Oars. Too long, too short, jointed, varnished, wood, alloy...are you satisfied?

Greenheart

Greenheart

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I seem to remember reading a good oar-thread hereabouts in the last year...I may even have initiated it...but I can't find it.

I've generally found oars to be less flawed than rowlocks, or the mechanisms that secure the rowlocks, or fail to do so...

...but equally, I've often felt that each sweep was ill-proportioned to the size of the boat, and that my effort might have been more beneficially-geared, using longer oars to drag through more water, shifting the boat further.

Then again, that may be nonsense. But if so, why wouldn't Britain's finest at Eton Dorney have used the same kit we do?

Is there a tried, tested, proven reason why oars aren't usually more than 6' long, other than the impracticality of storage?
 
dancrane said:
Is there a tried, tested, proven reason why oars aren't usually more than 6' long, other than the impracticality of storage?
Click to expand...

Yes. They're also cheaper to make and buy if they're shorter! Generally speaking ones longer than that are easier to row with in the average dinghy, in my experience. Obviously if the length is excessive they become unwieldy and heavy.

I think ideally the length is a compromise related to a host of factors such as how far out from the centreline the rowlock (or other pivot) is (otherwise they're unbalanced and hard work); how high out of the water the rowlock is; how strong the rower/heavy the boat; how rough the water; how much manouevring versus straight line rowing, etc.
 
Iv used oars longer than 6ft I think at least 8ft.
Of course the boat's were also bigger. 14ft or 16ft and an 18ft clincker.
I have used oars longer than these but it was a single sweep on whale boat with four banks. cant remember the length.
 
My inflatable came with a set of aluminium plastic bladed jointed oars.They were far too short so I removed the plastic handles and replaced them with wooden ones about 30 inches long.
I can now row the dingy properly and the wooden handles are far easier on the hands than the stubby plastic ones.
 
I was told that the rule of thumb is that each oar should be 1.5x the beam of the boat (or, more pedantically, the distance between the rowlocks).
So for a boat with 6ft beam, each oar should be 9ft long.
 
Robwhelton said:
I was told that the rule of thumb is that each oar should be 1.5x the beam of the boat (or, more pedantically, the distance between the rowlocks).
So for a boat with 6ft beam, each oar should be 9ft long.
Click to expand...

Aye, I wis told the same Rob.
The rowlock pivot point should be roughly a third of the way down the oar's length is another rule o' thumb til go by.
 
I sized the oars for Katy by sitting on the thwart and placing a broom handle in the rowlock. A 6' oar put the blade in the water at a natural height of the handle.

Actually I imagine all the dimensions are fairly critical. The position of the thwart, a board for your feet, the height and fore and aft position of the rowlocks. You need to be able to lift the blade high in a swell without your lap getting in the way. And oars presumably come in standard lengths.
 
Sculling blades

Sculling blades are ~280cm long, with the button ~88cm from the handle. The beam' of the boat (distance between the pins) is 158cm. More info can be found at http://www.worldrowing.com/files/download/5483

I've tried some in my fixed seat grp tender and it mostly worked ok, but there is a problem with the cross-over of one's hands due to the rowlocks being so much higher than the 'gates' on the racing boat.

I think that one has to make the oars shorter so the hands don't cross over (say a 2cm gap so one doesn't crush a thumb), and then stick with the same inboard to outboard ratio of 88 : (280 - 88). Hence the length of oar ends up entirely determined by the beam of the dinghy.
 
Interesting, thanks for the input. I felt sure the standard 2-meter variety could be improved upon.

Beam + 50% sounds a good working ratio. I'd begun to think oars were made to fit the chandlers' convenience, because you rarely see any that are longer the average customer is tall...
 
For my tender, a Mirror lookalike with topsides raised by about 2", I use 9 ft oars. It would be OK with 8ft but 9 gives ideal power. It's a bit awkward at close quarters but he whole object of switching to a hard dinghy was to make it practical to row in open water in adverse conditions.

I did have to move the buttons to suit the beam of the boat and give an overlap of about 4" between the handles (I row right over left, a hangover from my days in single sculls). I would prefer a proper set of sculls but they are £500+ a pair.
 
I suppose ten-foot oars need a passage through the moorings that's at least twenty feet wide...could get difficult on a dark night in a crowded harbour. All the same, nice not to feel reliant on an outboard just because it's quite a distance against the tide to the quay.
 
I used to row a Wayfarer quite sucessfully with a pair of 8' oars. 6' beam so probably about 5' 6" between rowlocks. 9' would probably have been better but wouldn't fit in the cockpit of the Mk1 boat that we had.
 
