SBH2OMan
Well-known member
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)
Here's the time to get on plane with the three scenarios:
Fuel Economy (statute MPG)
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)
Here's the time to get on plane with the three scenarios:
Fuel Economy (statute MPG)