Need Help with Prop and Motor Height

[mrv9teen]

Hey Guys,

I am trying to optimize my setup and I am running into a few unexplained problems that are starting to puzzle me. I have tried 3 different props so far and reading many forums and pages I am seeing others with much better results and setups so I am looking to the group for some help in pointing me in the right direction.

Boat Information
2002 Stratos Prostar 20XL
Yamaha VMAX 200 OX66 Motor
2 x 10ft Minn Kota Talons on the Back with Aluminum Talon Brackets (Mounted as High as I can go)
8" Pro Hi Jacker Manual Jackplate (Motor only has 1 hole higher I can go and Jack Plate is adjusted as high as it can go. When I measure the prop shaft to lowest hull pad I get about 4 1/2 to 5" but the highest I can go is only one more hole up on the motor to the Jackplate)
Minn Kota Ultrex 80#
Lowrance Carbon HDS12 on Console with 3D StructureScan Transducer
Garmin 1242 XSV on Helm with Livescope and GT2 Transducer
Hydrofoil SE Sport 300 (For help in holeshot and staying planed at low speeds)
Other weight considerations - 2 people, Empty Livewells, 15 Gallons of gas, about 150lbs of tackle and other stuff.

Here is what I have tried so far...

Mercury Tempest Plus, 25" Pitch, 3 Blade.
WOT - 5200-5300 RPM
Top Speed - 62mph

Quicksilver Nemesis (Aluminum), 23" Pitch, 4 Blade, 14" Diameter (8M0055537)
WOT - Over-revved very quickly and flew out of the hole.
Top Speed - Don't even know because it over-revved probably around 45 mph.
This prop experience was very strange because it flew out of the hole great but then over-revved so fast that it actually felt like to was spinning. Over-revved before I even hit 50mph. This was a brand new prop with a brand new hub. I even re-installed it to try it again thinking maybe I did something wrong the first time I tested it but it did the same thing. This prop was actually recommended by Mercury when I gave the specs of the Tempest Setup.

Michigan Wheel Ballistic, 25" Pitch, 13.75" Diameter, 4 Blade. (Part #435936)
WOT - 4900-5000 Trimmed as high as I could go
Top Speed - 63mph
This prop has higher mph but less RPM, the holeshot was about the same as the tempest. Didn't notice much of a difference in bow lift of performance in general.

Next Testing will be a Quicksilver Q4 in 23", 4 blade that I just bought. It hasn't come in yet but I am hoping it works out well. I really want to be at the 5800rpm range for this motor. I see guys on here with this hull posting how they are running 71-74 mph with 25 and 26" props but I just don't know how they are doing it. HELP!!!! lol.

I fabricated a holeshot plate to block some of the water from flowing up into the jackplate on take off and noticed a little bit of a improvement in the holeshot with no changes afterwards but from everything I have read it sounds like my motor is too low but I don't have anymore adjustment outside of the 1 hole left on the motor to bring it up on the jackplate. I don't know how people are getting them up to the 2.75 to 3" range. I know the talons have a negative effect on performance but it shouldn't be that much.

Thanks in Advance,
Matt

[mactlman]

24p bravo1 fs is what I have and it works great i ran 69-70 before talons and doubt you will get there either. most likely 65-66 if all is perfect

[Nightmare]

That remaining set of motor mount holes will gain you 3/4" if I remember right.

With that said, it still won't get you in the zone you need to be - if you're measuring things out correctly (4.5-5").... There shouldn't be a 1/2" of slop in that measurement.

In either case, NO prop change is going to compensate for a P2P that far off. How much leg you have in the water creates a profound amount of drag.

If you insist on pursuing the prop issue, at least move the motor up that last set of holes. You may have additional mounting holes left on the jp-to-hull set.

Whoever suggested the aluminum prop should be smacked with a ball bat... They're fine for an onboard back-up but have zero performance aspects and the blades flatten out under power/load just like you saw your rpms head to the sky.

Good luck.

[mactlman]

someone is selling him what they have instead of what prop he needs??? aluminum??????????????

[Coach185]

My 2003 Stratos 185 with Yamaha150 is set at 4.625 currently. Holeshot is fine, not great just fine. With your jackplate positioned as you describe i would like to hear how you went about measuring your PtP. Nightmare is correct in that you shouldn't have 1/2" range in the PtP measurement.

Trailer on flat surface
Level Bottom of boat
Level prop shaft or second best level catavation fin.
Measure flat surface to lowest flat surface of boat
Measure to center of prop shaft (center drilled area at end of shaft)
Do the math come up with a solid number
Is this how you measured your PtP?

I picked up a Javelin379 a few months ago. Measured PtP came up with over 5". Javelin389 takes one look at the pic i posted and says no way is it 5". Measure it again and do a better job.
Trailer wasn't on flat surface
Boat wasn't level
Prop shaft wasn't level
End result 3.5 PtP

[mactlman]

http://www.bbcboards.net/showthread.php?t=83680

[tdt91]

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