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Old 30 January 2014, 10:40   #11
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some good advice on here. get your tacho set up (don't wrap the wire around the ht lead too many times!)

judging from that pic looks like you need to trim out more, get the nose up.
You can get 10 x 18p merc choppers that work really well on these hulls, not quite sure if your 20hp will spin them. my mate got a 10 x 16 chopper for his surfcat with a tohatsu 30 and its really too little prop. Its a ron hill prop which we had to cut over an inch from to make it fit onto the splines! seems to be running alright now though.

Really you're only choice is ron hill for these small props, a 10 x 16 cleaver or chopper I reckon would work well on your hull. its a hit and miss with rons props, could be good straight out the box or may need some balancing.
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Old 30 January 2014, 10:49   #12
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If you're after proper performance I wouldn't bother with bunny props. cleavers or choppers are the only way. I've run 15p solas which i had cupped and pitched to 16p. Then a merc 18p chopper cupped. now running an 11 x 18p merc cleaver. the difference is night and day between the surface piercing props and the bunny ear.

Also if you haven't already you could try carbon reeds like Boyesen, increases compression a bit too. my slowhatsu 50 is at around 140psi.

If you go to a surface piercing prop you'll most likely have to raise the motor some more, probably at least another 10mm, these props like to be run higher, always having one blade out of the water.
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Old 30 January 2014, 13:17   #13
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ideal cheers roflhat tacho should be with me soon (tiny tach)

id does look relatively flat in that pic thats with one hole out it does seem to quicken up the further i trim out but then when going very slow i get alot of prop slip and it sits up at some silly angle till it drops on to the plane maybe here is a better pic with the same settings and the same prop

https://www.facebook.com/photo.php?v...type=3&theater

https://www.facebook.com/photo.php?v...type=3&theater

i have some boyesen reeds on order from the states which are estimated for delivery on the 10th of feb, the compression is fairly low 95psi on each but it does have a exhaust relif port to aid turning over, the squish seems near as dam it perfect at .50mm

so out of the 3 props you've run the merc cleaver is the best then, it does seem that most of the racers run semi or full cleavers, am i right in thinking they give a bit of stern lift where as a chopper gives more bow lift, which i can get from my trim as its only one hole out.

the only 10 spline offering i have found is a ron hill which like above ive read mixed reviews on, and they don't offer a thru hub version for my fitment will that matter, the leg is drilled so hardly any exhaust come out of the prop any way.

would i have trouble picking up water if one blade is surfaced?

9.5 X 15 Signature Propeller for 20-30 HP Yamaha Outboard Racing | eBay
Yamaha 20-30 HP Outboard Racing Three Blade Cleaver Propeller 10 1/2 X 15 | eBay
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Old 31 January 2014, 04:31   #14
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yes cleavers are stern lift and choppers are bow lift. my cleaver and chopper are very evenly matched, its hard to distinguish between the two when set up correctly.

The chopper is over the hub (small hub) but the cleaver is through hub (big) doesn't make much difference if you've done the above prop exhaust mod (hole in the leg).

I've got standard water pickup, no lwp, and it still picks up water fine, you'd be surprised how high you can go and still get pressure.

Out of the two links you posted I'd go for the second one, although I reckon you may want 16p or 17p seen as your motor is modded.
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Old 31 January 2014, 13:27   #15
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all good advice i think they do do a 16 and 17p too so may be worth looking at, guess it will all be down to the revs im pulling at the moment with my powertech 12

it just needs to stop raining
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Old 01 February 2014, 08:55   #16
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You can just lift the engine higher if you want more rpm, you can go from a 12 to an 18p cleaver and just lift the engine to suit. Obviously the danger is going so high you don't get enough water pressure.

If I use a 17p solas i can't hit the rev limiter at 5850, but if i use a 20p cleaver i can hit the rev limiter just because cleavers are run higher out of the water
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Old 11 February 2014, 12:36   #17
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boyesen reeds came yesterday so today braved the weather and went out in the eastury 6knot limit today even got hailed on, it was a little choppy and quite windy,

i started off with the trim set to where i used to find it best 1 hole out, was getting loads and i mean loads of bow lift i went vert at one point, lots of prop slip and took ages to drop on to the place get grip and was off,

move it in to the first hole trimmed right in less prop slip and get on the plane quicker, but still lots of bow lift, more than before which is weird, maybe this is because with all the mods its pushing more power

i notice i can hear the prop breaking loose quite often (probably because its alot higher)

any way here are my readings wot was between 6800 and 7100 and top speed recorded was 46mph
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Old 11 February 2014, 13:54   #18
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7100!!


I bet that sounds scary!
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Old 11 February 2014, 14:23   #19
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Yeah was ventilating a gooden now it's raised up and I've just checked on the power tech website my prop has 20degrees of rake which explains the bow lift from the extra power I've gained

The question now is do I get a full cleaver stern lift

Or

A semi cleaver which gives neutral lift

I'd like still to be able to use it on some swell I never use it in surf
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Old 12 February 2014, 09:52   #20
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7100 is high even for a yamaha! I reckon you need some more pitch on there

cleavers and choppers work almost exactly the same on this style of boat (despite one apparently giving bow lift and the other giving stern)
I wouldn't bother with a semi cleaver unless you're doing surf stuff.

I reckon a 16 or 17p cleaver would do you nicely. you'll probably have to get it worked either way so a Ron Hill should be alright
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