Category Archives: Pumps, Valves & PRVs

Leaking pressure release valve (PRV; Gumotex)

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PRV maintenance by Marcin

Durness beach

The other day we paddled the Seawave off Durness beach where the surf was bigger than I’m used to. Hitting a breaking wave as we paddled out didn’t help; the swamped boat needed tipping out at the next beach. It was a bit too offshore windy to roam, but it was still a thrill to be paddling on the very top of Britain, just 2175 miles from the North Pole (about the same distance south to the Canaries).
After the paddle I took care to dry, wipe down and roll the boat up on a sand-free rock bench, but lacking a hose back at the house, I had to rinse one bucket at time – not ideal. When I pumped up, the floor soon went flat: sand was in the seal of the floor’s PRV (what’s a PRV). It’s a thing that happens but in nearly 20 years of Gumotexing it’s never happened to me. Today was my day.

Seawave PRV

The design of the valve means that if the boat swamps in the surf, water laden with grit can enter via the six vents and pool in the valve body right above the seal. The next time it purges, sand grains can slip down onto the soft rubber seal surface and stay there, letting air leak out.
Because the chances of this are high, with a leaking floor PRVs are the usual culprit, not the nearby inflation valve with its sealed valve cap, or less still, a puncture. But don’t rule either out (the cleaning procedure for an inflation valve will be the same).

Fixing a PRV
Much of what follows is my take on Polishman Marcin S’s translated post linked above. It’s not how I actually did it, it’s how I would do it next time after quite a lot of trial, error and better ideas or procedures though up along the way.

Before disassembly, first try giving the PRV a darn good blow-through by pumping like billy-o and letting it purge. It will help to prise off the vent cap with a small flat screwdriver so grains blow away, not bounce back in. Pump up and see what happens. Chances are it won’t work.

Next I suggest putting the boat on a slope (to save water and weight) and flood the stern to establish the pace of the leak from the PRV. You will do it again at the end to see if there is any change. By dragging the boat around 180°, you can let the water slosh down to the bow while you remove the PRV at the stern at the high end.

  • Don’t try this; manometer leaking
  • Small bubbles rising from the PRV

Don’t plug in a manometer to try monitor the leak over a period of time; it cost me a few hours and a disassembly or two before the flooding idea proved my manometer was leaking from the base faster than the PRV. As we know, pressure gauges are plugged in briefly to get a reading, then as quickly removed. To test for a leak, water is best.

  • Six splines below the vent cap
  • Buy one now

You now know for sure the PRV is leaking so will have to remove and clean it. Flicking off the vent cap exposes the valve body’s six splines. Fit your Gumotex valve tool (or eBay clones from £6) and unscrew the PRV. As Marcin says: the plastic one will do; you don’t need the expensive metal one Gumotex also sell. Expect the PRV to be very tight. Marcin pre-lubed his, I didn’t but it undid easily enough. My boat is less than a year old.

  • What a tool
  • Don’t let the backing nut fall away (or the o-ring)

It’s easier to start unscrewing the PRV with the boat fully inflated, but separate the two parts of the valve only once fully deflated so there’s less chance of the backing nut inside the hull rolling away out of reach. Same with the loose o-ring on the valve body base; don’t let it drop into the abyss.

  • PRV with black o-ring
  • Rinsing; worth a shot

With the PRV in hand, you can see how it works: a spring-loaded valve opens upward when pressure from within reaches a pre-set level – on a Seawave supposedly 0.25 bar or 3.5 psi (but it might close as low as 0.20). As pressure drops it seals shut. At this point you might try rinsing under a tap while pushing the valve open, but you’re going to have to disassemble it anyway to check the state of the seal.

Set the o-ring aside and unscrew the 6mm locknut on the valve stem. Press on the sprung valve from the other side to stop it spinning as you unscrew the nut. But before you do this, count the number of threads or take a photo (above), as the position of the nut regulates the purge pressure; the more you screw down the nut the higher the purge pressure. I notice Marcin’s nut on his Solar was much less screwed in than mine (lower purge pressure). (At one point I tried screwing in my nut an extra turn to improve sealing, but it didn’t seem to make much difference; still closing around 0.2. Maybe a few more turns are needed, but of course you don’t want to go too far and compromise the floor.

Left: pliers to undo the nut; magnifying glass and torch to closely inspect the rubber seal. Right: the disassembled PRV. From top left: valve body, o-ring, valve stem with rubber seal, spring, spring cross-washer, 6mm lock nut.

Ooo-er, quite a lot of fine Durness beach on there.

I chose to clean the rubber seal with an ear stick and toluene solvent. (I tried, but decided not to remove the rubber seal from the stem). After carefully wiping off the grains on, around and under the seal, I dipped the whole thing in the toluene bottle cap (not too long as toluene is strong stuff on plastic; it dissolved the orange marker dot). Don’t forget to inspect and wipe the inside of the plastic valve body too.

