See also:
Packboat pumps
Flextail Max pump
What air pressure does a typical packraft run?
1 psi, 1.5, 2.5?
Answer at the bottom of the page.
Most inflatable devices come with an air pressure rating at which they perform best, including inflatable kayaks which run from 2psi/0.14bar up to 10psi/0.7bar in drop stitch.
On the cheapest vinyl Intex or Sevylor dinghies, as well as slackrafts there won’t be a number, instead you get a ‘stretch gauge‘ (left). With a Sevy you keep pumping until a sliding black tab settles between A and B; your squishy slackraft is probably now at less than 1psi but is good to go. Add a bit more air to try and make it feel less of a water sofa and the thing will burst a seam. It may do that anyway if you give it a week or two or look at it too long.
Right from the start packrafts never had air pressure ratings. You just aired it up with a flimsy nylon airbag (above) until you couldn’t get any more in. The airbag idea was surprisingly effective once you got the knack, and the bag weighed next to nothing. You then unscrewed it without trying to lose any air, quickly screwed on the cap, then topped off by mouth via the separate twist lock elbow valve (left) with all you had in your lungs. The more you blew the firmer you boat became – and that definitely made a difference to response on the water. It helped if you didn’t smoke and played lead trumpet in the local jazz band.
Once on the water all inflatable boats cool down and the hard-won air pressure inside drops a bit so you have to top it up again to get the boat firm.
What was the air pressure? As much as possible but what did it matter as you couldn’t overdo it with your lungs. Stronger lunged paddlers and opera singers paddled firmer boats. And anyway, such very low pressure would be difficult to measure with a normal handheld manometer.
These days most packrafts use simple and effective one-way Boston-type valves (left) which screw off for a wide open ‘fast inflation’ port for airbagging, but have a one-way valve built into the cap for topping up, just like a car tyre. What goes in, stays in so you can build up pressure and get the boat good and firm. No more crumby twist-locks and undignified topping up by mouth.
Better still, inexpensive pocket electric inflators like Flextail (above left) do the job of airbagging while mini handpumps (above right; adapted from party balloon inflators) can do the important topping up without giving yourself a lung hernia. But what’s the air pressure!? Who cares, it’s better than it used to be provided you could pump the handpump with all you had – I find it takes 100 jabs. A Flextail or similar will burn out long before it can get close to a handpump’s final pressure.
Kokopelli and French-made Mekong packrafts (and maybe others) feature a RIB-style Leafield D7 push-fit inflation valve. That’s push-fit as opposed to more secure bayonet fitting as on proper IKs and iSUP boards. It’s what Gumotex IKs used years ago and is actually not a bad idea on a packraft as the pump nozzle on the end of a hose will blow off the valve as pressure climbs, meaning you have to try hard to over-inflate the boat.
But these one-way valves have now made over-inflation a possibility, and we know how that can end. However, one thing we’ve learned with TPU packrafts over the last decade or two is that it’s virtually impossible to burst a well-made packraft using a human-powered pump, even a high-pressure iSUP barrel pump. You would really have to go at it or leave a fully inflated black boat out in the midday sun. The fabric and simple but strong sewn and heat-welded assembly spreads forces equally across the single chamber hull ring. So much so that MYO packrafts have become a thing for individuals with a big table and a sharp pair of scissors.
With a D7 valved packraft you could use a handheld manometer (left) with a push-fit adapter to read the boat’s pressure. Such manometers have a pin in their throat which pushes open the D7’s sprung valve stem just as the gauge body seals around the valve housing, so getting get a live pressure reading.
I don’t have a D7-equipped packraft at hand, but I do have a Bravo Alu 4 R.E.D barrel pump fitted with a 14.5psi/1 bar inline manometer (left). With an adapter jammed in the Boston’s threaded port I ought to be able to get a full-pressure reading off my Anfibio TXL.
I’m guessing about 2psi / 0.14bar to get a pinging firm TXL. It’s what my early Gumotex IKs used to run, using the now obsolete footpump. When the Seawave came out, rated at 3.6psi/ 0.25 bar, that was quite a revelation, though before that I ran a 4.3psi/ 0.3bar Grabner Amigo and you could have battered down a wall with that boat, proving that rigidity didn’t require drop stitch panels as long as the boat was solidly assembled. At Grabner prices, you’d expect that to be the case.
Back to the test. And the answer is…. just 0.1 bar or 1.4 psi. And this was with the TXL as tight as a drum such as I could never manage with the balloon handpump but might have with a K-Pump Mini.
Now we know.
Inflatable Kayaks & Packrafts 