Custom ultra light float tube

More playing around tonight.

First off, I am thinking of a way to make a stuff-sack that doubles as an UL sling pouch. Turn the stuffy inside-out and it'll have a tab to pin on a fly patch, maybe a small tippet pocket (where the patch kit otherwise lives), and a tab and loop for some hemos. Thing is the dims of the rolled tube make the bag a bit odd shaped... If not slung over the shoulder, maybe clipped to a D-ring on the tube instead? I really would like it to be a useful and flexible piece of kit though. Maybe it could be folded in half and only use part of the volume?


With it folded in half it could be used a lot like this gem that's no longer available:

Also, I got in a bunch of new valves to play around with since I've been pondering an inflatable backrest, and I didn't think the valves I'm currently using are suited for smaller volumes. I've been scratching my head and toying with elaborate backrests with sling straps and other accoutrement that freak me out as far as failure points are concerned, but it kept getting out of hand and weighing too much (in my mind I'd like the thing to weigh around 3 ounces max). Needing inspiration I grabbed a simple square pillow off of my kid's bed and threw it in the back of a prototype... Just might work!

Anyway, pics:

New valve -

Simple backrest:

I think with either some straps that run under the butt to the front seam of the seat or simply an extended flap that you sit on to hold it in place it should provide enough support without the weight penalty and complexity. That's less than an half a square yard of fabric so it should come in just under 3 ounces with valve and extra fabric for the sit-flap. On the plus side, it can double as an air-pillow for your tent or a rock-softener for sitting on in camp. I LOVE multi-use stuff.

Quick question - how much is too much weight for a backrest? Would you pay extra for this option? Hmm... I think I really need to go fishing for a day with and without the backrest and see how necessary it is for myself before I spend too much time on this... Regardless, at least I have something to test.

BTW, you'll notice the Vader tube is back. I'm playing around with a different seat thickness. This bright blue fabric is HEAVY (relatively) but I have it on-hand so I'm using it to prototype stuff. Even with the extra weight, Vader with the blue seat is still right at 30 ounces. Can't cry too hard... Due to the way I had to repair the tube though I'm using a non-production attachment technique - hence the suspenders. No, that's not the direction I'm going in. ;)

Would it be possible to have the stuff sack also be the back rest?
It COULD but generally drybags aren't 100% airtight so it would need reinflation every so often. Also that would make the stuff sack much larger than necessary.

I did have an idea as I was falling asleep last night of making an inflatable backrest that strapped around your waist which could offer better support and not be required to connect to the boat - kinda like a weightlifting belt but inflatable.


Lue Taylor

Lue Taylor/dbfly
Most of us need the exercise of lifting anyway beyond waving our arms and kicking our legs how else are we going to keep that spare tire down
Someone on the other forum brought up the question of fins..

I've been working on updating my fins for the last few days. Originally, the platforms were aluminum, but I figured that the material was overly strong and rigid for what was needed, and it was more difficult to work than necessary. Also, the failure of the original design was that the arrow shaft spars for the fabric webbing was too stiff, not allowing the proper curvature to develop and by extension propulsion.

The "OG" fins:

I went to the local TAP Plastic today and got some ABS. Boy is this stuff a joy to work! Lighter, not as stiff, and much less fragile boat skin scary as shiny aluminum. ;)

Also, the overly complicated spar to platform hardware has been ditched for easy, light, and durable zipties! I didn't stoop so low as to use duct tape, but I think these are perfectly suited for this application.

So, I went from tubular carbon spars to flat carbon spars. These as shown are a bit too flexible so I plan on epoxying a second spar atop the first to about half the protruded length to give a "fast action" to them - a little more backbone at the root and still allowing a softer bend at the tips. I also plan to attach the root of the webbing to the platform at the center as during my testing with Rev I the flappy bit near my toes would ride up and down too much.

Anyway, PICS!:

Simple, light, and hopefully effective. I'll be attaching a bungee to the back edge of the fabric foot pocket that will simply pull over the heel. Also, these are designed to be worn over just the neoprene stocking feet of waders. I figure nobody in their right mind would hike up into the hills with a 2 pound float tube with a pair of 3 pound wading boots. I've learned that even my 22 ounce mesh and rubber water shoes seem ridiculously heavy with my "new glasses".

Based on the weight that I'm seeing now and approximating the mass of the stiffening of the main spars plus the bungee, I'm guessing the total weight of the pair will come in at or around 10 ounces! :) That includes the extra ledge behind the foot pocket which is left on here out of convenience (the stock I had was 8" wide, though the design was for a 6" deep plate). I think the ledge does add a bit of comfort putting the pressure of the up stroke more on the heel than in the arch of the foot, but I may either trim or get rid of it altogether to save another ounce off of the pair?

