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Turn in or out, V-hull 33avs cleavers

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Turn in or out, V-hull 33avs cleavers

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Old 09-07-2018, 03:07 PM
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Location: Espoo, Finland, Europe
My Boat: 1999 Scarab 33 AVS MercRacing 700 Sci/ Sterling, NXT1
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Default Turn in or out, V-hull 33avs cleavers


HI All,
I have question about props, bit exotic with 33 AVS but still. I have Hering 37x17" rake 16 cleavers currently, and rotating like in the pictures. Engines are MercRacing 700 Sci's rebuilt by Sterling to 850hp, drives are NXT1's. Boat does easy 100kn but will start to suffer after 85kn about too much stern lift. Boat is solid on 85kn but after that start to feel bit "out of hand" but still runs nicely (no china walk, just feels bit nervous). by looking at few pics from it running it looks like the stern is too high compared to pics with XR's it had before.

So the question is should I run in or out?
And what size (diameter) I should be using?

I'm from Finland, Europe and we do not have lots of this kind of props to test lying around here, so by just testing I don’t have possibility to find correct set of props.
X-dim is around 1 to 1,5" inch due swim platform bottom the drives can’t be higher without destroying the boat, so I decided not to do that at the time.

Any thoughts? Advice?

Roope

Last edited by roope; 09-07-2018 at 03:43 PM.
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Old 09-10-2018, 11:52 AM
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Best info might come from Dan/Archer. I would reach out for him as he has probably played with more Scarab setups than any one else.

Besides props, it could be the NXT lower case messing you up a bit as well
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Old 09-15-2018, 07:02 AM
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What do you mean “start to feel nervous”, are you getting nervous at that speed or boat is acting weird?
NXT drives like to surface same as #8 drives, I’m not sure but from the photo it seems to me that those drives are sitting too low, this could be part of your problem, I understand that you can’t go higher with these drives, to begin these are massive drives for 33 foot boat...

Last edited by steelborn; 09-15-2018 at 07:05 AM.
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Old 10-17-2018, 07:26 PM
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FYI the way your props are turning will give you stern lift, reverse your props on your outdrives put your gear shifts in reverse, should give you bow lift, boat will drive a lot better.
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Old 10-17-2018, 08:19 PM
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NXT’s are rotation specific, you need to swap drives to change rotation... inside rotation pulls the tail down
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Old 10-18-2018, 02:28 AM
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I would test some 4 blade props. Less blade area = less stern lift. But this is just an educated guess at what might work.

Its a 33' boat, so 85 knots(98 mph) is pushing the hull's limits.
There were a couple of 33AVS's at LOTO that ran over 100 mph with Bravo's, but I think you are in uncharted territory with the NXT's and the only way you will ever know what works the best will be through testing.
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Old 10-18-2018, 04:30 PM
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Originally Posted by Ran C View Post
FYI the way your props are turning will give you stern lift, reverse your props on your outdrives put your gear shifts in reverse, should give you bow lift, boat will drive a lot better.
The transmissions will fail if you do this as there are only two clutch discs for reverse gear, meant for idle use only. You must switch the drives as stated in a later post.
Nice Pair likes this.
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Old 10-19-2018, 01:34 AM
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Originally Posted by Ran C View Post
FYI the way your props are turning will give you stern lift, reverse your props on your outdrives put your gear shifts in reverse, should give you bow lift, boat will drive a lot better.
Ignore ALL of this^^^^^^^^^^^^

Spinning inward creates more bow lift.
You have transmissions and cannot do what he is saying. You have to swap drives.
KNOT-RIGHT and rak rua like this.
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Old 10-19-2018, 12:37 PM
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I suggest you swap the drives to turn inward.
I would also suggest a 16.75 diameter propeller with a 18 degree rake.

Since you already own the 17x37's, I'd consider having us reduce the diameter and adjust the rake slightly.

Brett
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Old 10-19-2018, 10:34 PM
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Originally Posted by bbladesprops View Post
I suggest you swap the drives to turn inward.
I would also suggest a 16.75 diameter propeller with a 18 degree rake.

Since you already own the 17x37's, I'd consider having us reduce the diameter and adjust the rake slightly.

Brett
His pic shows spinning in already??
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