This is the time of year for all of us to be thinking about preparing our boats for hurricanes. It is good to know both what to expect and what preparations you should make. Proper hurricane planning can increase your safety and reduce damage to your boat.
There are a few terms that you should be familiar with in order to evaluate hurricane reports:
- WIND SPEED – The rate of motion of air, expressed in knots or miles per hour. Wind speeds of 70 to 130 MPH winds are likely during a hurricane. Winds of up to 200 MPH have been recorded.
- WIND FORCE – This phenomenon is expressed as “wind pressure”, which approximately quadruples as the wind speed doubles (the relationship varies slightly with temperature). While you might think that a 20-knot wind will exert double the pressure of a 10-knot wind, it is actually four times the pressure. An 80-knot wind exerts sixty-four times the pressure of a 10-knot wind.
- WINDAGE – Boats, buildings, other structures and objects each present a “sail area” to which wind pressure is applied. As the wind speed escalates, those sail areas become your worst enemy as they set objects in motion that would normally be stationary.
- STORM SURGE – abnormally high water levels result due to a combination of factors, including low barometric pressure and high winds. Tides of 10 to 20 feet above mean high water levels are not uncommon within 20 to 50 miles of the storm center.
- WAVE ACTION – water levels rise as a result of the storm surge. Barrier islands, sea walls and other structures that usually protect harbors become submerged. The increased expanse of water surface allows offshore wave action to move into otherwise safe harbors. Cleats, dock lines and other rigging can become stressed to a point that is far beyond design standards.
High winds will push your boat against docks, pilings, other boats, etc. In order to keep your boat safely moored, reduce the “windage” factor as much as possible. Remove your dodger, bimini, sails and anything else that adds to wind resistance.
Double up your dock lines and anticipate high water. Adjust your spring lines accordingly. Remember that the angle of your lines to the dock or pilings will change with the water level. Anticipate that change and take precautions against chafing. Chafing gear is available at marine stores or you can slip a section of hose over a line and tie it in place. You can also use duct tape to hold canvas wrapping in place.
Water infiltration due to heavy rainfall increases the likelihood of boat submersions. Accumulations of 6 to 12 inches of rainfall in a 24-hour period can be expected (up to 24″ in 24 hours has been recorded). You may have to seal up areas that normally don’t let water into your boat (but may during high winds and rough wave action). Also, be sure to clean out all deck drains and remove any loose gear that could cause a clogged drain during the storm.
In general, when storm forecasts begin, look your boat over and prepare for the “doomsday scenario.” Remember that an ounce of prevention is worth a pound of cure.
Until next time, we wish you clear skies, fair winds and calm seas!
World Wide Marine Training, LLC, is a U.S. Coast Guard Approved facility authorized to give examinations for captain’s licenses up to Master 200 Tons, Able Seaman up to Unlimited, STCW Basic Training, Radar, ARPA and other Endorsements. Please visit www.worldwidemarinetraining.com or call toll-free 866-249-2135.