Oar length etc

One of the reasons people buy our (traditional hard dinghy type) boats - often to replace or supplement an inflatable - is they are nice to row. Getting the oar length right is critical to this and depends on many factors including:
- beam of boat or more specifically distance between rowlocks
- nature of hull (easily-driven etc)
- strength and height of rower
- how the rower likes to row! Some will cross their hands in the middle, some like their hands almost together in the middle, some like to have their hands apart at approx shoulder width.

In our dinghies - which are easily-driven compared to an inflatable - a good working average is to have 2.5 (two and a half) times as much oar outside the boat (I should say the pivot point to be accurate) as inside it. So on a boat with 4ft between the rowlocks and the collars set so the oar ends meet in the middle you make the following calculation:
- Inboard length = 2ft (4 x 0.5)
- Plus outboard length = 5ft (2 x 2.5)
- Total length = 7ft

A tall strong person might prefer 7ft 6" oars whilst a shorter less strong person might prefer 6ft 6". As a typical couple might include one person in each category the best compromise if they both want to row will be 7ft.

It's all about gearing. For the example boat above if you had 6ft oars now and changed them to 7ft you will change the gearing from 2:4 to 2:5. Or increase it by 25%, big difference. Like driving your car at 70mph in 3rd gear or 5th gear (I'm making that up, don't know typical car gear ratios, but you get the point).

On boats like our Trio 14 (14ft long, 3ft 6" beam) you can use longer oars than this formula predicts, because the hull is very easily-driven.

The seat height compared to rowlock height is important, as is the ability to straighten out your legs, and distribution of other people. Ideally you want to be able to brace your feet against something solid and not hit your (or anybody else's) knees with the oar ends.

Keeping the boat trimmed correctly also makes a massive difference.

"Our" rule works for our sectional nesting hard shell dinghies (eg 8ft Pram and 9ft Stem), and would apply to most other similar boats, but may not translate directly to inflatables. But I would hypothesise that on most inflatables the rowing arrangement as supplied is not optimal...

Lastly, I don't know why but for me at least wooden oars seem to work better than aluminium and plastic ones. Suspect this is more psychology than anything else - they feel right!

Ian, Nestaway Boats Ltd
 
I just rediscovered this selection of oar quotes from the webpage 'The Rules' (sorry, forgotten address of it).

The length of an oar should be of half the beam (from lock to lock) times three, plus 6 inches West Marine

Alternatively, the length of an oar from lock to grip should be half the beam times three, plus 2 inches John Vigor

The calculation of oar length for one of my boats is based on a movement at the hands of only 700mm. The theoretical cruising speed of the boat is then worked out by taking the square root of the boat's waterline length in feet (Imperial units of measurement are good for some things) and multiplying the result by a figure between 1 and 1.4... A short fat heavy boat will be close to 1 while a really long light slippery boat will be at the other end of the scale. This jiggery pokery tells me how fast the water will be moving in relation to the boat, and by applying a slippage factor appropriate to the oar type, about ten to twelve per cent for the narrow blades I use, I can work out the shaft length needed to move the blade at the right speed when the handle is stroked through 700mm25 times per minute. John Welsford

In the context of small boats, the oar length should be about 7ft - at that length, in beamier boats the 'gearing' changes appropriately. Jim Michalak

In a boat designed for adults, rowlocks should be about a foot astern of the thwart or seat that will be used for rowing. Unknown

A length of 5 inches is about right for the grip. Never use a keg shape, but give the grip a taper of about 1 1/4 inches at the inboard end tapering to about an inch next to the swelled part of the oar. RD Culler
 
I think my oars for my 22' Drascombe Longboat were about 9' and were fine :D It was such an advantage being able to manoeuvre such a long boat without messing about with the engine.

The tip I was given was don't use nails to fix the leather collars, stitch them on instead otherwise the oars will just rot even with copper nails :confused:
 
I have tried longer oars on my AX-3.
Bit of a mixed result.
I could row it faster, but at the expense of flexing the boat more and hitting any waves a lot harder. And of course it becomes a bit comic in tight spaces.
Since my outboard is small and light, I don't tend to row it very far or against the tide, or against strong winds, but in small quiet places like the Yealm I'm happy with the oars.
 
My yacht tender is a 14 foot catamaran I have converted into a rowing platform using all the dimensions and ratios mentioned in Snowleopards link. The oars are windsurfer masts with ply/epoxy/carbon fibre blades to a design I stole off the web. The width between rollicks, height of the seat, distance fore and aft of the seat and footrests are the theoretical perfect and its a pleasure to row, oars are about 13 long.
 
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