My UL tube project...

[SHigSpeed]

I'm posting this series on my "home forums" but I figured you guys may be interested so I'll copy here:

Okay, first off, no, I haven't yet built my pram. It's still in the works, but on the back burner for now.

So what's new? Backcountry hike-in fishing! I gave in and tried it and found that I really like it! Best off, there are LAKES in the mountains, and I love fishing lakes, and most of all I love fishing from a float tube.

So what's a boy to do? My FishCat IV DX weighs a healthy 14 lbs and when fully deflated and folded is the size of a 2200 in^2 pack! Luckily, I was able to snag a Del Canty Lunker Hunter tube which fits the bill for packing (mostly). 3 lbs, bladderless coated fabric, packs small (about the size of a pair of breathables rolled up) and floats reasonably well. Add the half-pound inflatable backrest from my Outcast and the top halves of my thighs stay dry - though my knees do press up against the inside of the donut somewhat unfomfortably, and it sure does "weebles wobbles - but they don't go down" quite a bit more than my v-boat. The inflator bag works efficiently and weighs another half pound.

Here's the setup next to Scott V's FCIV:



And me sitting in it:



So now what? Heck, let's build one that's better! I used to sew and competed with stuntkites of my own design, I'm marginally skilled with a blade and fabric, and the sheepskin says that I've completed all prerequisites that somehow prove that I can design and build stuff...

Well, I first did my homework. What's out there? Well, the DC was 'it", though they stopped making it 20 years ago. Since then, the donuts have gone out of vogue, and the U/V-boats are what's cool and what works. The Creek Company U-Boat 2000 weighs in at supposedly 6 lbs, though it plunks your ass into the water and is somewhat ungainly. The Creek ODC420 Lightweight is 8 lbs, and you sit high and dry. Add the inflatable seats and it folds down relatively small - maybe a 1800 in^2 daypack? Both of these guys are a pack cloth and vinyl bladder deal. Fianlly, the "Cadillac" of UL tubes right now is the Outcast Trinity. 6 lbs, urethane coated 420 denier fabric, bladderless, packs down into it's own 1600 in^2 pack. With pack and pump I think they claim 8 lbs?

BUT, if 'ol Del could make a 3 lb tube 20 years ago, I can beat that right?

So I first decided what the basic design would be - bladder in skin, or bladderless? At first I thought that bladder in skin would be easier being a bit leery about sewing and sealing a bag. I looked around for lightweight bladder materials, tried to get information on the mylar that they use to make balloons that is heat sealable and super light. Unfortunately, nobody wanted to talk to me. While I was waiting for information about the bladders, I came across heat-sealable urethane coated nylons. Similar stuff to what Outcast uses, but it's lighter (70 and 200 Denier). Think Thermarest skins. Apparently it's not too hard to work with.

At this point it was decided - bladderless, heat sealed fabric. No sewing at all for the main bladder(s). Inflator bag and mouth inflated. No pump required.

Next I had to decide on the shape of the boat. Should I go V-hull like the Fish/Fat Cats? U-boat u-tube style? Caddis pon'tube style? After spending a lot of time Google image searching all possible configurations, I settled on a simple u-tube for ease of manufacture. The main bladder would be two flat pieces of fabric edge welded with a perimeter butt seam. Did the calcs at 5 psi (about double what any normal human can blow by mouth) and the seams would only have to take 30 lbs per inch of seam of force. Apparently no problem. Did I mention that I managed to strike up a conversation with a guy who markets ultralight packrafts? He's been a great resource to bounce ideas off of.

In addition to the simple u-tube "frame", there'd be a nice, fat inflatable seat to add buoyancy and to lift me out of the water. With this seat, I'd have the second bladder to give me some redundancy in case something terrible went wrong with the main bladder. Even the smaller seat bladder will give me more than 90 lbs of buoyancy. Great comfort that...

Now to the drawing board! I wanted a 12" diameter main tube that ended up parallel after inflation. Did some drawings, and printed out a scale drawing and started playing with some Press 'n Seal wrap. This stuff is GREAT for getting in the ball park with goofy stuff like this.

First try:



Ooops! I guess if you model it flat, it won't blow up quite the same. Since the outer radius of the bladder "shrinks in" but the circumference of the flat profile is longer than the final inflated outer circumference, the thing closes up quite a bit!

