Crew Weight and Weight Distribution
By Robert K. Smither
(From Lightning: Tuning, Tactics, Technique, and Sailing)
One of the most common errors made by novice sailors (and some not so novice) is the positioning of their crew weight. If both the skipper and crew are novices, this is quite understandable. When the skipper is experienced, it is difficult and bothersome to keep telling the crew to ‘get out’ or ‘get in.’ Often he does all the balancing himself to avoid this extra effort. The trouble with this is that if you start concentrating on tactics, it is easy to forget about weight distribution. If the crew is not used to worrying about it they probably won’t move either. The best way is to train the crew. One of the joys of having a well-trained super crew is that not only will they make all the right moves, but they will correct for the fact that you are not sitting in the right places as well.
Basically, the placement of your crew weight is used to control the angle of pitch (fore and aft) and the angle of the heel of the boat. This is a balancing of static forces. The more skilled crews also use it to help propel the boat. This is a balancing of dynamic forces.
Let us consider the static forces first. Most sailors have a general set of rules that they keep in the back of their heads things such as moving back on the runs, moving forward on a beat, especially in a short chop, heeling the boat in light air, etc. The trouble with rules like these is that sometimes they are right and sometimes they are wrong. Also, they are different for different crews.
There are many times when I do not move my crew back at all when we change from a beat to a reach or a run. If your boat is level and you are not dragging the bow or dragging the transom, you may be in the right place already. It’s the angle of the boat that counts, and that is all.
I had a good lesson on this point during our districts. We were a little slow on the first weather leg (did a ‘720’) and had to play catch-up on the first spinnaker run. We were gaining fast on the boat in front of us when his jib went into the water. He immediately sent his jib man up on the fore deck to retrieve it. The rest of the crew didn’t move. I smiled and thought, ‘Now we’ve got them. They will dig his bow down and slow down.’ Just the reverse happened. They picked up speed and began to leave us. When their jib man climbed back into the cockpit, they slowed down and we began to pass them for a second time. Once again the jib went into the water. Once again the jib man went up on the fore deck and very carefully put the jib under the shock cord. They gained three boat lengths on us.
Finally, I wised up and moved my crew weight forward. We went by easily. Both crews had been sitting back too far, they worse than us.
When they put a man on the foredeck they were about right. When in doubt, the basic rules are to sail it level (fore and aft) and sail it flat (athwartship), or with a few degrees of heel, depending on how much weather helm you like. The basic rules should always be expressed in terms of the angle of the boat relative to the water rather than in the type of motion expected from the crew. The distance your crew moves to make the proper adjustment depends on the crew’s weight. If they are heavy, then only small motions are needed; if they are light then large movements may be required.
I am a great believer in light crews, 420-440 pounds. You have to work harder in a blow, but in general it seems to pay off. Many of our national and world champions sail with their wives, daughters and girlfriends. If the two men on board are strong enough to handle the heavy stuff, then all you really need is an extra pair of hands and some brains. Pound for pound the gals compete quite well in this category. It is a little rough holding the boat down going upwind and you have to feather the boat down into the wind. But once around the weather pin you’re gone. As a rule of thumb, the better the skipper, the lighter his crew can be. If you are an intermediate skipper, you may be more comfortable with a medium weight crew of 440-480 pounds. When the wind blows, this weight is more comfortable and requires less work. Novice crews may find a heavy crew weight, 450-520 pounds, even more comfortable. These weights let you make more mistakes. This has its advantages when you are learning but it won’t win many races for you.
I am also an advocate for wearing extra clothes and a life preserver when the wind blows. This is motivated not so much to keep one warm or save a life, as it is to increase your crew weight. You often carry a sweater or jacket aboard anyway, and have to carry the life preserver. So why not turn their dead weight into live weight!
The only time it makes any sense to heel a Lightning to any appreciable degree is in very light air. The main object is to reduce the wetted surface of the hull to the very minimum. This reduces the frictional drag on the hull, which is proportional to the wetted area. In order to obtain any appreciable effect you have to be drastic and roll the boat over to a 40-degree heel. You must also move your weight forward or you will go in circles. In light air your rudder has very little effect on your course, so you must use your crew weight to balance the water forces against the wind forces. This is generally true independent of whether you are beating or running. The only exception is a light air run in which it pays to heel the boat to weather to help fill the spinnaker.
Balancing the dynamic forces is a bit more complicated. The most familiar case is a planing spinnaker run. Any crew that sits in one place and does not move frequently is going to be left behind. If you sit down on a surfboard, you may feel more stable, but you are not going to ride many waves very far. You can lie on a surfboard or kneel on the board and have some control. But the best control comes when you stand. This is true in a sailboat as well. You must move as if you were standing, even if you are sitting. Lightnings will not plane without reasonable size waves. The harder you surf the wave, the longer you will plane. The action begins when the wave begins to lift the transom and the crew moves forward. The crew stays forward until the wave grips the boat and begins to move it. Then, as the boat begins to plane, the crew moves back. This backward motion helps accelerate the boat and gets it up on a full plane. You must be careful not to move back too fast or too far or the waves will slip out from under you. As you pick up speed, you move back and trim the sails at the same time. Now it is a balancing act-a little forward, a little back. If you sit down, you are lost. The only way to learn this act is to do what the surfers do. Go out and practice; play with the waves; learn how it feels. You can learn if the way or the angle of the course isn’t right. Also you are less inclined to experiment if a competitor is breathing down your neck.
