Well the holidays are over and it is time to get back to work. In this issue of building a 36/600 I am going to go over the construction and installation of the radio board. Over the years of model yachting, I have seen and built a good number of radio boards. Some radio boards were complicated and their installation a nightmare until I saw one mounted on the keel box. In one of the past articles I described the radio board mount on the keel box for easy access and construction. In this article I'll describe the radio boards I have been using with great success.
To start, obtain the main material to construct the board with, a 3/32 or 1/8 inch sheet of birch plywood. Don't use plywood that is any thicker because it is overkill and don't use plywood any thinner because it will be too weak. The next task is to design the board itself, but before you do there are a few things to take into consideration.
The first thing to consider is what type of winch you are going to use. For a 36/600 there are two types of winch, drum and swing arm. Both types will do fine but how you use them matters how the board is designed. The one important fact when designing a radio board is even weight distribution of the electronics. If too much of the electronics' weight is on one side it can cause the boat to list slightly, and you don't want that.
If you are using a drum winch, design the board so when the line comes off the drum is right on the centerline of the board. The drum winch will be over to one side but not enough to greatly effect the balance. By putting the drum's line exit in the center will allow easy movement of line from the drum to the rear exit pulley.
If you are using a swing arm winch the placement of the winch on the radio board is a little different. To get the most line movement the swing arm winch must be as far to the side as possible without messing up balance. The longer the swing arm the greater amount of line movement. You will want the swing arm to clear the inside hull wall when it moves to obtain the greatest amount of line movement.
The first thing to do is cut out the radio board blank from the plywood sheet. My board's size is 3 ¼ inches wide and 4 ½ inches long, choose the size that works best for you. Once the blank radio board has been cut out, the next step is to mark and drill the two holes to attach the board to the radio board mount. To do this, measure the width of the board and draw down the exact center of the board. This will establish the board's centerline and on the centerline mark the two mount holes, (see example below).
Once the blank board has been cut out, centerline drawn, and two mount holes drilled on the centerline, temporarily mount the blank board on the radio board mount with two screws. With the blank board in place, take the winch and place it on the blank board to find the right placement. Once you have found the spot, mark it and remove the blank board. It is important that you make sure the winch does not touch the inside of the hull when it is mounted. If it does during operation it can start to create a wear spot on the inside of the hull. To avoid this and to find the correct placement for line travel, take a piece of stiff cardboard and make a template of the blank board. Cut the template to the same size of the board with the two mount holes in the correct spot. At this point mark and cut out a spot where you think the winch should be, and place the template with winch in it on to the radio board mount.
With the template in place, look under it and see of the winch is touching the hull. If it is make another template and move the winch over and cut a new hole. Next check to make sure the swing arm is working and not hampered. Once you find the right place for the sail winch, you can then add the hole for the rudder servo. The rudder servo's placement is not as critical as the winch's, just be sure you leave enough room for the receiver. To offset the winch's weight, put the rudder servo and receiver on the other side of the radio board.
After you have the template made to accommodate the inside of the hull, transfer it to the blank board and cut out the holes. One important item to mention about drilling the screw holes for the winch and servo. There is not much board area from the winch and servo holes and the holes are drilled. This will cause the board to chip, leaving a weak hole. To help avoid this, before I drill the screw holes, I apply a coat of Epoxy glue to both sides of the board. This won't stop the entire problem but it will at least cut down on it some. Drill the screw holes carefully and to the correct size. Once all cutting and drilling are done, mount all of the components and install the radio board inside the hull. At this point install the rudder linkage and find a place for the battery pack and test to make sure everything works according to plan.
Next time we'll attach the keel bulb to the keel fin and get some other tasks done. Fair winds!