You can build an A-frame rack like mine, but with the cross bars extended outside the A-frame to increase capacity. The rack shown holds up to six boats. Extending the crossbars would easily double that. The extended top bar (for a cover tarp) won't work with extended crossbars, unless you put top bars at the ends of the upper crossbars, too. To help support the extra weight, you may want to consider adding a third A-frame to the rack. Even with these modifications, the rack is inexpensive and easy to build.

You can see more pictures of the rack in my "Kayak Storage Rack" album on Webshots at: http://community.webshots.com/user/brian_nystrom-reg