Well, let's start at the beginning. First you want a nice set of racks to work on all sorts of different paddling perversions.

This was literally thrown together from scraps that I had around the place, mainly redwood, believe it or not, and it has held up for about twelve years, so if you used some decent wood it would work out fine. The pictures are fairly self-explanatory; I basically built a square bottom, then put two little wedges on two opposite sides to hold the upright rack in place, and then put a piece of plywood up those same two sides. I then drilled holes through both the upright racks and those pieces of plywood.

I could then run two bolts through both pieces to hold the upright rack steady.

I only ran a crosspiece across one side of the uprights so that they could be laid flat. This way when you take the racks somewhere else to work on a friend's boat, you can lay them flat; first the two uprights and then the two bottom pieces. If this is not a concern, then two crosspieces would probably be slightly better. This is what the piece of 1X 4 is for.

I then spray painted one side of each upright and each bottom piece a corresponding color, because the holes on one bottom piece only match one specific side of one particular upright piece. This makes assembly easier.

I went to an Army Navy store and got a piece of strap and then put it between the uprights so I have a sling to hold the boat.

By moving the racks closer or further apart you can hold almost any size boat.

The real beauty of a sling is that it allows you to turn the boat at almost any angle (for working in the interior of decked boats, for instance), and it will hold the boat stationery