Did some calcs and back to the drawing board...

Rev 2:



Ooops again! Guess one of my assumptions was wrong... Try, try again...



There! That's more like it...

Now on to a bigger model to see if things "scale" right:

Laying it out:



Blowing it up:



Looks good, but still a bit pinched in.

Also, you'll notice that the nice triangular shape of the "tits" on the drawing don't inflate well. It was at this point that I started playing around with this profile a bit:

Nope:



Nope:



Nope:



YES!!



Now that I had the geometry of the tube ends right. time for a full blown (no pun intended?) 1/2 scale model:




Pretty damn cool! Still a bit pinched in. Couple more degrees maybe? Nip there, tuck here...

To be continued...
[signature]

[SHigSpeed]

Quick dissertation on valves:

You can see on the pics above that I have a nice inflator tubes on the 1/2 scale models. Garden sheeting and duct tape work great, but not quite as quick to prototype as the Press 'n Seal. Anyway, you'd be surprised what valve manufacturers will send you for free as a sample!

These inflator tubes are similar to what Outcast uses on the Trinity and on their inflatable seats. Work well, but not made for big volume in or out. I needed something else for the main bladder.

I think everyone knows what a Boston valve looks like:



Pros: Light (1 oz including threaded seat), cheap ($4 for a replacement)
Cons: I couldn't find anyone who sold the damn seat! Everyone sells the valve but I guess the seats only get welded into the vinyl overseas in quantities of 1000s or more! I did finally find a way to get seats, but let's move on...

Halkey/Roberts-Summit style raft valve:



Pros: These things are great! They don't need to be welded or glued in, they have a nice feature that you can inflate them most of the way with teh valve open, then top off with the check valve active. They deflate just as quickly.

Cons: They are a bit expensive, and they're HEAVY! 3 ounces. And BIG! Rolling one or two of these into a packing tube would suck. To have 6 ounces of valve in a tube that weighs under 3 lbs is silly.

Finally, this guy:





This is what's in my DC tube and gets the job done!

Pros: Light (less than 0.5 oz), low profile, check valve, relatively fast inflate and deflate. Cheap - kinda. I found where to get them, but their minimum purchase is $500!! I did get some samples though.

Cons: Well? It's a bit cheesy looking but asking around with people that design and build inflatable things say that they've never had a failure. It does require it to be glued or welded in, but who cares?

I do have another couple of options yet to investigate (more samples in the mail - should be here Monday) but I think I'm set on the main valve for now. If I do smaller bladders (backrest maybe?) I may use either the tube inflator valve or maybe something like a twist close Thermarest valve.

So, now that I have the basic shape pretty much down, it's time for a full size mockup. You may notice that I used the Summit 2 valve in this as it makes inflating and deflating easy peasy!



You can see the Outcast seat in place to get an idea of what's to come.

For grins, check out the evolution of the tube and sketchpad:



The plan is to make it a bare bones and modular tube. So far, it seems like the tube and seat MIGHT be doable at right on 2 lbs. On top of that there will be a strap-on pocket option, possibly a backrest, big cargo drybag for the "trunk", stripping apron, and rod holders. Don't expect the all-singing all-dancing PVC rocket-launcher rod holders for this flyweight. I think even with ALL of this it'll be well under 3 lbs. Perhaps with all this and the inflator bag it'll nudge up to where the Del Canty was ala carte.

More musings to come, gotta get dinner going...
[signature]

[flygoddess]

Holy Cow SHig, you are ....incredible. You want something and you go for it.
Awesome!!!!!
[signature]

[pontoonman]

Thanks for the interesting post. I too, am always looking for ever lighter float tubes. There may be some materials like kevlar for skins which would allow for something super lightweight, but then, this may be hard material to work with for all I know.

A simpler approach that has been used successfully if you will be using fins is to modify an alpaca such as this: https://www.alpackaraft.com/store/index....&do=detail
Half of the floor can be removed and an inflatable seat cushion used for comfort and higher floatation. Might work for those that are sewing and design challenged such as me...

Hope this helps.

Pon



[quote SHigSpeed]I'm posting this series on my "home forums" but I figured you guys may be interested so I'll copy here:

Okay, first off, no, I haven't yet built my pram. It's still in the works, but on the back burner for now.

