Lachat.com

Bulkheads--they're big, they're brown, and in my case they're rotten. Water had long since wormed its way through the sealant at the chain plates and one window and down into the interior of the bulkhead. A bulkhead is what they call the interior walls in a boat. These babies don't experience stresses like walls do in buildings. A load bearing wall in your hom must endure compressive loads without buckling. On a sailboat you don't have a roof above you, you have a mast and the standing rigging that supports it. The basic process is that the wind pushes the sails, the sails stress the mast, and the mast transfers the stress to the bulkheads which transfer the force to the rest of the boat. Under normal sailing conditions there might be 5000 lbs of force on the chainplates. However, if you accidentally gybe you could put 20,000 lbs of force on them. If the rigging, mast, chainplates, or bulkheads fail the ship can violently dismast whipping metal wires around like band saws. On this episode of 'This Old Boat', Robert replaces the main bulkheads.