Those of us on the Gulf coast have some experience with tying up for hurricanes, so I thought I would pass on a method that let my boat survive Katrina's 15+ feet of storm surge at the dock...with only minor damage (the water rose so much that the bow rammed into the roof over the finger pier walkways). You use NEW 5/8 inch 3 strand nylon, run the lines from the back of the boat to over the bow, and from the bow mooring points over the stern. You need to have about 50-60 feet of line for each line for a typical 30 foot boat. Pad well where lines might chafe if the boat rises. You tie the lines tight, and the 15-20% stretch available in the NEW nylon line keeps the boat centered in the dock and allows for a rise of 10-12 feet before the stretch is gone from the NEW ropes. Most of us used two sets of lines, one set tied tight, and another set with a few inches of slack as backup for the first set. Of course, you have to have good points to tie to off the bow and stern to use this method.
It is imperative that you use only NEW rope as the system works because of the stretch and the lenght of rope. Most boats tied this way in my marina on the lakefront in New Orleans survived, those that didn't were generally sunk by other peoples boats that had broken loose, so help tie up your neighbor's boat is also good advice. The rope, once stretched, loses a lot of strength, so don't use it again for hurricane duty or such. It is also important to not use too large a diameter - 5/8" seemed to work well for boats such as mine, 37 Gulfstar, 20,000 lbs. Might use 1/2 inch for a smaller (less than 30 feet) boat.
Another old hand in the marina showed us this method, and it works well. It will handle the typical 5-7 foot rise from smaller storms very easily.
It is imperative that you use only NEW rope as the system works because of the stretch and the lenght of rope. Most boats tied this way in my marina on the lakefront in New Orleans survived, those that didn't were generally sunk by other peoples boats that had broken loose, so help tie up your neighbor's boat is also good advice. The rope, once stretched, loses a lot of strength, so don't use it again for hurricane duty or such. It is also important to not use too large a diameter - 5/8" seemed to work well for boats such as mine, 37 Gulfstar, 20,000 lbs. Might use 1/2 inch for a smaller (less than 30 feet) boat.
Another old hand in the marina showed us this method, and it works well. It will handle the typical 5-7 foot rise from smaller storms very easily.