So what's new? Backcountry hike-in fishing! I gave in and tried it and found that I really like it! Best off, there are LAKES in the mountains, and I love fishing lakes, and most of all I love fishing from a float tube.

So what's a boy to do? My FishCat IV DX weighs a healthy 14 lbs and when fully deflated and folded is the size of a 2200 in^2 pack! Luckily, I was able to snag a Del Canty Lunker Hunter tube which fits the bill for packing (mostly). 3 lbs, bladderless coated fabric, packs small (about the size of a pair of breathables rolled up) and floats reasonably well. Add the half-pound inflatable backrest from my Outcast and the top halves of my thighs stay dry - though my knees do press up against the inside of the donut somewhat unfomfortably, and it sure does "weebles wobbles - but they don't go down" quite a bit more than my v-boat. The inflator bag works efficiently and weighs another half pound.

Here's the setup next to Scott V's FCIV:

[.img][url "http://farm5.static.flickr.com/4078/4874641098_d8e21082a8_z_d.jpg[/img]"]http://farm5.static.flickr.com/...1082a8_z_d.jpg[/img][/url]

And me sitting in it:

[.img][url "http://farm5.static.flickr.com/4099/4892954966_6394b66bb9_z_d.jpg[/img]"]http://farm5.static.flickr.com/...b66bb9_z_d.jpg[/img][/url]

So now what? Heck, let's build one that's better! [.img][url "http://www.kiene.com/forums/images/smilies/smile.gif[/img]"]http://www.kiene.com/...lies/smile.gif[/img][/url] I used to sew and competed with stuntkites of my own design, I'm marginally skilled with a blade and fabric, and the sheepskin says that I've completed all prerequisites that somehow prove that I can design and build stuff...

Well, I first did my homework. What's out there? Well, the DC was 'it", though they stopped making it 20 years ago. Since then, the donuts have gone out of vogue, and the U/V-boats are what's cool and what works. The Creek Company U-Boat 2000 weighs in at supposedly 6 lbs, though it plunks your ass into the water and is somewhat ungainly. The Creek ODC420 Lightweight is 8 lbs, and you sit high and dry. Add the inflatable seats and it folds down relatively small - maybe a 1800 in^2 daypack? [.img][url "http://www.kiene.com/forums/images/smilies/smile.gif[/img]"]http://www.kiene.com/...lies/smile.gif[/img][/url] Both of these guys are a pack cloth and vinyl bladder deal. Fianlly, the "Cadillac" of UL tubes right now is the Outcast Trinity. 6 lbs, urethane coated 420 denier fabric, bladderless, packs down into it's own 1600 in^2 pack. With pack and pump I think they claim 8 lbs?

BUT, if 'ol Del could make a 3 lb tube 20 years ago, I can beat that right?

So I first decided what the basic design would be - bladder in skin, or bladderless? At first I thought that bladder in skin would be easier being a bit leery about sewing and sealing a bag. I looked around for lightweight bladder materials, tried to get information on the mylar that they use to make balloons that is heat sealable and super light. Unfortunately, nobody wanted to talk to me. While I was waiting for information about the bladders, I came across heat-sealable urethane coated nylons. Similar stuff to what Outcast uses, but it's lighter (70 and 200 Denier). Think Thermarest skins. Apparently it's not too hard to work with.

At this point it was decided - bladderless, heat sealed fabric. No sewing at all for the main bladder(s). Inflator bag and mouth inflated. No pump required.

Next I had to decide on the shape of the boat. Should I go V-hull like the Fish/Fat Cats? U-boat u-tube style? Caddis pon'tube style? After spending a lot of time Google image searching all possible configurations, I settled on a simple u-tube for ease of manufacture. The main bladder would be two flat pieces of fabric edge welded with a perimeter butt seam. Did the calcs at 5 psi (about double what any normal human can blow by mouth) and the seams would only have to take 30 lbs per inch of seam of force. Apparently no problem. Did I mention that I managed to strike up a conversation with a guy who markets ultralight packrafts? He's been a great resource to bounce ideas off of.

