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  150 Sport, 60HP 4-Stroke BigFoot EFI, 13" Black Max Prop

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Author Topic:   150 Sport, 60HP 4-Stroke BigFoot EFI, 13" Black Max Prop
Moe posted 07-10-2004 11:10 PM ET (US)   Profile for Moe   Send Email to Moe  
Since we wanted to start carrying a spare prop, and had loaded the boat to the point max rpm at WOT had dropped to 5,400 rpm with the factory 13-7/8" X 15" pitch Black Max prop, I bought a 14" X 13" pitch Black Max prop to try. We just got our new Garmin 178C color GPS/fishfinder mounted this week, so I had a chance to get some numbers with the 13" prop. Local small lake, almost no wind or waves. Higher speed runs were done in opposite directions with the same results. Slip numbers are from Jim Hebert's most excellent Propeller Calculator with 2.33:1 gearing (set for 2-digits, but I rounded the results to one).

775 rpm = 2.5 mph, 39.0% slip (idle)
1500 rpm = 5.0 mph, 36.9% slip
2000 rpm = 6.3 mph, 40.4% slip
3500 rpm = 15.5 mph, 16.2% slip (on plane)
4000 rpm = 19.0 mph, 10.1% slip
4200 rpm = 20.0 mph, 9.9% slip (70% of redline cruise)
5000 rpm = 25.1 mph, 5.0% slip
6000 rpm = 31.4 mph, 1.0% slip
6033 rpm = 31.8 mph 0.2% slip (WOT)

This was with the bimini in use, and all but about 125 lbs of the weight we carry when fishing, i.e. one cooler vs two, no 44 lbs of ice in that cooler, no bait bucket with 3 gallons of water, and only 1.5 tanks of fuel. Lots of other gear though, including the Porta-Potti with 3 gallons of water.

Compared to the 15" prop, the 13" feels and sounds like driving around in a truck with 4.30:1 gearing vs one with 3.73:1 gearing. I might get used to that. It feels like it pops onto plane quicker, but it wasn't bad with the 15". It does seem to hold plane at maybe 1-2 mph lower than the 15" but I have no data on the 15". It is turning about 200-300 rpm more than the 15" where it drops off plane, and I'd guess it's about 4 mph slower at 4200 rpm cruise. Might get a chance later this year to gather data on the 15".

Just some more data for the forum...

Moe posted 08-16-2004 08:07 AM ET (US)     Profile for Moe  Send Email to Moe     
Just to follow up on this thread for the archives, I've swapped the props back and forth on different waters. Here is the performance we're getting with the factory 13-7/8" X 15" pitch prop:

775 rpm = 2.5 mph, 47.1% slip (idle)
1400 rpm = 5.0 mph, 41.4% slip
2000 rpm = 6.5 mph, 46.7% slip
3200 rpm = 15.8 mph, 19.0% slip (barely on plane)
3600 rpm = 20.0 mph, 8.9% slip
4000 rpm = 22.7 mph, 6.9% slip
4300 rpm = 25.0 mph, 6.3% slip
4500 rpm = 26.0 mph, 5.2% slip
5000 rpm = 30.0 mph, 1.6% slip
5200 rpm = 31.8 mph, -0.3% slip (WOT)

Going from the 15" prop to the 13" prop:

At 20 mph, rpm has increased by 600, from 3600 to 4200

At 25 mph, rpm has increased by 700, from 4300 to 5000

At 31.8 mph max speed, increased by 800, from 5200 to 6000

The max speed numbers are with the cooler mounted at the bow, which helps the bow cut through chop without having to trim down. With the cooler in the stern area, speed goes up to 33.3 mph, and rpm goes up to 5400 with the 15" prop. I run the 13" prop WOT with the cooler in the stern, but I suspect max rpm will get close to the first stage of the two-stage rev limiter.


Moe posted 08-16-2004 08:10 AM ET (US)     Profile for Moe  Send Email to Moe     
I said:

I run the 13" prop WOT with the cooler in the stern

I should've said:

I HAVEN'T run the 13" prop WOT with the cooler in the stern

Jarhead posted 08-16-2004 08:29 AM ET (US)     Profile for Jarhead  Send Email to Jarhead     
It might be interesting to see what a 14P prop would do?
Moe posted 08-16-2004 08:45 AM ET (US)     Profile for Moe  Send Email to Moe     
Yes, it would. The 13" and 15" are aluminum Black Maxes. The 14" would be a stainless Vengeance, which I understand are uncupped duplicates of the Black Max design.

From what I hear, Whaler is now shipping the 150 Sport and 60HP BigFoot with a 14" Vengeance.

I'd suspect the 14" rpm numbers would be somewhere about midway between those I've recorded, with maybe 0.5-1 mph more top end due to the thinner stainless blades.

BTW, these top speed numbers are with the motor trimmed up past vertical. With the cooler aft, it's noticably out past vertical, and with the cooler forward, it's even further out.


Jarhead posted 08-16-2004 02:21 PM ET (US)     Profile for Jarhead  Send Email to Jarhead     
The reason I brought it up Moe is the 25hp Merc on my 130 Sport came with a 11P prop. The prop is great for a load with extra people on board but over revs at WOT with just me.

I tried a 13P but it was a real dog out of the hole and WOT RPM was too low.

A 12P worked out the best for just me and the normal fishing load, also cruises better than the 11P.

The 11P goes on for extra passengers. One inch made a neck of a difference. :)

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