Author Topic: Storm Management Offshore  (Read 906 times)

Offline HenryC

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Storm Management Offshore
« on: October 23, 2015, 09:34:48 PM »
The usual caveat in this sort of discussion is to point out that these are all general guidelines, not necessarily a checklist of sequential actions. Sea and wind conditions are infinitely variable, and can change unexpectedly; every hull and rig design responds differently to different circumstances. All boats are compromises and an attempt to be viable across a spectrum of possible conditions. You also should keep in mind that the skill and fitness of the crew must be taken into account. Some options may be too dangerous to be relied on, or may not have the intended results. Also keep in mind I have only been in one really bad storm at sea in a sailboat, and it did not approach survival conditions. I was also in a very good boat with a well-seasoned skipper. These notes are mostly book larnin’ and extrapolation from less extreme experience. And remember, whether or not you do survive a storm will often depend on preparations and training you undertook well before the weather went south.

At the first sign of bad weather, the first option is to proceed on your current course, but under reduced sail. Sail can be taken in by either bending smaller sails, like a storm jib, and by reefing the mainsail. Reefing is a procedure where the sail is partially lowered and excess sail area is folded up and tied off so it won’t flap around destructively in the wind. It is better to err on the side of caution here; it is preferable to reef too soon and too much than too late and not enough. If you overestimate the threat, you can always shake out the reef and proceed as before. The opposite may not be possible.

Now is also the time to make storm preparations. Make sure all ports and hatches are battened down, and all through-hull fittings are secured. Make sure everything below and on deck is properly stowed or lashed down and all emergency tools, spares and tackle are ready to go. Make sure the bilge is pumped dry and the cockpit drains are cleared of all debris. Make sure everyone has his safety harness on, and his lifeline secured when on deck. Life jackets are an option. True, they increase your survival chances if you are in the water, but they make you clumsier and more likely to fall in when you’re wearing them. I prefer not to wear one, but most authorities suggest you do.

Give the crew a hot meal, and save enough warm food and drink for the storm and its aftermath, cooking is dangerous in rough weather. If possible, take a fix and develop the best possible position and mark it and the time on the chart. You may not have the time or the opportunity to do any navigation during or after the storm, so you should have a good idea of where you are to base your dead reckoning. Study the chart and locate all possible hazards, like reefs, shoals or exposed coast lines. A good boat is better off in a storm in deep water, far from land. The coast is hard, seas are confused and turbulent there, and safe harbors hard to locate or difficult to negotiate. Regardless of what your instincts tell you, your chances are better well offshore. Run your engine briefly to make sure it starts easily, or if not, to notify you well ahead of time it may not be available if you need it. If anyone aboard is prone to seasickness, make sure they take their pills BEFORE they feel sick. Even the best sailors can get queasy, especially if they are working in cramped and chaotic conditions below. If possible, call the shore on the radio and advise them of your situation and position. If anything goes wrong, they’ll have a better idea of where to go looking for you afterwards. When preparations are complete, relax and rest. In the near future, you may be very busy. But also try to think ahead. Your vessel may be riding nicely now, but you don’t want to suddenly find yourself trying to claw off a lee shore in the middle of a stormy night, especially if you’re not quite sure where you are.

Really strong storms are quite rare, and you generally have plenty of warning. The steps outlined above are probably all you’ll ever need, but if things suddenly get worse, you are now ready to deal with them. Continue on your present course until conditions make it difficult or dangerous to do so.

