Max Speed Attainable with These Fgures

[Ron Hill]

LOL!!!!!!! If anyone could ever make a prop, or vessel as well for that matter, that will run in water at 100%, they would be BILLIONAIRES OVERNIGHT!!!!!! Hell, they'd rule the industry from powerskiffs to battleships.
There can be close calls (90+%), but 100% wont ever happen.

I had a 15 X 30 on my V-8 Johnson than ran through the kilo at 118 MPH. At that time, we figured it was 110% efficiency. I concluded, that Mercury didn't include the CUP as part of their pitch.

[pdt]

champ you have said it perfectly, thank you very much.

I was losing the will to live,.

im so glad to know there is someone else out there on the forum who truly understands physics.

once again thanks


now let the thread close.

[MWhite]

I don't know what all the hen-house squabble is for in reference to math. MATH DOESN'T LIE AND THE LAW OF PHYSICS DON'T CHANGE FOR NOBODY!!! All the pitch/RPM calculations are for is to determine prop slip.... AFTER TESTING!!!!!!!!!!!!!!!!
THAT IS IT!!!! Beyond that, you either have a good prop or some peice of crap that somebody carved on or cobbled up or a bad set up overall. PERIOD!!!

The GPS don't lie either and it puts pen and paper theory out the window. PERIOD.

[Ron Hill]

I'M ONLY STATING A FACT THE SMART PEOPLE ON THIS THREAD CAN TELL WHAT YOU ARE WEARING BY THAT ENDLESS STREAM OF BULL**** THAT YOU KEEP GOING ON AND ON ABOUT. HAVE YOU EVER BEEN IN A RACE OR RACE BOAT/ if you have prove it post pictures and speeds.Let us see how fast you can make a boat go.

I help several high schools with their Solar Race boat and three coleges with their solar race boats. I laugh, not openly, but one thing all these "KIDS" have in common is they have never driven a boat, never raced a boat, never been to a boat race and none of their teachers have driven a boat, or been to a boat race........But the colleges all have "COMPUTERS" to help them design boats. AND they all look about the same......thye look like submarines.

Chad and I had a "DISCUSSION" about my two motors, one prop theory. He said, one motor wasn't turning 7,200 RPM's....I never had a tach in the boat, so he might have a point, but I told him he was wrong.

I said, "Explain this. My OLD "C" Runabout ran 56 MPH on a good day. Same prop on my new boat ran 59-60 MPH. In my mind, my 30-H was turning 7,200 RPM's on both boats"

[pdt]

Mike go ask the other fellow to explain it to you.
because you will never belive me, even if I was standing on a stack of bibles with jesus Christ next to me backing me up.

[pdt]

ron you wrote

I said, "Explain this. My OLD "C" Runabout ran 56 MPH on a good day. Same prop on my new boat ran 59-60 MPH. In my mind, my 30-H was turning 7,200 RPM's on both boats" .....



how did you come to the idea of 7,200 rpms rons,

1/ did you just pick that figure out the air ?
2/ listen to the engine and could hear it was exactly 7200 ?
or
3? have a good idea due to the figures you had worked out with pitch ,gear ratio and speed reached ?

[champ20B]

I had a 15 X 30 on my V-8 Johnson than ran through the kilo at 118 MPH. At that time, we figured it was 110% efficiency. I concluded, that Mercury didn't include the CUP as part of their pitch.

Well then, you simply found that the figure given by the manufacturer wasn't right. It was inaccurate. The old pen and paper showed you that, so you went to see why it was!!

THANK GOODNESS FOR MATH (ESTIMATION FORMULAS)!!!!!!

[champ20B]

The GPS don't lie either and it puts pen and paper theory out the window. PERIOD.

What?????? No No No. One uses the formula to give a direct speed that is only "theoretical". One then takes the boat and records the ACTUAL SPEED ON THE "GPS". From these two speeds, one can see what the slippage is, or in Ron's case, if the pitch given is accurate or not. That's all it is and there is nothing wrong with it. Its a good thing!!

[champ20B]

In physics, a solid (ie; propeller) will displace a liquid (ie; water). Water is not stable material as a propeller in structure. Water will not stand up. It can be propelled or swam through but never tracked like solid ground. That is why 100% wont happen.

[HankFrazier]

in physics, a solid (ie; propeller) will displace a liquid (ie; water). Water is not stable material as a propeller in structure. Water will not stand up. It can be propelled or swam through but never tracked like solid ground. That is why 100% wont happen.

i have got a pretty good reputation when it comes to testing and tuning race boats and motors i do a lot of my own custom stuff. I also do a lot of custom work for other people.i have the fastest flat bottom aluminum boat that i have ever seen.and i have come to the conclusion that i am no where near smart enough to hold a conversation with pdt or champ 20b much less try to talk about how to make a boat go fast. I've only been doing it 35 years and as far as i can see ya'll can do in 10 minutes with pen and paper what it has taken me a life time to figure out.