Paddle blade surface area

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Adamv
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Paddle blade surface area

Post by Adamv » Thu Dec 13, 2007 5:24 pm

Does anyone know a way to determine/calculate the surface area of a paddle blade?

Thanks,
Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor

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Doug
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Post by Doug » Sat Dec 15, 2007 9:26 am

To be bold I went into a few shops with a tape measure.
If you like a particular (manufactures) model, their web site usually has the measurements on them.

Doug

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"Some people hear the song in the quiet mist of a cold morning..... But for other people the song is loudest in the evening when they are sitting in front of a tent, basking in the camp fire's warmth. This is when I hear it loudest ...." BM

Rick
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Post by Rick » Sat Dec 15, 2007 10:17 am

The simplest way might be to trace out the shape on a piece of graph paper, then add up the area of all the squares. Graph paper gridded off in mm and cm would be easiest.

There are also plinimeters used by professionals to measure area... consultants, designers, architects, drafting offices might have them. they need to be calibrated first by measiring a known area, eg. 100 sq cm = x units, then a conversion factor is applied against the readings on the plinimeter.

A third way, and probably accurate enough for paddles, is to weigh a piece of cardboard with a known area, eg 100 sq cm = x grams, then trace out the blade shape onto the cardboard, cut out and weigh that. Apply the conversion factor and you'll have a value for the blade area.

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Adamv
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Post by Adamv » Sat Jan 19, 2008 9:19 am

Thanks for the tips fellows. I tried Rick's idea with the cardboard and scale, and it worked pretty well, but then I came up with another idea that I think is more accurate, though a bit more complicated. I plotted half of the blade on an x-y graph, and then used a spreadsheet to plot the blade shape on a graph and then calculate the area underneath the graph. This area times 2 gives the total surface area of the blade. I was able to use this spreadsheet then to tweak the blade shape (by adjusting the width and length) to my exact specifications. I know, it all sounds a bit persnickety, but really works well, and now that it is set up, it will be very easy to use again in the future.

Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor

AlanWS
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Post by AlanWS » Tue Mar 16, 2010 2:54 pm

Since you have the spreadsheet and seem to enjoy the math, you might want to consider making the spreadsheet give you more than a single number for the area. As you put the paddle into the water, the effective area increases until the blade is fully submerged. You could make your spreadsheet graph the submerged area as a function of paddle depth.

I'm not sure whether this would be useful, but it seems that there should be some difference in the way paddles feel in use that could be sorted out.
Alan

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Adamv
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Post by Adamv » Wed Mar 17, 2010 9:32 am

Hi Alan,

I like the idea (and would indeed enjoy the math), but I'm not clear on what I would do with the information. Are you suggesting that I could play with the shape in such a way as to readjust the forces on the paddle as it enters and exits the water?

Cheers,
Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor

AlanWS
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Location: Shorewood, WI

Post by AlanWS » Wed Mar 17, 2010 3:17 pm

I'm not really sure what to do with the info, but I would suspect that if you tried various sized and shaped paddles, you would find that each had a different feel, that might be well represented by your graph.

Paddles with different curves might differ in their behavior in turning: some like long narrow ottertail paddles partly because the area increases gradually as they enter the water, giving a chance to make sure it's properly aligned for certain types of prying actions. A short wide paddle can enter fully more quickly, probably a benefit for short fast strokes. If you want a small area for most paddling, but a large area in reserve, making the paddle longer is an option.

What I was thinking of was just keeping a graph of each paddle I used, and then trying to notice how each felt in use, and what I liked about it. Eventually it might lead to something. Another interesting thought is that if two people had different requirements for their paddles, it might be possible to find a curve that both people liked. This could be a good spare expedition paddle.
Alan

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Adamv
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Post by Adamv » Thu Mar 18, 2010 6:29 am

Interesting ideas. Recently I've been into making and using bent shaft paddles, which I notice always have a shorter and wider blade. I'm wondering if there would be an advantage to adding 'reserve area' higher up, perhaps even on the bend for those times when you want just a little bit more push (I can't get the volume dial that goes to 11 in the movie Spinal Tap out of my mind when I think about this idea).

Also, my last couple of paddles have been quite flat at the tip of the blade. Perhaps making them more round would result in a more gentle entry into the water at the top of the stroke.

Certainly something to think more about.

Cheers,
Adam
Who travels not by water knows not the fear of God --- 17th Century Sailor

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