If you've ever cycled, you've rowed. In a lot of ways the two activities are similar. The gear can be very simple and cheap or very complex and expensive. The effort can be very relaxed and enjoyable, or very high strung and demanding. Also, the weather makes all the difference in the world in either sport as to the what can be accomplished.
This essay will explore mostly the simple, cheap, relaxed and enjoyable side of the sport.
FIXED SEAT ROWING
Figure 1 shows a fixed seat rower. His rear is attached to the boat by friction to the seat. His feet should be braced against solid foot braces. The handles of the oars are usually about chest high, or slightly below, when he pulls. The oar handles may overlap each other during some portions of the pull, although it's more comfortable for the casual rower if they don't.
The oars are held to the boat by common pivoting oarlocks. They are somewhat free to slide in and out of the locks such that the distance from lock to handle can be adjusted.
The blades of the oars are dipped into the water with each power stroke and lifted clear with each return stroke.
That's about it.
Here is what the oars do: In effect they are levers that gear up the speed of the rower's hands.
Most people in a good (but not racing) row boat will pull at 25 to 30 strokes per minute. Let's say it's 30 strokes per minute (2 seconds per stroke) to make the figuring easy. And let's say that stroke consists of 1 second of power and 1 second of recovery. If the rower pulls the oar handles through 3 feet with each pull, as shown in Figure 1, then the oar handles are moving 3 feet per second, which is 2 miles per hour.
(One might argue that hull speed and blade speed aren't the same because there is some slippage of the blade in the water. Certainly this exists when you try to start any boat from rest, especially a large heavy boat. But once up to speed in good conditions good rowing boats don't exhibit much slippage. I've noticed that an oar blade produces a small vortex on the water's surface when the power stroke is first delivered, and another small vortex, twisting the opposite way, when the power stroke is stopped, usually when the blade is lifted for recovery. In calm water the vortices are very clear and stay that way for a while. You can row along and see a string of them on each side of the boat. I base my observation that there is little blade slippage on the fact that the starting and stopping vortices of each paddle dip are usually only inches apart once the boat is up to speed, while the paddle dips themselves are spread well apart. Pete Culler said that a good rowing boat will carry or glide about the length of its hull in between strokes. I agree. So a good 16 footer will glide about 16 feet between strokes while its blade vortices might be within 6" of each other. Blade slippage would be 2 or 3%.)
How fast will the boat go? Here the problem is how to match the power delivered by the rower to the power required to push the hull through the elements. (The elements for the time being will be assumed to be just the drag of calm water. That is to say it is a windless and waveless day.)
What is the power of a typical rower? I don't really know. I'm sure there is a very wide range of abilities. I recall that one might expect a long distance recreational cyclist to put out about 1/10th horsepower for hours at a time. Bike racers apparently can pedal 1/2 horsepower for a good while. And I think I saw in Scientific American a long time ago where a multi-time Tour de France winner pushed a dynamometer at a full horse power for an hour!
It's interesting to guess at the load on the oar handles while pulling them at 3 feet per second. A horsepower is defined as moving 550 pounds through 1 foot in a second, (established back in the old, old days when horses were used to lift seepage water out of mines) so 1/10th horsepower would be 55 pounds through 1 foot in a second, or 18.3 pounds at 3 feet per second. But the rower, unlike the cyclist, is actually pulling only half the time, on the average, since half of his time is spent in a powerless return stroke. So his boat might think he is putting out 1/20 hp on the average.
Well, we're not out to win the Tour de France. To a certain extent with a rowing boat, the issue of power delivered becomes moot. The nature of hull drag for boats that don't plane assures that they all go about the same speed. Figure 2 shows what I think the power requirements might be for a boat like my Roar2 in normal one man rowing trim. (These power figures are all guesses.) You can see that power required rises sharply at a hull speed of about 4.5 mph. With a steady 1/20 hp of our rec rower she wants to go 3.5 mph. With 1/10 continous hp, say a maximum power for a short burst of arm power, or an easy continuous power for a small electric trolling motor, she wants to go 4.3 mph. The Tour de France winner might go 7 mph if his arms were as strong as his legs. A tenfold increase in power gives only about a twofold increase in speed.
