I think I have the idea how to make a new drawing, it will be ready soon, its learning curve. You can buy blocks of almost any of plastic from companies like "Port Plastics" or "Piper Plastics", I think they have a web sight, I know they have a complete catalog on CD. I buy rods and plate Teflon and make bearings and any thing part I need that will better frictionless. Delrin comes in two main forms, one is especially for any kind of load bearing and will outlive the boat in salt water. Just hose it off . It can be readily machine with simple wood tools and but is best done on a lath or mill. Until I get this drawing together,I now have a program called autosketch which may help. I will try to explain. The existing board (old) can be center of effort marked and the area calculated. It comes to about 2.65 sq ft.. The depth remains the same, the width will be adjusted according to the area to match the existing center of lateral area . This can be done several ways but cost can be used to keep the number of ways limited. For me and I am not concerned with hitting something, so I can use the simple screw method in the new board. The new board will smaller in the truck but the same size when extended. A screw jack principal is used with the nuts buried in the lead weight. the round lead plug is inside the Teflon foil, which inch idea the trunk. it slides up and down on two easily cut to shape Teflon bushing the same foil shape as the board (dagger style). It would be wise at this point to use a stainless steel steer as this is already availed form trailer jacks, only the nuts an are special because they are buried in the lead weight. Most parts can be made with simple tools and it easy to remove for cleaning or any repair. The top of the screw handle to fits through the top of the centerboard trunk. BUT again I will try to build a small model first. The excess space in the trunk casing can be filled in, So water has no access to the iron ballast from the outside anyway. Silicone and bronze are great choices but are very expensive their cost could go as high as $1400.00. The difference in weight from old centerboard to new sliding board becomes the keel bulb, approx 61 lbs on each side. Its all a learning curve right now. What do you think of adding a soft rubber flap to either side of the board to wipe the board as it goes up and down.