Another example of dynamic balance is hiking on a boat in large seas and strong gusts. Anticipation is the key. You must be like an orchestra leader and move a half a beat ahead of the wind and waves. You have to hike out just before the gust hits, but not too soon or the boats will roll to weather and soon as the puff begins to ease, you have to be moving in. Otherwise the boat will roll to weather and the skipper will lose the rhythm of the waves.
I like to roll the boat over the top of large waves. It’s something like a roll tack, but you don’t tack. If you set up a rhythm of movement that matches the period of the waves, you can have your sails moving to windward to the crest of the waves and to leeward in the troughs. This tends to compensate for the slowing of the boat at the crest of the wave where the water is moving against you. It also lets you dig your lee rail in when the water is moving with you and pushing you to weather. It takes practice for the crew to learn how to do this smoothly, but when they do, it is a lovely sensation. You will know when you’ve got it right.
Still another example of balancing dynamic forces is the case of beating to weather in a short chop with wave crests from four to 20 feet apart. This type wave pattern has a time period of motion of a Lightning when it undergoes a fore and aft pitching motion.
Under these conditions the boat can seem to be fighting the waves, bucking and bouncing around. You seem to hit every wave the wrong way. When this happens, the boat moves in a way that is out of phase with the waves. The water is coming up when the bow is going down and vice versa. This can increase the wave drag on your boat by a factor of two or three and can really slow you down. The wave has your number, if you like, or maybe you have its number. Either way, the result is disaster.
There are only two solutions. Either you change the time of motion of the wave relative to your boat by bearing off 15 or 20 degrees, or you redistribute your crew weight which changes the time period of motion of the boat’s pitching.
Obviously, in a race you don’t want to fall off I5 to 20 degrees on a beat, so you shift crew weight in one of three ways.
If you move the crew together and concentrate them in the center of the boat, you will shorten your time period of motion. If this brings you more into phase with the waves, things will improve. On the other hand, concentrating the crew may throw you even more out of phase. If so, the right move is to spread out your crew weight, lengthening the time period of motion.
If neither of these crew weight shifts works, you can try heeling the boat and moving crew weight forward, This reduces your slapping into the water. If someone were to push your bow into the water, it would be easier with the boat heeled than with the boat flat.
Finally, I would like to leave you with a pet theory of my own. I believe that a tense, alert crew results in an increase in boat speed over the boat with a relaxed crew when sailing in a seaway. The important thing is muscle tension and rigidity relative to the boat. The basic idea is that if the object moves easily relative to the boat, the waves will do work, pushing it around. The energy absorbed in this process will come out of your boat speed. People are rather loosely coupled to a sailboat. They are forever slipping, sliding, falling out of the boat, etc. Furthermore, they are soft, flexible and floppy. Some of you may remember an article I wrote in the 1970 Year Book in which I measured the contribution of the different parts of the Lightning to its pitching moment of inertia--the hull, mast, boom, rudder, sails, etc. The test consisted of placing the boat on its trailer, supporting the tongue of the trailer with a spring and measuring the period of oscillation of trailer up and down. As I added each item, I calculated what the effect would be if the object were perfectly rigid and securely fastened to the boat. For relatively rigid things, such as the rudder or a tightly rigged mast, theory and experiment agreed quite closely. For more flexible things, such as a loosely rigged mast, loose gear or sails, the effect of the object was larger than the calculation for the rigid object. This increase over the rigid object can move out of phase relative to the rest of the boat.
In the Yearbook article I referred to the ratio of the experimental result to the theoretical value for a rigid object as the ‘floppiness factor.’ For most things it had a value of 1.1 to 1.3, but for people the ‘floppiness factor’ was way up in the 2.0 to 2.5 range. No matter what I did or how hard the test crew tried, their ‘floppiness factor’ would not go below 1.8. Furthermore, it was very difficult to get reproducible results. Before I could finish a ‘bounce test’ of two or three minutes duration, they would begin to relax and their ‘f’ factor would begin to rise and change the result.
My conclusion from all this is that you must do what is necessary, beat your crew, throw cold water on them, get to the weather mark first, whatever turns them on. But get them excited and tense and you will have super boat speed. One approach that seems to work pretty well is to sign on as crew the most attractive gal in the yacht club. This not only solves the problem of finding a light crew, but also solves the problem of finding a steady second crew, while reducing your ‘floppiness factor’ at the same time. So wives and girl friends should not get annoyed when the skipper