It makes sense that your old trampoline was stretched and that the solid Vinyl is a stiffer material. You can use a rope / block and tackle to prebend the sidebars to help.
mmiller wrote:
On a 14 or 16 you can "pre-bend" the sidebars before tensioning the center lace. We do not use double grommets down the center and get tight tramps without a huge effort.
Use the mainsheet system. Lay the blocks and line on the tramp "unsheeted" from side to side bar... in the center. Add a line to the base of the blocks that can reach around the sidebar, under the tramp and meet the top block. Tie off. Pad the side bars with some cardboard where the line goes around the sidebars. Sheet the system to bend the sidebars in by over 1". We sheet till the tramp gets a little pucker shape along the sidebar. Cleat the blocks and tighten the tramp using moderate tension. Using the vise grips, dowell or just holding the line at each grommet as you go. Tension the aft lace last and then release the block set.
We use this system and get over 1-2 inches of prebend in the bars for over 1 inch after releasing.
Worst loads on a grommet are during tensioning each one... this saves effort and grommets.
Use the mainsheet system. Lay the blocks and line on the tramp "unsheeted" from side to side bar... in the center. Add a line to the base of the blocks that can reach around the sidebar, under the tramp and meet the top block. Tie off. Pad the side bars with some cardboard where the line goes around the sidebars. Sheet the system to bend the sidebars in by over 1". We sheet till the tramp gets a little pucker shape along the sidebar. Cleat the blocks and tighten the tramp using moderate tension. Using the vise grips, dowell or just holding the line at each grommet as you go. Tension the aft lace last and then release the block set.
We use this system and get over 1-2 inches of prebend in the bars for over 1 inch after releasing.
Worst loads on a grommet are during tensioning each one... this saves effort and grommets.