The point is that large increases in power give only small increases in speed once "hull speed" is neared. So for recreational use it's wise to think in terms of easy steady power that you can maintain for hours, if needed. The big power can be held back for use in hard conditions like pushing into a wind, through a current, or past some rough water.
So let's say the skipper is pulling the boat through the water at 4mph. But his hands are only moving 2 mph! The oar makes the difference in speed easily possible.
If the oar were 84" long (7 feet), and 56" of that were outside the lock, and 28" were outside the lock, then a 2 to 1 ratio will be achieved.
Figure of 3 shows the "freebody" diagrams (the balance of forces) of the oar and the rower and the boat. With the configuration shown the 18 pound load as a 9 pound load on each handle is balanced by a 4.5 pound load on each blade. So the process of gearing up the speed by a factor of 2 has also reduced the balance load on the blade of the oar by a factor of 2.
The forces on the rower's body are also shown in Figure 3. His 18 pounds of force in his hands must be reacted to the boat some way. If he has no feet bracing at all, then the force goes out of his body as friction where he sits. It can hurt a bit after a while! The usual solution is to brace the feet solidly. A handy bulkhead or hull frame might do. Custom cleats for the feet to push against attached to the hull are also common.
If the rower now turns downwind he may find his 1/10th half time horse will push the boat at 5 mph. To get that without changing his stroke he can slide the oars out so that he has 24" inboard and 60" outboards. As shown in Figure 4 he will now have 3.6 pounds of force at the blade of the oar. Less force is required there now since the wind is helping to push the boat along.
Now let's imagine the rower encounters a headwind that slows the boat to 3 mph. How does he match his 1/10 th intermitant horsepower to the new speed? If the rower slides the oars in so that 32" is inboard of the locks and 52" is outboard, his 2mph, 9 pound application at each handle will be geared up to 3.2mph at the blades. As shown in Figure 4 the blade will balance now with 5.5 pounds of force at the blade. That's an increase over the first condition and it's that extra blade force that will help push through the headwind.
One can see from the above discussion that rowlocks that are pinned to the oars in one position don't allow this change of gears, so to speak. (They may have other advantages. More on that later.) By moving the oars in and out over an 8" range we have "regeared" the boat speed to vary over 50% without changing the handle force or speed.
And one can see that the total length of the oar might not really enter into the discussion, only the location of the pivot point effects the gearing of the oar. But the length of the oar does have effects. The longer the oar the less of an angle it will sweep through and the more efficient it becomes. Also the oar must be long enough so that the handles fall conveniently at the hands. But an overly long oar can be a problem, too. An overlap of the handles that many might find very awkward will develop. And the long oars may simply be a bother in confined rowing areas.
NEXT TIME...
We'll take a short look at sliding seats and relatives and a look at setting up the rowing gear.
ROWING2
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GEAR TO INCREASE POWER
(Before we get too involved in this I should mention that I have never tried any of the following techniques myself. This is just a paper study for me. If you think I've really blown the analysis, let me know with details and I'll rewrite with corrections.)
Increasing power will improve speed. Remember the formula for power is an arrangement of force, time and distance.
One way to increase power is to work out at the gym a lot and increase your muscle size such that you can pull with more force. Then slide the oars out a bit such that the extra force you can develop is converted into extra hull speed.
Another way to increase power is to quicken your stroke, pulling with the same force through the same distance. The increased oar handle speed is instantly converted to increased blade speed. You'd be rowing with lots of short quick strokes. This method works well with short boats that don't carry well between strokes.
You could also lengthen the stroke, keeping the force and stroke frequency the same. With any boat, especially a fixed seat boat with short oars, there are limits on the stroke length. If the oars start sweeping through large angles, efficiency will be lost.
