At which point the morse lever is at about 1.30pm and the engine revs at 900rpm. After that, the morse lever starts to engage the throttle, and the gearbox lever moves just a tad more to almost top dead centre.

With the cable disconnected, it doesn't really tell me anything else, it just corresponds to wherever it would while it is connected.

Is it possible that it should just be nipping up that gearbox lever that little tad more ie almost to 12 o clock?

The flow from the back of the prop looks central now.

ps: a small spring flew off when I undid the cable, or rather when I moved the gearbox lever which by hand was initially stiff, now quite floppy. Not sure where it goes as it wouldn't fit on to the thread of the nut that goes in the gearbox lever, but I didn't take anything else off!

Edited October 24, 2017 by Johny London

[Flyboy]

The spring that flew off sounds like the selector lever detent so you will have lost the ball as well.  Without the ball and spring there will be no positive neutral position of the lever.

[nb Innisfree]

Detention for the balls up. 

[mross]

If you post a photo of what you disconnected someone might be able to help.  I think you mean the spring came from the fitting on the end of the cable, not part of the gearbox, am I right?

Edited October 24, 2017 by mross

[Flyboy]

4 hours ago, Johny London said:

 

 a small spring flew off when I undid the cable, or rather when I moved the gearbox lever which by hand was initially stiff, now quite floppy. Not sure where it goes as it wouldn't fit on to the thread of the nut that goes in the gearbox lever, but I didn't take anything else off!

I think this is the clue.

[mross]

He says, 'moved', not 'removed'.  I don't think it's that easy to remove the gearbox detent mechanism when you are merely disconnecting the cable.

[Johny London]

Non the less, I think that might be whats happened - the gearbox lever was stiff, something pinged off then it wasn't. I fished out a spring from the oily watery mess under the engine - who knows what else is down there! will investigated further tomorrow and report back.

thanks.

[Flyboy]

1 hour ago, mross said:

He says, 'moved', not 'removed'.  I don't think it's that easy to remove the gearbox detent mechanism when you are merely disconnecting the cable.

It is if you move the lever past the forward or reverse detent.

[Johny London]

Yep, that's what I did.

[Flyboy]

34 minutes ago, Johny London said:

Non the less, I think that might be whats happened - the gearbox lever was stiff, something pinged off then it wasn't. I fished out a spring from the oily watery mess under the engine - who knows what else is down there! will investigated further tomorrow and report back.

thanks.

Check that the lever has 3 detent positions ie fwd/ neutral/reverse. If it doesn't, and rotates freely then you've  probably had the spring and ball pop out.

[Johny London]

Yes it's definitely rotating freely, Will resolve tomorrow, if I can find the ball. Honestly, I'd expect better from the legendary prm150!