In addition to the simple u-tube "frame", there'd be a nice, fat inflatable seat to add buoyancy and to lift me out of the water. With this seat, I'd have the second bladder to give me some redundancy in case something terrible went wrong with the main bladder. Even the smaller seat bladder will give me more than 90 lbs of buoyancy. Great comfort that... [.img][url "http://www.kiene.com/forums/images/smilies/wink.gif[/img]"]http://www.kiene.com/...ilies/wink.gif[/img][/url]

Now to the drawing board! I wanted a 12" diameter main tube that ended up parallel after inflation. Did some drawings, and printed out a scale drawing and started playing with some Press 'n Seal wrap. This stuff is GREAT for getting in the ball park with goofy stuff like this.

First try:

[.img][url "http://farm5.static.flickr.com/4039/5138192689_e09c6ee7d1_z_d.jpg[/img]"]http://farm5.static.flickr.com/...6ee7d1_z_d.jpg[/img][/url]

Ooops! I guess if you model it flat, it won't blow up quite the same. Since the outer radius of the bladder "shrinks in" but the circumference of the flat profile is longer than the final inflated outer circumference, the thing closes up quite a bit!

Did some calcs and back to the drawing board...

Rev 2:

[.img][url "http://farm5.static.flickr.com/4068/5138804654_0bc0e935d6_z_d.jpg[/img]"]http://farm5.static.flickr.com/...e935d6_z_d.jpg[/img][/url]

Ooops again! Guess one of my assumptions was wrong... Try, try again...

[.img][url "http://farm5.static.flickr.com/4026/5138806920_c27f22661c_z_d.jpg[/img]"]http://farm5.static.flickr.com/...22661c_z_d.jpg[/img][/url]

There! That's more like it...

Now on to a bigger model to see if things "scale" right:

Laying it out:

[.img][url "http://farm5.static.flickr.com/4003/5147307023_cc48986500_z_d.jpg[/img]"]http://farm5.static.flickr.com/...986500_z_d.jpg[/img][/url]

Blowing it up:

[.img][url "http://farm2.static.flickr.com/1145/5147313199_62dfd4bd00_z_d.jpg[/img]"]http://farm2.static.flickr.com/...d4bd00_z_d.jpg[/img][/url]

Looks good, but still a bit pinched in.

Also, you'll notice that the nice triangular shape of the "tits" on the drawing don't inflate well. It was at this point that I started playing around with this profile a bit:

Nope:

[.img][url "http://farm5.static.flickr.com/4018/5148049480_283110d5d7_z_d.jpg[/img]"]http://farm5.static.flickr.com/...10d5d7_z_d.jpg[/img][/url]

Nope:

[.img][url "http://farm5.static.flickr.com/4012/5150108129_8289e3aaa0_z_d.jpg[/img]"]http://farm5.static.flickr.com/...e3aaa0_z_d.jpg[/img][/url]

Nope:

[.img][url "http://farm5.static.flickr.com/4004/5150722972_66079ca336_z_d.jpg[/img]"]http://farm5.static.flickr.com/...9ca336_z_d.jpg[/img][/url]

YES!!

[.img][url "http://farm2.static.flickr.com/1256/5150114379_5f8fd4d3fb_z_d.jpg[/img]"]http://farm2.static.flickr.com/...d4d3fb_z_d.jpg[/img][/url]

Now that I had the geometry of the tube ends right. time for a full blown (no pun intended?) 1/2 scale model:

[.img][url "http://farm2.static.flickr.com/1263/5162869383_573a72fe4b_z_d.jpg[/img]"]http://farm2.static.flickr.com/...72fe4b_z_d.jpg[/img][/url]
[.img][url "http://farm5.static.flickr.com/4054/5163479362_e987cf1e0e_z_d.jpg[/img]"]http://farm5.static.flickr.com/...cf1e0e_z_d.jpg[/img][/url]

Pretty damn cool! Still a bit pinched in. Couple more degrees maybe? Nip there, tuck here...

To be continued...[/quote]
[signature]

[pontoonman]

Here's their ultralight paddle https://www.alpackaraft.com/store/index....&do=detail and there is also other parts that might be useful for your project, like seats, etc. These add weight, but then you can eliminate waders and fins, and have something that can do class II rivers as well as lakes.

Pon



[quote pontoonman]Thanks for the interesting post. I too, am always looking for ever lighter float tubes. There may be some materials like kevlar for skins which would allow for something super lightweight, but then, this may be hard material to work with for all I know.

