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jody
08-27-2001, 06:30 PM
I have a 79 Vector with a 135 Mariner,took a spin on the Red River in Alex. La where I live this weekend with a GPS.It ran 70mph at 6800 rpm's with 25 pitch drag prop the boat weighes about 1550lbs with me in it, with a 6 inch set back. Does the mph sound about right or should it be more or less?

patches
08-27-2001, 06:58 PM
by the common calc. that would be spot on with a 2:1 gear and 15% slip not sure what your gear is but your figures don't sound far off

jody
08-27-2001, 07:07 PM
I think I have 1.87.

Raceman
08-28-2001, 04:48 AM
Jody, try this:

http://www.rbbi.com/folders/prop/propcalc.htm

If you've got 1.87's you're slipping about 18%, 13% if it's 2:1. I'm not familiar with 135 Mariners off the top of my head and without a year model it's hard to find the Merc comparison, but if it's one of the old inlines the gear ratio would be 2:1 or l.78:1. I'd have guessed that the V6's 150HP and below had 2:1's, but don't know for sure. Best thing to do is rotate the flywheel by hand and count the prop rotations. I don't know what you mean by 25" drag prop, but I wouldn't think it'd be hard to get that Vector to 10% or less with the right set up.

jody
08-28-2001, 08:14 AM
The motor is a 1989 V-6 2.0 liter. I put a set of carbs off a 175 Merc. I gained about 600 rpms.