As I mentioned I will be occasionally posting some of the writing of Jerome FitzGerald. I have read and reread all of his books (Wind and Tide, Sailing with Purpose and Sea-Steading). Jay is an opinionated SOB and I like that. While many people will tell you what you can't do without and engine Jay tells you how. He is really an inspiration for the enineless sailor. But having a thick skin is a must. If you are looking for him to reaffirm your beliefs you will come away bruised and battered. In my case, I don't sail for Jay, I sail for myself so I find his books a good read full of information that I find invaluable.
By permission, here is information on how to build a sculling oar.
Along this road, most all of what I read from modern sources when I built my first sculling oar was total bullshit, applicable only to dingy and such and there pointless--so I’m going to save you the hassle of the same mistake. It will cost you a couple hundred bucks to do build a sculling oar, so there’s no sense in failing. As well, to work right, a sculling oar needs to be built for a certain person on a certain boat to get the geometry right. This geometry is vastly more important than any other feature of the oar. So, we’ll figure it out.
So, I’m going to explain the whole deal to you so you can design a sculling oar.
First: why row, or why scull?
Rowing is very simple and simple in context. An oar is just a paddle. You push in through the water and it moves the water more or less at the same rate you push. The length of the oar allows you to get more(usually unfavorable) leverage so as to move more water more quickly. It generates speed. It generates power in direct proportion to how hard you push. On a small boat, and to me this means any boat of less than 4 tonnes or so, it’s a very sensible option. Not only does rowing allow for forward motion, but backwards, and also will aid turning. If this is your option, and you have a little boat, it’s easy. Mount good solid oarlocks go at it. You can’t overdo the mounting of the oarlocks.
Sculling has nothing to do with rowing, and the action is utterly different. It doesn’t move water in even close to the same way. What a sculling oar is—not a paddle—but a propeller. And it’s a really really big very shallow pitch propeller. If in powerboat terms a “square” propeller—one that is say 36 inches in diameter and moves 36 inches of bite in one revolution—is considered powerful, a sculling oar is off the scale. Rather than square, a typical sculling oar in propeller terms could be a 200 x 36 screw. As such, and like the effect of any screw or other inclined plane, it generates a great deal of force at the expense of speed. As such, it’s the only sensible option for a large heavy boat, that you’re not going to move at more than about a knot or two anyhow.
The difference between a conventional propeller and a sculling oar is this. A propeller goes round and round. A sculling oar only makes about a quarter of a revolution and then reverses. Obviously that wouldn’t work with a propeller, as you’d go forward then backward, but on a sculling oar the oar is rolled so the pitch is reversed for the return stroke. This reversing “diving leaf” pattern is the key to sculling.
Ok, so there are different ways making the pitch reverse—but I’m going to describe the from the perspective of the plan old western bargemans sculling oar. I’ve come to believe this is the best. Yulohs, the Ro, all that, they all do the same thing. None is more magical than the other or in my mind significantly more effective. You don’t or won’t get something for nothing. You won’t replace even a small outboard with a sculling oar. You’re just not big enough to generate the juice. I imagine a sculling oar is about the equivalent of a ½ horsepower outboard. Still, you can move a big boat with that in a calm, applied smartly. It will keep you from drifting onto a beach when you can’t sail. Don’t expect to row out to the islands for the weekend unless you’re some kind of gorilla.
So back on topic, there are several different ways to make the pitch reverse. One, you can just grab the oar and rotate it. This works on little boats but will mess your wrists up in short order on a large one. A yuloh uses a lanyard that you give a jerk to to get it to roll. We’re going to use a lanyard, but we’re not going to touch it as jerking the rope back and forth will tear your hands up.’I’ve seen trailer hitch balls and all sorts of other stuff too. No, no, we’re just going to the simple thing. We’ll just put a bend in the bottom of the oar.
On a traditional barge style sculling oar there is a pronounced bend to the lower end of the loom(what the shaft is called) before the blade. This is there for two reasons . First of all, you want to be able to stand on deck, facing aft, with inner end(handle end) of the oar just about at chin level. You want the middle of the oar to be at the chock at the transom, but as the blade intersects the water you want to do so a better than 45 degree angle. 60 is better. Why? Because just like a propeller, you want it facing aft, not up, as it’s the sensible way to direct the force that comes off the blade.
