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Old 14 October 2022, 18:10   #21
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If you have the money according to steel developments you can get 5% more out of a stainless prop for me the Sib hull doesn’t lend its self to fine tuning. Reading chipcos post my Mercury 365 hd with my engine topped out at 22knots with the 11 inch prop dropping to 20 knots with the 10 inch prop all this is in perfect conditions but not on the same days kind of agrees
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Old 14 October 2022, 19:07   #22
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I'd agree with "a SIB hull doesn't lend itself to fine tuning" at the end of the day I'm not trying to emulate Roflhat in a sausage keel SIB.
I've noticed on a lot of pictures I've seen recently 4 bladed props, why? What's the advantage/disadvantage?
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Old 14 October 2022, 19:36   #23
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Originally Posted by Steve509926 View Post
I'd agree with "a SIB hull doesn't lend itself to fine tuning" at the end of the day I'm not trying to emulate Roflhat in a sausage keel SIB.
I've noticed on a lot of pictures I've seen recently 4 bladed props, why? What's the advantage/disadvantage?


I’m a big fan of 4 blade props on RIBs.
+ more grip, lower planing speeds, better holeshot.

- increased fuel consumption, initial cost, slightly lower top speed.

For me, it’s the equivalent of putting all terrain tyres on a 4x4.
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Old 14 October 2022, 19:57   #24
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I’m a big fan of 4 blade props on RIBs.
+ more grip, lower planing speeds, better holeshot.

- increased fuel consumption, initial cost, slightly lower top speed.

For me, it’s the equivalent of putting all terrain tyres on a 4x4.
So would you say a 4 blade prop would be good for a choppy / rougher sea with a heavier load ie: camping gear? and choosing a 4 blade prop, is it the same 9.25 x 10 but 4 blades?
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Old 15 October 2022, 21:08   #25
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https://www.boats.net/blog/3-blade-v...ade-propellers

Bit of info
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Old 16 October 2022, 09:32   #26
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Thanks Jeff
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Old 16 October 2022, 17:01   #27
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Whilst I’m well aware of the advantages of 4 blade props, why complicate the matter on super lightweight sibs with portable size motors…up to 25hp. Heavy boat hydrodynamics not applicable methinks.

After years of use with numerous sibs, run latterly with a couple of current 20 horse efi motors, stock 3 blade props run just fine. Not yet found any 3.5 to 3.8m sib (or even our little 3.4 rib) which doesn’t perform with OEM 3 blade 10 or 11” pitch props.

A moderately loaded sib certainly doesn’t need the extra lift provided from a 4 blade or benefit from any extra mid range grip so why lose some top end performance. The merits of any extra surface area from a 4 blade is just wasted imho.

Each to their own I suppose.
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Old 16 October 2022, 17:46   #28
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Whilst I’m well aware of the advantages of 4 blade props, why complicate the matter on super lightweight sibs with portable size motors…up to 25hp. Heavy boat hydrodynamics not applicable methinks.

After years of use with numerous sibs, run latterly with a couple of current 20 horse efi motors, stock 3 blade props run just fine. Not yet found any 3.5 to 3.8m sib (or even our little 3.4 rib) which doesn’t perform with OEM 3 blade 10 or 11” pitch props.

A moderately loaded sib certainly doesn’t need the extra lift provided from a 4 blade or benefit from any extra mid range grip so why lose some top end performance. The merits of any extra surface area from a 4 blade is just wasted imho.

Each to their own I suppose.

The reason for the question was to gain knowledge rather than anything else chipko, as I didn't know what benefit could be gained by a 4 blade.
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