A lovely, clean PRV seal. Reassemble and carefully screw down the metal nut onto the soft plastic valve stem to where it was – or what you prefer.

  • Grit-catching foam filter

Marcin suggests sticking some sponge under the vent cap to catch grains in future. Sounds like a good idea. These are easily removed/rinsed/dried or replaced by flipping off the vent cap.

  • Edge caught in thread
  • Tooling on
  • Clip on the cap

A quick Hail Mary to Saint Columba and you’re now ready to refit the valve. You shouldn’t need any lube other than a bit of water for things to reassemble smoothly, though I decided to lube the o-ring with some TiZip silicon grease.
I found as you start screwing in by hand it feels like it’s cross threading. It isn’t: the edge of the fabric is getting caught in the thread. Back up and jiggle the valve body and loose fabric around to make sure the body has slotted and centred its flange into the fabric hole.
Pump back up, tighten the PRV down some more, but probably don’t clip on the vent cap just yet as you may be going back to square one, as I did (partly because the fitted manometer was leading me astray).

Now flip the stern back downhill and let the water slosh back over the Seawave’s valves. I found the PRV purged for about a minute, then abruptly stopped with an odd underwater squawk … but carried on leaking slowly. Another removal and check and refit and there’s still a very slow leak – a 2mm bubble every 2-3 seconds, but with the floor now lying in the warm afternoon sunshine, that may be normal purging. I decide it’s as fixed as it can be. A few hours later, all was normal again and we are all much the wiser.

Moral of the story: if you think sand-laden seawater may have pooled in your PRV (most likely from crashing beach surf, not normal, deep-water paddle-splash), back on shore flip the vent cap off and rinse the PRV cavity with fresh water, ideally flipping the boat upside down, so any grains flush out.

Coastal Packrafting

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Rebel 2K main page

Around here the inshore sea paddling is exceptional, even if packrafting the inland lochs is also pretty good. Having done most of the latter routes, I thought I might try some coastal packrafting.
Garvie Bay arcing west to Achnahaird Bay looked like a good one and happens to parallel probably the best walk on the peninsula which we’ve done many times. That route could be a 20-km combination of cycling, walking and paddling, but as it was the last calm evening for a while, we thought we’d go out together in the kayak and I’d try the packraft on the way back. That way everyone got to play.

A light NW breeze blew onshore as we cut across Achnahaird Bay like a blue fin tuna. The approach of HW meant we slipped through the submerged skerries of Rubha Beag and into the crab’s claw inlet of Camas a Bhothain (Bothy Bay). This seemed a good spot to deploy the packraft with the aid of my exciting new gadget, a mini electric pump. I unrolled the boat over the water and let the pump buzz away for a couple of minutes, topped off with the hand pump, then clambered aboard.

  • Buzzing noise
  • Man the lifeboats!

Paddling away, I realised this was the first time I’ve paddled my Rebel 2K unloaded and I was a bit shocked by the bow yawing. Now fully back-heavy, one good swipe of the paddle and it could flip a 180°, just like my old 2010 Alpacka Llama.

Ah, but in my haste to launch the lifeboat I’d forgotten to fit the also-untried skeg which comes standard on the 2K. I waddled over towards Rubha a Choin beach and slipped it on easily, while the Mrs transferred to the Seawave’s front seat.

I’ve been ambivalent about the value of a skeg on a packraft, but now back on the water the yawing was notably reduced. If you think about it, a packraft actually pivots from a point around the middle of your swinging paddle, not from the stern, as it feels from the seat. The centre of mass behind the pivot point does make an unladen bow yaw more, but the stern will yaw too; just less and unnoticed.

  • Skegging ‘eck!

On the Wye my 2K was fully loaded with the centre of mass moved forward and which minimised any yawing, even without a skeg. (With a heavy load over the bow a reduction in yawing is well known with packrafts). Now unloaded and with the bow riding high, swish-swosh yawing was exacerbated, but is actually happening at both ends of the boat. So any type of fin or extension of the stern (like the post-2011 Alpackas – right – and all subsequent copies) will constrain this, while not affecting steering. So, bottom line: skegs work on a packraft and are easy to retro-fit.

  • A short-but-wide packraft actually pivots from near the centre, not from the back as the impression suggests

All the remains is a packraft’s agonisingly slow speed. These are not boats made to enjoy the sensation of flatwater paddling; they are boats to enjoy getting to out-of-the-way places easily. Any type of disturbance to progress, be it wind or current, may slow you to a stop, or worse. Something like the longer Nomad S1 I had would be better for this while still being packable. Still, in these ideal conditions it’s nice to float along observing the coastal features.

