Boat Oar Designs

Any modifications made must be done within the constraints of the specifications laid out in the rules.

in shell boat racing, the boat oars haven't changed much, but the boats have. modifications have been made in the hull's shape and even in the choice of materials.

the most important improvement in the game was the "sliding seat" which multiplied the power of the rowers, where formerly only the back and arms were involved, not also the power of the legs helped.

as a general rule, "selecting your oars will depend on the type of rowing you plan to do and the boat used. The range of types includes everything from simple knockabouts to composite fiber sculls. A well made set of spruce spoon oars is perfect.

The oars should be correctly fitted to the beam and length of the boat. the required length of your oars is about twice the beam of the boat. Smaller dinghies and tenders have the oars set so their grips are across from each other about 2 thumbs apart on the return stroke. On larger craft more leverage is gained, giving a more powerful stroke by overlapping the grips 5 inches or so. Maneuvering is a little easier with non-lapped oars, particularly for a beginner."

while there are no rules for oars design or material, obviously the acid test for such a modified oar will be the rower himself. surely its weight and bouyancy will be critical factors for its acceptability.

Sources:

http://www.whitehallrow.com/legacy_html/rowing.php

http://www.rowinghistory.net/Equipment.htm

FISA Rules

You mentioned the sliding seat, which I think lets the rower move toward the front of the boat as he pulls on the oar. Doesn't the reactive force slow the boat a little? Perhaps if the rower pushed with his feet on a plate that also moved the oarlock toward the back of the boat as he pulled on the oar, the reactive force would help speed up the boat. His seat would be stationary. This might be a hard rowing technique to learn.

If what you said is correct, Earth will move a little, in the opposite direction, at the instant a rocket is launched.

True: and it does! But the mass of a rocket compared to the mass of the earth is minuscule, whereas the rowers in a boat are far more massive than the boat.

One variation that's been tried is "swivel handles" on the oars that prevent twisting of the rower's back. Unfortunately, the rowers don't like 'em.

Swivel handles are shunned because there is no way to 'feather' such an oar. Keeping the oar flat on the return reduces windage and the possibility of splashing in the wrong direction (how embarressing!). Like those stupid rowlocks w/ the pin through the oar. Hate em!

I know, 'cause I been rowed hard and put away wet too many times.

An oar is not like a wing. You want a wing to pass unimpeded through the its fluid. You want an oar to resist passing through its fluid. An oar is a lever, and its fulcrum is the center of pressure against its vertical surface. If you watch a racing shell boat in operation you'll see that the center of pressure is almost motionless during a stroke. The lever is almost totally efficient and any further improvement could only be marginal.

Don Shepherd

Then simply making it from modern lighter/stronger materials, and, making it longer would improve it.

"Lighter, stronger materials" might be OK for the racer that throws his oar away after every race, but nothing beats Sitka Spruce for oars or paddles. Wood has a natural 'spring' to it as well as fatigue resistance greater than any fiber reinforced plastic. In fact even greater than steel. Once an FRP oar is soft, it's DONE. No fixing it. Wood can be fixed almost indefinately.

Like others have said: Oars, paddles, and boat designs have been evolving over thousands of years.

See you on the water.

Hello Don,

Oar can be considered a liver; agreed. But what kind of liver? In my view, it is a second class liver with certain amount "SLIPAGE" at the fulcrum. The fulcrum is the tip of the oar and will move by a certain distance, which depends on several factors, in the popposite direction of the motion of the boat. your seatement that "its fulcrumis the center of pressure is almost motionless" is not correct. the pressure point actually moves horizontally (in reality the pivet points of all oars) in the direction of the movement of the boat. If your statement was correct, the boat would hav remained stationary and only the water only would have moved. In your view, the oar is a first class liver which is not correct.

Sorry that I spelled it wrong!! Afterall Engilish is not my mother toung.

I am not quite sure that Iwas agreeing with Don. What do you think Don? You are correct. I neglected "its". Thanks for the correction.

I have only seen a different oar design at Reelfoot Lake Tennessee. THe old wooden "lake" boats had a steel plate on the hull and a jointed oar set that propelled you forward in the water. This design was evediently necessary since the lake was 5 ft deep and filled with tree stumps just under the surface of the water. These were great for Crappie fishing but tended to stop a boat suddenly or heave it over to one side as it deflected off the stumps. The lake looks normal and all water on a calm day but on a windy day you can see the stumps in the wave troughs and would swear you could walk across the lake from stump to stump.

