Jack plate setup question

[UglyBug]

Ok I have a question that I know someone has the answer to. I have. Ranger 188vx with a merc 175 opti on. I have leveled the boat (not the trailer) leveled the motor with a level on the cav plate. I know I am low, my question is from the pad using a t square I read 17.75 inches to the floor. From the center of the bullet to the floor I am 13 inches which means I am 4.75 inches below the pad. Which I know is to low. However when I measure from the center of the prop shaft to the floor I am 13.50 inches which means I am 4.25 inches below the pad. Can someone please tell me where I should be measuring from and what depth I should set it at.

Ok so I was bored this afternoon and I wanted to play around with my setup. I took a piece of cedar and cut it so it just fit under the pad( just finger snug ) I then took my prop off, had to anyway to Grease it for the season. I placed the board up against the prop shaft and lightly tapped it once. This left this beautiful little round black circle from the engine exhaust, took the measurements and I now have a 100% accurate measurement of 3 3\8 below pad

Thanks everyone for your help.



Modified by UglyBug at 4:50 PM 3/18/2012

[mdtritn21]

Do you have a jack plate? If you do set shaft at 3 1/4" below pad if you don't have a plate set it at 4". The surface your measuring from could be out that much.

[Ranger 188vx]

Brian, you have the pad to floor ok, now, your measuring from floor to the center of prop shaft, and don't change the level of the boat. If you have to, take your prop off to get it right the first time. If you have a jack plate, lower motor down to 3.25 inch. Then mark it on your jack plate(if you have one)so you will always have a reference, without measuring it again. If your running a 23p tempest +, you will probably run out of rpm's.

[UglyBug]

Thx Ranger188vx you are correct I am running a 175 merc Optimax with a tempest plus 23p, and what you suggested is exactly what I ended up doing. Took off the prop ( gave me a reason to play ) Marked the place where it rubbed to jig I made measured from top to the center dot made by the prop shaft and like I mentioned it was a perfect 3 3\8. I will us this as my starting point some say I should be 3.5 others 3.25 so I split the difference and will try. When ever the water opens up