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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.
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 –
- 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.
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.
After part 1, now we move on to outboard, inboard, handle and sleeve.
To decide your overall oar length you need to agree first your outboard length (in conjunction with blade area and shape – see later), then your inboard length.
The outboard length of the oar is measured from the blade tip to the centre of the sleeve. This length sets your “gearing” in conjunction with the arc through which you row, and with fixed thole pins, there is a finite limit to this arc length at both ends of the stroke. “Gearing” refers to the ratio between the size of the arc through which you row and the outboard length of the lever (oar).
In gig rowing the maximum size of the arc is dictated by the width between the rowing thole pins and so the size of the arc is something that you cannot change (although many crews may actually be rowing less than the full arc potential). However, it’s worth pointing out that some 50 year’s worth of data shows that in fixed or sliding seat rowing the arc from the catch to the point where the oar is at 90 degrees to the centreline of the boat (the “orthogonal” – new word for the day?) ideally needs to be about 60 degrees, and from theorthogonal to the finish not more than 35 degrees. This gives a total of 95 degrees.
In gigs it’s possible to achieve this total arc, but unfortunately you can’t get much more than about 50 degrees at the catch (in bow seat, helped by the curve of the gunwhale of the boat), whilst it is possible to row more than 35 degrees at the finish. Gig rowers over the past 20 years have been striving to get a longer arc at the finish by rowing the handle past their body, but this extra 10 degrees does not actually move the boat – rather, the boat is towing the blade out of the inside of the puddle, and this is even more pronounced if the finish is not accelerated. In fact rowers may benefit by concentrating on maintaining acceleration all the way through to the finish (ie “shorter but harder”).
Imagine in this diagram that a crew is rowing through an arc of 90 degrees with an outboard oar length of 295cm (pins to point A) – this would represent a very hard gearing. You can see from the diagram that for the given arc the “chord length” (A to A) represents the distance the boat is moved per stroke. Equally with a less strong crew using an outboard oar length of 278cm (pins to “B”, and chord length of B to B in diagram), the gearing is much easier because, for the same arc angles, the boat is moved a lesser distance.
It is interesting therefore that some leading men’s crews are currently using an outboard the same length as their ladies crews (!) this suggests that either the men’s crews are geared easier than their optimal (and maybe also rating higher), or that the ladies crews are geared harder than their optimal…?
(images showing position of leather in different places mens vs womens crew – same boat, same seat. Yes, ok, they’re probably using different kit but you get the idea – Ed.) You can see that the Men’s Crew (left) are rowing towards the inboard end of their sleeve (harder gearing, but perhaps too short inboard length?), whereas the Ladies Crew (right) are rowing towards the outer end of their sleeve (easier gearing, but perhaps too long inboard length?)
This length is measured from the end of the handle to the middle of the sleeve. The traditional inboard length of gig oars prior to the resurgence of gig rowing in the 1980’s has been quoted as “3 inches less than the width of the boat” at each seat across from the rowing pins. [If anyone could confirm this please contact us! – Ed]. In those days the longest pair of oars at 3 & 4 seats were about 14ft (426cm) overall, and the shortest around 12’6” (381cm). It’s interesting to note that whilst the outboard lengths of gig oars have reduced to be more appropriate to the shorter racing distances, the inboards have also reduced significantly!
The reduction in length inboard has had a significant effect on technique because with longer inboards (3 inches short of gunwhale etc) the oar handle was rowed into the ribs. During the 1980’s and 90’s the inboards got a lot shorter in order (we presume) to row the handle past the body. Over the last 5 years however we observe that fewer crews are rowing the handle past the side of the body, and more have elected to use a stronger finishing position with the end of the oar finishing to the ribs roughly in line with the centre line of the body.
Amongst the top crews this trend may be more evident in the ladies crews, and this would be because they are often not rowing on the centre of their sleeve but have pulled the oar more inboard in order to reduce the outboard length (gearing). This has also had the added benefit that they now have slightly longer inboard lengths and are therefore drawing the middle to the finish of the stoke with their bodyweight much more behind the oar handle, rather than leaning out away from it and rowing the handle past the side of the body.
