On Wed, 24 Nov 2004 13:38:37 GMT, Short Wave Sportfishing
wrote:
On Wed, 24 Nov 2004 07:46:41 -0500, Dave Hall
wrote:
On Tue, 23 Nov 2004 18:09:33 GMT, Short Wave Sportfishing
wrote:
This morning, while burning some old gas in the Ranger, I took the
following sequence of pictures at various speeds.
Couple of comments:
Nice lake. Where is it?
Webster, MA. Lake Chargogagogmanchaugagogchabungamungagog.
How do you handle the boat single handed with no dock at the ramp?
What - you can't launch without a dock? What a wimp... :)
Simple, boat comes off the trailer, bow line attached to trailer, pull
boat to the side, beach same. The boat has a keel guard.
I guess I'm guilty of being a wimp then. I can't get on my boat
without having access to the stern, so beaching it at this time of the
year is not the best way to stay warm and dry.
I also don't have a keel guard and I have an aversion to scratching up
the nice shiny gelcoat.
I'm not used to seeing the tach so high and the speedo so low. At 5000
RPM, I'm touching 70 MPH, so if I saw that, I'd think my prop was
slipping or severely ventilating.....
It's not.
I know. It's just a radical departure from the "norm" that I'm used to
seeing.
Your boat was planing between 2000 and 3000 RPM judging from the shape
of the wake. My experience has shown me that the wake develops a white
frothy churn as it starts to rise up out of the water (about 2000 RPM
on my boat). The froth eventually retreats to a large "hump" almost
resembling a rooster tail just before fully on plane. As the wake
finally flattens, that is the point that you are officially
"on-plane". At that point your MPH will jump up sharply with a slight
rise in RPM (due to the load lessening).
Mine is pretty much the opposite. At 3k, the boat leaps up to 4k and
the speed goes from 20/23 to 30/35 and we're off to the races. It's
quite interesting to watch and experience.
See my post to DSK about the prop thing.
Your prop experiences are somewhat odd. Every inch of pitch should
change engine speed about 200 RPM. But more importantly, if the engine
is propped at the point where the sum of torque and H.P. are the
highest (Usually near the top of the rated RPM range), you should see
a greater speed than the same style prop with a lower or higher pitch.
It's strange that your speed remains constant while RPM is all over
the place. I would think you should see SOME difference in speed.
Also, higher rake props will add bow lift and allow you to trim
farther up, which should result in less wetted hull surface(drag) ,
and a corresponding increase in speed and RPM.
Setback engine brackets allow the engine to be placed in an area of
less turbulent water, which then allows you to raise the engine
height, and thereby reducing gearcase drag, which also translates to
higher speed.
I can slowly push my boat up to 3000 RPM and not be going more than 15
MPH initially. Once it goes "over the hump", the speed will quickly
rise to about 40 MPH, and the tach will jump to about 3400 RPM. When I
back it back to 3000, the speed will hold at 38 MPH. I can drop it
back to about 2300 RPM, and about 22 MPH with the tabs down before it
falls back off plane.
I can't hold plane much below 20.
I can't either. If not for the trim tabs, I wouldn't be able to go
much lower than 25. Then again, my boat isn't designed for slow
speeds.
Dave
|