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Prop selection

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Old 01-07-2003, 12:26 PM
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Question Prop selection

Ok I need some good advice I have a 25' stepped hull Larson
Senza running a 350 mag with a gen 2 alpha YA I KNOW IT NEEDS A BB setup! Anyways I running a 2 props a Stilleto ss
21 pitch vented and a Quicksilver II ss 21 I only tried the stilleto
Top speed of 51 max with 2 adults 3/4 tank
Its vents a lot if u try to take off without trimming all the way down. Any recommendations the rpms is about 4700 wot
wanted to pick up some MPH thur hulls,K&N and Manifolds are going on this spring they might help some

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Old 01-08-2003, 12:16 AM
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Old 01-08-2003, 08:22 AM
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Hmmmm I would want to know were you can do all that prop swapping we were talking about.

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Old 01-08-2003, 08:24 AM
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well I been told to try a mirage 4
cause my slip is high
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Old 01-08-2003, 08:53 AM
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I would put this ??? In the tech Q+A area

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Old 01-08-2003, 08:55 AM
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I wouldn't put a whole lot of effort into the props until you have the motor work done.

As a general rule you will want to run a four blade prop with a stepped hull. The water is aerated at the transom and a three blade tends to slip quite a bit

Vented props are really for outboards, an I/O has enough torque at the bottom end and doesn't require the vent holes. You can have the vent holes welded up if you really wanted to run the prop.

A Bravo 1 four blade prop in the 22 range or a Hydromotive quad IV in the 21 range should work well for you. In either case I would go with a rubber hub, in the case of the Hydromotive, or the plastic hub in the case of the Bravo 1. The alpha drive does not last too long with a solid hub prop behind it.

Hope this info helps.

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Old 03-12-2003, 12:37 PM
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Another Senza owner...Wish I'd sprung for the 25 Spectre when I bought mine new way back when...I compensated now by turning the stock 350 into a 383 Stroker...Really woke the boat up.

On the prop question, I noticed a huge difference during prop testing when I tried the Laser II SS. This prop was the most forgiving to trim before slippage kicked in. Also allowed me to trim higher than stock prop and pick up a few more MPH. Also tried a Revoltion 4 blade...Smooth for sure & bit pretty hard (pitch was too high at the time before the engine work to tell about slippage).

Word of advice...Pick up Dennis Moore's book on Chevy Small Block Marine Performance...he gives some tips on camshaft timing that may help you pick up some HP easily (HP Books).

Enjoy the Spectre...How's it ride in 3-4' Chop?
 
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Old 03-12-2003, 01:47 PM
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great ride with the stepped hull
but a stepped hull cant use a vented props at least that what I been told by the prop dudes , I do have the Dennis book.
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