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Richard McKinney
United Kingdom
4 Posts |
 Posted - 26 Jul 2011 : 14:54:23
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Can anyone help me with what size of prop should be on a Norman 266(my prop is at the bottom of Loch Lomond. I have looked at Prop Calculators on the internet, but do not have enough information to complete:
Name: Current Liability
Engine: Ford Essex V6 petrol, 175 bhp, Revs 2500
Speed about 8 mph (downhill)
Gear ratio 2:1 ?
Boat length 26'-6"
Beam 9'-6"
Boat weight 3.5 Ton
Prop shaft 1.25" dia
Prop slip ?????
Prop pitch ????
Any advice would be greatly appreciated
Thank you
Richard |
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trevork
3949 Posts |
Posted - 07 Aug 2011 : 23:23:53
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cliveshep
Thailand
1324 Posts |
Posted - 08 Aug 2011 : 06:33:47
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You could give Mike Bellamy a ring at Lancing Marine, here: http://www.lancingmarine.com/ as Mike is heavily into engines,drives etc for all types of craft. Failing that, a builder of craft with similar hull characteristics might be persuaded to help, perhaps Birchwood, http://www.birchwood.co.uk/ or one of the Thames or Broads Boatyards although you'd take pot luck on the validity of the advice. French might also be able to help you, here: http://www.frenchmarine.com/marine_engineering_services.aspx or Mermaid who used to fit Essex engines http://www.mermaid-marine.co.uk/
Sorry, it's early in the morning and I'm only half awake! Good luck with that!
The cost of boating is insignificant compared to costs of a young wife and two teenage kids! |
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Deano
United Kingdom
1843 Posts |
Posted - 08 Aug 2011 : 10:04:31
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Clemments Marine in St Neots.
Despite their very commercial website, they are the worlds specialists in this kind of thing and you may be impressed at the pricing too.
They re-prop 1000's of leisure craft.
Dean - Boating on the Great Ouse.
Freeman 30 "Silver Gem"
See the photos http://www.flickr.com/photos/54758027@N00/ |
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trevork
3949 Posts |
Posted - 08 Aug 2011 : 11:25:19
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Thought you were ploughing around on "Phantom" this week Dean?
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Richard McKinney
United Kingdom
4 Posts |
Posted - 15 Aug 2011 : 20:59:19
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Hi, I have been advised that a 16/10 or 16/12 prop is approximately what the boat needs. I managed to get a 16/10 from eBay and should be able to trial it in about a weeks time. If it is underpowered, I may have to go up to the 16/12. I'll let you know how the trials go.
Thanks to all for your help. |
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mike
United Kingdom
80 Posts |
Posted - 16 Aug 2011 : 11:28:22
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You can down load a Propeller Calculator from tinternet, Castle Marine do one but there are many more, it will do all the sums for you.
Its still a black art though as there are many different ways to work out the best prop size
Mike |
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Deano
United Kingdom
1843 Posts |
Posted - 16 Aug 2011 : 18:12:30
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There is no "CORRECT" prop size that can be calculated for a boat.
I picked this up during discussions with an employee of Clements Marine.
You can vary the size and pitch of a prop and it will still the be CORRECT prop for the boat. How you use the boat is also a great factor. Do you need low speed control for locks and moorings? Do you need good acceleration? most of us would say no to that as a requirement, but it is also strangely linked to deceleration or stopping, so can be important!! What about top speed? Fuel economy??
The CORRECT prop will be a compromise, factoring in some of the above. It is not a Black Art, just not a popularly understood art!!!
Dean - Boating on the Great Ouse.
Freeman 30 "Silver Gem"
See the photos http://www.flickr.com/photos/54758027@N00/ |
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Richard McKinney
United Kingdom
4 Posts |
Posted - 25 Aug 2011 : 20:39:47
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I fitted a 16-10 propeller which I bought on eBay. The boat is now running smoothly, but requires slightly more revs to get the same speed I had with the old prop. I have good slow speed power for turning and sufficient for cruising, so I'm quite happy.
Thanks to all for your suggestions and advice.
Richard |
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Which prop?