Figure 1 shows the usual sliding seat arrangement. Here the rower sits on a seat that slides on rails, his feet are strapped into shoes which are fastened to the hull. In position A, the start of the stroke, the oarsman has his arms extended and his knees drawn up such that his hands are near his ankles. By extending his legs on the power stroke at the same time as he pulls on the oars, the rower greatly increases the length of his stroke compared to a fixed seat. The seat looks to be sliding about 2' during the stroke. In the diagram he has about 4-1/2' of oar handle stroke, about a 50% increase over a fixed seat. If the cadence of the stroke is the same as for a fixed seat, a 50% increase in horsepower would result. (He might also pull with a lot more force on the handles, but remember all the force he generates will transfer through his arms and hands. So I wouldn't expect a large increase in handle force in a long run.)
All the forces produced on the rower's hands are reacted through his feet alone and the human body is well built for that. None of the force reacts through butt friction.
Here are some arguments against the sliding seat.
For one thing the sliding of the seat may require a long space. (But the boat should be long anyway to take advantage of the extra power.)
The sliding seat can be a hazard in rough conditions. That may be a double hazard because you must strap your feet to the boat for the system to work.
The length of the oars must usually be increased because if you double the length of the stroke you will double the sweep of the blade. The angles the oar will sweep through will become excessive and inefficient if the oar is not lengthened. The lengthening of the oars will usually mean the addition of outriggers to help place the oar handles conveniently.
All these things may be worth the bother if you are the right person in the right boat. But maybe not. As shown in the figure I dreamed up for Roar2, a 50% increase of the power will increase boat speed about 15% . Instead of going 4 knots at full stretch with a fixed seat you might make 4-1/2 or 5 knots with a sliding seat. Normally I advise against it for a shorter boat. A longer narrow boat will probably be needed to take advantage of the sliding seat.
And increasing the speed potential of the boat will do no good if you don't pack the extra horsepower needed to push it to the higher speed. The rowing rig is just a transmission to match your power output to the needs of the boat.
There is another set up - the sliding rigger. In this boat the rower is seated on a fixed seat. The riggers that hold the oarlocks are not secured to the hull but instead are fastened to a sliding car which also contains the foot brace. The rower's feet are tied to the brace as with the sliding seat. But now his feet push the rowlocks aft as he pulls the handles forward. The overall power effect is the same as for the standard sliding seat. But the details are a bit different. For one thing the rower's weight doesn't shift around causing trim changes and hobby horsing. And all the force on the rower's hands reacts through his butt again. I've never seen one of these rigs in action. I read somewhere that when first tried in racing shells decades ago the sliding rigger boats easily beat conventional sliding seat boats and were soon written out of the rule books. Maybe so.
Figure 3 shows the system Ron Rantilla developed. Ron started with a standard canoe in which you paddle facing forward, (an advantage of paddling as opposed to rowing). To avoid having to transfer the paddle from side to side for directional control (an advantage of rowing and double paddling over single paddling) he mounted two paddles on a pillar in the center of the boat. The paddles attached to the pillar with a springy thingy that carried a lot of the paddle weight while allowing flexibility to paddle. Thus he was able to work each paddle with each hand. Ron lengthened the paddles into oars and thus he was able to row facing forward, (his "oars" were pivoted in the center of the boat in this case, not at any oarlocks, and his hands were outside the pivot). Forward facing push rowing has been used for a long time in certain areas and seems to be an inefficient way of using the human anatomy. Even fancy articulated oars that allow you to pull row while facing forward have never begun to achieved the efficiency of regular pull rowing. But Ron's system does allow forward facing pull rowing without the mechanical losses of an articulated system. Then Ron found he could run lines from foot pedals though pulleys to the oar looms and get his leg power into the equation. Then he found, that by attaching the leg lines just right and adjusting the center pillar springy thingy just right, he could make the oars dip just the proper amount under power and feather the proper amount on retrieval. No hands required in the proper conditions!!