If you are offshore in deep water, wind and wave will be all you have to deal with. The wind may get stronger, or change direction, so this will dictate your storm strategy. The other factor is the seas. Are they big but gentle rollers (good), or steep walls of water, (bad). Breaking seas are particularly dangerous, they will not roll under the boat, they may tend to fall on top of it, and keel, rudder and hull cannot get a grip on them, the boat will be unstable and hard to steer. A big wave breaking on top of the boat can cause severe damage, sweep crew over the side, or knock you down. The first one will leave you out of control, and helpless, the second can fill you up with water, and the third can send you to the bottom. The seas (generally) run from the same approximate direction as the wind (but not exactly). Sometimes there may be more than one pattern of seas and swells, of different size, shape and direction, superimposed on each other; wave forms occasionally interfering to create holes or mountains on the surface of the sea (“rogue” waves). Its up to the skipper to pick a course that will minimize the potential of being overwhelmed, and of course, there are no hard and fast rules. The boat’s design characteristics and the weather conditions will decide which strategy is the safest. The good news is men have been building very good boats for hundreds of years now, and learning how to handle them. Small yachts have survived the worst the sea can throw at them, some long after they were abandoned by their crews! But never forget some were lost without a trace, too.

When conditions start becoming dangerous, or intolerable, the first storm strategy is to “heave-to”. Heaving to reduces the strain on hull and rig and allows the motion of the boat to settle down. Most storms can be handled this way, but the boat is not going anywhere. It is facing the wind, presenting its strongest part, the bows, to the seas, and backing down gently to leeward, absorbing the shock of wave and weather. It allows the vessel to ride fairly level and gives the crew a chance to rest, cook and, if necessary, make repairs.

The maneuver is accomplished by coming about, but instead of allowing the the jib to flop to leeward, keep it sheeted hard to windward, forcing it to backwind. The mainsail is loosened after tacking, but sheeted tightly after the boat comes on the new tack, yet not close-hauled. The rudder is placed as if to make a windward turn, and lashed down. The idea is that sails, rudder and keel are all balanced against each other. If the boat falls off due to pressure on the jib, the main will eventually fill up and try to bring her back up into the wind. If the boat makes too much headway, pressure on the jib will prevent her from doing so and force her back off. Small adjustments to rudder and main sheet tune the forces until the boat is balanced. The two sails work against each other keeping the vessel lined up between a close reach and into the wind, with her bows taking the brunt of the storm. A good sea boat’s hull and rig are designed to heave to easily under shortened sail; she will be able to ride out a full gale with a minimum of struggle, oscillating gently on and off the wind. It is a smart thing to do if you have plenty of sea-room, and wind and seas are not extreme and do not vary too much in strength or direction. The disadvantage is that you are not necessarily traveling in the direction you want, or need, to go. The old square-riggers hove to under a spanker aft, and foretopsail aback forward, with a few staysails rigged aloft between masts to help keep her balance. This kept the ship stopped in one spot to ride a storm, wait for her turn to enter a harbor, or lower and recover small boats.

If the weather, hazards to leeward or the ship’s mission will not allow heaving to, the vessel is given the choice to either run downwind, or point upwind, or to otherwise pick a course that minimizes stress on the vessel.. Again, her choice will depend on conditions and her design, or a combination of the two.

Beating into a storm is rough work, hard on man and ship. The advantages are that the vessel is under control, taking the weather where she’s strongest and most buoyant, and she can be easily slowed down or sped up by falling on or off the wind. The disadvantage is that you may be making very little headway, and that your speed will be added to the seas and wind, increasing the risk that something will be carried away or stove in. The control you have when beating allows you to take the seas at the optimum angle: too steep and you may be stopped cold or pushed back, too shallow and you may be rolled over. But you have control and can pick the safest angle.

Running with the wind also has advantages and disadvantages. The ship rides easier, the ship speed is subtracted from the wind, but she may be harder to steer. You can run downwind carrying no sail at all, under bare poles, or add a small scrap of sail forward, such as a tightly sheeted storm jib, to help keep you pointed downwind. It allows the helmsman some control, using rudder alone to surf down the seas at an angle, minimizing the risk of being pitch-poled (to have your bows dig into the trough in front of you and a wave crest hitting you astern and throwing you end-over-end into the sea: the absolutely worst thing that can happen to you.

