proper height

[Nason]

What is the proper height to run a chopper below the pad( center of prop shaft to bottom of pad)?

I am running now 3.5 inches from bottom of pad to center of prop shaft wit a 10.25 x 18p chopper,turning 5800rpms. If I try to come up to 3 inches below pad it just blows out. Do you think a larger dia prop would be better?

[Mark75H]

on what boat?

[Nason]

its a home made 14' semi V aluminium hull with a 14" pad (weight of hull withhydraulic jack plate 450,motor 204 )

[Nason]

47183

[Nason]

4718447184

[Nason]

47185

[Nason]

47186

47187

47188

[fs5]

hi mate i've run a few choppers on my slt boat ,but its a tunnel hull .
dose your motor ventilate getting on plane?or dose it ventilate at full noise?
if its struggling to get out of the hole ,you can drill a couple 1 inch hole in your gearbox to relieve the exhaust .it will jump on plane after that,but your motor "will be very loud".
i have run ron's choppers and the merc small hub old style and chopper 2 to max where my motor stops pumping water and they still bite at that height.
cupping it will help but if you go to far it kills it.

[FrenchPhil]

There is no "proper" height as long as there's no water starvation. If you want to go faster try a cleaver. What's your current speed at WOT ?