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Old 02 September 2005, 05:03   #1
Country: UK - England
Town: nr Truro
Boat name: Cub
Make: Osprey
Length: 5m +
Engine: OB 90
Join Date: Jun 2005
Posts: 6
Should I change the Prop

Just after a bit of advice, knowledgable or otherwise :-)

I've got an Osprey Sparrowhawk, fairly old but in good nick. This year I've re-fitted the elctrics and put a new Mariner 2 stroke 90 on the back, and she flies.

I'm on the North Coast of Cornwall so she often gets used in rough weather for general mucking around, wave surfing, and saftey boat cover for local pilot gig races.

The Osprey site reckons the top speed is 40 knots, but the most I can get out of her is about 35 on a reasonably flat sea, and at this speed there is a fair bit of wobble.

Is there any point in changing the standard Mariner prop to get more speed or better economy (mutually exclusive I assume) ?

What do you think ?
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Old 02 September 2005, 05:26   #2
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Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,837
Chris, I recon thats probably your lot without going to S/S props(mine did 32 knots with 75 hp) and then raising the engine height. However if your operating in surf and close to beaches then I would keep the Ali prop because if you do run aground hopefully the prop will bend before the gearbox, and keeping the engine low on the transom will help keep the prop in solid water in the surf. It might go faster higher up but for normal use it will be a pain loosing drive more easily.

I would cary a spare prop though, perhaps a cheap plastic one, just in case as a get you home measure.


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Old 02 September 2005, 09:53   #3
Country: UK - England
Town: Manchester
Boat name: Venus
Make: Osprey 18 appx 1988
Length: 5m +
Engine: Selva S1400 / 100hp
Join Date: Jun 2005
Posts: 17
I have an Osprey 18 (about 1988) which I'm told is the fore runner to the Sparrowhawk. I don't really know the Sparrowhawk but if your nose is as flat as mine, 35 in a half decent swell is more than refreshing. Nicely over the 1st bump & straight through the 2nd. Repeated over an afternoon can be kinda wet. Do you really want to do 40?
Phil - on the good (ish) ship Venus
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