A simpler approach that has been used successfully if you will be using fins is to modify an alpaca such as this: [url "https://www.alpackaraft.com/store/index.cfm?ProductID=126&do=detail"]https://www.alpackaraft.com/...ID=126&do=detail[/url]
Half of the floor can be removed and an inflatable seat cushion used for comfort and higher floatation. Might work for those that are sewing and design challenged such as me...

Hope this helps.

Pon



[quote SHigSpeed]I'm posting this series on my "home forums" but I figured you guys may be interested so I'll copy here:

Okay, first off, no, I haven't yet built my pram. It's still in the works, but on the back burner for now.

So what's new? Backcountry hike-in fishing! I gave in and tried it and found that I really like it! Best off, there are LAKES in the mountains, and I love fishing lakes, and most of all I love fishing from a float tube.

So what's a boy to do? My FishCat IV DX weighs a healthy 14 lbs and when fully deflated and folded is the size of a 2200 in^2 pack! Luckily, I was able to snag a Del Canty Lunker Hunter tube which fits the bill for packing (mostly). 3 lbs, bladderless coated fabric, packs small (about the size of a pair of breathables rolled up) and floats reasonably well. Add the half-pound inflatable backrest from my Outcast and the top halves of my thighs stay dry - though my knees do press up against the inside of the donut somewhat unfomfortably, and it sure does "weebles wobbles - but they don't go down" quite a bit more than my v-boat. The inflator bag works efficiently and weighs another half pound.

Here's the setup next to Scott V's FCIV:

[.img][url "http://farm5.static.flickr.com/4078/4874641098_d8e21082a8_z_d.jpg[/img]"]http://farm5.static.flickr.com/...1082a8_z_d.jpg[/img][/url]

And me sitting in it:

[.img][url "http://farm5.static.flickr.com/4099/4892954966_6394b66bb9_z_d.jpg[/img]"]http://farm5.static.flickr.com/...b66bb9_z_d.jpg[/img][/url]

So now what? Heck, let's build one that's better! [.img][url "http://www.kiene.com/forums/images/smilies/smile.gif[/img]"]http://www.kiene.com/...lies/smile.gif[/img][/url] I used to sew and competed with stuntkites of my own design, I'm marginally skilled with a blade and fabric, and the sheepskin says that I've completed all prerequisites that somehow prove that I can design and build stuff...

Well, I first did my homework. What's out there? Well, the DC was 'it", though they stopped making it 20 years ago. Since then, the donuts have gone out of vogue, and the U/V-boats are what's cool and what works. The Creek Company U-Boat 2000 weighs in at supposedly 6 lbs, though it plunks your ass into the water and is somewhat ungainly. The Creek ODC420 Lightweight is 8 lbs, and you sit high and dry. Add the inflatable seats and it folds down relatively small - maybe a 1800 in^2 daypack? [.img][url "http://www.kiene.com/forums/images/smilies/smile.gif[/img]"]http://www.kiene.com/...lies/smile.gif[/img][/url] Both of these guys are a pack cloth and vinyl bladder deal. Fianlly, the "Cadillac" of UL tubes right now is the Outcast Trinity. 6 lbs, urethane coated 420 denier fabric, bladderless, packs down into it's own 1600 in^2 pack. With pack and pump I think they claim 8 lbs?

BUT, if 'ol Del could make a 3 lb tube 20 years ago, I can beat that right?

So I first decided what the basic design would be - bladder in skin, or bladderless? At first I thought that bladder in skin would be easier being a bit leery about sewing and sealing a bag. I looked around for lightweight bladder materials, tried to get information on the mylar that they use to make balloons that is heat sealable and super light. Unfortunately, nobody wanted to talk to me. While I was waiting for information about the bladders, I came across heat-sealable urethane coated nylons. Similar stuff to what Outcast uses, but it's lighter (70 and 200 Denier). Think Thermarest skins. Apparently it's not too hard to work with.

At this point it was decided - bladderless, heat sealed fabric. No sewing at all for the main bladder(s). Inflator bag and mouth inflated. No pump required.

Next I had to decide on the shape of the boat. Should I go V-hull like the Fish/Fat Cats? U-boat u-tube style? Caddis pon'tube style? After spending a lot of time Google image searching all possible configurations, I settled on a simple u-tube for ease of manufacture. The main bladder would be two flat pieces of fabric edge welded with a perimeter butt seam. Did the calcs at 5 psi (about double what any normal human can blow by mouth) and the seams would only have to take 30 lbs per inch of seam of force. Apparently no problem. Did I mention that I managed to strike up a conversation with a guy who markets ultralight packrafts? He's been a great resource to bounce ideas off of.

