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Old 20-11-2007, 10:32 AM   #1
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Country: uk
Location: liverpool
Interests: sailing ribing
Boat name: llyn raider
Boat make: 7m xs rib
Engines: 200 merc opti
Cruising area: n wales

Join Date: Nov 2006
Location: liverpool
Posts: 214
prop choice

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.
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Old 20-11-2007, 11:34 AM   #2
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Country: UK
Location: Salcombe South Devon
Occupation: Racer and builder
Interests: Winning races
Boat name: BananaShark
Boat make: BananaShark 34' Race
Engines: Twin Yanmar BY 260's

Join Date: Mar 2004
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Quote:
Originally Posted by andyxs View Post
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.
It's a good place to start, especially if you can borrow one - I think there are a couple of people up your way on the tube site that may be able to help - have you tried moving any heavy moveable things towards the back of the boat? Anchor for instance?
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Old 20-11-2007, 12:08 PM   #3
Registered User
 
Country: uk
Location: liverpool
Interests: sailing ribing
Boat name: llyn raider
Boat make: 7m xs rib
Engines: 200 merc opti
Cruising area: n wales

Join Date: Nov 2006
Location: liverpool
Posts: 214
will try and borrow one for the weekend. think the boat yard has a couple of 19s i could try. any idea on type for top end. have no experience but cleaver/chopper etc and what can i expect from them? know im asking alot here as well. thanks cookie.
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Old 20-11-2007, 02:48 PM   #4
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Country: UK
Location: Salcombe South Devon
Occupation: Racer and builder
Interests: Winning races
Boat name: BananaShark
Boat make: BananaShark 34' Race
Engines: Twin Yanmar BY 260's

Join Date: Mar 2004
Location: Salcombe South Devon
Posts: 4,632
Quote:
Originally Posted by andyxs View Post
will try and borrow one for the weekend. think the boat yard has a couple of 19s i could try. any idea on type for top end. have no experience but cleaver/chopper etc and what can i expect from them? know im asking alot here as well. thanks cookie.
Engine height may also be an issue - it should be revving a bit more than that with a 21 really - Are you sure it's a 4 blade laser? As far as I know they are all 3 blades - could it be a Trophy or something else? A Raker is generally a faster prop (we used a modified one at Coniston), but you have to consider what you will be losing - for instance moving the engine up a couple of bolt holes and changing propellers may make it less useful for skiing etc.
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Old 20-11-2007, 03:40 PM   #5
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Country: uk
Location: liverpool
Interests: sailing ribing
Boat name: llyn raider
Boat make: 7m xs rib
Engines: 200 merc opti
Cruising area: n wales

Join Date: Nov 2006
Location: liverpool
Posts: 214
good point. think i will keep it simple to start with and see where it gos but defintaly guna get hold of a 19". thanks cookee.
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