Thank you, there are few parts of this build that I approach with dreaded fear but this was one of them. Dan C described how to do same with a compass but neither my cheap or better compass allowed the lead to touch the deck while holding the compass vertical. I thought I was being stupid with my solution and more stupid adding a line level to it........ As usual I had to reinvent the wheel and came up with the Bubbleator :)

: Well done Dan, the scribing process you did is the way to do the
: job. The resulting curve on the deck is complex because of the
: intersection of the cone shape of the carbon recess and the
: compound curve of the deck. I can't think of any other way of
: deriving the curve other than using the actual cone to project
: it as you have done.

: You may know this already, but just in case, I will mention that
: when you do the deck, the most important two elements in the
: scribing process are to make sure that the carbon recess unit is
: held rigidly still, in the exact orientation that you want to
: install it, and to keep the scriber consistently level, that is
: with the marking point of the pencil directly below the contact
: point on the recess surface. In essence, you are projecting the
: contact point straight down onto the surface of the kayak,
: simulating what will happen when you drop the recess into its
: waiting hole. When log house builders use a scriber to fit logs
: to one another, the scriber unit actually has two level bubbles
: in it to ensure that the contact point and the marker point
: remain absolutely vertical from one another.

: Once the hole is cut, you can finesse the fit by sanding the hole
: edge, then sit your recess unit in the hole, trace the hole
: outline onto it, and cut it to shape. (all assuming that I
: understand what you have in mind :) )

: Best regards,

: Allan Edie