In addition to the simple u-tube "frame", there'd be a nice, fat inflatable seat to add buoyancy and to lift me out of the water. With this seat, I'd have the second bladder to give me some redundancy in case something terrible went wrong with the main bladder. Even the smaller seat bladder will give me more than 90 lbs of buoyancy. Great comfort that... [.img][url "http://www.kiene.com/forums/images/smilies/wink.gif[/img]"]http://www.kiene.com/...ilies/wink.gif[/img][/url]

Now to the drawing board! I wanted a 12" diameter main tube that ended up parallel after inflation. Did some drawings, and printed out a scale drawing and started playing with some Press 'n Seal wrap. This stuff is GREAT for getting in the ball park with goofy stuff like this.

First try:

[.img][url "http://farm5.static.flickr.com/4039/5138192689_e09c6ee7d1_z_d.jpg[/img]"]http://farm5.static.flickr.com/...6ee7d1_z_d.jpg[/img][/url]

Ooops! I guess if you model it flat, it won't blow up quite the same. Since the outer radius of the bladder "shrinks in" but the circumference of the flat profile is longer than the final inflated outer circumference, the thing closes up quite a bit!

Did some calcs and back to the drawing board...

Rev 2:

[.img][url "http://farm5.static.flickr.com/4068/5138804654_0bc0e935d6_z_d.jpg[/img]"]http://farm5.static.flickr.com/...e935d6_z_d.jpg[/img][/url]

Ooops again! Guess one of my assumptions was wrong... Try, try again...

[.img][url "http://farm5.static.flickr.com/4026/5138806920_c27f22661c_z_d.jpg[/img]"]http://farm5.static.flickr.com/...22661c_z_d.jpg[/img][/url]

There! That's more like it...

Now on to a bigger model to see if things "scale" right:

Laying it out:

[.img][url "http://farm5.static.flickr.com/4003/5147307023_cc48986500_z_d.jpg[/img]"]http://farm5.static.flickr.com/...986500_z_d.jpg[/img][/url]

Blowing it up:

[.img][url "http://farm2.static.flickr.com/1145/5147313199_62dfd4bd00_z_d.jpg[/img]"]http://farm2.static.flickr.com/...d4bd00_z_d.jpg[/img][/url]

Looks good, but still a bit pinched in.

Also, you'll notice that the nice triangular shape of the "tits" on the drawing don't inflate well. It was at this point that I started playing around with this profile a bit:

Nope:

[.img][url "http://farm5.static.flickr.com/4018/5148049480_283110d5d7_z_d.jpg[/img]"]http://farm5.static.flickr.com/...10d5d7_z_d.jpg[/img][/url]

Nope:

[.img][url "http://farm5.static.flickr.com/4012/5150108129_8289e3aaa0_z_d.jpg[/img]"]http://farm5.static.flickr.com/...e3aaa0_z_d.jpg[/img][/url]

Nope:

[.img][url "http://farm5.static.flickr.com/4004/5150722972_66079ca336_z_d.jpg[/img]"]http://farm5.static.flickr.com/...9ca336_z_d.jpg[/img][/url]

YES!!

[.img][url "http://farm2.static.flickr.com/1256/5150114379_5f8fd4d3fb_z_d.jpg[/img]"]http://farm2.static.flickr.com/...d4d3fb_z_d.jpg[/img][/url]

Now that I had the geometry of the tube ends right. time for a full blown (no pun intended?) 1/2 scale model:

[.img][url "http://farm2.static.flickr.com/1263/5162869383_573a72fe4b_z_d.jpg[/img]"]http://farm2.static.flickr.com/...72fe4b_z_d.jpg[/img][/url]
[.img][url "http://farm5.static.flickr.com/4054/5163479362_e987cf1e0e_z_d.jpg[/img]"]http://farm5.static.flickr.com/...cf1e0e_z_d.jpg[/img][/url]

Pretty damn cool! Still a bit pinched in. Couple more degrees maybe? Nip there, tuck here...

