Planer boards allow boating anglers to cover a much wider area than they could by simply trolling lines behind the boat. The board's design causes it to swing far to the outside of the boat's path. Commercial planer boards can be expensive, but you can make your own to save money. This design is for a small board suitable for trolling a single fishing line.
Cut a bevel of 30 degrees at one end of the board. (Without a mitre saw, estimate this angle drawing a line from one corner to a point 1 1/2 inches back from the opposite corner.) After making this cut, decide whether this planer will be used on the right or left side of the boat. To make a right side planer, hold the board so that the bevelled edge is to the left with the bevelled side toward you. Reverse the position for a left side planer.) Mark the bottom of the board for the next step.
Use a router to cut a 1/2-inch deep, 1/4-inch wide groove into the bottom edge of the board, starting 1 3/4 inches from the square end, ending 1 1/4 inches from the leading edge of the bevel. Fill this groove with split shot sinkers, then seal them in place with epoxy. If you have the equipment to melt lead, you can simply fill the groove with molten lead. Sand the board smooth.
Attach the shelf bracket 1/2 inch from the upper edge of the board with the back edge of the bracket 3 1/2 inches from the back of the board. The bracket should be mounted with the right-angled corner up near the top of the board. Attach the screw eye to the back edge of the board, 1/4 inch from the bottom. Paint the entire board with two or more coats of brightly coloured paint to make it more visible in the water. Finish with coats of polyurethane for waterproofing.
Attach the large split ring to the front hole in the shelf bracket, then attach the planer board's tether line to this ring. Attach the small split ring to the screw eye, then attach the alligator clip to this ring. Cut small pieces of vinyl tubing to slip over the jaws of the clip to protect the fishing line.
Rig your planer board by letting out your fishing line behind the boat, then clipping the line into the alligator clip on the board. Put the board in the water and feed out the tether line, allowing the board to pull to one side of the boat's path. Tie off the tether line. When a fish strikes, it will pull the fishing line free of the alligator clip so you can play it normally.
Make a board for each side of the boat for better coverage.