Prop fouling followed by loss of power

[Punk Stig]

OK, so whilst in london I made the mistake of not noticing my rope fall into the cut, whilst reversing to let out someone from their mooring I obviously sucked it into the prop, quick forward blast to attempt untangling (not realising it was the rope at this point) to no avail, so drifted in to some moored boats, tied up and got in the hole.

40 minutes of hacking away at the rope and eventually I free the prop.

Now, I'm not imagining this but when in reverse, and only in reverse gear there seems to be a lot less thrust than there was prior to the incident, the only thing I've checked is the bolts onto the prop shaft which are all tight, and even if they were loose would have had an effect in forward too, so, I'm definitely not imaging this, there is a loss of power in reverse, any ideas?

[Nightwatch]

Have you definitely cleared ALL the remaining debris?

 

Sounds,to me, like you may have left some behind.

[OldGoat]

In similar incident(s), I've had the same.

A further visit darn the weed 'atch produced a smaller quantity of detritus - poly bags and the like - you would have thought not significant to affect motion but it did, especially in reverse.

 

(wot he said above while I was typing this)

[Punk Stig]

Have you definitely cleared ALL the remaining debris?

 

Sounds,to me, like you may have left some behind.

Positive, as thanks to London canals I've been down there twice more since the incident, it just seemed odd to me that forward seems to be unaffected whereas reverse is!

[John V]

I once had a very obscure fault that gave similar symptoms so it might not be your problem.

 

.............................................however...................................................

 

On one boat I had there was a fault that showed up as a lack of power at high rev's when reversing, it didn't seem to be any worse at low/med revs but soon as you started to go full astern there was no apparent increase in power. it gradually got worse and there then was a noticeable delay before the ahead power became available when changing from astern to ahead.

The fault was a sheared woodruff key on the prop.

When going astern the prop was slackening slightly on the taper and slipping on the shaft, it only being noticeable at higher revs as at slower speeds there was enough friction for it to still "drive". When you then went ahead the thrust from the prop drove it back onto the taper.

 

It was only when the wear increased that It became noticeable enough for me to work out what was happening.

[bottle]

Can only advise another trip down the hatch,

 

Check the shaft at the rear of the prop, before it enters the boat..

 

It may be something, that is tightening on the shaft but only in reverse.

 

Also check the nut that holds the prop on, have had detritus attached to that that then goes back into the prop and fouls it.

[Tiggs]

Check you still have a split pin on the nut too.

[matty40s]

Is your rope still hanging in the cut......

[Punk Stig]

cheers guys, i had previously thought about checking for any bolts on the prop to the shaft but subsequently forgot I had thought of that, worrying memory patterns!

I shall have a look a the weekend when I change the oil and filter on the engine too!

[bottle]

Check you still have a split pin on the nut too.

 

Ah! yes but no, but yes.

 

I do not have one.

 

Mine has a stainless steel 'tab washer' saves having to re-drill the shaft for a split pin when the prop has been refitted.

[PGD]

Some yrs ago we had a prob on the Stratford. Lost all power, prop wouldn't spin clear in reverse so into weedhatch. Nothing on prop. I ended up calling out RCR. We could only think there was a prob with the Hurth box, so the engineer planned to come back the next morning with a recon one.

 

Frustrated and bored, I took the hatch off one more time & felt below the prop... resting on the skeg was a mass of kapok like insulating material. We must have picked it up going past a building site a short distance ago. In gear the prop sucked it up & choked the drive. Out of gear it fell back where it couldn't be seen.

 

Once removed she ran as sweet as a bird.

 

So... I suggest you reach right down & check if there's anything lying on the skeg that you might have missed.

 

Good luck.

Philip

[J R ALSOP]

Bet you keep the rope on the cabin top from now on.