Testing Powertech OFS4 vs. Solas Titan 3 and Permatrim

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SBH2OMan

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Good evening gents,

In my ever-expanding search for better performance and fuel economy, I decided to try out a 4-blade prop to get more "stern lift" and improve planing efficiency. My local prop guy (Valley Propeller Service in Ventura, CA) recommended the Powertech OFS4 prop in a 13p.

Part of the testing also including a "before and after" by removing the Perma-trim (he insists that the Permatrim will hinder performance)

Let me start by stating that I now have extensive EMPIRICAL data that tells me that the Perma-trim actually does very little to help with performance or planing efficiency, at least with a 4-blade prop on my particular boat. The only effect it had on planing was to reduce the average time from a dead stop to planing by about 0.3 seconds (yes, thats 1/3 of 1 second). I ran about 25 "jack rabbit starts" where I was sitting still on the water and then MASHED the throttle, doing some trials by "feel" (me judging when we were on plane by the feel from the helm) and some by my assistant watching the spray pattern behind the boat. Both were pretty much identical. The Permatrim had NO EFFECT on the minimum planing speed, nor the RPMs required for planing. I'm now feeling kinda dumb for drilling a bunch of holes in my lower unit, frankly....

Note that the sea state today was IDEAL for prop testing.
Dead flat calm, light and variable winds, and about 58º air temp. Fresh bottom paint (literally just splashed her today). No gear or ice on board and only 50 gallons of fuel with two guys. (a very light load!)

Vessel is 1993 2320 EC with Honday BF225 engine with 600 hours. One thing I noticed today is that when it was new, it would wind up to 6100 rpms, but today we could only get her to kiss 5,800. There was an ECU update about a year ago, and I wonder if that has something to do with it. Other numbers compare very closely to previous data I've recorded for the Solas Titan 3 prop.

Any way, on to the cool graphs... Needless to say, the search will continue for a better prop - this one was worse in just about every category. Planing efficiency, fuel efficiency, top speed, you name it - it was worse all around!

Heres a comparison of SOG (statute MPH)

2016-01-11_19-34-49.png


Here's the time to get on plane with the three scenarios:
2016-01-11_19-40-51.png


Fuel Economy (statute MPG)

2016-01-11_19-42-12.png
 
Brent, I have no explanation for the less than desirable results that you had with the Permatrim. I know that on my 2120 it has been a tremendous improvement. I didn't graph the results but I can say for sure that I have less bow rise getting on plane, quicker on plane, and hold a much slower plane speed. I'd say minimum plane speed was reduced by about at least 3mph. My 2120 also had a porpoising issue that was also corrected by the Permatrim. I'm very surprised that it didn't work for you. I'm also surprised by the performance numbers that you have posted with your set up. They seem lower than most with similar HP. Maybe it's the extended cabin or the bracket that makes the difference? I can actually say the Permatrim made a bigger difference than the 12 X 18" tabs did for me. Interesting? With Permatrim and tabs 1/2 or so deployed, I've held plane as low as about 15mph and about 2500 RPM's. I have the 17T Yamaha 3 blade black steel prop.
 
Yea here are so many variables that it's hard to draw good conclusions. I can definitely say that the permatrim doesn't do much for us, but you never know for sure until you try. I was convinced this 4-blade prop would be a huge improvement in low speed planing and cruising economy. NOPE! :)
 
I have the stock trim tabs (12x12 I think). Motor is mounted in 3rd hole down.
 

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