Oars, part 1. Measuring to provide a spec.

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For a long time we’ve been meaning to sit down and start to put together some articles on the various parts of the sport, whether they be equipment based as in this series of articles or on fitness training, boats, maintenance, coaching, analysis, crew selection, club fundraising and so on. In this the first of the series we’ll be taking a good look at the oar. Shapes, sizes, development, the past and the future. By the end you’ll be talking for hours about the merits of 3mm of extra curvature in a big sea and a headwind. Probably.

Oars. Or, “how to measure gig oars to provide a specification”

When all is said and done, rowing is a simple sport – get fit and strong (ok, that’s another massive article!). Reach forward, place the blade and accelerate it through the water, then take it out and repeat until you can see all competitors behind you – job done.

Then one day you’re ready to place an order for a new set of oars to replace your existing ageing ones. You’ve saved the £2000 or so needed and are about to sign on the dotted line…

CPGA Rule 22 : All paddles [oars] to be made of timber and of traditional shape blade”

But will they be the right ones, will they suit your club, members and boats? If you’re new to this then what on earth do you ask for when talking to your manufacturer? How much do you know about your existing kit? What do other clubs use, and what on earth is a “traditional shape blade” anyway?

Well, the traditional shape was 32”(~810mm) long blade, widest point at tip, and a picture (from Suttons Blades) of one being varnished is shown below. They survived for about 100 years from the mid 1800s, probably not at all like the kit you currently row with.

Traditional blade shape – Suttons Blades

The making of a wooden oar is an art in its own right. The oar is arguably the most personal part of the rowing process, a living connection between your hard won athletic frame and your crew’s best performance. Every tree and plank will have different density and consistency lending itself to different types of oar. The lifetime’s skill and development by the builder means they’re able to match your requirements to the wood they have in stock and making the right choice will lead to precise, light and balanced kit. The perfect oar will transform your enjoyment letting you relax and trust your kit to work for you stroke after stroke.

Measuring and specifying an oar.

You might have your favourite oar, you might have used one from another club and found it better or worse than your own. But why, and how to quantify this ‘feel’?

To get a feel for your existing kit, you’ll need –

  • A tape measure (ideally a soft one and a metal one).
  • A known weight such as 25lb (11.34kg).
  • A couple of things to balance oars on (like the back of a chair or trestles).
  • A metre rule, spirit level or other straight edge.
  • Vernier callipers.
  • Scales such as bathroom ones.
  • A willing helper.

What to measure –

The oar.

  • Overall length (from end of blade to end of handle)
  • Inboard length (from end of handle to middle of sleeve)
  • Outboard length (middle of sleeve to end of blade)
  • Sleeve length and type (leather or plastic)
  • Handle length.
  • Weight in kg.
  • Diameter of shaft under sleeve (take average of measurements either side of sleeve using callipers or the soft tape measure to get a circumfrence then work out the diameter)
  • Balance point – distance from end of handle to where the oar balances on a point. A simple way is to use the back of a chair with a narrow edge to find this point. The further the balance point is from the end of the handle the “lighter in the hands” the oar will feel.
  • Stiffness – how much the oar deflects for a given load. On a level surface, mount the oar level between the middle of the sleeve and the end of the handle. Firmly hold down the end of the handle and check the height of the middle of the blade above from the ground.

Next, hang your test weight from the end of the shaft (just where the blade starts – aka “the neck”). Re-measure the distance between the centre edge of the blade tip and the ground – the difference (deflection) gives you the relative stiffness or softness.

Our tests found a new, stiff stroke oar deflected about 80mm whereas a soft oar was 140mm or more.

A bit more background on stiffness, balance and overall weight.

Stiffness.

The stiffer the shaft the less deflection under load, and the more “direct” feel but more jarring. When the crew places their blades in the water at the catch and connects they are effectively taking the full weight of the boat and crew. The stronger the rower the more able they are to pick up this weight. The faster the rower makes the connection the more efficient and explosive they have to be.

So, the stiffer the oar the more superhuman the rower has to be! If the oar is too stiff for the rower then you’re likely to simply “bounce” off the catch or pull the blade through more shallowly or injure your back from the jarring (or break the oar). There is no point in having a mechanical system that the rower cannot handle as it’s most likely the rower that will break down. Therefore the less strong/fit the rower, the less stiff the oar should be.

In general the “weight” of the crew is felt by the stroke pair and the “speed” is felt more by the bow pair. Given this, stroke rowers could err towards a softer shaft.

Too stiff an oar for the power of the crew will probably slow you down whereas too soft an oar won’t necessarily slow you down as long as you accelerate through to the finish. A soft oar that bends on the catch will unbend at some point during the stroke so that the energy stored in the oar will not be lost. With weaker crews the oar may unbend during the power phase of the stroke but ideally the bend initiated at the catch should be maintained right through and will unbend just before you release the blade.

Balance and overall weight.

Ok, “lighter in the hands”? – clarification needed here – this doesn’t relate to the overall weight of the oar on your scales but is the relative feel of the weight of the oar in the hands when in use when rowing. Sometimes an oar that is heavy overall may have great balance and feel light and quick to use in the hands as much of the weight is in the handle. A few kgs here or there compared to the overall weight of a gig are immaterial but the feel of oars light in the hands are a real bonus especially for your forearms, acceleration and clean release (even more so for lighter/juniors crews). On the other hand if it’s too light it will be inclined to fly up in strong headwind conditions and will need more accuracy.

Our tests showed that the heaviest stroke oar we measured was 5.5kg and the lightest 4kg. All things being equal the #4 oar will be the longest and heaviest overall. The lightest balance for a #4 oar was at 195cm and the heaviest for a #4 oar was at 177cm. For a stroke oar the range was 170cm to 178cm.

Clearly the balance point depends on the overall length is only meaningful between oars of the same length. Oar #3 and #4 being the longest overall may tend to be lighter balanced than stroke or bow oars.

Next article – measuring and thoughts about handle, inboard, outboard and sleeve.

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2 Comments on "Oars, part 1. Measuring to provide a spec."

  1. Pingback: Oars, part 2. Outboard, inboard, handle and sleeve : GigRower … Pilot Gig, Cornish Pilot Gigs, Gig Rowing

  2. reinhard

    Hello,

    I have been studying your article on the search for how to balance oars. Now I have a problem with understanding the balance point and how it relates to an oar feeling light in the hands. You write the further the balance point is from the end of the handle the lighter it feels. This is where I am getting confused. The oar lock will be somewhere at about 1/3 of the oar – 1/3 inboard and 2/3 outboard – thats the way it is going to be for our 2.4m oar for our boat. To me this means there will be more weight outside than inboards. The oar we bought is not tapered and has no counter weights inboard. Its a simple flat board with a round loom all the way. We haven’t tried it out yet since its still early spring and the water is much to cold.
    Would be great if you could help to get this right. I am certain I have mixed something up.

    Thanks for your help!
    Regards,

    Reinhard

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