To be continued...[/quote][/quote]
[signature]

[SHigSpeed]

[quote pontoonman]Thanks for the interesting post. I too, am always looking for ever lighter float tubes. There may be some materials like kevlar for skins which would allow for something super lightweight, but then, this may be hard material to work with for all I know.

A simpler approach that has been used successfully if you will be using fins is to modify an alpaca such as this: [url "https://www.alpackaraft.com/store/index.cfm?ProductID=126&do=detail"]https://www.alpackaraft.com/...ID=126&do=detail[/url]
Half of the floor can be removed and an inflatable seat cushion used for comfort and higher floatation. Might work for those that are sewing and design challenged such as me...

Hope this helps.

Pon
[/quote]

For sure packrafts have their place. Thing is Alpacka's lightest raft is 4 lbs 6 oz, more than twice my target "bare" weight. I've considered (and still may try later) making a small raft with the hole to make a mini-UL Watermaster. I like the idea of oars or a paddle for those long runs and windy days. That said, my tube is a strictly backcountry stillwater tool.

Kevlar is very tough, but by itself it isn't airtight so you'd need a bladder. Also, it's not really useful unless you actually either cure it in an epoxy or line it with other fabrics as it "gets fuzzy".

The material I plan to use for the main bladder is about 6.5 oz/yd^2, already coated, no sew, and no bladder needed. There also is a 4 oz/yd^2 material that will probably also work, but a bit more fragile.

At 2 lbs, though, you're pretty much butting up against diminishing returns right?

Hopefully I can make some 8 oz. waders and some 1 lb/pair fins to go with it, so bare bones tube/waders/fins I'd come in at 3.5 lbs? That'd be cool...

_SHig
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[SHigSpeed]

Oops, I didn't realize you had linked to the SUL Alpacka. Still over 3 lbs and at 13" wide inside it's quite snug. Probably handles more like a kayak than a raft.

And $490, ouch! I'm aiming at something that could sell for half of that.

That said, it would be fun to build a packraft...

_SHig
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[pontoonman]

Yes on the watermaster idea, but its been done already as indicated on the second reply here; http://forums.flyfisherman.com/forum/sti...float-tube

Seems like it would be more comfortable and stable than any kayak when converted to a watermaster, with your legs hanging down as ballast, though you would have to add back weight of fins and waders. At least you could have the option of lifting your out and rowing as well.

Pon

[quote SHigSpeed]Oops, I didn't realize you had linked to the SUL Alpacka. Still over 3 lbs and at 13" wide inside it's quite snug. Probably handles more like a kayak than a raft.

And $490, ouch! I'm aiming at something that could sell for half of that.

That said, it would be fun to build a packraft...

_SHig[/quote]
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[flygoddess]

Larry Tullis, one of the main designers for North Fork Outdoors (Scadden)

He has been doing this awhile.

I am still interested in SHigs findings.

So you don't plan on putting any kind of material over this?

And next, why so light? What is the final / everything / loaded and headed out weight you are looking for?
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[SHigSpeed]

[quote pontoonman]Yes on the watermaster idea, but its been done already as indicated on the second reply here; [url "http://forums.flyfisherman.com/forum/stillwater-fly-fishing/ultralight-float-tube"]http://forums.flyfisherman.com/...ltralight-float-tube[/url]

Seems like it would be more comfortable and stable than any kayak when converted to a watermaster, with your legs hanging down as ballast, though you would have to add back weight of fins and waders. At least you could have the option of lifting your out and rowing as well.

Pon
[/quote]

I've come across that thread in my homework reading! True, with the self stabilizing nature of having your feet continuously trimming your flotation, it would be better than any kayak. I don't think with your feet up you'd be near the speed of a true 'yak though. Add to that even with my feet down in my Canty which is wider than the Alpacka, it's not as stable as I'd like. Not that I'd flip or anything, but it's not rock solid like my Outcast tube.

Yeah, fins, waders, and a paddle right? Oh well, can't have it all... That said, I still am seriously considering trying to build a wider, more stable UL watermaster type boat, but in my dream world I'd like to be able to stand and cast from it. I guess at that point I wouldn't be packing it into a high lake anyway, so just build a damn pram right? Oh, wait, no flippers... DRAT!

Update on the progress soon...

