front rowing system for canoe

With Sqiddly-Diddly's system the bearings on the track have to deal with a moment.

 

messy, track needs to be curved to increase distance of oar blade's

sweep in relation to distance of handle's sweep.

The tighter the curve or shorter distance of hand-grip to the track the 'higher the gearing'.

I think I feel your concern over "fearsome load" of the bearings, but I'm fearless on that count as even "small, cheap" bearing can take tremendous loads these days and we are only talking out 1/2 human effort of semi-endurance level of output.


Maybe 1/8horsepower and 20ft/pounds worth of force multiplied by a factor of 8 can still be easily handled by two $5 bearings that weigh less than 4 ounces.

I'm saying "two bearings" because with a set of four (two on each end of the 'carrier' two would be under pressure(front inner, back outer) at any one time.

Only one diagonal set would need to be strong enough to withstand the Power Stroke and the recovery bearings could be lighter.



Yes, they have rearview mirrors for row boats but even truck sized wouldn't help much for sightseeing or picking through shallows or spotting game. And there is a whole group of people who are "backup challenged" in auto driving or have stiff necks. I'm definitely going to try and design a naturally switchable frontwards/backwards feature into it.



I'm thinking with a curved-track-carrier it might be possible to have the benefits of oars/outrigger setup but have the oars more out of the way, and have the curved-track-carrier installed at the gunnel so it would be less in the way than outriggers for docking, switching to paddling, fishing, etc, because the hand-grip/blade stroke ratio is determined by the curve radius and distance of grip to track.

I'm thinking of grip positioning at least 12" apart at the end and beginning of the stroke, and of course somewhat wider(just over "shoulder width"?) in the middle of the stroke, rather than the overlapping handles of a rowing shell.

I think keeping the center of the boat open at all times would be convenient and work well with fishing poles, shotguns, open beer bottles, dogs, children, bongs and hookas, and even camera tripods.

 

The Gig Harbor setup looks a simple and effective way of forward rowing and I don't see the logic of making the movement more complicated with bearings and a track. The more mechanics you have in the system you add friction and parts that will jamb (bits of seaweed etc.) and of course rust.

The Gig Harbor uses self lubricating bronze bushes, also hard plastic bushes would be suitable.

What I didn't like about the setup in the first video was the mechanism was attached to the very end of the oar and I believe there would create failure in oar material.

 

Things I don't like about double-jointed front rower.....

http://www.forwardfacingrowingsystem.com/faq.shtm

1)Looks like the oars sweep too far astern, too far from perpendicular to the direction of the boat's travel and thus wouldn't be efficient.

2)Only shown with short oars and dinghies(beam over 50"). No semi-high performance/swift cruising rigs shown. I'm hoping to use 9ft+ sculling oars with some "overdrive" on 17-19ft car top-able canoe with beam of 48" or less, with less radius of stroke to keep the oar blade faces more perpendicular for more efficient bite.

3)Cost: Front Rower oarlocks cost $495, and oars are $195(says you can buy your own for around $250-300. Also says some experimentation may be needed to find your sweet spot. That is some pricy firewood(although I expect the 'mistakes' would be just right for other rowers of other body dimensions. I want a rig that could use standard sculling(or 8' standard solid wood) oars without any mods whatsoever, just clamping them into padded collars. Yes, pairs of "sculls" are about $300-600 new, but this wouldn't be rendering them otherwise unusable, and any adjustments could be done by swapping them for sightly different lengths(there are also adjustable sculls) or more likely just repositioning them in the clamps.

4)Front Rower drills into fairly pricy(and less car-top-able dingy(or dory). I want a rower that would work with a used Coleman or Grumman canoe or Scanoe, which can be found on Craigslist for $200-300.

 

Diddly,
If you want efficiency Get Ron Rontillia's system. If you want cheap just row the way we've been doing it for centuries. I've got Rontillia's rower and I'm going to get the Gig Harbor oars too. Then I need a better rowboat.

 

G'day Sqiddly

I looked at the Utube of the rowing system and I couldn't see the oars at the stern problem you mentioned.

All in all a leverage system is a leverage system. And according to my physics teacher, the effort you put into a leverage system and the power you get at the end is related to the distance between the force and the fulcrum (the pivoty bit) and the fulcrum and the load. If you want more distance at the oar end it means less distance at the force end = more force.

That is why rowing sculls have a sliding seat so they can get more movement at the force end and the fulcrum extended from the boat's side to get more load.

You also said you wanted to shorten the oars so they are at shoulder's width apart which will require more force to get the same load.

There is less force required when the oars are towards the stern, but as you said less efficiency. But, it is like saying "I am going to drive my car off in top gear all the time because it is faster."

It would be a good exercise to load your boat up with all your goodies including weights to equal your weight and pull the boat with a spring balance and see what sort of force you need to move it, with tests against wind and waves. Divide the load end length of the oar by the force end and multiply that by the measurement on the spring balance. That is the effort you have to put in on each and every pull of the oars.

Outboards looking good.

 

Having spent a lot of time working on a reversing linkage, similar to the many commercial ones that have been available since around 1875, I can say that it isn't simple.

The ratios between the three levers/links make a big difference to the velocity relationship between the oar handle and the blade at different point through the arc of each. It's easy to get a system whereby the oar handle moves through a greater angle than the blade in one part of the stroke and a lesser angle than the blade at a different part of the stroke, or vice versa.

From all I read, it seems that the part of the stroke after the pin doesn't produce much motive force. It seems that the part of the stroke from the catch (the point where the blade is first immersed) to the point where the oar is perpendicular to the direction of motion (i.e. at the pin) is the most productive. Motion behind the pin doesn't contribute as much drive.