Frank 12,

The curve of the oar was the major change. It is said that an Alaskan prospector/miner/gold panner invented the curved sweep used today.

The advantage is that near the end of the stroke the angle of the oar tip provides more propelling force than a straight one.

Jon

Hi, Frank12!

While the oarlock is the fulcrum of the force applied to the paddle surface of the oar, it is not 100% true that the best propulsion can be obtained by a direct application of the paddle's surface to the medium it resists.

Eddie currents rolling off the edges of the paddle face diminish its effectiveness. In order to combat these, oars have been faded off from a robust center to a finer edge. In the case of a racing canoe, this has been combined with cupping to increase the paddle's surface contact with a greater amount of resistant medium while the transverse section is designed as above to avoid turbulence. In swimming, the speed swimmer's arm stroke now follows the body line to eliminate the need for extra energy to get the former amount of push used by a deep stroke becoming more useful by following the body's bow wave through the length of the swimmer.

Following these lines of reasoning, it might be an idea to try spoilers trailing off the back edges of the paddle face to remove the turbulence even further from the application of energy. Of course, due to the dip and remove action of the shell rower, the spoilers should be slim and flexible to avoid resistance entering and leaving the water. Silicone might be a good material, since it's light and can be molded almost to a fine edge.

Anyway, if you're looking for an improvement, and this hasn't been tried yet, it might be worth a look. Apologies to anyone who's already devised this.

Mark

You all might be interested in this site: http://www.atkinsopht.com/row/liftdrag.htm.

Oar designs have been around since time was conceived. If you come up with an "improvement" which hasn't been tried and rejected through experimentation, go for it. It is a bit like trying to "improve" the lever, the world has been there and done that...

See http://www.concept2.com/us/oars/default.asp also http://www.crokeroars.com/rowingoars.htm

http://www.dreheroars.com/

for some of the work done on sweeps and sculls. A 2000 meter race is less than 7 minutes for an elite mens single scull. If the difference in propulsion efficiency is 0.1%, the margin is .42 seconds most races are won by a smaller margin.

There has been a lot of work in fluid dynamics, physiology and sports kinematic done on the sport. See some of the articles by Dr Volter Norte and others.

Crew is a great life time sport for both the mind and body.

I would guess they have a standard paddle, and that the boats are standardized. I am a kayaker. I believe the Olympic kayaks are standardized. I don't know about the paddles. Premium kayak paddles are feather light and have various scoop designs to catch more water. The length depends on the size, strength and technique of the paddler.

Hi, D C!

The OP asked "Do racing rules make such modifications impossible?"

Yours is the only response that tells us the answer to that question; and it is

"yes, the rules make such modifications impossible in terms of reducing drag because the blade dimensions are restricted, but nod in the direction of attempts to reduce partial drag in important places on the paddle [by re-aligning the centers of effort using blade placement on the shaft and blade shape, as others have shown in here] without changes in edge dimension."

GA for the factual direct response to the OP.

Had they not been restricted as you have shown in your quotation of the rules, quite probably they could be redesigned with less drag to improve the speed of the hulls, as I wrote in my response to Frankie12. But my design clearly exceeds the blade taper's currently allowed limits. It might not, though, if the dimensions of the spoilers held to the rules. What do you think?

Mark

First Rule: Rules are meant to be broken!

As a scratch builder of an ILCA 'Lightning' (#14542 'Tesseractyl'), with specs. and dwgs. from one of the largest racing fleets in the world, I knew that the big boys had done everything possible to refine to a faster shape. Rudder, drop fin keel, flotation, and even the mainsheet bridle must come under the 'Rule'.

What to do? Paraphrasing the rule on the bottom arcs (nonpariel sharpie) "the arcs may not be less than an 8' radius, nor more than 14' R."

Screw'em sez I. I made the arcs a parabola. Fits the rule (succesfully measured) and will give you a nosebleed in the right conditions. AKA a screaming reach.

In order to make a paddle/oar more efficient use Occams Razor. You can't add anything that will not break down. And we who are trying to reduce weight use a lot of sandpaper.

Tink outta da box!

Carl

Hi Mark,

Where on earth did you get this quote?

"yes, the rules make such modifications impossible in terms of reducing drag because the blade dimensions are restricted, but nod in the direction of attempts to reduce partial drag in important places on the paddle [by re-aligning the centers of effort using blade placement on the shaft and blade shape, as others have shown in here] without changes in edge dimension."

