How to make a propwash pickup
If the rudder you have doesn't come with a built in pickup, a prop wash pickup like the below picture may be added. This type of pickup is designed for a surface piercing propeller. Because the top half of the propeller will be out of the water while at full speed, sending water into the water pickup. This type of pickup will cause less drag then having the pickup dragging in the water.
To start this project you will need 12" long brass tube, 5/32 or 3/16" works well.First you will need to make the tube in the shape of a "J". If you have never bent tubing check out this page, How to bend tubing. Once you have the piece of tubing bent , cut a 45 degree angle (see below picture) in the tubing to help it catch the water that's flying off the propeller. To mount this in the hull drill a hole the same size as the OD (outside diameter) of the tubing. Use a quick drying CA to temporarily attach the brass tubing to the hull. Then use a quick drying 5 minute epoxy to permanently attach the tubing. Don't be cheap with the epoxy there will be lots of stress on this part, whether it be water flying off or from a crash. If this breaks off, the hull is breached and it wont take long before the boat sinks! This is one of the reasons I make the hole above the water line for the tubing.
These aren't the only ways to make a water pickup, but they are the most popular and will cause the least amount of drag!