In summary, inboards have gone from traditionally much too long for our current “sprint” racing, to too short inboards in an effort to increase the arc angle at the finish. (NOTE – it’s one thing to row a low and efficient rate for mile upon mile to meet a ‘Tall Ship’, compared to 10 or 20 minutes flat out on a race course). Rowers may now be finding a more optimal inboard length to facilitate the required 90 degree arc, whilst at the same time keeping the upper body weight and power behind the handle.
When choosing your overall oar length, first decide how long the outboard should be to give the optimal gearing, then decide the inboard length, all based on the physique and technique of the rower. The sum = the overall length.
This is essentially the narrower part of the inboard which is not varnished. Simply measure from the inboard end of the oar, to the end of the bare wood. We don’t have any dimensions for the diameter of the oar handle, but this should vary, dependent on the rower. Ladies with smaller hands will require narrower handles, whilst men with larger hands will require wider handles (fairly obvious really). If the diameter is too small the fingers will be very flexed when hooking round the handle and this will create extra tension and fatigue in the forearms. Too big, and the fingers will not be able to hook round the handle sufficiently to grip at all.
The diameter of the handle should be narrowest at the inboard end because all that is needed for the outside hand is to hook the fingers rounds. For the inside hand, the handle should be slightly thicker because the inside hand feathers the oar and a bigger thickness here means a smaller wrist movement to feather.
The length of the handle will depend on how far apart the hands are on the oar. In any sort of rowing the longer the inboard length of oar, the wider will be the hand grip naturally, and conversely, the shorter the inboard length, the narrower will be the grip.
The 1980’s and 90’s development of shorter inboard oar lengths have led to many gig rowers closing their grip up to even touching, whereas with the traditional long inboard oars the hand grip was very wide. Again, the ideal is something between the two, with the hands about 1 to 1 ½ hand’s width apart.
With the hands very close together, the shoulders tend to hunch at the catch, and through the middle to finish of the stroke there’s much less lateral control of the blade especially in rough seas.
Rowing with the hands 1-1 ½ widths apart encourages the body to twist in to the catch, and in behind the work at the finish (following the arc of the oar), and this ensures that the maximum force, and correct angle of force, of the body is applied to the blade.
(images, close grip and wide grip. Yes, the boat on the right is a sliding seat boat. The surfboat pic we had was even more extreme. Forgive me!)
If the hands are too wide apart, the inside arm will start the catch very bent, and this is likely to cause early fatigue in this arm.
Finally, it is probably better to have longer handles than at present (increase from the current 40cms to around 48-50cm). This will cover the variable inboard lengths required when men’s and women’s crews are sharing oars.
The length of the sleeve will be decided by how much length you want inboard and outboard of the rowing pin, and this is normally 18 inches (46cm) which assumes 9 inches inboard/outboard. This provides sufficient length of sleeve to give less strong crews the option to reduce their gearing by rowing with more oar inboard. Equally, in a strong tail wind a very strong crew may wish to move their sleeve outboard to make the gearing harder.
If the oars are always used for the crews for whom they were made, then a shorter sleeve of say 12 inches would suffice. However, because most oars are used by a range of rowers from juniors to top class men, then the basic sleeve “setting” for each crew will need to be different, and therefore an 18” sleeve is optimal.
Over the last 5 years some crews have tried using the plastic sleeves used by sliding-seat rowers, but it seems that they have been rejected by most, although not all. The plastic sleeve is harder and therefore more “pitch” sensitive, and crews have found them harder to control, and particularly harder to keep covered in the water. This is not a problem for sliding-seat rowers because the oars have a “D” shaped cross-sectional sleeve which fits into a rowing swivel. Leather is more ‘forgiving’ and easier to control, especially with the latest narrow lacing, however, the thick lacing on older oars does reduce arc length because of the thickness of the leather plus the lacing. Also, the thick lacing can interfere with the accuracy of the catch if the lacing touches the aft tholepin.
On the other hand, the plastic sleeve offers a narrower diameter sleeve, and this in turn enables fractionally larger arc angles to be achieved. Also, the smoothness of the plastic reduces the friction on the pins, and there is less need to grease them compared with leather sleeves. Finally, the plastic sleeves can be replaced in minutes since they only need to be slipped on and then heated with a hair dryer to ‘shrink’ them into position. Only time will tell if more crews use plastic sleeves or not.