Note: This step can be done at any point during your packraft’s construction. It will be easiest if done before the tubes are completed, but can also be added to a completed packraft with a single-layer floor. If you are doing this step before your tubes are completed, remember to leave at least 5 cm unsealed around the perimeter of both floor pieces so you can attach the tube pieces!
If you have purchased the double-layer floor option with your DIY Packraft kit, you may want to make your floor inflatable to insulate your legs from cold water and to provide some extra padding.
There are two different methods for making the floor inflatable:
- Sealing the floor pieces directly together in strips
- Adding baffles between the floor pieces
Option 1: Sealing the top and bottom floor pieces together in strips
The quickest and easiest method is to follow the normal construction procedure, but instead of using a full-size clothes iron to laminate your floor pieces together, use your heat-sealing iron to seal the two floor pieces together in strips (following the pattern in the diagram above). Install a Small Valve on the upper floor piece so you will be able to inflate it. Between the heat-sealed strips (where the floor pieces are not heat-sealed together) will inflate when you add air through the valve. (Remember to leave gaps between the sealed strips to allow air to move between them!)
Option 2: Adding baffles between the top and bottom floor layers
Note: Fabric for making baffles is not included in the kits but can be purchased separately. Scraps will work fine, as the baffles do not have to be made from continuous pieces.
A more elegant (but also more time-consuming) method of making an inflatable floor is to install baffles in a similar pattern to that pictured below. (Baffles are strips of fabric that span the vertical gap between the bottom and top floor layers. High quality sleeping bags and camping air mattresses feature baffles because they provide a more consistent thickness and better insulation.)
The heat-sealing procedure for installing baffles is illustrated in the inflatable seat video and instructions, and it basically makes your floor into an inflatable mattress.
Example floor baffle layout – modify as desired.
I got pretty fancy with my baffles and had them tapered so the floor was 7 cm thick under my butt to 4 cm thick near my feet, and 3 cm thick near the front and rear of the floor. I also made the center baffles taller than the outer baffles, so the side-to-side cross-section of the floor looks like a squashed diamond. (This level of complexity is not required.)
I recommend making your baffles no more than 5 cm tall (excluding the parts that are sealed to the floor pieces) because as you inflate the floor it draws the sides of the packraft together somewhat, and the thicker your floor is, the more pronounced this effect will be. (Adding more baffles and making the outboard baffles shorter than the central baffles will also help to minimize this ballooning effect.) For this same reason, do not inflate your floor fully – it will pull the sides in less if it is only partially inflated. (If you stand on the floor, your feet should rest on hard ground, but when you sit on it, you should be elevated on a cushion of air.)
High strength and puncture-resistance is not required in the baffles, so they can be made from either 210D or 40D fabric.
Tip: When you bond the baffles to the first floor piece, orient them all with the TPU facing in the same direction – this will make it much easier to bond them to the second floor layer (see Make an Inflatable Packraft Seat for for details).
Tip: You can cut holes in your baffles to lighten them and improve air flow.
Making the floor airtight
Whichever way you choose to make your inflatable floor (with baffles or by sealing the floor pieces together in strips), you will need to heat-seal a perimeter 2-3 cm wide around the inflatable part of the floor so it will hold air (if you are making the inflatable floor before your tubes are finished, remember to leave at least 5 cm around the outer edges of the floor pieces unsealed so you can attach the tubes).
When sealing around the edges of your inflatable floor, be sure to keep the top and bottom floor pieces aligned, and avoid creating wrinkles or folds in the fabric, as air could escape through the fold if you seal it in place.
Tip: If you find that your floor is ballooning too much after you’ve sealed it up, you can still heat seal the top piece to the bottom piece in some extra spots or strips.
Questions? Please leave a comment below.
18 Comments
David · August 17, 2023 at 10:25 pm
I recently purchased (sorry, no offense to your DIY, as I am a DIYer in many areas of life) a Kokapelli Twain. I have since discovered your site. Well done! I plan on making a floor I can insert or place on top of the Twain’s tub floor. This should add rigidity and stability to the raft. I will first cut to size a closed cell sleeping bag pad and see how that works and get the size and dimensions just right, then I will will construct an inflatable floor based on your non-baffle method, sealing the top and bottom pieces in strips.
The Twain can hold two persons, but the front seat position back-rest on my model (that’s several years old) totally sucks and provides the person on the front seat virtually no support. I am going to DIY a much better inflatable or foam-based back-rest. The current back rest barely makes it past one’s butt crack. Useless. And I don’t feel like paying Kokapelli or another supplier $60 to $80 for a front seat back rest.