Paddling back down the east side of Achnahaird Bay, a back-breeze made progress feel achingly slow. Lately, I’ve come to value metres per second (m/s) as a metric of wind or paddling speeds. Something moving past you (or vice versa) at three metres per second is easy to visualise, though I suppose we can all visualise a 3mph walking pace, too. It’s what YR uses and is easily converted to ‘double + 10%’ for miles per hour (so 5 m/s = 11.18 mph). Or just double it and you nearly have knots (5 m/s = 9.8 kn), for what that’s worth. Crawling past the rocky coast it looked like I was doing 1 m/s at times. We had a race: diminutive Mrs in a big, long kayak; me in the packraft. Within ten seconds the Seawave streamed away while Bunter frothed up the water like a cappuccino machine.

Oh well, you’re as fast as you are. Like cycling in Tajikistan rather than Kazakhstan, for the best experience match your routes with your mobility and conditions. Next calm day I’ll do the full Garvie loop.

Tested: FlextailGear Max Pump / Plus

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Pumps for IKs and Packrafts

Update May 2022.
Charged Max Pump packed up after a year/20 uses. Slide switch was off so not accidentally discharged. Plugged into computer; no charge light. Plugged into USB wall socket (as have done before): very bright light followed by smoke… Replaced with the boxy, orange, heavier, notionally waterproof Max Pump Plus for £23.

In a line Cheap, light, compact, USB rechargeable and fast, for when air-bagging is a faff or awkward.

Cost Max Pump £24 on amazon.
Max Pump Plus £23

Weight 148g + nozzle 8g.
Max Pump Plus 170g + nozzles
(Packraft airbag 110g).

Where used around UK

Light, compact
Faster than clumsy air-bagging – handy on a narrow bank/shore
Can suck (vacuum) as well as inflate
Ought to do > 15 fills
Max Pump as a conventional stiff slide switch, not ‘touchy’ inductive switch on the newer Max 2 version. Max Pump Plus has a silicon covered press switch.
Will do other stuff, like airbed mats and fire embers
Newer models can be used as a power pack, have LED lights, are IPX7 rated and can be programmed to sing Waltzing Matilda.

None of the supplied nozzles with Max Pump jammed nicely into a Boston valve
My Max Pump packed after less than a year and about 20 uses. Replaced with bulkier Max Pump Plus
Only replaces air-bagging; still need to top up by mouth and/or hand pump
Will discharge eventually, unlike manual methods, and will eventually die for good

What they say
My name is Max Pump 2020. I can quickly inflate and deflate your swimming tube. air mattress. and other inflatables. With vacuum bags .I can create more capacity for your suitcase and wardrobe at home. When in outdoor.I can provide oxygen for your burning ovens. enabling you to enjoy your food more easily.

Apple, pump with nozzle and my Boston adapte

rMax Pump
Max Pump Plus

Review
An electric pump to save a couple of minutes’ packraft air-bagging? Do me a favour! That’s what I think when applied to bulkier IKs where a two-way barrel pump is fast and easy. But factor in cost, weight, size, USB rechargeability plus supplementary uses and, for a packraft, FlextailGear’s range of pumps (above) is worth a punt.
Air-bagging is a clever idea to inflate a typical packraft, but on some days it’s not the most intuitive of actions, perched on seaweed covered boulders. Once a day is fine, but on a trip where you’re airing up and down a few times a day, the effortlessness of the Max Pump is welcome. A good case to point was my paddle on the Wye where accessing my Rebel 2K’s internal storage pockets to get to the camping gear each night meant re-inflating the boat every morning. The Flex pump would have made this less tiresome. Another example is getting back from a tiring sea paddle and wanting to reinflate the boat to rinse and dry properly. Plug in the Flexy and get on with other after-paddle chores.

Max Pump adapters but none fitted a Boston valve’s two ports just right
Actually the grey rubber nozzle (right) will push and seal into the main threaded port, and with my second Max Pump Plus, there was a hard plastic nozzle to fit a Boston’s mushroom valve (middle) too.
But to reduce loose bits, I made a 2:1 adapter (left) to fit both ports, using tape to make a good seal.

Out of the box
With Max Pump I got the pump, four nozzles, a short USB-A lead and a small bag. While one nozzle loosely fitted a Boston valve’s threaded airbag port / dump valve, nothing fitted the one-way valve body. You’d think with Boston valves so common on Chinese-made slackrafts, packrafts and cheaper IKs, this Chinese brand would include a Boston valve nozzle. Luckily, I’ve amassed loads of adaptors and nozzles, and one 16mm (5/8″) adaptor fitted the pump’s main nozzle and jammed into the Boston port. [The orange Max Pump Plus included a nozzle for the valved port].

