top speed 21 daytona 1985

[speed]

should i be happy with 74.4 mph running a 260 merc at 4500 ft elev. 14 inch set back 24 pith prop 2 people 10 gallon gas ?

[stoker2001]

that elevation can be akiller,so can two people (depending on weight);) 21 daytonas can be real heavy too.IMO your not to far off considering elevation.under perfect setup and conditions i think 95 is all with 260 power

[stoker2001]

of coarse that would be with 28 or taller pitch

[O/B Dude]

2-3 mph loss for every 500 feet of addl altitude on most boats. Smaller motors and larger boats feel it more than other rigs. Your rig, properly set up should run in the mid 90's at sea level. Subtract 18 mph using 2 mph as a rule of thumb, and thats right about where you are now. I dont think you will get much more out of it but try different props and engine heights. I would also try running a 26 Mazco RE 4. 4 blade props work great for high altitude boats. Other 4 blade props work well as long as they are 14.5" diameter or larger and have bow lifting abilities. Stay away from smaller diameter props whether 3 or 4 blade. 4 blades allow higher transom heights and will let you trim out a bit further to help fly the hull. At high altitude, my RE4 is the fastest prop I have. At lower altitude my 3 blades are a bit faster.

Hope this helps.

[speed]

thanks for the replys. how much more would i see with a 4 blade ? i would like to get to 80 mph the motor is only turning 7000 rpm.

[O/B Dude]

Hard to say. A 4 blade doesnt make the boat go faster, as much as it allows you to raise the motor higher and trim out a bit further to free the hull. Thin air not only reduces engine power but also produces less lift in the tunnels. I would bet 3-4 mph would be a good bet if you raised the transom height to take advantage of the extra blade in the water. See if you can borrow one. You never know...may be the ticket or may run run crap. Different rigs like different props.