D C's answer is excellent, and does not say anything remotely close to what you are saying above. In his very complete and well-prepared answer he provides the rule: "The construction, design and dimensions of boats and oars shall, in principle, be unrestricted." Only minimum thicknesses are restricted, which leaves tons of things to experiment with.

He also says: "In answer to this thread – a great deal of work has been and is going on to improve the equipment in rowing."

It is as if you have read his response and then turned around and said he is completely wrong, according to your view.

Geez -- go visit a rowing club.

Hi, Blink!

re "Where on earth did you get this quote?"

***Having seen that it is not a direct quote, it was my hope that intelligent interpretation of the statement would indicate that it was a paraphrase in summation to the OP's question. I'm sorry to have misled you.

I had used the overall set of responses, including that of D_C, for whom I awarded a GA for the most direct response, to arrive at the paraphrase that enlarged upon, not just quoted, what he reported. I wrote that: "as others have shown in here". Next time, greater clarity of intention and no quotation marks! _{hope I remember this!}

As a breakdown, these are the concepts I was following:

***yes, the rules nod in the direction of attempts to reduce partial drag

D_C: "In regards to equipment, FISA has very few limitations, mostly safety based with the exception of minimum weight requirements which helped protect wood shell builders for a while, and the banning of sliding riggers that prevented a major shift in equipment design and the obsolescing of the existing fleet..."

***but nod in the direction of attempts to reduce partial drag in important places on the paddle [by re-aligning the centers of effort using blade placement on the shaft and blade shape, as others have shown in here]

***"without changes in edge dimension", refers to D_C's continued response:

"The edges of blades must have a minimum thickness

throughout as follows:

- oars 5 mm,

- sculls 3 mm.

This thickness shall be measured 3 mm from the outer

edge of the blade for oars and 2 mm for sculls."

***and ..."make such modifications impossible" refers to my own suggestion for reducing blade drag, after which I asked D_C whether sticking to the rules for blade edge but adding spoilers within the dimension regulations might be allowed. (The inventor in me squeaking up. )

I sincerely hope I'm not making up anything, Blink. Be more generous with me in your literal interpretations, willya?

And try to stay apace with the posts.

Other than getting me ould fat body back into shape, I'm not sure how my heading off to the boathouse will help the discussion, though I appreciate your good thoughts.

Mark

You can only imagine how otherworldly this seems. We must operate on quite different linguistic and logic systems.

D_C's only response to this thread, so far, is post number 20, in which he is responding to the OP. The OP uses the term "such modifications" to include modifications not limited to cupping, flippers, and changes in length.

Your post 21, responding to D_C's post, says:

The OP asked "Do racing rules make such modifications impossible?"

Yours is the only response that tells us the answer to that question; and it is

"yes, the rules make such modifications impossible

That is completely wrong. "Such modifications" refers, as you say, to the OP's question which suggest some modifications that can be included in the class "such modifications." "Such modifications" are clearly allowed, and the rules explicitly state that, and spell out the few areas in which there are limits. You seem to be trying to claim that "such modification" in the second sentence refers specifically to your own suggested modification, but no capable reader will share this impression. You eventually ask about your own modification at the end of the post, not at its beginning.

That you subsequently asked D_C "What do you think?" (regarding your own proposed modification) has nothing to do with your incorrect summary of his post.

You accuse me of being excessively literal, but if you say "Black is white," a reasonable response is to say "No, black is not white." Otherwise we engage in kindergarten conversations about the room lights being on or off. etc.

I am not surprised that you do not understand why a visit to a rowing club would be beneficial. You would find that if you made such a visit, that you could engage in conversations all day long about such issues, and have just scratched the surface.

I wonder if perhaps you have your browser set so that posts are not chronological.

Hi, Blink!

Perhaps if I quote this last post of yours back to you without the excess commentary, you will be able to see more clearly what I was referring to.

***The OP asked "Do racing rules make such modifications [here referring specifially to "the design of the boat oars"] impossible

***D_C's only response to this thread, so far, is post number 20, in which he is responding to the OP. The OP uses the term "such modifications" to include modifications not limited to cupping, flippers, and changes in length.

***the rules explicitly... spell out the few areas in which there are limits

Of course, D_C goes on to spell out the limits, which clearly make certain modifications (those other than shape and positioning on the shaft) illegal, and therefore (at least legally) "impossible", (including, as it happens, the use of my earlier posted tapered spoilers whose edges do not conform.)

