Max Speed Attainable with These Fgures

[MWhite]

max possible attainable with these figures would be 61.27 mph at 7400 rpm. with a 1.83 to 1 gear ratio.

if the speed obtained is over 61.27 then the figures given are wrong, as this is maximum possible efficiency.
to get higher speed at those rpm's with this gear ratio would need larger pitch than 16 inch.

.

u did this with figure in the first one with 1.63 or 1.83 mind is 1.83gearcase

[pdt]

1.83 gear ratio.
the original post with 1.63 was typing errors
the post now has correct figures.. 61.27mph is maximum possible.

[MWhite]

max possible attainable with these figures would be 61.27 mph at 7400 rpm. with a 1.83 to 1 gear ratio.

if the speed obtained is over 61.27 then the figures given are wrong, as this is maximum possible efficiency.
to get higher speed at those rpm's with this gear ratio would need larger pitch than 16 inch.

.

Well u off alittle on the first one, but close 60.8 on gps with a fishing wheel is bout where it runs in fishing mode,, the second one is off a lot more.

[pdt]

ok so with the speed figures you gave for the first one, the rig is running at just 1.94% under maximum possible speed.
that means there is no chance of making that better with those figures if they are infact true ( if the prop is definitely 16 pitch) there are people spending millions to get this close.
but there ya go.

now what about the second one ?

7200rpm 20 pitch 1.83 gears = max possible of 74.52 mph. that's providing its 20 pitch.
if your over this speed then again the prop must have more pitch.

but if this is as efficient as the first prop you should be getting 73.07 mph

[pdt]

the efficiency of the 16 prop is probably a lot lot better than you might have thought.
to get a prop working that efficient is incredible, and even ron hill would love to be able to say his props can guarantee this on any boat.

[pdt]

ok
at 7200 rpm with 20 pitch its 74.52mph max possible

at 7300 rpm with 20 pitch its 75.56 mph max possible

[MWhite]

ok so with the speed figures you gave for the first one, the rig is running at just 1.94% under maximum possible speed.
that means there is no chance of making that better with those figures if they are infact true ( if the prop is definitely 16 pitch) there are people spending millions to get this close.
but there ya go.

now what about the second one ?

7200rpm 20 pitch 1.83 gears = max possible of 74.52 mph. that's providing its 20 pitch.
if your over this speed then again the prop must have more pitch.

but if this is as efficient as the first prop you should be getting 73.07 mph

wrong on the second one, phil. sorry bout that u got me running alittle faster than I can run on my ole fishing boat. by 3mph, so there u go your figures aren't always right.

[pdt]

if at 7300 rpm your doing 72.5 mph then you are running at 4.04 % under maximum possible. nobody could complain about that sort of efficiency.
anything under 8% efficiency on a race boat is very good, under 5% is something that many only dream of.

now you see that when someone gives figures like 10 or 15mph more than possible, they are either lying or the figures are wrong.

your boat is fantastic for its efficiency, not many are that good ..

my figures are not wrong, my figures only show what is only the mx possible. there is no way I or anyone else could know what speed below this max you can get.

you should be a very happy chappie with such low percentages,

[pdt]

I wonder what it would do with a mercury 22 pitch bronze 2 blade that used to be run on the old 85hp merc.

[MWhite]

if at 7300 rpm your doing 72.5 mph then you are running at 4.04 % under maximum possible. nobody could complain about that sort of efficiency.
anything under 8% efficiency on a race boat is very good, under 5% is something that many only dream of.

now you see that when someone gives figures like 10 or 15mph more than possible, they are either lying or the figures are wrong.

your boat is fantastic for its efficiency, not many are that good ..

my figures are not wrong, my figures only show what is only the mx possible. there is no way I or anyone else could know what speed below this max you can get.

you should be a very happy chappie with such low percentages,

I got many years of doing this, so formula and theory aren't always right here ok,,,, I've done lots of time testing and tuning and set up plays a major factor on the way a boat will perform as with a prop.,, u can have 3 of the same pitch props and the same diameter and 1 out of the three will be faster than the others, lots of things come in to play, the boat weight, the weight in the boat, wind, temperature, the motor height, tork, just to name afew,, u don't just go throw a motor on a boat and it runs this, I had to work to get it there. I use a gps (not a phone gps) and its pretty accurate, and my boat is a stock production 15/48 weldbilt boat not a race boat.