ICDEDPPL

I need some help , mostly because I don`t know wtf I`m doing .
(these are all just preliminary measurements )

I figured out my crankshaft centerline.
Seems to be 18 3/8 from the bottom.(the hull is at an angle so I`m not sure exactly which side of the tape measure to read but it`s close either way)

This is how I got to that conclusion:
Measured 4" down from center hole then to bottom of hull.

ICDEDPPL

Since a #5 drive is 18 11/16 propshaft to driveshaft that puts me 5/16 below the bottom with the #5 drive.

18 3/8 - 18 11/16= 5/16.

I think I did that right .

ICDEDPPL

I want the SSM6 2" above bottom.

#6 is 18.63" from propshaft to Drive shaft .
taking into account the 13* transom angle. 18.63/cosine of 13 degrees =19.120" (not my math , thanx Jeff Wagner)
Then 19.120 plus 2 5/16?
That`s 21.43. Not sure if this is correct.

ICDEDPPL

Assuming that is correct what happens when 10" boxes get thrown into the mix?

1Zoom

Dan, you will need to measure if there is an angle on the boxes, or if they are square. If they are square take the angle of the transom, divide the angle into one inch to see how much drop per inch at that angle. Measure the length of the box and times it by the drop per inch. This will give you the measurement of how much lower the X dimension will be. Think rise over run upside down. If the boxes have an angle, positive or negative you will have to allow for the combination. If the boxes have the same angle front and rear as the transom it will cancel out any drop.
If you have any questions call me.

IGetWet

Does the #6 transom assembly not account for any transom angle? You’ll also have to figure a number for water rise with the ext boxes. If it rises 1” for 12” of set back, then 10” would equal .8333”.

Unlimited jd

Ssm 6 transom assemblies account for a 13* transom angle.
I’ve never used the math measuring along the transom, I measure perpendicular to the running surface.
If you want the propshafts 2” below the bottom set the crank centerline measurement at shaft to shaft +2”. The boxes move the drive straight back, they look like they have rise in them, but that accounts for the 13* transom angle so the drives don’t end up lower.
2” above sounds like a good spot for them, the Old School top gun with a notched transom was 1” below the bottom, transom notched, no boxes and had no issues getting on plane. I was trying to talk Kevin into going up 2” with that setup when he had it.

ICDEDPPL

Once I get the drives I`ll attach to the boat and make sure the drives end up where I want them .


I leveled the boat, ran a laser across the strakes on each side. Found center, measured 18" from center to find center of each drive.
Then went up 2"

That should get me pretty close if i`m doing this right lol

ICDEDPPL

These should help quite a bit

bigfarmer

Just curious why the extension boxes???