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The support posts belong in the open areas on the boat's deck. Each post needs a bottom and top cap to hold it in place properly. Place the first post near the bow, making sure it's at least 10in (25cm) above the highest point in your boat. Place a second post near the boat's stern. If you wish to make your own posts, measure the boat's height from the deck to the highest point. Purchase 2in 4in (5.1cm 10.2cm) wood posts 10in (25cm) taller than your measurement, then fit them with foam caps purchased online. You only need 2 posts for small powerboats. Place additional posts to support the shrink wrap on larger boats. Install an additional post for every 8ft (2.4m) of boat length you need to cover. Run a support strap from the back end of the boat to the front. Thread it through the grooves on the support post caps. Then, lay more straps side to side across the boat, including a single strap through each cap. Buckle all of the straps to grab rails or cleats along the boat's edges to keep them locked in place. Make sure the straps are tight and secure. They form a stable frame to fit the shrink wrap over. If the straps look loose, the shrink wrap will also be loose. If you can't find a place to anchor the strapping, run it all the way down to the trailer underneath the boat. Measure from the end of the strapping to about 8in (20cm) below the metal rub rail around the edge of the boat. Cut new straps to length, then tie the straps to the cleats and edge rails. Shape the free ends of the straps into well-tied loops about 12in (1.3cm) in size. Tie the straps in place using a basic overhand knot. Using a different kind of knot is also fine as long as the straps are well-secure. Start at the rear or stern end of the boat. Run a new piece of strapping through each of the loops you tied, making sure it fits tightly against the boat's side. When you get back to the stern, tie the ends of the strap together with a buckle. Pull the strap as tight as you can before tying it. For assistance, use a strap tensioning tool, available online and in most shrink wrap kits. You can tie the perimeter band around the boat's propeller. Use it as an anchor point to keep the strap tight and secure.
Set up support posts along the center of your boat. Tie the support posts in place with polyester straps. Tie loops to the end of each piece of strapping. Wrap a perimeter band all the way around the boat.