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To notch or not to notch?

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Old 12-29-2002, 10:37 AM
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Default To notch or not to notch?

Hi!

I have a Phantom 25 offshore hull with a Promax 300. It runs relative wet and need a lot of positive trim .Top speed 78 mph in spring spinning a Tempest 26 at 6.150 rpms. In summer 76 mph at 6.050 rpms.

Currently I run 7,5 inches setback. I have tried 12 inches of setback. The boat was faster, but tailheavy in high seas (despite trimtank in front). Best overall result has been 7,5 inches setback - CMC powerlift + spacers.

When I ran 12 inches I used a seperate stainless steel bracket + the CMC powerlift. Weight in all 170 lbs... in steel.

The boat is a 1985 model and has a classic 24 degree V bottom without a notch. The new 24 feet version has a notched transom of 4-5 inches deep. I consider to cut out a notched transom on the old Phantom. What do you think about this? Then I get easier bowlift without adding extra weight aft. Any ideas would be appreciated.

Cheers and thanks, Toffen -Norway
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Old 12-29-2002, 12:17 PM
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Default Notch vs not notch?

Hi Catmando!

Too much work. Looking forward to the summer. Dreaming about my new second hand Skater 28 w/twin 2.5 Offshore Races engines ready for 2004... A lot of work to do in 2003 on this one. I has to be rerigged completely, but look forward to the day she is on water ready for 115 mph runs!

Meanwhile, I may buy a new Promax 300X or a drop on 300X powerhead from MADEFI pulling 350 HP. This and some mods to the bottom of the ol' Phantom should make 83-85 mph possible...

What do you think about the notch transom idea?

Cheers!

Toffen
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Old 12-29-2002, 03:03 PM
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toff,

go back to the 12" setback and add a fin to the ventilation plate on the motor. you'll get your speed and can fly level with the plate. you can try a commercial plastic one (like a stingray) or go with a custom aluminum plate.

I ran 9" setback on a 16' with a notched transom and couldn't get decent cruise attitude till I added the fin. Course I didnt run it in real big water either.

Just a cheap and easy thing to try before you go to chainsawing the running surface of your boat.
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