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Right Prop?

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get1on

New member
I have a 25' parker Sport cabin with the deep vee hull. Running a honda 225 on a stainless marine bracket. I currently have a SS 15 x 15 prop and am capable of 30 mph at WOT burning 16 gallons an hour. Does anyone have any insight as to if there might be a better prop to use? It takes a little longer than Id like to get on plane and seems to be really bogged down in the mid RPm range.
 
I would highly recommend that you talk to the guys at PowerTech props, they will match your engine directly to your hull.

This is what you will need to provide them:
Hull length
Hull material
Boat Weight
Boat Manufacturer
Boat Style (deep V-Hull)
Planing Fin (yes/no)
Jackplate/Setback Plate (yes/no)
Trim Tabs (yes/no)
Motor Brand
Motor HP
Motor Year
Current Prop Brand
Prop material
Prop Pitch
Number of blades

also
Hole Shot - good/Ok/poor
Mid-Range Acceleration - good/OK/Poor
Top End Speed
RPMs at Top End
What speed does it plane at
What speed will it hold plane
Porpoising (yes/no)
Chine walk (yes/no)
Blowout (yes/no)


As you can see it is not easy but they matched me with a prop in 5 minutes for my Everglades 211cc / Honda BF225 that was a 15 pitch, no loss in top end speed compared to the 19 that was on it but now I am at least getting 5900 RPM at WOT.
 
You sure that Parker is a deep V? Didn't think they made a deep-V, just modified-V. I can stand to be corrected on that.

The key to the 225's performance is to make sure your WOT is right at 6000 rpm. You need to find a prop that will do that.

I have the modified-V C-Hawk 25 DLX which is the exact same hull as on most of the Parker 25's. I'm running a 14.25 X 15 SS 3-blade Honda prop, and I'm quite pleased with the performance. At WOT 6,000 RPM, I'm getting right at 40mph on flat water, but get slight porpoising. So I drop the trim tabs one notch, which gets rid of the porpoising, but drops the speed to about 38.5 mph. Unfortunately, my fuel flow meter says I'm chewing up 20 gallons per hour at WOT.

So, you may be slightly overpropped. See if you can borrow a 14.25 X 15 and see if that doesn't help the performance and give you the 6000 rpm you should have.

Last year I kept a log of GPS speed and fuel consumption at different RPM's ranging from idle to WOT. Then I entered those into an excel spread sheet and did line charts. My best efficiency was 4600 rpm, where I could cruise at 29 mph while using slightly over 10 gallons per hour.

Hope this helps.
 
It is a 21 degree DV model not the 16 degree MV. I went out last night and was able to turn the 225 up to 6200 RPM before it went flat at 18 GPH and 32 MPH so I'm wondering if I just need to have my current prop cupped to a 15 x 17 I had about 120 gallons of fuel in the tank and I have a 187 gallon Capacity so I was about 3/4s on the fuel weight.
 
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Okay with the Parker DV - I stand corrected. I learn something new every day.

Your RPM's are good and your fuel usage is about right for WOT, so at this point I think you need to experiment with props, trim, and possibly mounting height. Seems like you should be getting better than 32 mph. I could be prop slip, which the cupping may help address. Each boat is different.

I assume you have played with different trim angles. I was a little surprised at the trim angle that gave me the best speed at WOT. It was several notches above center. Given how "ass heavy" that C-Hawk is, I expected best performance at center trim or lower.

Also, when the Honda 225 was first set up on my C-Hawk, it was too low. The center of the prop hub should be level with the lowest point on the transom. Then, for every foot of offset from the transom, raise the center of the prop hub 1 inch. I have a 30 inch Armstrong extension, so the center of my prop hub is slightly over 2.5 inches above the center line. That seems to work well for my hull.

Another good check on mounting height is to observe the cavitation plate at WOT. It should be just skimming the top of the water coming off the transom bottom.
 
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