Wind

— by Charles T. Low, author of Boat Docking
— for By-the-sea [ 1997 December ]

Wind contributes more to the challenge of docking than all of many other factors combined. Although there are indeed other individual circumstances in which docking may be exceedingly difficult, wind tops the list not only because it can be so hard to deal with, but because it is so common a confounding variable. Wind features prominently in boaters’ casual banter about docking, and we all often observe it as the source of trouble for a variety of boats in and around the docks.

Wind make things happen quickly! Compare this to those rare, completely calm days, when a docking can be halted at any stage, giving lots of time to re-organize our thoughts and our lines (in that order!), or to move to a different spot on the boat in preparation for fending off or for stepping ashore. Not so when a wind blows! Even a light breeze of 5 or 10 knots, common enough that we wouldn’t want it to deter us from boating, imparts a sense of urgency and immediacy to what would otherwise be a much more relaxed docking.

Different boats and types of boats vary tremendously in the intensity of their responses to wind, but the general principles apply to all of them. Each boater deduces individually just how much the various wind effects apply to his or her boat, largely by experimentation, on the water. (Hint: practise. Try things! If unsure of the way a boat will respond, make your initial observations in other than close quarters.)

Blown Around — The most obvious wind effect is that it blows a boat along. What is less apparent is how fast it can move a vessel. Beginning boaters often recognize the quality of the wind’s effects more than the quantity! Wind often doesn’t give you a lot of time to sit and ponder your situation!

Even less widely appreciated is the very strong yawing (turning) effect of the wind on a boat hull. This applies to supertankers as well as to canoes, and to all boats in between (unless they have sails up, in which case the yawing effect is different in nature — but that’s a separate discussion).

The result is that the boat is blown broadside to the wind. If this seems counter-intuitive to you, it may be some slight consolation to know that it does to me too, but regardless, that’s the way it is. Physicists have drawn wind pressure diagrams (in their spare time) which show why hulls react this way, and by golly, they’re right. You can try it: take the boat out of gear, center the helm, and then wait — some hulls will turn beam to wind very quickly, others slowly, but there are very few, if any, exceptions to the rule that they do go beam to wind.

Exceptions? Well, a vessel with high windage at one end or the other may “weathervane”, to some extent. Planing hull power boaters take note: your bow is high and light, and your stern deep and heavy. (We’re talking about your boat, still; don’t let this affect your body image.) Nonetheless, you’ll be amazed at how weakly most boats weathervane, and at how strongly they go broadside to the wind.

A related caveat about the yawing effect of wind is that it varies enormously, in some boats, depending on which direction the boat starts from. Put the higher windage end of the boat towards the wind, and the vessel will turn quickly, and vice versa. So, to take our planing hull power boat again, if taken out of gear while in a headwind, it will blow broadside to breeze quickly; but if it starts out stern to wind, it may be some time before it gets around to turning. The implications of this will arise shortly.

Going broadside to the wind means going broadside to the waves, too, in most cases — not a big consideration in close quarters, but worth noting should you ever suffer engine failure on the open water.

Maneuvering In Wind — We will examine handling a vessel in various combinations of i) making headway vs. making sternway, and ii) in winds coming from ahead, astern, and abeam.

• i) Headway —
  1. Head Wind — This requires a bit of a balancing act: the bow often wants to “blow off” to one side or the other, so it’s a bit like walking on a fence. You don’t know which way it’s going to go, and when it goes it can really go. Furthermore, consider the wind just starting to turn the boat: the sides of the vessel now make an “inclined plane” with the wind, which will push the hull sideways. (Does this seem to be getting complicated to you? Me too, and it isn’t over yet.)
     The next thing the skipper will do is to go ahead, in forward gear, with the wheel hard over, to steer the bow back directly into the wind. But, adding in both the direction the hull is pointing, and the direction of the propeller’s discharge current, there are now many forces pushing the boat sideways. Vigorous engine power may be required to steer the boat, so you can see how much sideways movement can occur even when the bow “blows off” just a little.
     No wonder the boat seems to have a mind of its own, especially for beginners, or for those who don’t boat very often, or who haven’t thought about it very much. One of the main techniques to cope with all of these effects is anticipation — know your boat well, and think a few steps ahead of where it is now, and of what it is doing at the moment. Experience helps a lot!
     The slower you go, the more the wind steers the boat, and the less you do. The clear problem is that you have to go more and more slowly, thereby losing your ability to steer, as you complete your docking. Eventually, of course, you have to go so slowly that you stop! Knowing and recognizing the normal effects of wind on the hull can only make your difficult job at least a little easier.
     
