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      Prism portage yoke     

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11/08/2022 06:00PM  
I am looking for ideas for a DIY yoke for my Wenonah Prism with a tractor seat. The yoke that you can buy that clamps on the seat rail mechanism sells for $250. I have searched for ideas without any luck. I suppose I might be able to build something similar to the commercial version but I have my doubts. Weight is also a concern. Any ideas?
 
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portagedog09
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11/09/2022 04:00PM  
Traveler, you sure can build a good lightweight comfortable yoke for your Prism. It just takes a bit of skill and time. Here's a thread with some examples - solo yokes made by folks on the board. There are also some other links in that thread.
I've made several and in that thread is a very nice, strong one I made for Magicpaddler's Rapidfire solo from cherry with quick release cam clamps. I have a much simpler version on my Merlin II in ash that weighs in at 28 oz. with EVA foam pads and is very durable. Getting the right hardware and having the tools to do it is the key. If you feel over challenged, I could be persuaded to help out. Good luck.

pd
 
11/09/2022 06:48PM  
Portagedog, thank you so much for taking the time to respond. I had looked for and found some of those threads but I had not seen the yoke you made for Magicpaddler with the large foam blocks. Very interesting solution. I had assumed that the Prism uniquely demanded some kind of system that connected to the seat mechanism (like the commercial version) but I can see how your solution still gets ones head away from the seat.

If you were making another one would you still go with the very thick foam blocks to achieve the height or have you thought of alternate builds that you might prefer next time around?

 
portagedog09
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11/10/2022 04:53PM  
You're welcome Traveler. That yoke was custom built to MP's specs. He requested a certain amount of lift to make sure it cleared the seat. Thick EVA foam was hard to source or expensive and I ran across some foam yoga blocks at wallyworld that fit the bill and was cheap and knowing MP isn't particular about asthetics, purple it was! I've since sourced some reasonable priced 3" thick grey stuff that I can custom cut from a small "sheet". One of the main goals of that project was to keep the weight down and being sturdy and very light, it works. It's not bomb proof, but one can easily and cheaply repair/replace the pads. A lot of the other heavy nylon covered pads are all mounted on heavy plywood with lots of heavy hardware. I think his yoke came in at like 42 ounces, which I was very happy with because it beat his old yoke by about a half pound, looks insanely better, and is overall stronger. I have thought of other ways to raise the pads, but so far nothing has come up that will beat the weight. It's all a compromise. I'm open to ideas if anyone has suggestions, but I'm working within my tools on hand and reasonable materials. Cabon fiber would be awesome (Muddyfeet built a cool one) but costly. Most of my builds have been for clamp on gunnel types - his being more challenging because of the Rapidfire gunnel shape (NOT flat!). If someone were to ask me to build one, I'd look at the boat it's for and custom build to that and what they were looking for in a yoke - light? cheap? sturdy? durable? I built two bomb proof ones with the heavy pads for an outfitter/friend after he saw mine - he needed them to be dependable and customer proof! It just depends. I'm not afraid of a bit of a challenge.

pd
 
11/11/2022 09:29AM  

Okay, portagedog, here is an idea. I would be glad to know if you think it has any merit. If my drawing is unclear or the photo is bad I will try again.

My idea is to make a typical clamp-on yoke out of ash or basswood or something with some kind of typical clamping system. In order to gain headroom I am considering the idea of "struts" that mortise into the yoke and rest against the seat slider bars for support. I haven't thought far enough along to have a plan for exactly how the pads attach to the struts. I have no idea on weight but I suspect the struts can be narrowed a bit and still be strong enough.

Any thoughts on this?
 
MagicPaddler
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11/11/2022 12:30PM  
The EVA foam that portagedog used on my yoke is stiffer than what most folks use for pads but he cut then to fit my shoulders so that spreads the weight out and cups my shoulders so the canoe does not slip. The yoke works very nicely and PD’S woodwork is beautiful.
 