I haven't seen Ron's system in action but there are certainly several advantages. None of the stroke power need be transmitted through the arms and hands - they can just be used to guide the oars if needed. You face forward. You sit in one position. You're feet aren't strapped to the boat.
Clearly there is some complexity of gear involved, but it's all pretty reliable and understandable and efficient. I guess the reaction forces on your body go out through the butt again. I would think a conventional sliding seat boat could boast more "power" because the rowers arm and back movements can add to the length of the stroke.
Ron wrote about his invention and experiences in MESSING ABOUT IN BOATS several times. He's not a racer but has raced the system with some success against sliding seat ocean racers. Like the sliding rigger experience, some of the conventional sliding seat racing organizations won't let him compete.
ROWING3
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MAKING SOME ROWING GEAR
But first, reader Lincoln Ross wrote a letter about my last essay:
"Just read your latest essay on rowing. While I agree with most of what you say, I think that sliding seats may be a little better than you're giving them credit for.
In rough water, those long oars can help you stay upright. I've been out in a recreational shell when it was rough enough to fill the footwell with water, and had no real problems. And the reduced windage is nice. I suppose the tied in feet could be a little tricky if you didn't wear a life vest. Where you do tend to flip is right at the dock. I've been out maybe 50 times and flipped, I think, twice. Both times right at the dock. Once next to a Charles River whitefish (ugh!). If you never let go of the oars you don't go over. Sliding seats let you use your largest muscles, so I think power output would be up for most people. It's a better workout. In a really skinny boat it's the only way to actually work hard.
Lincoln Ross"
Thanks much for the info. I agree especially with the comment that a long skinny fast boat will need a sliding seat to reach its top speed.
MAKING A SET OF OARS....
How long?? That's a tuff one and I avoid it by saying on each set of my plans I show the oars I recommend for the boat. All knowing Phil Bolger said in his first book, "Generally speaking, a good deal less than twice the spread of the locks will serve, and I'd prefer to have oars a little short of the ideal than much too long." I like to use 7 foot oars on good rec rowboats like Roar2 or a light dory that tend to cruise at about 4 mph. Slower boats can use shorter oars. I use 6-1/2' oars on Piccup which will cruise at 3 or 3-1/2 mph even though it has more than 4' between the locks. Short oars work well on larger slower boats too, for example 7' oars are fine for Birdwatcher and AF4. They probably move at about 2-1/2 mph. The idea that the longer the oars the faster you will go is simply not true.
Anyway, I'm going to show drawings for 7' oars which are about the most useful length for me.
WHAT KIND OF OARS....
The oars I make are really derived from the patterns of the late Pete Culler. They are characterized by having heavy square looms inboard of the locks and long narrow blades in the water. An example is shown in Figure 1.
The square looms are easy to build, help balance the oar, help locate the oar in the locks, and keep the oar from rolling around on the wales.
The long narrow blades go against modern thinking of spoons, but for long rowing, long and narrow is the way to go. The average mortal can only pull so much of a load, in spite of what an Olympian might do. The Culler blades can match the mortal's pull. They might slip a bit when starting a heavy boat from a standstill, but once up to speed, the have full grip on the water. They balance better. They are less fatiguing. They have less windage. By the way, the oars of traditional Irish caurrahs have no blades on their oars. Neither do the paddles of some traditional kayaks.
WHAT YOU NEED...
Oars are made from four materials - wood, glue, leathers and varnish.
For wood, I use 1x6 pine boards. The pattern shown in Figure 1 will just barely make an oar from a 1x6. I try to buy a single board long enough to get out both oars. For example, for a pair of 7 foot oars, I buy a board 14 feet long if I can. That way the oars will be a close match on weight, stiffness, and color I like to use soft wood like pine, It is easy o work and makes a light oar. It need not be clear wood although clear is easier to work Small solid knots are fine and look good too. I've never worried too much about grain because the sticks get laminated and tend to stay straight. But the straighter the grain the better.
