Pescadora
Seaman Apprentice
- Joined
- Oct 25, 2006
- Messages
- 37
Mercury was not kidding when they said their new X-7 alloy prop rewrites the laws of physics. I played with a number of props in my new rig this year, but the Enertia 14.82x16p beat them all.
Here's some numbers.
In my case, the Merc prop selector was right on. However it took me a month
or so to discover this propellor needs to be trimmed up quite a bit higher
than the stock prop to get the most out of the installation.
The stock prop (Yam F150 - Crestliner Mirage 2000) would blow out when the
gauge passed the half-way mark on the trim indicator. This is with motor
mounted on the second hole. My operational altitude is 3000ft, which as a
lot of effect on a normally aspirated four-stroke motor. Stock prop would
give almost 30mph @ 4500rpm and 34.5mph on top end @5400. Hole shots with
the 15"x17P were good. The prop would not stay hooked up in a top speed
turn, even a moderate turn. You had to cut the throttle to hook up again.
The 14.82"x16P Enertia behaves much better. Trimmed to the halfway mark, it
gives 31.5mph @ 4500rpm and 39mph on top @ 5500. This baby will not blow
out unless you cut hard right and then hard left immediately afterward. It
re-engages right away, without chopping the throttle. When I decided to
trim up some more, I discovered even more speed, albeit with a little more
touchiness in turns. At the three quarter mark, the big Crestliner is
nicking 41mph at 5600. Any more trim gives more RPM with a slight loss in
speed. So 3/4 up is the definitely the limit. I suspect at sea level I
would pull 58-5900rpm and probably another 3-4mph. All speeds are GPS.
Check the slippage calculations (2.00 gearcase). 21% on the aluminum prop.
3% on the Enertia. Amazing.
Hole shot is still good. Maybe just a touch slower coming off idle. This
could be the weight of a steel prop versus aluminum. Or maybe I should try
some PVS aperture plugs. Next year.
The X7 has be some kind of miracle prop to give better everywhere. Kinda
goes against the laws of physics.
Here's some numbers.
In my case, the Merc prop selector was right on. However it took me a month
or so to discover this propellor needs to be trimmed up quite a bit higher
than the stock prop to get the most out of the installation.
The stock prop (Yam F150 - Crestliner Mirage 2000) would blow out when the
gauge passed the half-way mark on the trim indicator. This is with motor
mounted on the second hole. My operational altitude is 3000ft, which as a
lot of effect on a normally aspirated four-stroke motor. Stock prop would
give almost 30mph @ 4500rpm and 34.5mph on top end @5400. Hole shots with
the 15"x17P were good. The prop would not stay hooked up in a top speed
turn, even a moderate turn. You had to cut the throttle to hook up again.
The 14.82"x16P Enertia behaves much better. Trimmed to the halfway mark, it
gives 31.5mph @ 4500rpm and 39mph on top @ 5500. This baby will not blow
out unless you cut hard right and then hard left immediately afterward. It
re-engages right away, without chopping the throttle. When I decided to
trim up some more, I discovered even more speed, albeit with a little more
touchiness in turns. At the three quarter mark, the big Crestliner is
nicking 41mph at 5600. Any more trim gives more RPM with a slight loss in
speed. So 3/4 up is the definitely the limit. I suspect at sea level I
would pull 58-5900rpm and probably another 3-4mph. All speeds are GPS.
Check the slippage calculations (2.00 gearcase). 21% on the aluminum prop.
3% on the Enertia. Amazing.
Hole shot is still good. Maybe just a touch slower coming off idle. This
could be the weight of a steel prop versus aluminum. Or maybe I should try
some PVS aperture plugs. Next year.
The X7 has be some kind of miracle prop to give better everywhere. Kinda
goes against the laws of physics.