I have tried to take advantage of the inherent asymmetry in a simple reversing linkage to have as great an oar blade acceleration through the pin (relative to the handle angular acceleration) as possible, with lower relative acceleration at the catch. Whether this is the right thing to do or not I don't know, but intuitively is seemed like something good to aim for.

Jeremy

 

Hi Jeremy,
I've only just got to work and it's early. Well 8:20 is early for me.
From what I understood from what you wrote about the blade acceleration and I think you wanted less acceleration at the catch (thank you for the new word in my vocabulary) and less when the oar is 90 deg. to the boat.

It would appear to me that because the blade has to cover a longer distance at the catch because of the arc, the blade would have to go faster in relation to the forward speed of the boat and slower ie the same speed as the boat when it is perpendicular.

Is there an optimal angle for the oar in relation to the surface of the water?

 

Paddle wheels?

I was wondering how well a couple of independent, hand cranked paddle wheels would do.
Probably less drive but much simpler.

 

GTO,
I saw a guy w a side wheeler canoe that used feet only that kept up w casual kayak paddlers. It made quite a fuss with the water and looked like work to me. A mechanical device to incorporate one's arms into the act would be of great benefit.

 

It seems that oars are the subject of a lot of research, with some conflicting views on how they work!

The general view is that the oar blade works as a foil, producing lift (which translates to motive force) and drag (which translates to wasted energy). At different points in the stroke the blade is acting in different ways. It starts off with blade lift generating the most force, then, by the time the blade is perpendicular to the boats major axes blade drag is the major source of motive force. It seems that there is a general assumption that the blade only moves through the water at around 10% of the boat's velocity, so it is virtually stationary from the perspective of an observer on land.

This tells me that the relative flow velocity over the blade has to be low, around 10% of hull speed, but varying with relative angle. There are some research papers on the web that go into a lot of detail, but to be honest, the range of performance variation from differing blade shapes seems modest. The greatest variation in performance seems to have come from weight reduction (particularly in oars and boat hulls) plus the increasing capability of athletes (something that's apparent in other sports).

There is now some evidence that seems to suggest that current cleaver type oar blades do a better job than is needed, as top crews are using shorter oars because they can't physically pull the big blades at maximum rate.

The general arc of a blade where it is most effective seems to be the centre section, from maybe 45 degrees before the pin to around 30 to 40 degrees behind the pin. There is some advantage in getting the catch angle as far forward as possible, it seems, because it allow greater time for blade acceleration by the point that it passes the pin.

I'd guess that pretty much all of this stuff goes out the window when rowing in rough weather though, as all the evidence seems to suggest that small oar blade areas moving quickly through a relatively small arc at a fairly fast rate is more effective in rough water.

All the above should be read whilst bearing in mind that I'm no expert - I just read a few rowing research papers before designing my forward rowing system to try and understand how oars work. I could easily be wrong!

Jeremy

 

Jeremy, thanks for the summary of the research papers. Very much appreciated. Would it possible for you to post references to several which you found to be the most illuminating or interesting?

I'm particularly interested in the view that blades act as a foil. Does the thinking seem to be that a blade acts like an airfoil with attached flow, or is it along the lines that the force the blade produces is not neccessarially aligned with it's relative motion to the water?

 

I think the oar blade is supposed to be Sea-Anchor and the most

efficient in position for the face is 90 degrees from direction of travel....


unless someone is talking about generating force similar to a Hobie Mirage flipper system.

I tried that with conventional sliding seat rowing shell (just sat in one place and moved the oars up and down instead of back and forth, angling blades as I experimented for best angle).

Worked pretty good, considering 90% of the oar in the water was non-productive cylindrical shaft. Worked about as good as "backing"(or forward rowing with power stroke away from chest).

Like the Hobie Mirage, both strokes are "power" as the blade stays in the water.

Pengin-Wing-Rowing, sort of like a single oar set on the transome, but different.

Maybe a pair of longer wooden canoe paddles, with the shaft at the blade slightly flattened and the paddles secured to the gunnels with loop of rope or other means to keep them in place for the 'reach for the sky' stroke(wouldn't be needed for "hands downward, ends of paddles upword" stroke.

 

Jeremy, I think "top crews" use big cleaver with shorter shaft

because the bigger the oar face the less percentage of energy is lost in turbulence around the edges.

The reason for the shorter shafts is the human body generates so much more energy-per-hour at certain fairly high "rpms" or Strokes-per-minute. Same reason bicycle racer's bikes are gears for well over 60rpms, and even casual riders are told 'should be around 60rpm, common mistake to pedal in too high a gear' and most Health Club machines will try and tell you the same.

A few heavy lifts will have you exhausted without expending much energy or calories(although some calories are expended later as body repairs strained components).

 

Jeremy,

I have a pair of wooden "spoon" blades, and a pair of cleaver blades. The most noticable difference is at the catch, the cleavers are immediatly hooked up and providing power.
Do remember that I am an old neophyte, not one of the 60+ rpm guys.
Mostly I like the cleaver blades because they are very easy to get to catch and release easily. The release is almost effortless compared to the spoons. I really like that instead of being a little late and getting smacked in the chest.

Just the impression from a beginner.

The research is very interesting. For me it would be interesting to be able to get the startling power at the catch through out the stroke and therefore be able to use a smaller lighter blade. The turbulence stimulators glued on the outer edge of the cleaver blade seem to really work. No scientific proof, just the only thing I can visibaly see.

Marc