A good DIY inflatable backrest is something you should develop as I think you would sell a bunch of them! I like your seat a lot!
Will Nettles · January 30, 2018 at 8:01 am
A tip from sea kayaking DIY: A fiberglassed wooden core hull can suck a lot of heat even off southern California. What I’ve used for years now is cut up cheap yoga mats. I think 1/4″ is about $15 on Amazon and 1/2″ is about $25-but is very cushy. Both are great insulators and seem to hold up pretty good to UV light. I can see for pack-raft camping a pad cut to be snug in the the raft also being useful in camp and even as a partial length sleeping pad.
I don’t have any pack-raft experience so this might be a been-there-done-that or maybe the shape the bottom takes makes it not workable. Based on sleeping pads inflatable would probably be a better insulator than a pad. I also like to have a piece of 1/2″ for snow camping. I can cut out a leg hole in the snow and then sit on the pad.
Matt (Admin) · January 30, 2018 at 8:12 am
Thanks Will – it’s a great idea. I often use a short piece of 1/2″ blue foam camping pad as insulation under my legs (the kind that was standard back in the day before Therm-a-Rests were invented). It’s pretty much the same thing as a yoga mat, as far as I can tell, but maybe a bit lighter. I cut it short to fit under my calves and feet because I use an inflatable seat as well. The foam pad is also great for hiking, as you never have to sit directly on the wet ground, rocks, or snow, as you pointed out. I’ve carried one for years in my pack and am always glad to have it!
Mark · January 22, 2018 at 5:30 pm
Any progress on the inflatable floor for V3?
I was thinking that a removable drop stitch floor would be a very handy addition… could leave it at home when lightweight is a priority, or pack it along when more rigidity/flotation is required. I’ll be investigating this a bit more later but I was curious how your progress on a V3 floor is going first
Matt (Admin) · February 7, 2018 at 9:01 am
Sorry Mark – I missed this comment. I haven’t had a chance to make one yet, so if you get to it before I do, please let us know! I plan to make one along the lines you’ve suggested. Cheers!
jonw · October 31, 2017 at 3:13 am
G’day Matt,
Just ordered some samples so I’m still in the very early design thought process, but I’m thinking about an inflatable floor, probably just because all the fancy pool toys I’ve used have them. If I order a kit does the inflatable floor need to be factored into the order?
I guess the floor pieces would need to be somewhat larger/wider to avoid the problems associated with ballooning, all the while having the original size sides once inflated. Tricky if you want to avoid any ripples around the edges.
I have some patternmaking experience (but no raft building experience!) so I think I can work out how to solve this, but I’m kind of hoping you’ve sorted this out already Matt : )
I like the idea of having a second chamber and a boat that does not need assembly at the water, but if a better and easier option to just order some ripstop and make a whizz-bang, full length, seat- floor-backrest and then tie this in somehow, would you have a pattern for that?
Cheers
Jon
Matt (Admin) · October 31, 2017 at 8:36 am
Hi Jon, I haven’t had a chance to try an inflatable floor on the V3 yet, but I’m leaning towards a separate inflatable insert (like a full length seat) because it’s easier to construct/repair and doesn’t cause the distortion you mentioned. It’s a pretty simple project that can be done after the packraft is completed, and a few people have already started it. Depending on how thick you want it to be and what size packraft you’re making, you’ll probably need 2 m of fabric (you might be able to use 1 m). Eventually I’ll make one with a seat and backrest, but I just haven’t had time yet. Cheers!
Pete Houston · September 23, 2017 at 8:55 pm
Have you considered any design ideas for making a self-bailing floor?
Matt (Admin) · September 26, 2017 at 10:22 am
Yes, I plan to install several of the two-way press-fit valves in the floor to make a convertible dry floor/self-bailing floor. When the valves are open it will be self bailing, and when they’re closed it will be water tight, so I can adapt it to the type of paddling I’m doing.
Tyler · July 21, 2017 at 3:35 pm
Is the top piece of the inflatable floor sealed to the bottom piece of the floor or to the tubes?
Matt (Admin) · July 21, 2017 at 4:18 pm
I made mine by sealing it to the bottom layer of the floor of an already completed packraft that previously had a single-layer floor. If you’re adding an inflatable floor during construction, you can seal the top piece to the bottom layer of the floor to make an airtight chamber and then fold the excess fabric up around the edges and seal that to the tubes, as shown in the instruction step detailing how to install a double-layer floor.
My new favoured method is to make a separate and removable inflatable insert that fits in the packraft (basically a full length seat), because it’s less complicated and doesn’t pull the side tubes towards each other when it’s inflated, as an integrated inflatable floor does.
