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Old 20 November 2007, 05:01   #1
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Country: UK - England
Boat name: llyn raider
Make: xs
Length: 7m +
Engine: 1 200hp merc
Join Date: Nov 2006
Posts: 211
prop choice options

have a 7.2 meter warped v xs rib with a 200 merc running a 21" 4 blade lazer 2 prop and i get 58mph at 5000ish revs with a little chine walk. got the ecu print off and its never been over 5400 revs. and less than 5 mins over 5000 in 250 hrs. wondering if i need to go down a pitch or alter prop type? have no experience with props. first instinct is to go down a pitch but was wondering what you guys think. looking for a bit more on the top end if poss as acceleration is already good.
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Old 26 November 2007, 20:21   #2
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Country: Australia
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Make: avon
Length: 4m +
Engine: yam60hp 2stroke
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chine walk

chine walk will happen for a number of reasons,,a starting test is to trim up and see if theres any play in your steering,also sum engines have anti vibration mounts,(rubber),,and at speed with lots of trim they can cause chine walk as the mounts flex,,,mottor wobble,,if thats ok then see where the water is breaking,,,your engine may be to low on the transom engine height adjustment can also yeild good economy figures as theres less drag,so u get better fuel economy with more speed when needed,,its a matter of trial and error but much cheaper than buying props to try
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Old 27 November 2007, 13:53   #3
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Andy it its top speed you are after you may want to try a 3 blade prop?

As I understand 4 blades give you better hole shot at the cost of top end speed.

What height is your anti ventilation plate in relation the bottom of the transom?

Chris
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Old 28 November 2007, 11:48   #4
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The first thing I would do is raise the motor on the bolt holes and see what happens. It's bound to raise the top end rpm but may not raise the top end speed. Could also cause slippage but at least it doesn't cost anything to try as opposed to buying another prop for 400.
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Old 28 November 2007, 12:45   #5
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thanks guys will have a play with the height
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