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Old 11 September 2009, 10:28   #11
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Wont this have buggered the flow of water coming of the tips of the prop ? Maybe with 8hp it not to noticable & as a back up not any problem- but guess if you did this on a prop bolted to a 50 + hp motor you'd soon feel it ?

Props are not the most efficient things anyway, but I thought that when you get into the full on fluid dynamics of drag etc ( its been a while since I did this at uni, or for anything else on Aircraft) this can have major impacts. Best simple example being the winglets on airliners using the analogy of the wing as a prop blade .
made a card template to get the same or near profile as the original ,so theres no dodgy corners,,,,one big advantage with our club is we have a lot of members that are ex ship builders/ designers and marine engineers so you always have some expert overlooking your shoulder .lol,
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Old 11 September 2009, 10:39   #12
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You think so eh?
What will it do then?
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Old 11 September 2009, 10:49   #13
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What will it do then?
The time walk?

So what do you think lads? Go up to 21"?
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Old 11 September 2009, 10:59   #14
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made a card template to get the same or near profile as the original ,so theres no dodgy corners,,,,one big advantage with our club is we have a lot of members that are ex ship builders/ designers and marine engineers so you always have some expert overlooking your shoulder .lol,
Result on that one !
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Old 11 September 2009, 11:00   #15
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The time walk?

So what do you think lads? Go up to 21"?
Find out what rpm your doing first.
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Old 11 September 2009, 11:02   #16
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Will do
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Old 11 September 2009, 12:22   #17
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There are essentially three things you can vary with a prop - pitch, diameter & # blades.
Those are the directly selectable variables (i.e. the ones as you say, are marked on the tin.) Others include overall weight (lighter props spin easier, but also slow down quicker, as in coming back into the water), blade cup (the concavity of the blade face; helps hold water on the blade), blade shape, venting, blade thickness, probably a host of others. None of which are advertised.

Which, all in all, is why, if you want the best performance, you've got to test props rather than just selecting one from a catalog.

jky
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Old 11 September 2009, 12:24   #18
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Which, all in all, is why, if you want the best performance, you've got to test props rather than just selecting one from a catalog.

jky
Wish I had the money and time to do that.
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Old 11 September 2009, 12:31   #19
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Wish I had the money and time to do that.
Yip,

It's not cheap and it's easy to get carried away looking for perfection. There's a outfit in Florida who run sort open days where you have a go with various props they provide...and buy what you like nothing like it here though.

if you really want to go off your head, look up lab finishing..
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Old 11 September 2009, 12:39   #20
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Yip,

It's not cheap and it's easy to get carried away looking for perfection. There's a outfit in Florida who run sort open days where you have a go with various props they provide...and buy what you like nothing like it here though.

if you really want to go off your head, look up lab finishing..
Jesus!
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