  2. Tail Wind — In general terms, this situation favors the skipper more than any of the others. The boat controls fairly easily, and if there is any weathervaning tendency of the bow, so much the better. The apparent wind speed will be less than the true wind speed (subtract from it the vessel’s speed), which can lead to a false sense of security. Remember about that wind, even though it now doesn’t feel like much — it will still grab at the boat when it comes time to turn, or to slow down and stop.
  3. Beam Wind — A beam wind pushes the boat sideways, so you “crab” through the water, to compensate. Unlike crabbing in a current, in a wind the hull actually goes diagonally, to some extent, through the water.
     Having turned the boat a little bit into the wind, however, the hull no longer sits exactly broadside, any more, and so the wind tries to yaw it! This requires the skipper to “hold some helm” — maintain a little steering force against the yawing tendency of the wind on the boat.
     Again, realize that if you suddenly need to turn into the wind, you may have your work cut out for you. It’s going to take some engine power, and some time, and the arc you cut through the water may be wide.
• ii) Sternway —
  1. Head Wind — In many boats, this simply cannot be done gracefully. The wind blows the bow off to one side or the other, and unless you have enough of a keel, or a keel effect (with some true deep-V planing hulls, for example), you aren’t going to be able to control it. Your “course made good” over the bottom may be less than predictable. Even full deflection of the rudder or outdrive with forceful use of power often fails to swing the bow back directly into the wind, and even if it does, the whole cycle just starts all over again.
     So, what if you want to back into your slip, and the wind is on the nose? Certainly, we have all seen this done successfully. Perhaps the helmsman was able to swing the boat head to wind, and then quickly back in before the bow went errant. Commonly, a line is thrown or taken ashore, and helps to control the vessel from the dock. But in really windy weather, even experienced boaters often just defer to the Forces of Nature, discard their usual docking position, and go in “bow to”, with the wind blowing over the transom.
  2. Tail Wind — This does not present nearly as big a problem, and the reason (other than that one end of the boat may have higher windage than the other) is that your steerage apparatus (rudder, outdrive, etc.) is now facing the wind. The bow may not follow the stern in a completely straight line, but at least you can likely keep the stern close to the desired course. (Some boats steer very poorly in reverse, for other reasons than wind effects, but for now, we assume adequate steering authority.)
     We were talking about weathervaning, a moment ago. The idea now is that, although the hull does not weathervane very much on its own, it can be convinced to do so by the application of a little engine power.
     I agree with the frequent admonition always to go ahead in rough weather, to stay in forward gear, not to back into your slip, for example. This has general applicability. But it is worth remembering about the good steerage afforded by backing into the wind — if it works well in your boat, it may come in handy some day!
  3. Beam Wind — Here again, as in reversing in a head wind (above), the wind exerts an adverse effect on your bow, over which you have little control. The boat tends, of course, to drift abeam, downwind. To correct for this, the skipper orders “Helm to wind!”, in a gruff and surly voice, endearing himself to the crew. The wind, now, tries to blow the vessel back broadside, requiring further steering correction, which, at some point, suddenly becomes effective, and the bow weathervanes suddenly and violent downwind. Not good! The description and illustration convey only feebly what, in many (not all) boats, is an almost impossible maneuver: sternway in a beam wind.
     Those of us with boats which can maintain course under these conditions should just rejoice (and sure, take the credit!) — the rest of us find that avoiding this situation is the better part of valor. For those rare occasions when the violent, wide swing of the bow is exactly what you want, I say again as I have said before: know your boat! Once started, it’s not so easily stopped, so don’t go playing around with it in close quarters unless you have the “feel”, the experience to predict fairly accurately how the vessel will respond to wind of that particular strength from that particular direction.

Conclusion — There is no conclusion to Boat Docking — the potential for more progress never ceases. Thank goodness that this is the case; how unexciting life and boating would be otherwise!

As surely as the wind blows, understanding its effects on boats is half the battle. (Add up all of the “halves” that constitute this struggle, and you have quite a large “whole” — the various factors must intersect and overlap!) One of the many other “halves,” “Momentum,” was discussed here recently, and between it and wind rests perhaps two-thirds (the math is getting less convincing) of the understanding required for close quarters maneuvering for small craft.

Let this information soak in and become a part of you, by practical experimentation on the water, and expect it to continue gradually to ingrain, more and more deeply, for your whole boating career.

The End
Wind — for By-the-sea [ 1997 December ]
Copyright © 1997 ctLow

About the book — Boat Docking (Close Quarters Maneuvering for Small Craft) is a recently published book about how to dock a boat! It contains many concrete examples of boat docking, from the elementary to the advanced, and also has chapters discussing the theory of close quarters maneuvering.

  This is a softcover publication, 7"x9" (18x23 cm), 88 pages in length, with roughly 25,000 words and about 140 clear, simple illustrations. (That's a lot of illustrations!) It's a comfortable (winter) evening's read, or a ready on-board reference and discussion document.

  The distillation that has resulted is not, to our knowledge, reproduced elsewhere. This book is tightly focused only on slow-speed handling of small craft, and as such it is very complete and thorough. It has an excellent balance of technical analysis and practical boat-docking recipes.

Charles T. Low, the author of Boat Docking, is a recreational boater in the Thousand Islands on the St. Lawrence River. He and his family spend much of their summer vacations, weekends, and many evenings, on the water. Charles likes the beauty and tranquility of the islands, and also enjoys boating — an excellent match of process and product!

Visit the Boat Docking web site for further information.