These will not work very well with donut tubes as they are designed to be slipped into while fully afloat. Not durable or ergonomic enough to really waddle around shore in. Still, should be a piece of cake to get into from an open-front tube. I will say a leash or a floatie should be considered as I don't believe they'll float. I COULD build in a nice air bladder into the web? Nah...

If you don't mind taking zipties with you and "building the fins" at the lake, these should pack up very tidy as well, though hanging them from the pack shouldn't really pose any problems. The spars can go in your rod tube, and the rest stack flat and fold up.

I like.

Oh, BTW:

How's THAT for sticking the landing? Doubled up spars included - though I tried gluing them and they were TOO stiff. They're just layered in there now. All up, bungees and ready to test.

Likes: JE


The wanted posters say Tim Hartman
I am again impressed with your development of the fins.

Given your predilection for lightweight innovative design, I'm kinda expecting to see an ultra-light cold-fusion powered trolling motor for that tube! ;)
Took the tube and fins to a Mother's Day pool party and waited for a lull in the water activity.

Verdict? The fins work GREAT! The right amount of flex to get easy propulsion and very easy on the ankles. No feeling like the spars are overstressed or at risk of breaking. I seem to be able to get a good clip going but in a small pool it was hard to tell absolute speed.

The bungee worked well if not a bit loose. I had a cord lock adjuster on it initially but the one I had wasn't tight enough not to slip under tension. The one thing that needs attention is the spar location fixing. I has hoping that just the tension on the zip ties wouldn't allow them to shift, but with all the flexing they did. The main spars shortened up and the cross spar that holds the mid-web at the toe wiggled free and sunk to the bottom of the pool. I had to have one of my boys dive down and retrieve it.

I have solutions for all of these issues, but they all make it more difficult to do a field tear down off the units without snipping zip ties.

I really would like to have an easy "inside the pack" solution but I suppose PITA is better than none, and none won't technically be the end of the world.

I'm not giving up yet but the most important design goals (weight and effectiveness) seem to have already been met.

Fins Update:

I've been continuing to work on the fins since I pool tested them last. Unfortunately this means that I haven't done any tube testing, but the two really go hand-in-hand.

At any rate, I've been working to tidy up the design and shave some more weight off.

First off I rounded off the heel edge of the plate to remove some excess weight, then I cut out another disk under the arch of the foot within the pocket to lose a bit more weight. I was a bit leery of losing the structural rigidity of the disk material, but it turns out that the webbing root spar does a great job of adding some backbone to the front edge of the plate.

I also cleaned up the webbing to be a one-piece affair and glued on some stoppers to fix the geometry better.

Finally, I added a cord-lock to the bungee to allow easier adjustment, though it does add 0.2 ounces to the affair. A simple "tie a knot and forget it" would do the trick in a pinch.


Down to 9.3 ounces! I will be downsizing the foot hoop spars a size or two and I can use a thinner fabric (this is a 200D vs 70D that I make the tubes out of) but I'm not sure if I can bring the weight down to under 9. Regardless, I think it's acceptable. ;)

Finally, here's a photo of it on over a neoprene stocking foot. In this photo I have a thin sheet of foam between the foot hoop and my foot. I suspect that this volume of foam is all that should be needed to float the fin should you ever drop it or have it come off.

I have a trip to Yosemite planned with my boys this weekend, but I hope to hit a couple of my favorite walk-in lakes the following and get some float time with the setup.

Big tube update:

Cliff's Notes version - The tube catches fish. Lots of fish. Lots of BIG fish!

Full version:

This last weekend was planned to be two full days in the Sierra Nevada hiking into remote fishing spots to test out the two most recent prototypes of the SUL tube. Fish the blue tube on Saturday for some giant brookies and Sunday for some smaller but plentiful cutts. 3 miles each way Saturday across open high plains, 2 miles through the trees Sunday.

Drive out on Friday night to a way-station in South Lake Tahoe, then up well before the crack of dawn and drive south an hour and a half to the trailhead.

At the trailhead, my pack included the tube, standard breathable waders, fins, lunch, 1.5 liters of water, 2 fly outfits, net, flybox and all other fishing gear, and extra layering clothing. Total weight was just north of 12 pounds. Hardly felt the weight, and it was compact as you can see in the photo. My friend packed in his ODC420 Lightweight (with inflatable seats) which isn't a half-bad option from the existing choices, but just the tube is 8+ pounds and it took up a huge chunk of his 80 liter pack. All my gear, BTW, fit in or on my 28 liter pack.