Now consider what happens when you swing the oar—that bend wants to twist the oar in the notch and drag behind the stroke. As it does so, it imparts an angle of attack, of bite and pitch, to the blade, doesn’t it? There you have it—self feathering.
The biggest difference between dingy sculling oar and big boat sculling oars is the amount of bend. You don’t need a lot of bend in a little sculling oar because it will bend a bit and feather. A big oar won’t—or shouldn’t as you’ll be throwing all your body weight on it and you’ll just bust it. You’ll be quite amazed at the power it makes. We’re talking about hundreds of pounds of thrust.
Hence the lanyard on the inner end. Obviously as the blade dives, it wants to pick up the handle end. You can’t let that happen, as you lose all your thrust. So, you have a lanyard on the inner end holding the loom down so all you have to worry about is hucking the shaft from side to side. I find that I like to put both hands over the end of the oar and pull squat from one side to the other. When you have the motion right, the dig is so hard it will nearly support your weight. Practice. You’ll see.
So, at this point we can see that the power we’re building will raise all hell on your transom unless it is built to take the prying action of a 4x4 sixteen or so feet long. Don’t even consider silly little oar locks, or even big ones. You’ll break them. What you want is a nice rounded chock at least 2 inches thick and 5 inches deep, backed up with a couple bronze thole pins of maybe 1 inch on either side to make sure you don’t roll the oar out. It needs to be husky. Don’t make a mistake about that. If anything breaks while you’re sculling, you’ll either spill it in the cockpit hard or go over the side, which would be stupid. Keep the chock well greased. Use Vaseline or Bag balm, as I find that keeps best.
How to build a sculling oar.
Buy a clear fir 4x4 14-16 feet or so long, depending on your boat and aforementioned geometry. This will be the loom. Longer is generally better, if you can stow it. If you can’t find one, you could laminate one up, but clear is nice.
For the blade, you’ll want a piece of some wood, a good hard fir is fine but ash, elm, white oak, or other will work as well—about 6 to 8 inches wide about 36 inches long. This will be the blade, which will be clothespinned into the end of the loom shaft. Some people will be tempted to get all weird about the profile of the blade, about foil section and all that. Great. Fair it, but beyond that I don’t think it matters much. Just be sure that if you put a wonky profile into the blade make it face the right way! Don’t laugh—the nicest sculling oar I ever saw had the lift face in backwards. Bulge in the wing forward, which is up, towards the lift, or the low pressure face, right? Think propeller!
Take the skillsaw and make two rip cuts clear through the 4x4 starting from the what will be the lower end of the loom up towards the center. This splits the 4x4 at that end into three pieces, which will allow you to bend that end. Make the cuts so that the remaining piece in the midde of the 4x4 is the same thickness as the head of the blade.
With the skillsaw make the square 16 footer into an octagon by setting it at 45 degrees and taking the corners off. Be careful, of course, as if you cut an artery you do no sculling.
Now the clever spar makers bit. Mark the oar with a felt tip at 1 foot intervals. Figure that in the middle two feet it will remain about four inches thick. Figure at the handle end, and probably blade end too, it will be about 2 and a half thick and round. You want nice taper but not stand around in a nicely pressed pair of carharts and fart with a drawknife for two weeks. So, set skill saw back to 90, and set the blade depth to 3/4 . Take the saw and cut a whole bunch of cuts into the last foot of both ends. Now set the saw to about an 1/8 less and do the same to the next foot in, of both ends. Repeat until you get near the middle. Now get a beltsander with 36 grit or tougher—or a powerplane if you’re brave, and peel away until all the saw marks are gone. Bingo, you’ve got a double tapered, round loom shaft.
Notch back the center piece of the 4x4 ten inches or so you can stick the blade in there.
Set up a bending jig. Stick the loom end under something immovable, over a pivot point, and dog, handybilly, bar clamp or something the lower end into the shape you want. Test fit, release. It will be a husky bend. Don’t let it snap back and bash your face. Shoot the scarfs full of semi-thickened epoxy, crank her back down, stick the blade in, and clamp the whole works together with 4 or 5 c-clamps.
Let the glue set up. You’ve an oar. Finish it to your personal level of fetish.
Copyright 2006 Jerome FitzGerald
With my dwindling blog posts, it will come as no surprise that I am ending my KnockaboutSloops blog. All along this blog has been a personal resource that I have used to journal and organize my thoughts during the design and construction of Bolero, our custom engineless Knockabout Sloop.
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