We picked up a matched pair of new Nissan 6hp 4 strokes for Ariel #45 and Commander #105 .
Will run them side by side with various props to determine best pitch to push boat .
55lbs of sweet quiet nearly clean propulsion.
We picked up a matched pair of new Nissan 6hp 4 strokes for Ariel #45 and Commander #105 .
Will run them side by side with various props to determine best pitch to push boat .
55lbs of sweet quiet nearly clean propulsion.
I'll be very interested in the outcome. I have the 5hp Nissan 4 stroke (love it - as you said, clean and quiet) and still have the original prop. Thanks,
Dan
Mercury ,Nissan & Tohatsu ( same motor, all made by Tohatsu ) recommend a 8x7 prop on the 6 ,5 & 4hp for displacement hulls ( the 4 comes with it ) the 6 & 5 come with a 'square prop' 8x8 ( actually 7.9x7.9 ).
My mechanic , from his experience , say to skip the 7 and drop to a 6 or 6.5 pitch . He's a licensed Nissan service center and seems to know what's up .
I'm going to buy a 8x7 try it and log with the GPS what it does then have it re-pitched to 8x6 and see what that does .
The following is over-simplified and not scientific;
at 4000 rpm the 8x8 prop is trying to go somewhere between 20 and 30 knots . Not going to happen on an Ariel .
At 4000 rpm the 8x6 prop is trying to go somewhere between 12 and 20 knots .
now you have slip and losses that can be 50% which brings you down to 6knots which is close to hull speed .
All that wasted revolutions on the 8x8 is like spinning the tires on a car , not getting you anywhere fast , the 8x6 is like switching to a fatter tire with more tread ,or a lower gear, that delivers all the bite to the road and propels you forward & stops you when you engage reverse.
The only drawback about downpitching ;
If you use the same motor on a dink or skiff that planes , it wont go as fast because you have shifted to a lower gear .
It only takes 5 minutes to switch props so buy a spare and have it pitched lower .
Mike G
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