If you're planning to cover a small boat that resides on a trailer or a larger boat that might spend the winter in storage, a frame provides ventilation and keeps the cover from pooling with rain water. By making it yourself, the frame can be configured to accommodate the cover you plan to use or one you plan to order.
PVC pipe and fittings make a lightweight frame assembly that can be secured to deck railings and cleats using nylon ties or straps. With PVC you can make the frame for a larger boat in sections that connect with male-female slip fittings for easier installation.
Measure across the stern from one corner of the deck to the other and note this dimension. Determine the height you want the frame and note this dimension as well. Make a three-piece PVC pipe frame to these dimensions with 3-way elbow connectors at the corners. The remaining port in the the 3-way connector will receive the upper side rails of the frame.
Use the same procedure to make a frame section that will stand near the bow. Attach small cleats to the cross pieces if you plan to hold the frame in place with straps. Check the dimensions of the frame sections before cementing any connections.
Turn the 3-way connectors so the open ports are facing the same direction. Prime and cement the ends of the pipe pieces and insert them securely into the connector. For the intermediate frame sections, use 4-way connectors at the corners. The open ports on the 4-way connectors will receive the upper side rails of the frame. Measure, cut and install the upper PVC pipe side rails and connect the frame together.
Cut the PVC pipe at mid-span of the bow and stern sections and insert a 3-way connector in each. Make similar cuts at mid-span of the intermediate sections and insert 4-way connectors. Cut lengths of PVC pipe to fit between the frame sections from bow to stern as a center support for the cover. Make sure the open ports are facing correctly before cementing the 3-way connectors in place.