Wednesday, July 31, 2019

Emergency Plan for Severe Thunderstorms

I haven't blogged for a while.  But yesterday I went day sailing with friends on Lake Champlain.  Soon after our return, an unusually severe thunderstorm went by resulting in some deaths on the water.   I realized that I never blogged before about strategy in those circumstances.

When you live aboard full time, you can't follow the advice to not go out on stormy days, or to get off the lake when storms approach.  Libby and I rode though dozens of such storms, day/night, offshore/lakes/rivers, sailing/powering/anchored, aware/surprised.   From that, I think I can express a general strategy for sailboats caught in severe summer thunderstorms.

  1. Be aware of the approaching weather.  Use all available info sources.  Today's forecast.  Your eye on the sky.  Weather alert radio.   Probably the only time you will get caught completely by surprise is when you are at anchor and asleep.
  2. If anchored, and if severe weather is forecast,  someone must stay on anchor watch all night.  No alcohol for anyone onboard, and don't allow everyone to sleep at the same time.
  3. If under way, and if there is adequate time to go to a sheltered spot, do so.  Never try to race the storm. Be cautious about going ashore.  Getting caught in a dinghy (or even walking on a floating dock) when the storm hits is more dangerous than being on board your main vessel.  If you are not 100% certain that you can make shelter with 20 minutes margin, then stay put and use your time to prepare. 
  4. Get the sails down and secured,  and the engine running on standby.   Loose items on deck must be put below or well secured.   A furled sail that spontaneously unfurls in high winds is a major danger, don't let that happen.   A roller furling jib should be secured with a shackle, not just the furling line.  The main sail must be firmly lashed to the boom with rope, not canvas or bungee.
  5. Consider your location.  If you are surrounded by nearby shoals, you are highly vulnerable.  Get out of there ASAP.   If not (the usual case) your primary strategy is to stay where you are and ride out the storm.  Intense summer thunderstorms seldom last more than 15 minutes. In the open sea, 15 minutes is too short to build up huge swells, so wind not waves is the main concern.  If you try to seek shelter during the storm, there is a risk of moving from a safe place to an unsafe place.   It is less risky to stay put.  
  6. If the depth and the bottom and the condition of your ground tackle are favorable, and if you have enough advance warning, drop anchor and set the anchor.  Use 10:1 scope.  If not, then you will rely on engine alone.   Even if the engine fails, you will not drift more than 1/2 mile in 15 minutes.
  7. One helmsman on deck, everyone else down below.   Everyone wears a life jacket.
  8. Use the engine to maintain your position.  If anchored, use the engine to reduce strain on the anchor rode.   If you have GPS, that is the best tool to monitor that you maintain position.   If the engine fails (or if you have no engine in the first place) and you have more than 1/2 mile safe water behind you, then stay calm, go below, close all hatches, and wait it out as you drift.
  9. Turn your VHF on to channel 16, and listen for nearby distress calls.  Do not chat on the VHF, especially not on channel 16.  If you hear a nearby call for help, you can respond after the storm passes.  Do not attempt a rescue during the storm.   
  10. When the storm passes, use your cell phone to notify worried family or friends that you are safe.