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Post by flatdog on Oct 31, 2016 19:00:45 GMT
Be very careful selecing a replacement.by 'just looking at a sheet of dimensions' v your engine/gearbox output. You would be better off having a diver check it out properly, taking measurements for you and checking if the pitch and size is visible on the blade or shaft. (it should be there) Increasing the pitch will increase the load on your engine, which may become smokey as it's struggling to meet the torque outside it's optimum power.
Gearboxes can slip as they wear out so you may also consider this as a possible fault.
Personally, I'd pull the boat if the vibration is bad and do the job on the hard. -
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Post by Deleted on Oct 31, 2016 19:04:01 GMT
Be very careful selecing a replacement.by 'just looking at a sheet of dimensions' v your engine/gearbox output. You would be better off having a diver check it out properly, taking measurements for you and checking if the pitch and size is visible on the blade or shaft. (it should be there) Increasing the pitch will increase the load on your engine, which may become smokey as it's struggling to meet the torque outside it's optimum power. Gearboxes can slip as they wear out so you may also consider this as a possible fault. Personally, I'd pull the boat if the vibration is bad and do the job on the hard. - All good points. Thanks Boat needs to have some bitumen thrown at it anyway so probably worth booking a dry sock or getting it craned out somewhere at some point.
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Post by JohnV on Oct 31, 2016 19:07:12 GMT
Is a dry sock a witty sock puppet ?
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Post by Deleted on Oct 31, 2016 19:32:46 GMT
I don't know. And you know what - Frankly my dear, I don't give a damn
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Post by faffer on Oct 31, 2016 19:53:35 GMT
May i digress a little from the original question ( bloody nora thats a posh word for me...digress ll ) . If need be i will start another thread.
Just a thing that has been on my mind about enigne sizes and props. If i had a 60hp outboard an it had a certain prop fitted whcih was the wrong spec would it reduce the speed a lot.
Just thinking on if if i had a 60hp outboard and two different props i could swap them for where ever the boat was being used, as we know canal and lake speeds are different from river and sea.
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Post by flatdog on Oct 31, 2016 20:21:05 GMT
May i digress a little from the original question ( bloody nora thats a posh word for me...digress ll ) . If need be i will start another thread. Just a thing that has been on my mind about enigne sizes and props. If i had a 60hp outboard an it had a certain prop fitted whcih was the wrong spec would it reduce the speed a lot. Just thinking on if if i had a 60hp outboard and two different props i could swap them for where ever the boat was being used, as we know canal and lake speeds are different from river and sea. First Q, If the prop was smaller then the engine would rev quicker and the boat wouldn't go very fast = heavy on fuel. Too large a prop and it would be similar to a car in top gear, crap, stalling at low revs and not much take up when accelerating and it would struggle to maintain speed = heavy on fuel. Second Q, yes you can. Props should be correctly matched to specific use. You want power and economy then nice torqey motor and broad pitch. You want speed and performance then high revving and flat pitch. IMHO of course.
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Post by bargemast on Oct 31, 2016 21:00:02 GMT
The 4 blade prop I had seen on ebay seems to have a 16:1 taper and from what I can gather almost all UK canal boats have 12:1 taper. So it might not fit anyway. L3.5" . taper 1.3/8 > 1.1/6 is what's written on the advert. My prop has a 4" boss length so may be completely different. Not sure really. On this side of the Channel the standard taper for props and propshafts is 1:10 , to give you an idea of the props a place like Vetus (there are many others of course) has available : linkhttp://www.vetus.com/stern-gear-systems/propellers/vetus-3-bladed-propeller-p3b-20-x-14-right-handed.html
Peter.
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Post by IainS on Oct 31, 2016 22:10:53 GMT
The 4 blade prop I had seen on ebay seems to have a 16:1 taper and from what I can gather almost all UK canal boats have 12:1 taper. So it might not fit anyway. L3.5" . taper 1.3/8 > 1.1/6 is what's written on the advert. My prop has a 4" boss length so may be completely different. Not sure really. Assuming the 1.1/6 is a misprint for 1.1/16, I make the taper about 11 to 1, so it might well be 12 to 1, ( or 10 to 1) allowing for inaccuracies in measurement.
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Post by bargemast on Oct 31, 2016 22:55:07 GMT
The 4 blade prop I had seen on ebay seems to have a 16:1 taper and from what I can gather almost all UK canal boats have 12:1 taper. So it might not fit anyway. L3.5" . taper 1.3/8 > 1.1/6 is what's written on the advert. My prop has a 4" boss length so may be completely different. Not sure really. Assuming the 1.1/6 is a misprint for 1.1/16, I make the taper about 11 to 1, so it might well be 12 to 1, ( or 10 to 1) allowing for inaccuracies in measurement. A boss of 4" is pretty close to 10 cms, if it's 10cms then the best thing to do is to remove the prop, which has to be done anyway, and then messure the diam of both ends of the hole in the boss, if there's 10mm difference between the 2 it will be a 1:10 taper.
If you find the right diam/pitch prop of which the taper is different, there's always a possibility of making an adapted sleeve to fit the taper of the shaft on the Inside, and the taper of the prop on it's outside.
But the easiest would be to find a prop that doesn't need any additional work done, that just fits and gives you the desired gain in performance.
Peter.
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Post by Deleted on Nov 1, 2016 7:49:15 GMT
The 4 blade prop I had seen on ebay seems to have a 16:1 taper and from what I can gather almost all UK canal boats have 12:1 taper. So it might not fit anyway. L3.5" . taper 1.3/8 > 1.1/6 is what's written on the advert. My prop has a 4" boss length so may be completely different. Not sure really. Assuming the 1.1/6 is a misprint for 1.1/16, I make the taper about 11 to 1, so it might well be 12 to 1, ( or 10 to 1) allowing for inaccuracies in measurement. It says 1.1/6 - I did wonder if it meant 1/16 as you suggest as 1/6 is an odd measurement..
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