11/11/2022 12:35PM  
Thanks, Magic. I like that idea of cupping the foam to help keep things in place. I can see how that might be really helpful. I am wondering about using some foam that I have from some bleacher seat pads. They are about an inch thick and I wonder if I could glue it maybe 3 layers thick.
 
portagedog09
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11/11/2022 03:40PM  
Nice of you to join the convo MP!

Traveler,

I understand your drawing and what you're trying to visualize. There's a thousand ways to skin a cat and if it "works" it's not wrong, just different. It looks like you're trying to combine the Wenonah style pedestal mount with a clamp on gunnel mount yoke. What I'm not seeing is the benefit of that. It seems to add complexity unnecessarily. And probably weight. It'll also be 'bigger' than either of the other designs by themselves and I'd be concerned about the 'legs' or struts getting caught up in something when not attached and potentially damaged. Another thing to consider is the higher you make the mount for the actual pads, the larger that lever will be and it will need to be stronger to withstand the amount of torque load on it. How much I don't know, as I've not tested anything like that but mathematically it makes sense. I'm sure it could be successfully done, but I made the choice to go with a lower mount/taller pad for two reasons - less complex and lower weight. MP's original design that he made used some hollow boxes that the pads were then mounted to and it worked but was more complicated to make and a lot less elegant of a design (sorry MP!). You can get some appropriate glue and assemble a taller or thicker pad that should last - just understand that the glue joint will probably not be as flexible as the rest of the pad - and that may be just fine for how you intend on using it. I had thought about doing that too but just didn't like having to do that when I knew there was one piece stuff available. One thing to keep in mind about your stadium seat foam - or any foam - is the compressibility of it. How far does it compress with a given amount of weight on it (the canoe) before it stops compressing and takes a load. I think you really only want it to give enough to be comfortable on your shoulders. As MP metioned, the EVA I used is a bit stiffer but the way it's curved, keeps the load centered and spreads it across the shoulder better than a flat pad. FWIW.

Regarding wood choices - basswood is a very soft 'hardwood' as compared ash, cherry, oak or something along those lines (and more porous). I think you would have to go with a thicker piece to get the same level of strength. I did some comparisons of weight per cubic inch of several hardwoods vs. pine (much lighter) and for the amount of wood used, there was not a significant weight difference and so I go with the harder, stronger wood.

pd
 
11/11/2022 07:18PM  
Wow, you are a wealth of good information! I definitely did not consider your point about the size/shape when the yoke is not attached and I can see that my design could be more awkward and fragile. I agree that could be a problem.

I have already begun a trial build so I will continue and see how it goes. My thinking about weight was that by making use of the seat rail for additional support I would have something like a little truss that would allow me to use thinner wood.

I decided to use 1/2" poplar that I had and see how it goes. My Prism only weighs about 30lbs so we'll see. I will post some pictures if I make enough progress to believe it will even work. I don't know if poplar is a stupid choice — it's what I had.

Trial and error. :-) Thank you for the good advice!
 
11/12/2022 08:50AM  

The jury is still out as to whether this design has promise. So far so good, I guess, but until I attach pads and get it on my head I really have no idea.

Regarding the use of poplar I have done some research. Clearly not the best choice but from what I have learned it may have the strength for this application. My only "test" was to try to bend the yoke around my knee.

Regarding water resistance poplar will require a lot of careful babying. This version is more or less a model to test the design. If it shows promise I might try to make one out of ash or birch. On the other hand as I live in Arkansas and only get to the BWCA once every year or two I do not put a lot of stress on my equipment. The yoke I have on my '62 Thompson I made out of untreated 3/4" plywood and it has lasted 35 years. :-)

I'll let you know the results when/if I actually get this thing on my head!
 
11/13/2022 09:24AM  




I think it works. I only tested it with a short walk around the yard and it is still held on the canoe with temporary clamps but so far so good. The weight is 28.5 oz without varnish or permanent clamps.
 
portagedog09
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11/13/2022 03:18PM  
Looking pretty solid Traveler. If it does what you need, that's all that counts!

pd
 
11/13/2022 03:26PM  
Thanks I appreciate the encouragement and advice! It's fun making stuff.
 
MagicPaddler
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11/14/2022 02:54PM  
It is fun seeing new ideas
 
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