Shorties on 46 triples
09-11-2008, 09:02 AM
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Shorties on 46 triples
Anybody have positive feedback on using Bravo XR drives and 2 inches Shorties lowers on a triple 500 hp BT46SC ? Was the speed gain worth it ? Finaly what Pitch used on Props ? Thanks
09-11-2008, 11:15 PM
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Since you are on here giving advice, maybe you can explain where the drive spacers that I bought and paid you for three weeks ago are?
09-12-2008, 08:08 AM
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09-12-2008, 08:58 PM
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reply to shorties on a triple 46
Hi Fantom,
I don't believe you'll find the trade off of slightly more speed worth the loss of handling. Getting on plane will be difficult, as cavitation will be significant. Your ride quality will likely deteriorate as you'll lose the leverage of the deeper X dimension (on these particular hulls). If you intend to do any ocean or rough water trips, DON'T USE THE SHORTER DRIVES. You'll cavitate at just the speed you'll need to safely run thru bigger stuff like 6 ft. and above 28-32 MPH and not beat the snot out of the boat and it's crew.
If you're still determined to try them, use a 5 or 6 blade prop, probably in the 28 to 29 pitch range for the outside drives and 29 or 30 inch on the center drive (assuming 1.50 ratios). Try to find a diameter of greater than 14.5, more like 15 inch diameters.
Good luck, let us know.
Steve David
I don't believe you'll find the trade off of slightly more speed worth the loss of handling. Getting on plane will be difficult, as cavitation will be significant. Your ride quality will likely deteriorate as you'll lose the leverage of the deeper X dimension (on these particular hulls). If you intend to do any ocean or rough water trips, DON'T USE THE SHORTER DRIVES. You'll cavitate at just the speed you'll need to safely run thru bigger stuff like 6 ft. and above 28-32 MPH and not beat the snot out of the boat and it's crew.
If you're still determined to try them, use a 5 or 6 blade prop, probably in the 28 to 29 pitch range for the outside drives and 29 or 30 inch on the center drive (assuming 1.50 ratios). Try to find a diameter of greater than 14.5, more like 15 inch diameters.
Good luck, let us know.
Steve David
09-15-2008, 06:36 AM
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Shorties 46
Thank You Steve for the precious advise, I did not thiink that the use of the shorter drives would cause these problems. But I would ask you whit the standard XZ drives 1.5 ratio, What pitch would you recommend using MAXIMUS PROPS ?
Also, The 46SC is factory mounted whit a Bravo 1, 30 pitch prop on port side, and 32 pitch center & stbd side Bravo 1 prop is this normal ? or specific to this type of hull ?
Also, The 46SC is factory mounted whit a Bravo 1, 30 pitch prop on port side, and 32 pitch center & stbd side Bravo 1 prop is this normal ? or specific to this type of hull ?
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09-23-2008, 01:14 AM
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Fantom,
Sorry for the tardy response, we had our final Unlimited Hydro race this weekend in San Diego.
The Maximus is a good prop for bow lift. As has been stated, the more efficient the prop (less slip) the more constant load on the drive system and the greater chance of drive failure (BTW all Merc drives of the XR variety will ultimately break with anything over 400 HP) As for differing pitches on the same boat. Generally on a triple the center drive has the highest X dimension in relative terms, and thus an easier swing thru the water. Also the outboard prop that is rotating opposite of the center will tend tend to steal water from the center prop and allow higher RPM, hence the larger pitch of the center drive. Hope this helps,
Steve
Sorry for the tardy response, we had our final Unlimited Hydro race this weekend in San Diego.
The Maximus is a good prop for bow lift. As has been stated, the more efficient the prop (less slip) the more constant load on the drive system and the greater chance of drive failure (BTW all Merc drives of the XR variety will ultimately break with anything over 400 HP) As for differing pitches on the same boat. Generally on a triple the center drive has the highest X dimension in relative terms, and thus an easier swing thru the water. Also the outboard prop that is rotating opposite of the center will tend tend to steal water from the center prop and allow higher RPM, hence the larger pitch of the center drive. Hope this helps,
Steve
