Tempering, that's the hardening term. duh

db, I've never felt the need to temper aluminum, or done it. But that technique was "explained" to me while the annealing was "demonstrated". I remember the two applications explained for different uses in building a canoe using aluminum tubes.
I've used annealing several times since so I could flatten a tube to replace a thward and not have it split. Such as shortening a thwart to move it back to make the gear area bigger in front of the stern position.

I guess my description is a little hard to picture. Wife took the camera to
Colorado, I'll post a picture when she gets back.

Woodsy - interesting, we NEED a picture.

Jim J Solo - I thought quenching only hardened ferrous metals. Huh. Learned something new ... thanks.

My Wenonah Spirit (royalex) has no chamber, but has a bow slider. For years my wife asked  for some type of foot brace in the bow. I finally made one out of 3/8 plywood.  I cut it to the shape of the hull. It tucks up under the gunnels and braces against the grab handle then runs down to the floor at a 45 degree angle. A bungie cord attaches it to a cord run through the grab loop holes. The bungee allows it to hinge up and down and there is room to slide a dry bag into that space. I stuck 2 traction strips to it. I then made three legs to attach to the bottom so it doubles as a camp table. I am now back in good graces.

Working with aluminum tube you need to think about "annealing". I think that's the right word?
If you ever tried to flatten an end of a tube and it split. It's because it was heated then cooled quick to make it stiff. Something you would want in a thwart but not in a tube for a slider seat. For that you'll want to heat the tubes and let them cool slowly. That makes it slightly springy and less likely to crack over time.

The thwart tubes can be stiffened again after flattening the ends by heating again and cooling fast in water.

Actually, I do not work with metals, I am a high school assistant principal, I just know that when working with materials like aluminum tubing it is best to have the correct or as close as possible measurements, and some people prefer fractions, and others decimals, and it was no problem to put both.   

I don't think you would have problems putting in the slider at all...  I think the biggest problem would be how to fit the slider tubes on the seat, but again I think you could use the conduit holders to keep it in place.    

I put a removeable 3rd seat  that I built in mine so I could paddle it solo, (when there was no wind of course) I have since bought a Wilderness solo and don't paddle th SR 18.5 solo any more.   I also built a seat back that slides onto the bottom of the seat and does a good job of giving you support.   Here's a link to a picture of it on my solo...

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Bruce

Thanks for the help Bruce. This should help a lot. Looks like it would not be too expensive to fabricate. I had thought of contacting SR to see if I could just buy it as a kit, but they have never responded to the e mail I sent them last Wednesday. Not a stellar example of customer service, but I think I’ll try again; if the price is right I wouldn’t mess around piecing it together. Of course it is all contingent on them actually acknowledging I asked them something.

Let me just take a wild guess; you work with metals at a fairly high level of precision? No too often I see someone describe a dimension in both fractional and 4 place decimal formats. Kind of a giveaway there.

Gimp,
I could not load the pictures here as my camera takes too big of pictures and I did not have time to resize!

And here are the specific for the seat:

The three Aluminum tubes are 30 inches long and about 1/16th (.0625)inches thick.

The four Aluminum angle brackets are 5.75 inches long and held in place with 3 rivets through the hull.  They are spaced 35 inches apart (outside end to outside end)  the back bracket is even with the bow thwart 72 inches from the end of the canoe.  The angle stock is about 1/8th (.125) of an inch thick.

The tubes and brackets are held together by single bolts are you can see.

The under seat tube is 1.25 inches in diameter and about 1/16th thick, it is the length of seat, it is spot welded to a piece of angle stock that is about 1/16th of inch thick that is screwed into the seat with two screws.
You might be able to use something different for the sliding part, like the brackets that are used to hold wiring conduit.

here is a link to an online aluminum source:

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If you need anything else leet me know.

Bruce

The black foam was used years ago in Bells, b4 the modern vaccuum bag tanks....we had patterns and used a japanese pull saw for the rough cut and then shapped in the belt sander and glued in with contact cement-the creekrunner is 16 years old, totally abused, and I have only re-cement once....didn't really need too but I wanted to use up the little bit I had left. The souris is decent sized up front...for me anyway....what about knee pads for bucking those head winds...or could you cut wedges of black foam.. glue them in and cover with knee pads.....just and idea.

Gimp,
Let me know if you want me to take some pictures of my sliding seat and take the deminsions for you and put them on here.

Bruce