Similar to a pitch-pole, and almost as bad, but much more common, is to broach. A broach is when the bows dig in to the seas and the boat can’t move, and a following sea knocks the stern to one side. The result is your boat dead in the water, out of control and broadside to the weather. Pitch-poles and broaches are possible if the boat is moving faster than the waves. The ideal condition is to have the waves moving faster than the boat, so they can roll beneath you and past you without striking you full force and knocking you around. In spite of the downwind force, and the help of the storm jib, the boat wallows and wanders, and the helm requires constant attention.

My one yacht experience in a storm gave me a chance to prove myself a downwind helmsman in just such conditions. We ran before a following sea, just slightly slower than the waves, which rolled beneath us to crash ahead in a roar of silver foam and bubbles. It was a clear, full-moon Pacific night in October, about 20 miles offshore of Big Sur, and the waves were clearly visible (they looked four stories high, but the weather radio assured us they were just 19 feet from trough to crest). When traveling slower than the waves, the major hazard is to get pooped: To have a wave not slide under your stern, but to break on top of you. It happened to me once that night, completely soaking me in 55 degree water and dumping a ton of water in the cockpit. It took it about a minute to drain out the scuppers, during which time the boat refused to respond to the helm (because of all the extra weight aft and the shift in the center of lateral resistance). Fortunately, she was a good little ship, a 28' Bristol Channel Cutter, built for just this sort of thing.

In survival conditions, the ship may simply be overwhelmed, when she cannot be sailed any longer. The next fall back position is to throw out a sea-anchor, or drogue, and just ride it out as best you can. Sea anchors are large objects dragged behind a boat on a long cable to keep her pointed in one direction, lined up with the wind. They can be simply piles of junk and damaged rigging, a spare sail, even several parallel loops of line, any object that will provide resistance to the flow of water. Or you can buy compact, stowable commercially built sea anchors made of canvas stretched over metal frames, like big underwater kites, or fancy parachutes that deploy underwater and can be collapsed with a tripline for quick recovery. The resistance of the sea anchor keeps the boat from racing too fast under the influence of the wind. The cable should be long, so it will bend and the long catenary will provide a shock absorber against sudden shocks when the boat is struck hard by a wave. Sea anchors can be streamed from bow or stern, the former to keep the boat facing the wind and moving too far, the latter to allow her to drift downwind and give to the waves easier if you have plenty of sea room in that direction. The cable should be as long as possible to allow the anchor to go deep, but not so long the anchor will foul on the bottom. If a sea anchor gets tangled up on a reef or other obstruction the boat will be tied to one spot, unable to roll with the punches, and the seas may smash her to bits. Some sea anchors even have provision to affix a can of oil. Punched with a few holes from an icepick, the oil will leak out and float on the surface of the water between the anchor and the boat, smoothing the surface and keeping the waves from breaking. (Yes, ‘pouring oil on troubled waters’ is not just a colorful figure of speech.) A little oil purportedly goes a long way. If for any reason the sea anchor doesn’t work, don’t attempt to bring it back aboard in a storm. You won’t have time. Cut it loose.

And when all else fails, you just let the ship fend for itself, go below, and secure the hatch. As long as the boat doesn’t fill up with water and sink, you will probably survive. Even here, you have options. You can lash the rudder amidships and hope she’s pushed along to help ease the strains (running the risks of pitchpole, poop and broach). Or lash the rudder to one side and let her lie a-hull, taking the waves broadside, even if she’s rolled over, she may ride easier this way. As long as the boat remains watertight, she will float. But remember, once she floods, the weight of her keel and engine will drag her to the bottom.

Now is the time to put that life vest on.
http://sailboatdata.com/imagehelper.asp?file_id=1953

« Last Edit: October 24, 2015, 01:08:37 AM by HenryC »

Offline Tim Gardner

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Re: Storm Management Offshore
« Reply #1 on: October 24, 2015, 07:09:25 AM »
A good read !
"The sea is selective, slow at recognition of effort and aptitude, but fast in sinking the unfit"  - Adm Felix Riesenberg.

Offline tmw

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Re: Storm Management Offshore
« Reply #2 on: October 28, 2015, 09:24:36 AM »
Today I learned that pitchpole, broach, and poop are things we don't want to do in a sailboat.