: I now place the paddler's center of mass a minimum of 3" aft of the
: boat's
: LCB, assuming 12" forward of the lower back to be the center of mass,
: with
: the back / inside of the coaming placed 18" aft of the LCB. I used to
: place
: the paddler center of mass at the LCB, but some weathercocking tendencies led
: me to move the center of mass aft.

: Tom

Tom,

The paddler’s CG is 3 inches aft of the LCB because the empty kayak’s CG is 12 inches forward of the LCB. The moments (force times the distance perpendicular to the force) will balance about the LCB. The weight of the kayak multiplied by its CG distance to the LCB must equal the paddler’s weight multiplied by his CG distance to the LCB.

So if the paddler is 200 pounds and 3 inches aft of the LCB and the kayak is 50 pounds then its CG must be located 12 inches forward of the LCB.
200 x 3 = 50 x 12

I have found on my kayaks their CG's (empty) are located about one inch aft of half their overall length.

Now if you add 10 pounds in your front hatch 60 inches forward of the LCB you will also need to add 20 pounds in your aft hatch 30 inches aft of the LCB
(200 x 3) + (20 x 30) = (50 x 12) + (10 x 60)

Dave