_SHig
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[SHigSpeed]

Woot! Good progress tonight. I laid out and built my seatbottom and I must say it's DAMN close to right on. It may be a skosh longer back to front than I'd planned, but that'd be easy to fix - though I may not. I'll have to mull over how it'll affect the center of buoyancy.

So, this thing is THICK so it'll be rigid as heck. No collapsing in on the middle for this boat.

Pics:

















Man, I can almost feel the ripple on the water...



_SHig
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[SHigSpeed]

Few more pics for tonight...



Even with the ginormous Summit 2 valve and the goofy tube valve location, this thing will pack down compact. The plastic thickness is probably pretty close to the fabric thickness. Without the valves affecting my folding method, the read deal will pack down smaller.



[IMG]http://farm5.static.flickr.com/4144/5193642261_f452a835eb_z_d.jpg[IMG]

Probably order fabric on Monday. Too bad I won't get it in time to tinker over T-Day weekend... Maybe I'll go fishing?

_SHig
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[flygoddess]

That is soooo cool.
To me it looks like it might be a little too much floor, you legs will be even with the front of the tube.

Like here is the 6' Escape.



Here is the 9' Renegade:



The only problem I see you might have, is all that floatation in the seat and the tube, you will not lean back, but you will be able to lean forward.
I put a battery (60 lb) motor and a 20 lb dog on the back of mine it it is still level.

No this can be a good thing, or you might feel like you are sliding out.

Keep it coming...you are so fantastic!
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[SHigSpeed]

Yup, for sure I think I will shorten the front of the seat. That's what I was thinking when I was musing about the center of buoyancy thing. As it is I have 16" or so from the front of the seat until it starts to arc in. I think I can safely lop off maybe 3" or so and sit "in the curve" with my backside if I need to.

I wish I could extend the fronts of the tubes a couple of inches too, but the way the fabric widths work out it doesn't look like I can go any longer.

_SHig
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[flygoddess]

Unless you made it four bladders? Look at the Scadden RAMPAGE. It is 10 1/2 foot, but I was just referring to adding two from bladders.
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[SHigSpeed]

[quote flygoddess]Unless you made it four bladders? Look at the Scadden RAMPAGE. It is 10 1/2 foot, but I was just referring to adding two from bladders.[/quote]

Additional bladders is tough to do without a LOT of extra work. I could just tack on extra fabric to lengthen but that's not "cool". Besides, gotta keep it tidy and small. I'd rather lose a very small amount of stability rather than add weight and complexity.

That said, I could re-orient the pattern such that each top and bottom sheet could have one seam right at the back and make the 'toons as long as I want. Might do this for future versions and add a crossbar and oars.

_SHig
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[flygoddess]

Gotcha. I thought you were looking for stability?
Anyway, this is great...keep going.
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[SHigSpeed]

Another update for today:

So as I mentioned before, the floor/seat came out a bit too long - I'd be afraid that if someone were to sit up close to the front the boat would go tail up and you may feel like you were sliding out of the dle. I intentionally made the first ridge larger to keep you in place, but the 'toons didn't feel long enough out front to steady the boat.

SO... I took 4" out of the seatbottom. That worked out to be the distance between baffles so no re-engineering at this point, just cut out the sliver and re-tape.

Photo essay below:













So, I think the proportions and balance are MUCH improved. Because the floor is shorter there will be less room for stuff behind you, but when you're high-lakes fishing you really don't take a lot of stuff anyway right? Also, that's what the UL drybag will be for - lunch, jacket, spare reel, etc.

Now, once I get the patterns and manufacturing jigs needed to make this, it wouldn't be too tough to scale out the pontoon lengths and stretch the seat, put a footrest crossbar in, and add oars? Or weld two of these front to front and make a mini-Watermaster. Just use a heavier grade of fabric and it'd be river-ready!

Too much fun...

_SHig
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[flygoddess]

Looking good! Just that valve on the seat looks like it might be a little uncomfortable....LOL Or not[laugh][laugh][laugh]
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[TubeDude]

[cool][#0000ff]Nice work. Definitely getting there in the ultra light department.[/#0000ff]
[#0000ff][/#0000ff]
[#0000ff]Sorry I can't offer any creative insights. I seem to be going the other direction...with all the PVC, motors, series 27 batteries, etc. I suspect that my rod rack weighs more than your whole setup. But I am not planning to hike it in a few miles either.[/#0000ff]
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