For glue I prefer plastic resin "Weldwood" glue and doubt if there is anything better for making oars. Pour some in a cup and squirt in cold water until it has the consistency of normal woodworking glue like "Elmer's. I've found it to quite true that this glue will not set properly until it is a t 70 degrees F for twelve hours like it says on the can.
For leathers I don't use leather. I bind the 8 inches just below the square section of the loom with synthetic mason's twine, about 3/32" diameter. It lasts for years.
For varnish I use ordinary oil based spar varnish.
Now let's talk tools. The tool I use the most in making oars is a bandsaw and I hate to say that because it's not a cheap or small thing that everyone will have. The problem is that you've got to saw a 2-1/4" thick blank. Hand saws will work and the effort should get you in shape for rowing. After all, oars were invented long before the bandsaw. But I see Dave Carnell has built oars using his table saw and Bruce ----- built oars with his sabersaw.
HOW TO BUILD...
first cut the 1x6 boards to the proper length. lay out the centerline with a straight edge. Then draw the pattern for the center piece, the one with the blade., around the centerline. Cut out the center lamination following the line closely with your saw, because the outer laminations of the blank are made from the off fall and there isn't much extra.
You can draw patterns of the outer pieces and cut them out. But it's easier to glue the pieces directly to the center piece and trim them after the glue cures. Trial fit the outer pieces. You may have to trim them for the proper shape where they blend into the blade area of the centerpiece. When you are satisfied, butter them up well with glue, and clamp them in place. You may need to tap in a a light temporary nail to keep the pieces from sliding around on each other because almost all glues are quite slippery until they start to set. Try to get glue squeezed out all around. And be sure the blank is resting straight while curing. Walk away from the blanks until the glue has cured hard.
After cure, trim the outer pieces to match the centerpiece. Use a plane and sander to work these pieces to their final lines, being careful that these faces remain square to the other two unworked faces.
Now cut the two unworked faces of the handle and loom of the oars to their final dimensions. Draw centerlines down the two worked faces and lay out the shape of the handle and loom. Cut to the lines and sand smooth. At this point the cross section of the oar from handle to loom is square.
The oar drawing shows how much of the loom is left square. The rest is to rounded. You start by drawing lines on handle and loom that allow you to make the cross sections octagonal. You can draw them using the gadget shown in Figure 2. Then cut down to the lines with a half round rasp where the lines blend to the square section of the loom. Then use a drawknife or plane to remove the rest of the material down to the lines along the shaft. Now she's eight sided. To round it you're supposed to sixteen side it and then round it out. To tell you the truth, I leave mine eight sided, including the handle and the are which fits in the rowlock.
lastly you need to trim mass out of the blade. I plane the blade down so its edges are 1/4" thick. Then I use the front roller of my belt sander to hollow the blade slightly on either side of the center, leaving a ridge in the center.
I think the only critical part of these oars strength wise is the 1-1/4" section where the blade meets the loom.
Give the oars a good overall sanding, but leave the handles rough.
Wrap the rowlock area, from the square section down 8 inches toward the blade, with mason's twine. Wrap it tightly and use knots to secure it.
Give the oars three coats of spar varnish. That includes putting varnish on the twine binding. It will go a long way towards holding the binding in place. Don't varnish the handles.
An easy and effective "button" can be made be added to the bound area, to provide a stop which will locate the oar lengthwise in the lock, by wrapping it tightly with three wraps of 1/4" shock cord, and tying the cord with a square knot. If the tension in the cord is right, it will stay firmly in place while rowing and yet allow repositioning up and down the bound area to change rowing leverage when required.
A ROWING SEAT/DITTY BOX....
Figure 3 shows a rowing seat/ditty box that I've been using for years. You might have to tinker with it a bit to get it to fit your butt. As for the height of the box, it is nice for a bar placed across the rowlocks of your boat to cross you at belly button height. That would include any padding on the seat such as a flotation cushion which you should have on board anyway. For that matter a stack of two or three stiff flotation cushions can make a pretty good rowing seat.
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