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 Post subject: Weighing a Canoe??
PostPosted: February 22nd, 2005, 10:24 am 
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Hi,

Just interested in confirming the weight of my canoe and wondered what is the best way to accurately weigh the thing.

I thought of putting it on the bathroom scale but figured you wouldn't be able to read the dial with the canoe on it.

Your thoughts on this matter would be appreciated.


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PostPosted: February 22nd, 2005, 10:36 am 
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Set the scale outside and weigh yourself. Then pick up the canoe and put it on your sholders and weigh yourself again.

subtract your weight from the last number and that's your canoe weight.

Boneli

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PostPosted: February 22nd, 2005, 10:42 am 
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This is a common way to weigh boats, however it is only as accurate as the scale. I have seen "bathroom" scales off by 5-8 lbs on my weight (235lbs). Typically they weigh lighter as the weight increases. I must say though, that my mother in law has a really really old one that is bang on!


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PostPosted: February 22nd, 2005, 10:47 am 
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Erik wrote:
This is a common way to weigh boats, however it is only as accurate as the scale. I have seen "bathroom" scales off by 5-8 lbs on my weight (235lbs). Typically they weigh lighter as the weight increases. I must say though, that my mother in law has a really really old one that is bang on!



True Erik, but if it's off! The two measurements will be off the same amount so the difference between the two off weights should get you close. Usually you would calibrate the scale before stepping on to it.

Boneli

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PostPosted: February 22nd, 2005, 10:50 am 
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Another way... set the end of the canoe on the scale so that it's vertical and read while it's balanced for a second or two... can be done on a calm day outside. Or placing the side of the hull at the balance point on a block of something light, like styrofoam on the scale. Also spring fishing scales... weigh one end and then the other while someone's holding up the opposite ends and add the two weights up.

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 Post subject:
PostPosted: February 22nd, 2005, 10:55 am 
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What happens Boneli, is that in the top end the scale gets slow. this is not a callibration issue is a linearity issue (besides who has test weights sitting around the house to callibrate with anyway?). So what happens is that it may be accurate up to 50lbs lets say, then from 50-100lbs there may be 2lbs error, then 100-200 there may be 6 lbs error so now at 200lbs you have an 8lb error so infact the whole of the error would be seen in the "weight" of your boat.

Not only that, but i have been at the doctors on their cheapy little scale and i can move my feet forwards or back and change my weight by 10lbs.

Sorry if this doesnt make sense, what i am trying to say is, its gonna be close, but if you really want to know if the boat is 50 or 55lbs, this is not the best method.

I would like to bring a proper scale out to a "get together" of some sort for people to use. Would be kinda fun!


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 Post subject:
PostPosted: February 22nd, 2005, 12:10 pm 
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Location: Toronto, Ontario Canada
How to weigh your canoe:

Method 1: Obtain a teeter-totter. canoe on one end, known weights on the other!

Method 2: Go to nearest lake. It helps if its a calm day. note water level. place canoe in lake. Quickly take note of new water level. Calculate volume of water displaced by multiplying area of lake by delta of water level.

Method 3: obtain a 'perfect' bearing (friction free). Place canoe on bearing, Evacuate room of all air. exert a known ammount of force against the canoe. Measure resulting acceleration of canoe. Calculate mass of canoe from force/acceleration = mass.

Method 4: Climb mountain. Ask Swami how much canoe weighs.

Method 5: Convert canoe into pure energy. Measure energy created. Use e=mc^2 to calculate mass of canoe. Converting energy back to canoe is left as an exercise to the reader.

I'm alot of help <g>
Cheers,
-ben


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 Post subject:
PostPosted: February 22nd, 2005, 12:27 pm 
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There's also a more traditional way, dropping the canoe from an airplane at a known altitude and noting the amount of time it takes to hit the ground. Then correcting for surface area, air resistance, temperature, thermals and the speed of light. Also, the appropriate acceleration rate, 32 ft/sec/sec minus resistance, until terminal velocity is reached, needs to be added in.

This technique has been especially valuable for bush pilots who wanted to verify the correct weights of various pieces of cargo.

"Cripes, I knew that passenger was lying about the weight of that canoe. Only 47.583 seconds of freefall."

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 Post subject:
PostPosted: February 22nd, 2005, 12:51 pm 
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Funny! :lol: i am guessing these are pokes at me for questioning the accuracy of a bathroom scale.

all i am saying is dont be surprised if your weight ends up off by 5lbs, that is all :doh:


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 Post subject:
PostPosted: February 22nd, 2005, 12:51 pm 
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I would recomend the bathroom scale with and without subtraction method, it will get you close enough.

I like to weight my canoes and have done the above bathroom scale method, being very careful to watch for historisis (sp) and be as consistant as possible each time.

I got a weight but still didn't believe it.

So I spend $100 and got a digital postage scale good for 100 lbs. (I also got a 5 lb scale for small pieces.) It reads out in 1/4 lbs or 0.1 kg.

I made a support so I can put a canoe on it with out having to hold it and the scale has a tare weight option on it, ie, the scale will "zero out" the holder.

The weight from the digital scale ended up being almost the same as the bathroom scale. It just cost me the $100 for the extra level of confidence in the number.

Dan


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 Post subject:
PostPosted: February 22nd, 2005, 1:20 pm 
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The wait of my canoe is directly proportional to my desire to paddle. If I don't paddle the canoe waits. If I paddle, it waits less.

Yea, I know, makes no sense. Just had to post to catch up to Boneli.

Dave

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 Post subject: Deer scales
PostPosted: February 22nd, 2005, 2:21 pm 
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Location: Freeland, Maryland USA
I have taken canoes to the hunting and fishing store near my house and weighed them on the scales they use for whitetail deer. Those scales are a platform-style beam-balance so it's easy to set the midships of the canoe on the platform and get an acurate weight.

(It also helps that I know the guys who work there).

Side note - I used to weight canoes when I would receive them for review and have yet to find one that was "underweight"; Royalex and composite boats were often a few pounds overweight, poly boats often more than that and occasionally I'd get a boat that was absurdly heavier than the listed weight.

One outfitter I deal with weights their boats on a doctors office type triple beam scale by resting them balanced sideways on a chine. The weights they've found seem to be consistent with what I've found - a few pounds over the listed spec is common.


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 Post subject:
PostPosted: February 22nd, 2005, 3:45 pm 
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May be of interest;
http://www.greenval.com/weight.html

Doug

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 Post subject:
PostPosted: February 22nd, 2005, 5:13 pm 
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Tripper wrote:
Yea, I know, makes no sense. Just had to post to catch up to Boneli.
Dave


? :roll:

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 Post subject:
PostPosted: February 22nd, 2005, 7:31 pm 
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I agree with Erik - bathroom scales are BIG FAT LIARS


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