Wednesday, September 30, 2015

Shaping up a set of store bought oars.


Lets get the jokes out of the way, the one about this being a “two oars-power cruiser”  and the one about “keeping things on board oar-derly “. Oh, and the one about the Greek Bireme that docked too close in at speed, “Dis-Oared-‘er”.

With that out of the way,  I want to show how I go about turning a pair of off the shelf machine made oars into something that I like to use.  As they come they’re robust, but very heavy and unbalanced, tip heavy so a lot of downward pressure on the handles to lift the blades on the recovery.

So to make them easier to use, more pleasant and just “nice” I cut the oversize blades down a little, shave the blades thinner with a ridge down the middle to keel them sufficiently stiff, and slim the shaft from the “leather” down to the “neck.

Oars should ideally be matched to the boat, this one being a sailing boat will have a little more resistance than a lighter and more slender boat, so needs oars that are slightly more stiff than the ones for the pure rowing boat.
They need to be practical too, which means a thicker blade and a more robust tip so I can use them to pole the boat in the shallows or push off a jetty somewhere.

The species of wood used needs to be taken into account, European Ash (Fraxinus Excelsior) used to be commonly used and is tough, resists damage and makes a reasonably good utility oar .  But its heavier than I like, and the costs more than I like to shell out for a pair of oars that I’m not going to use as the boats primary propulsion.  This is a sailing boat after all.
Spruce, (Picea Sitchencis) by comparison is much lighter and is strong for its weight but crushes very easily so an oar made from this may be easily damaged.

All that’s a bit academic though, as the ones that are available off the shelf here are stated to be “Tasman Pine”.  Good old Pinus Radiata,  actually not bad stuff for this use if chosen carefully.
Its mid range in weight for a softwood, fairly strong for its weight and if kept well coated with varnish reasonably stable.
So that’s what I’m working with today.

For a boat of this anticipated resistance to movement I prefer a slightly narrow blade, 90mm wide at the tip, 80mm wide at the neck end, 6mm thick at the edges of the blade, with a prominent ridge down the middle to stiffen it, the neck will be around 30mm through the vertical axis ( that’s in line with the blade) and full width which in this case is about 40mm at 90 deg to the blade, a fat oval section there to orientate the thickest part of the section to the load.

Tools.  Making that hollow section from the ridge down the middle of the blade out to the edges is what stops a lot of people.  I’m fortunate to have come across  a round mouthed spokeshave and as a tool “enthusiast” ( not what my wife calls me) I bought it just in case I found a use for it.
Its not rounded front to back, this one is radiused from side to side so makes a hollow. Ideal.
But there are other ways.  I”ve used the nose end of a belt sander, offered up at an angle and run along it will carve a hollow, a small angle grinder with 40 grit sandpaper on a flexible backing piece will do an excellent job with practice, a random orbital sander would do the job and in fact that’s what I use to do the finishing, and if you are either very determined or very lucky, you can use a hand plane with a rounded blade and bottom.
By lucky and determined, I mean that while those are rare its not that big a deal to make one. To make mine I used a worn out horse hoof rasp for the blade, lots of grinding required but its good steel, a block of beech for the body, an offcut of Australian Jarra for the wedge and a piece of copper rod to retain the wedge.
There is lots of information on making planes out there on the net, but most of them overcomplicate things, but if that’s the way you want to do it, you’ll find it.

So having bought my “store bought” oars,  which incidentally cost not a great deal more than enough of the more “suitable” material in plank form, I first made a couple of simple “holders” to clamp the shaft in order to work on them.

Next was to mark out the blade and the neck with a ruler and a sharpie marker,  that shape being cut out with a jigsaw and the edges planed smooth and straight.

The next step was to mark the center of the edges with the marker, and use a standard block plane to shave a bevel down the face of each side so the outer edge is at the desired thickness.
This is a guide, don’t go much past that. That’s the thickness you are after.

Next is to taper the shaft from leather to neck.  That’s a straight flat, starting very narrow at the leather and gettting wider and wider as it gets down to the neck.
You may need to remove some material at the neck to get this taper right, use a standard spokeshave here to make the hollow from the taper you are planing to the curve where the blade starts to swell out to its full width. 
Don’t round this area off yet, that comes when the blades are done.

Out comes the tool you have chosen to remove the material from the blade to make it “hollow” from the center ridge to the edge.
Work out from the marked centerline down the ridge out to the edge, I work from the tip in toward the neck as with the taper on the edge the grain is better to shave this way.
The random orbit sander can remove all the little ridges that the spokeshave or plane makes, so don’t fuss too much, just try for no lengthwise humps or hollows.

When the blade is hollowed and thinned both sides,  then fair it into the neck, remember that this is the high stress area of the oar, don’t remove too much material here,  where that central spine merges into the wide part of the neck is the critical part.  Don’t thin that down.

Round the flat that you’ve planed onto the shaft into the body of the shaft aiming for a shape at the neck which is more like an oblong with the corners well rounded than a true oval or ellipse, sand off smooth and coat with varnish or paint.

I’ll be painting the outboard end of the blades with white paint, the regular flashing of the white is visible from surprising distance. 

I’ll be fiberglassing the tips by the way,  it reduces the chances of splitting the oar when pushing the boat off rocks or such.  Just a little strip of 50mm tape folded over the tip and epoxied into place.

I’ll go into the leathering and the shaping of the handle when I get around to that stage.
In the meantime, these oars have lost about 15% of their weight, and that almost all of it from out on the blade end which makes them much easier to use.


  1. Oar maybe a row-locking good read for those who want to paddle their own canoe?

  2. I'd guess that they'd then be able to "Sweep" all before them.

  3. Thanks John, very nice summary, I got the oars out at the weekend.

    One question when you say that you "tapered the shaft from leather to neck". - Is that an all round taper or did you leave more wood in one direction i.e. perpendicular to the blade for additional strength?


  4. Thanks John, very nice summary, I got the oars out at the weekend.

    One question when you say that you "tapered the shaft from leather to neck". - Is that an all round taper or did you leave more wood in one direction i.e. perpendicular to the blade for additional strength?


  5. Thank John, Great tut-Oar-ial. I have a pair of 9 1/2 Ash Gulls for our North Shore Dinghy, and they are Oarfully heavy. Nice and strong, but now with your excellent guidance, and can put them on a diet, so to speak. All the best. John