Originally Posted by Griff (Post 4682526)

It doesn't really work that way. Slip is not wasted thrust. It really doesn't take hardly any hp to spin the prop if its slipping. If you reduce your slip, most likely your rpms will go down when the same amount of throttle is applied.......which is not the same as running at the same rpms. You are thinking that reducing slip is linear with speed and by reducing slip, it will automatically increase speed by the same percentage. If you decrease slip, it will create more load and reduce rpms.

Look at it this way.....Which one is better??? Assume they have the same cruise rpms and speed and handle equally well
Prop 1 runs 72mph at 5000rpms with 22% slip
Prop 2 runs 68mph at 5000rpms with 12% slip

Which one is better???

Originally Posted by Trash (Post 4683251)

And to add to what Griff said, if the boat were tied to shore and put it gear prop slip would be 100% all the time. So slip is not always about the prop, but can also be how hard the hull is working against the prop (i.e. hull drag is high).

Bottom line is wrong prop for the particular application can account for poor slip numbers but also hull/drive setup can impact slip numbers. I believe you have a setup issue if you can only run around with the drives all the way down.

No, I don't have any pics of the boat running at cruising speed or at any speed. The Bravo 1, 28 pitch props that came with the boat SUCKED. Some Formula owners swear by them. I don't. I increased the Diameter of my props to15 1/2" and decreased the pitch to 26P. That Increased my speed by 5MPH and decreased the slip, in some areas by half.

About the fuel. I keep the gas tank full because,
(1) Condensation. I'm in Florida.. It's HOT. It's Humid. Enough said.
(2) Out of the 113 gallons I carry, I may burn 1/2 in an outing.
(3) Practicality. Once on the water, I'm not going to cut short my enjoyment because I have to stop what I'm doing to put damn gas in the boat.
(4) Safety. I'm also not going to run out of gas when the going gets good. Or if I want to extend the day.

NOW for you late comers saying your boat with 1/2 a tank of gas compared to a full tank is, Night and Day. WELL mine is night and day now with the removal of 300 lbs of cast Iron ( That's about a 1/2 tank in weight) and different props. The boat Jumps up on plane now along with the improvements mentioned above. And I'm still carrying a full tank of gas.

And Trash, You forgot to say that if I left my boat home, I'd have 0% slip.

SO again, how can I get the drives out with out losing speed. How would drive spacers effect the geometry?