View topic - Help understanding weight capacity guidelines

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PostPosted: July 20th, 2014, 4:25 pm 
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Joined: January 19th, 2014, 1:24 pm
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Location: Toronto
I wonder if someone could help explain how to best interpret the weight capacity measures used by the various manufacturers.

For example:
Swift gives 2 measures for the Shearwater - Optimum Load Range, 120-260 lbs and Industry Capacity, 400 lbs
Nova Craft simply gives a lb capacity
Others give a capacity such as 300 lbs at the 6" freeboard.

So if you are 250 lbs, have a 75 lb dog and 50 lbs of gear would you be pushing the limit of the Shearwater or, with the last example, riding up to the gunwales?


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PostPosted: July 20th, 2014, 4:53 pm 
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viewtopic.php?t=38765&p=359497


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PostPosted: July 20th, 2014, 4:54 pm 
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Location: Geraldton, Ontario Can
Think you looked at the Osprey specs. Optimal load fro the shearwater is 180 to 320. I have found the swift numbers to be pretty good. I think your weight numbers, even for the Shearwater, might be pushing it. I contacted swift and asked them if they would consider making the Raven in a composite layup, and the answer was no. The Raven would be a better canoe for your load, but they only make it in royalex, and who knows what will happen to that model now that royalex is on the chopping block.

Chestnut Pal can make a nice big solo canoe, Nova Craft makes one.


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PostPosted: July 20th, 2014, 5:03 pm 
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Maybe Swift will buy T-Formex from Esquif and keep making the Raven.

You can put 400 lbs in the Shearwater but it will paddle and turn sluggishly.. I'd only do that at the start of the trip if 125 lbs of that were water..ie consumables.

Dogs really complicate the equation. Simply because a 75 lb dog is a moving weight. even the most well behaved switch positions and some dogs need more room.. My 75 lb dog requires the Raven..all the other solos make her uneasy and she will STAND all the time.


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PostPosted: July 20th, 2014, 5:09 pm 
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There is no industry standard. Capacities can be stated in many ways, and it's really difficult to compare the values from manufacturers unless they are the same measurement.

In the case of Swift, the optimum load range is a performance related capacity. Between those numbers the boat will perform the best. Less or more than the numbers and the boat will suffer some performance degradation. Often with a tripping load a canoe doesn't perform as well as it does with just a paddler, so you can often go above a optimal number a little without being dangerous. I'm not sure exactly what a Industry Capacity is, but for the Sheerwater I'd say that seems to be about where I'd think the boat is really becoming overloaded.

There are a few different types of depth measurements you will find. You mention the 6 inch freeboard. That means that 6 inches at the shallowest portion of the boat are still sticking out of the water. A 15 inch deep canoe has 9 inches underwater at the 6 inch freeboard, conversely a 10 inch deep canoe has only 4 inches below the surface. I don't like the performance of any canoe with only 6 inches of hull out of the water regardless of boat depth, but 9 inches of canoe below the water is going to perform horribly.

The opposite measurement is often labeled as capacity at the 4 inch waterline This would be how much of the hull is submerged. Again for a 10 inch deep canoe, the 4 inch waterline leaves only 6 inches above water.

So while there are plenty of different ways to measure capacity. All the weight you put into the canoe negatively effects performance unless it's trained muscle. So keeping a hull as close to it's optimum performance capacity will make you a happy paddler at the end of a long day, and an even happier paddler after a long day with a couple km of steep portages.

PK


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PostPosted: July 20th, 2014, 6:32 pm 
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But remember there is a little leeway in performance capacities.. Ten percent plus minus is not noticed by most people.


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PostPosted: July 28th, 2014, 7:23 pm 
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^^Thanks for the explanation pknoerr.


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