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BANG and boat stopped


LadyG

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4 hours ago, Bee said:

I sometimes look at the colossal flywheels on ancient engines and wonder what would break if a log or something jammed the prop, something would have to give.

Back in the 1960's, I used to crew an ex-working boat which had a massive V4 Turner diesel engine, but jamming something in the prop never stopped the engine because it had a shear pin joint, and all that broke was the mild steel shear pin. It was my job to replace it which took less than five minutes, (with the engine still running!) Mention has been made of shear pins on outboards, but do old former working boats still have them?

 

 

Edited by David Schweizer
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18 minutes ago, David Schweizer said:

Mention has been made of shear pins on outboards, but do old former working boats still have them?

 

2 hours ago, zenataomm said:

Sometimes the more savvy amongst the vintage engine brigade have an arrangement in the prop shaft to take a shearing pin, and very wise they are too.

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2 hours ago, zenataomm said:

Sometimes the more savvy amongst the vintage engine brigade have an arrangement in the prop shaft to take a shearing pin, and very wise they are too.

However it takes a bit of head scratching to get it right.  Should the pin be too much of a weak link then snatching reverse in an emergency can cause it to do its job, possibly at the worst possible moment. (considering you just snatched reverse in an emergency).

<snip>

 

?

The shear pin jopint on Pisces was clearly weoll thought out, The shaft was about 2 1/2" diameter with a female cup which slid over it, the pin was 1/2" mild steel and was an interference fit, the only potential problem was lining up the holes, but we overcame that by marking the shaft and the cup. From memory the pin only ever sheared when the prop was fouled, I have no recollection of it ever shearing during normal operations.

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14 hours ago, Alan de Enfield said:

 

Remembering that as you (LG) were in reverse when you 'got the bang' you may need to unwind the sleeping bag the opposite way to the one you may expect.

yep, thought about that but I am no wiser...................

I tied a cord to the bag in the weed hatch to try to get leverage, it did not work. I then attacked from outside with boathooks [2 off], the cord appeared, but still did not unravel, enrolled assistance of random strong men, boathook gave up... but my cord still attached. 

 I had a total wash and watched TV for the rest of the day.

Ready and willing to have another try today 

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12 hours ago, Arthur Marshall said:

Most of us single handers get offers of help at locks, which in my case (dodgy knees and back now) is usually gratefully accepted. Most folk are careful these days. I repay the compliment whenever I can.

Can't you get a breadknife or hacksaw into the weedhatch and just cut the thing to bits? 

Breadknife  and Stanley knife did not work, I am going to try assorted saws today, weedhatch is barely accessable.................. 

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4 hours ago, LadyG said:

Breadknife  and Stanley knife did not work, I am going to try assorted saws today, weedhatch is barely accessable.................. 

Weedhatch on some boats seem to be an afterthought by some builders!

Keep at it. Nil Desperandum!

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On 23/08/2020 at 15:58, Bee said:

I sometimes look at the colossal flywheels on ancient engines and wonder what would break if a log or something jammed the prop, something would have to give.

I jammed a log between the prop and the skeg whilst turning under the junction bridge at Great Haywood. There was a bang and a loud whirring sound and I instinctively pulled the gear lever into reverse, at which point the log shot out. The engine didn't stop and nothing broke because Lister marine gearboxes are designed with this scenario in mind and the clutch plates slip at excessive torque. The colossal flywheel and the crankshaft connecting it to the gearbox were unharmed.

 

MP.

Edited by MoominPapa
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27 minutes ago, MoominPapa said:

I jammed a log between the prop and the skeg whilst turning under the junction bridge at Great Haywood. There was a bang and a loud whirring sound and I instinctively pulled the gear lever into reverse, at which point the log shot out. The engine didn't stop and nothing broke because Lister marine gearboxes are designed with this scenario in mind and the clutch plates slip at excessive torque. The colossal flywheel and the crankshaft connecting it to the gearbox were unharmed.

 

MP.

My relief valve just lifts

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11 hours ago, LadyG said:

Breadknife  and Stanley knife did not work, I am going to try assorted saws today, weedhatch is barely accessable.................. 

Unlike on cruiser sterns where you can really get in there and cut off the offending object!

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In the BW days I was told that if a 'foreign' object in the water stopped your boat, BW were responsible as it was in their canal obstructing navigation.

 

As a idea, phone C&RT and see what they are prepared to do to unblock the canal because your boat cannot move due to their negligence in allowing the item in the canal.

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23 hours ago, Alan de Enfield said:

 

It is common practice to have a shear pin thru the prop on outboard engines - prop hits something and the pin shears simply replace pin and carry on.

 

Generally there are several shear pins and split pins kept in a 'holder' underneath the outboard 'cover'.

Got sent on a week long big tree felling course many years ago (much fun it was to) the instructor gave us the smallest tirfur in the world to carry onto site.

 

Obviously we made much about his small equipment, slightly grumpy he got all snotty and promised us it was man enough and "in all the years it has never let him down and it still has it's original shear pin"

 

Guess who destroyed the shear pin :)

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10 hours ago, Athy said:

Are you not a member of RCR? They would get you going again.

I may need a diver or haul out at the marina, three hours today and only 1 cubic foot of stuffing, if that. 

I'll go and get a junior hacksaw and a packet of blades tomorrow, tried everything else including knives/box cutter and ice axe.

A dip in canal looks more and more likely ...... could be worse, I think ...................

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14 minutes ago, LadyG said:

I may need a diver or haul out at the marina, three hours today and only 1 cubic foot of stuffing, if that. 

I'll go and get a junior hacksaw and a packet of blades tomorrow, tried everything else including knives/box cutter and ice axe.

A dip in canal looks more and more likely ...... could be worse, I think ...................

Always keep on board  - when at sea its lobster-pot lines, on the canals its mattresses.

IMG_20160924_101247.jpg

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13 hours ago, LadyG said:

Breadknife  and Stanley knife did not work, I am going to try assorted saws today, weedhatch is barely accessable.................. 

Noooo, not a Stanley knife. 
f**king hell no!


with a long bladed knife , like a bread knife you can make long dragging cuts after checking any fingers are out the way. 
Hold what ever it is taught with the other hand while dragging a cut with the other. 


But not a Stanley knife !
Ouch

 

Edited by Goliath
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3 hours ago, Tracy D'arth said:

In the BW days I was told that if a 'foreign' object in the water stopped your boat, BW were responsible as it was in their canal obstructing navigation.

 

As a idea, phone C&RT and see what they are prepared to do to unblock the canal because your boat cannot move due to their negligence in allowing the item in the canal.

 

2 hours ago, Goliath said:

Noooo, not a Stanley knife. 
f**king hell no!


with a long bladed knife , like a bread knife you can make long dragging cuts after checking any fingers are out the way. 
Hold what ever it is taught with the other hand while dragging a cut with the other. 


But not a Stanley knife !
Ouch

 

@Goliath ... Are you anywhere near,  it's not a job for a lady, ?

Edited by LadyG
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