Gerry · April 5, 2017 at 8:32 pm
Regarding seat backs, SOTs (sit-on-top plastics) have metal (copper) anchor points/loops built into their frame to connect the seat to via carabiners. If is possible to build in such hooking points to a packraft during construction. I’m completely new to packrafts; haven’t seen one except in a picture; so apologies if this is a daft question.
Sunpowered · April 6, 2017 at 1:03 pm
I’m looking at a Johnston Backband. Check out https://lucmehl.files.wordpress.com/2011/12/packraft-backrest.jpg
Looking at the pimp my packraft site, I see them laying out the attachment patches and determining ring and loop layout by force vectors. They’re using all kinds of nasty glues and stuff but I’m thinking that it would be easy using Mats heat sealing techniques with d-rings in place of the loops.
Matt (Admin) · April 6, 2017 at 8:13 pm
Yep, it’s definitely possible using the tie-down attachment methods shown on the How-To page and in the Forum. I would just be careful about placement, because a seat back can have a lot of force on it, and it may deform the shape of the packraft if it’s pulling too much in the wrong way. My hunch is that the best results will be from attaching the seat back to the floor or to the seat bottom.
Sunpowered · April 2, 2017 at 8:04 pm
Still building my first raft so no experience yet with the issues of the inflatable floor. I can however, imagine what that most of the weight is on the back of the floor causing the air to push up the front. What do you think about dividing the floor in two? One section-about 30-40cm at the back and the front part of the boat comprising the second. This should stop any issues with lengthwise air movement but might make the floor less streamlined due to the transverse weld line.
Also, has anyone made a seat back or is it even necessary? Can one lean up against the rear tube?
Matt (Admin) · April 3, 2017 at 12:28 pm
I do think a seat back is a good idea, but I haven’t got around to making a post about it yet. One can certainly lean up against the rear tube, but adding a seat back will improve comfort and allow you to sit more forward in the boat, if desired.
With adequate baffles or through-welds near the front of the floor a separate air chamber shouldn’t be required, but it wouldn’t hurt, and you would have the ability to adjust the air pressure independently (plus a third air chamber, if safety is a concern).
Cheers!
OlympicMtnBoy · March 31, 2017 at 8:26 am
Thanks Matt, I’m finally done with my tie downs and moving on to the next step which would be tubes, but it seems like I should do the inflatable floor first now? That seems like a lot of baffles compared to your seat and to other packraft inflatable floors with 4-6? What difference did it make from the first version or is that theory to make it more rigid fore-aft? Also you made the baffles shorter toward the edges, but do they taper at all bow to stern? Fattest point under my butt? And why not run them the full length (with holes in the baffles)? And do I seal around the perimeter of the floor leaving a 5cm flap? Or just attache the second floor layer to the baffles and then seal the perimeter after the tubes?
I’d love to see a video or more pics when you get a chance. I’m still trying to get it in my head how to align everything properly before I have the tubes made up but I’ll start thinking about it in earnest tonight.
Matt (Admin) · March 31, 2017 at 8:41 am
Hi Stewart,
I just sketched the baffle locations in that diagram, and erred on the side of more, rather than fewer. The only real benefit of having more baffles, as far as I can tell, is that you get less of that ballooning effect I wrote about, so the sides are pulled in less – but you can get the same effect by just not putting as much air in your floor. I ended up sealing the top to the bottom in a few places after the fact, because I hadn’t put in enough baffles near my feet (that’s where the air wants to go when you sit down because there’s less weight there).
My hunch is that most people will naturally blow up their floors until they are firm, but that will pull the side tubes together so they wrinkle… I’m working on a redesigned floor that will account for this and eliminate the wrinkles when fully inflated, but it’s not ready yet.
You can definitely run the baffles the full length – just note that the floor bends up at the front and back of the side tubes, so the baffles will kink a bit. That shouldn’t make much (if any) noticeable difference. In the diagram I added those short little baffles along the hinge lines, but I’m not sure if they actually make a difference. When I made mine, I added sideways baffles there, but I don’t recommend doing that because it’s difficult to seal the top floor piece on if you have baffles facing in different directions.
I think I mentioned I made my baffles 7 cm under my butt tapering to 4 cm under my feet, and about 2-3 cm near the ends.
I think you will find it easier to seal the perimeter before the tubes are completed and tape the 5 cm flaps back until you’re finished sealing the tubes to the floor. Once the tubes are in place, they tend to get in the way when you’re sealing the perimeter (it’s hard to position the top floor piece correctly and avoid touching the tubes with the iron), so if you can get the floor airtight first, you won’t have to work so hard at it.
Thanks!
Matt