So three miles later we show up to the lake and have the place to ourselves. Nobody shows up until after 2:00 in the afternoon. Not a puff of breeze, clear skies, mild temperatures, birds singing, fish jumping. Nirvana!

Setting up:

...and then it was on like Donkey Kong!

It was pretty much bendo all day long. Sight fishing to cruising and holding fish until later in the morning when the wind came up, but even with the chop the catching never let up.

The blue boat floated and fished like a champ. I caught about 50% more fish than my partner, clearly due to the float tube design. :)

Has there ever been a better view that this?

Funny thing - I'm generally a 100% catch and release kind of guy, but it is actually encouraged to take the limit of two larger fish (minimum 16" - the biologists say that the super rich diet these fish enjoy not only make them mutant-looking footballs but it kills them once they reach a certain size due to heart failure!) and my friend has been bugging me let him cook up my catch. So, this trip I did harvest one 19"er and one 21"er for the grill. When it comes time to clean and bag the fish it was only then that I realized how much these things weigh! I must have put 5 pounds or more of cleaned brook trout into the pack, and at the end of the day my waders had to be strapped to the outside for the hike out! Heh...

On day two, we slept in a bit (up "late" at 5:00) and headed towards the trailhead at 8400'. Forty-five minutes later as we neared the destination, we were rudely met by a gate across the road. WHAT!? Dammit!!

Oh well, there is always somwhere else to go in the Sierra so off we trek to a lake that I had visited before but never fished.

Looks like the blue boat is better than the black as all I caught at this lake were these:

At any rate, the small mod I did to the seat of this one for development seemed to achieve the desired result so it goes on the latest rev.

Since this lake was a bust, we moved on to another drive-up lake and put in. It was windy, but we had an unlimited number of these guys to play with. The ones in the other lake would have been bigger than these, but the tug was better than nothing:

At this point I let my partner take a test drive with the tube and fins:

Looks like he likes it!

I did borrow his tube and fins (Outcast clipboard fins) and I found that the tube handles pretty much just like my Fish Cat IV Dx but the fins were way too rigid to kick effectively and they were pretty hard on the calves and ankles. Pretty light (both my fins weigh just over what one of these do, BTW), but I would not be happy using these full time even if they were as light as the ones I built.

So, it couldn't have been all good, right? Well, these shakedown tests are for highlighting improvements and weaknesses.

For one, on the Saturday, the lake was ringed by a wide edge of tules, so there was very limited shore access. Of course I managed to put a small hole in the seat and over the morning I started to sag a bit into the water. Wouldn't you know it I'm halfway down the lake from the launch, my buddy is starting to nail them in quick succession, and I have to kick upwind to shore so I can top off the seat! I was prepared as I had taken a roll of repair tape, and I did find the hole, but it took me out of the game when there was serious catching being done. GRR!! Yes, I will be making a top-off tube for this very situation. Also it's definitely a good idea to have tape with you any time you venture out with a tube made out of such lightweight material. You can always Aquaseal it when you get home.

In addition, on Sunday as my friend was kicking the tires, one main spar on one of the fins gave way as he was fighting the chop and wind. I'm pretty sure I understand the failure mechanism so there will be a design update to address this issue. Of course I had a spare set of spars in the pack so I was able to do a quick field repair and be back in business. Interesting thing was he could make similar if not better time into the wind with his one fin as I could on his ride with the two Outcast units.

One thing that I put to rest was that with the extra foam in the foot pocked these fins float pretty well:

Finally, overall the boats were stable and comfortable. The slightly wider and thinner seat on the black boat seemed to add a bit more stability at the cost of riding a bit lower in the water. I feel that this tradeoff was definitely worth it.

Overall a very gratifying weekend. Great fishing with a good friend and solid progress on the project. I'm pretty much satisfied with the design of the tube and making headway with the fins. I'd like a few more people to take a spin in the tube, especially heavier guys. Even with my utter lack of physical conditioning, eight hours of fishing and six miles of hiking did not leave me with an aching back or flipper-leg cramps though I would be lying if I said that I wouldn't welcome a nice backrest on the tube. Definitely not a deal breaker, but I'd consider packing the extra four or five ounces for a bit more comfort...

Getting closer every day...



Well-Known Member
Thanks for the update. I enjoy reading about your field test. I haven't used my float tube in so long that I forgot how important the back rest is. I need to re-look at your posts about the fins. I don't really understand the design, but I'm intrigued by their light weight and how well they seem to work for you.

I can't believe you're fishing at above 8400'. Our lakes at 6000' are still iced over.


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