My question re modifications to those theoretical spoilers is not a part of D_C's explanation, nor did I write that they were. After all, I couldn't have asked him about the possibility of introducing spoilers until after I reviewed his posting where I learned the answer to the OP's question. So the question is not part of an argument, yes. But it wasn't intended to be, and it couldn't have been anyway.

My style of answer included not only D_C's quotation of the definitive ruling showing the absolutely limited allowability of blade design, but also some of the variables that would otherwise be allowable... but when all's said and done are still completely engraved in stone at a given point by the limitations imposed by the rules concerning edge dimensions.

Even my thought about spoilers, while potentially being able to push those limitations, (assuming some material soft and malleable enough to make them could be developed) must still be bound by them.

Perhaps parsing what I wrote was not as important to any of us as getting the definitive answer to the OP given by D_C. [And even that I appreciated his clarity-- expressed in my own slightly more inclusive style through the use of paraphrasing _{which I'll try to improve on in future, if I remember} -- enough to give him my GA may not have been as useful to the OP as the response to his question.]

Mark

Hey all

See FISA Bye-Law to rule 31, 1.6 below

1.6 The edges of blades must have a minimum thickness

throughout as follows:

- oars 5 mm,

- sculls 3 mm.

This thickness shall be measured 3 mm from the outer

edge of the blade for oars and 2 mm for sculls.

This rule was made to protect the crews. Boats do veer out of their lanes. When this happens, oars will clash, and athletes could be hit with the edge of the blade. The blades look enough like hatchets without allowing a sharp edge. That is why the thickness is controlled. It is a safety issue, with the intent of preventing serious injury in the event of a crash.

Similarly:

1.1 The bows of all boats shall be fitted with a white ball

shape, minimum diameter 4 cm, in hard rubber or a

hard material. If this is an external part it shall be firmly

affixed to the bow of the boat, if an integral part of the

hull construction it shall afford equivalent protection and

visibility to a ball.

This rule was formulated to limit injury to crews in a crash. I was involved in a crash between two doubles. Doubles are blind sculling boats, without a cox. Even with a bow ball, we injured the bowman in the other boat. These boats are wicked fast, and silent.

Back to the blades. Vortex generators are currently used on blades. The proposed spoilers do not look like they would be an improvement, based on my experience, and the current research. Most of the flow at the catch is along the blade. Speed improvements seem to come from improving the lift of the blade.

But Mark should make up some of his spoliers and go row. He should first row the blades himself so he can feel the way they work in the water. Then try a series of 500 m pieces with evenly matched crews, swapping equipment every other piece. Run trials over many days, in a variety of conditions, wind, chop, cross winds, currents, deep water, shoal water, etc then do some analysis to see if you have something.

Good luck. Let me know if you make boats faster.

Hi, D_C!

I don't have any time to do this now myself, but I'll contact some of the local rowing clubs (there's one across the street) to see if they're interested. Certainly, if spoilers on the paddle blades haven't been tried before now, they might be worth investigating.

By "swapping equipment every other piece", do you mean once with the change followed by once without it ...and so on?

Mark

I am sure to trip the 'rules' for oars monitor by suggesting that their be a pivot installed at the paddle. The notion being that the angle of attack should be held constant & at its most efficient throughout the stroke. This is not possible with the 'stiff' setup we have now. Maybe a 'tensioner' can be installed at the grips to controll the 'flex' at the paddle. Another issue is the shape of the craft. Perhaps the boat can be 'lifted' off the water using a forward leading edge. Something like a surfboard to relieve the craft of some of the drag caused from being in the water. This leading edge should emerg from the water as the top speed is achieved. Maybe a split pontoon setup is best since stability would enhance the rowing platform/stability. Thanks Carlos

"The choices you make might be mistakes but it's never too late to turn around." Johnny Lang- musician

Hi, Guest!

Lifting the bow (and the stern!) off the water while lengthening the water line are improvements made in both yacht and fast motor craft design to allow increased speed while retaining stability. Consider becoming a Marine Engineer. You might like it!

The idea of the tensioner controlling blade flex reminds me of changing propeller pitch. Brilliant concept. Rather than just manually accomplishing this at the oar handle for a single sculler or calibration purposes, a coxswain --in addition to adjusting the cadence-- might also be able to adjust all --or any-- oars in three planes remotely to suit the circumstances as the race progresses.

Mark