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08-16-2010, 10:42 AM
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#31
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Energy Crisis
 Platinum Member
Join Date: Jul 2006
Location: Rockwood, MI
Posts: 1,288
37 Active Thunder, 28 Apache CC, 12' Thunder Cat, RXP 255's
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To drop or not to drop, that is the question.
Question to ponder on in regards to running at higher speeds and flat water stability. Would it be best to drop the prop shaft depth 1" or ad extension boxes which would result in 1" deeper and cleaner water. I have had recommendations on both and would like to see what the consensus is on the application of both concepts or another way of thinking ? We needed a good technical thread anyway.
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08-17-2010, 12:00 AM
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#32
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Platinum Member
Platinum Member
Join Date: Jun 2001
Location: Michigan
Posts: 3,342
It's how well you go fast
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don't go deeper and not back on that boat! NOT with todays prop tech!!!
__________________
Joe Skrocki
Engineering and Marketing Systems Consulting
joe@gofastjoe.com
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08-17-2010, 07:51 AM
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#33
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Energy Crisis
Platinum Member
Join Date: Jul 2006
Location: Rockwood, MI
Posts: 1,288
37 Active Thunder, 28 Apache CC, 12' Thunder Cat, RXP 255's
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Quote:
Originally Posted by audacity
don't go deeper and not back on that boat! NOT with todays prop tech!!!
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Please explain your thoughts. I have changed from stock Bravo lower to Imco shorty lower with 2" spacer and am curious as to the difference. I used to run Hydros (faster prop) now am running the maximus (still dialing in), the hydros will porpois the boat past 90 mph in smooth water, would this be due to the difference from Bravo lower to IMCO ? Just want to fully understand the difference between the 2 setups.
Last edited by laszlo01; 08-17-2010 at 07:58 AM.
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08-17-2010, 11:00 AM
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#34
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Platinum Member
Platinum Member
Join Date: Mar 2002
Location: Indiana
Posts: 1,904
2004 37 ActiveThunder
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It's my understanding that these things don't like the imco case in a standard length. scarab98 (Tom) was having the same problem with his. I don't know they may be fine as a shorty. Some of the hop may be traced to the prop diameter. Have you run it without the spacer?
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08-17-2010, 11:42 AM
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#35
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Platinum Member
Platinum Member
Join Date: Jul 2005
Location: Houston, TX
Posts: 1,130
2007 37 AVH Active Thunder
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Quote:
Originally Posted by laszlo01
Please explain your thoughts. I have changed from stock Bravo lower to Imco shorty lower with 2" spacer and am curious as to the difference. I used to run Hydros (faster prop) now am running the maximus (still dialing in), the hydros will porpois the boat past 90 mph in smooth water, would this be due to the difference from Bravo lower to IMCO ? Just want to fully understand the difference between the 2 setups.
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This is the issue with modifing the boat after market. Pat set the step height and bottom config based on power. You bottom was set up for 525's and bravo's. I would look at what pat did with RadioActive and Thunderstruck. They had simular power and drive set up. BTW full round ear props are tough to run at those speeds so is a full length drive versus a shorty.
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08-17-2010, 12:27 PM
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#36
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Energy Crisis
Platinum Member
Join Date: Jul 2006
Location: Rockwood, MI
Posts: 1,288
37 Active Thunder, 28 Apache CC, 12' Thunder Cat, RXP 255's
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Quote:
Originally Posted by crb76
This is the issue with modifing the boat after market. Pat set the step height and bottom config based on power. You bottom was set up for 525's and bravo's. I would look at what pat did with RadioActive and Thunderstruck. They had simular power and drive set up. BTW full round ear props are tough to run at those speeds so is a full length drive versus a shorty.
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Hull runs 112 so should not be an issue. LOL Thread was ment more to be a technical input and open discussion for those of us who like to play with prop drive and HP settings to get the most out of our boats, working with BBlades to dial it in and I can tell you the boat and Hull loves the HP, just mearly looking to discuss the various options as well as secrets I may have not considered. I am running a bravo top with IMCO shorty and 2" spacer for initial setup, testing BBlades Maxi props and a custom set as well this afternoon. Here is a pic for the guys that sent me a PM request.
Last edited by laszlo01; 08-17-2010 at 02:43 PM.
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08-18-2010, 04:38 PM
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#37
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Energy Crisis
Platinum Member
Join Date: Jul 2006
Location: Rockwood, MI
Posts: 1,288
37 Active Thunder, 28 Apache CC, 12' Thunder Cat, RXP 255's
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Update, long tube 5 blade props plane fast with 1500 to 2K rpm with drives tucked in and half tabs, no prop slip at all and snap on plane, zero prop slip in hard turns at 70 mph and great cruise speed of 72 MPH @ 4200 rpm as well as awesome mid range punch (will put you in the seat). The IMCO shortys with 2" spacers like about 2 clicks positive trim and no porpoise across the rpm range in to the mid 90's, neutral or negative trim caused porpoise with the test setup on the IMCO's. This was under flat calm no chop conditions, more to follow......
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08-18-2010, 04:48 PM
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#38
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Platinum Member
Platinum Member
Join Date: Mar 2002
Location: Indiana
Posts: 1,904
2004 37 ActiveThunder
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Are those 15.5 inch Maximus?
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08-18-2010, 05:24 PM
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#39
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Energy Crisis
Platinum Member
Join Date: Jul 2006
Location: Rockwood, MI
Posts: 1,288
37 Active Thunder, 28 Apache CC, 12' Thunder Cat, RXP 255's
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15 and 5/8 32's as a base line, now we know where to tune to. Hydro is also doing a coustom long tube P5X for us as well.
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08-18-2010, 07:14 PM
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#40
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Life is good lb:)
 VIP Member
Join Date: Aug 2004
Location: Paducah KY KY Lake
Posts: 3,525
39 Lip-Ship Cigarette 700 Zuls
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Quote:
Originally Posted by laszlo01
15 and 5/8 32's as a base line, now we know where to tune to. Hydro is also doing a coustom long tube P5X for us as well.
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dia too big .
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