Optimum drive height (prop shaft)
#1
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Optimum drive height (prop shaft)
I messured the distance from the bottom of the boat (in front of the drive) to the prop shaft. The distance is 5 1/4 inches on my 38 Fever. Do you think IMCO shorty's would improve speed and handling? Currently running 90 mph with twin 750's.
#3
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Re: Optimum drive height (prop shaft)
Shorties may give you a better top end but not much handling. As you go up there is less skeg in the water so therefore less control in the turns. Put the drives at parallel and run a straight edge to the propshaft. On our 38 race boat the center of the shaft was one inch above the centerline. Short drives may also hurt you getting up on plane. Also the props you use will need updating. As you go up you can turn bigger props. We have several sets of props for sale. Hydros, Herrings, Mercs. Roger 336 214 6900
#4
Re: Optimum drive height (prop shaft)
Roger, did you ever run a non-step 38 Fever? If so, what x-dim did you run? I am thinking that my X-dim is deep and could benefit from being raised without hurting getting on plane. My current x is 18.5"
Thanks, Todd
Thanks, Todd
#5
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Re: Optimum drive height (prop shaft)
No, ours has steps. I would go up two inches and then if needed you can add 1/2 or 1 inch spacers. I would also use Imcos because they are faster than Merc. sportmasters. We used Imcos to set the record this year at 112.025 with stock 525's. Keep an eye on your water pressure though because going up too much can be a problem. Does your boat have low water pickups on the drives? If you go up always remember in turns your skeg is not as deep, so be careful. Roger
#7
Re: Optimum drive height (prop shaft)
Thanks Roger,
I have had issues with extremely high water pressures and installed pop-off valves to help eliminate the problems. This was with standard bravo pickups. Will have to see what the outcome is with shorties.
Todd
I have had issues with extremely high water pressures and installed pop-off valves to help eliminate the problems. This was with standard bravo pickups. Will have to see what the outcome is with shorties.
Todd
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Re: Optimum drive height (prop shaft)
Jan 2004 issue of power boat mag tested 35 lighting with 650hp mercs and sport master shorty 1 inch spacers 1.5 gears 37pitch brovos. Boat ran 104 with good acceloration. So I am going to try it. I have whippled 500's , sport master shorties just arrived Also going to use a 1 inch spacer only my gearing is 1.36 with 30 pitch 5 blade maximus props.Also changing to 380 tabs. See what happens when spring comes.
#10
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Re: Optimum drive height (prop shaft)
What year is your boat. You may want to try it without the spacers first and only install them on if you can not get on plane or have a water pressure problem. Be sure to keep an eye on the water temp. guage all through the RPM range.