The rubber bung adapter fits
With added tape my combo fits both ports

Off a computer allow two hours to fully charge the pump out of the box. After just three fills (12 mins?), it took just hour or less to get the green light. Off the mains is faster.

Two-and-a-half minutes

I estimate the volume of my Rebel 2K was 240 litres, (12 jerricans) so at the claimed flow rate of 300 L/min (currently the highest in Flextailgear’s range of mini pumps), that ought to take less than a minute. In fact it took 2:30s to reach the equivalent of airbag pressure (full volume; above).
But this was pushing through the one-way valve, (like a car tyre) not direct into the hull via the airbag port / dump valve which has no resistance.
Now with a bigger TXL with a volume of around 350 litres, I inflate directly through the screw port into the hull: 2:20s and if you’re quick you don’t lose much air screwing the cap on. Then I Flex for another 30s via the valve (or do 20 breaths to save the battery) and finish off with the handpump.
According to the Flextailgear table above, my heavier orange Max Pump Plus has 10% less power and max pressure than the Max Pump, but it’s hard to verify any of this data other than weight. The fact is, either pump does a packraft in a couple of minutes.

My comfy full-length Exped Synmat XP 9LW – which also needs air-bagging to avoid humid breath – inflates in just 25s. And as many will know, air-bagging a sleeping mat in a cramped tent when you’re worn out is not one of the joys of camping.
The Max 2020’s 3600mAH lithium battery is claimed to run for 40 minutes, so that ought to do at least 10-15 raft fills plus a few mats, when camping. I imagine the Max Plus will be the same.

Deflating either of these items is of course as easy as rolling them up, but getting the last bit of air out can be tricky, even though it can save a lot of packed volume. Pump suction definitely works on my Seawave IK because the one-way valve can be pulled open with the bayonet nozzle. On the packraft and mat, you have to suck from the unvalved airbag port, and by the time you’ve plugged that, some air gets drawn back in. I find just rolling up, squeezing, then sucking the last of the air by mouth works best, as your hands are free to get to the valve cap fast.

Max Pump Plus will do my Anfibio TXL in under 3 mins

Last word to Sven from Anfibio: “Can’t live without one anymore. Cannot remember when I last used an inflation bag.”
These young people, honestly. 

Inflating the packraft on the water from my kayak

[Max Pump Plus: 170g + nozzles] [Max Pump Plus: 170g + nozzles]

25% off Fernhurst IK & Packraft guides

Buy my Inflatable Kayaking; A Beginner’s Guide direct from Fernhurst Books at 25% off if you sign up for their newsletter. Click this or the image below. More about the book here. You can also buy it off amazon.uk for about the same cost, depending in their discount and postage fees.

My similar Packrafting Beginners’ Guide is due in May 2022.

Tested: Tyre pump adaptor for inflatable kayaks

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Pumps

You may have seen these bayonet/car tyre adapters on eBay in recent months (left). The bayonet end clamps into your IK’s raft valve (won’t work on Boston valves). The other end is a regular Schrader valve like on your car/bike wheel. Attach that to your 12-volt Halfords tyre compressor and you can inflate your IK from your car battery. No more of that effortful, back-breaking pumping!

Me, I’ve never seen the value of electric pumps for IKs. (Packrafts are another matter). You can only use them near a power source, or the rechargeable battery will run out. And how hard and slow is inflating an IK with a good barrel pump anyway? As IKs catch on with more mainstream recreational users (whose cheap boats may come with a rubbish pump), some find manual pumping too tiring. What is this world coming too?!

The difference between tyres and IKs:
• a car tyre is a low-volume, high-pressure vessel (~30 litres @ ~30psi)
• an IK has high volume but runs low pressure (3 chambers of 50–160 litres @ ~3psi). Drop-stitch has less volume but runs much more pressure.

That’s up to five times more volume in an IK, but at a tenth of the pressure. I would guess the swept volume of my better-than-average car pump (left) is 3–5cc. My Bravo RED 4 barrel pump is 2 x 2000cc (it pumps on the up and the down strokes).
Even if my 12-volt compressor whizzes along at 1001rpm, it will still take a long, long time to fill a 160-litre IK floor. But for a fiver, I thought I’d prove myself right.

The Test
The easiest way was to pump up my Seawave’s floor to the point the PRV purged at about 3psi. The actual psi is immaterial but it’s consistent.

No surprise: it took less than a minute to pump up the 160-litre floor with the barrel. With my car tyre pump it took over 7 minutes.
And if you want say 4psi in the sides, or a 10psi drop-stitch boat, the duration of the tyre pump (or effort with the barrel pump) rises exponentially. It will take forever with the car pump adapter and I think the tyre pump would auto shut-off or burn-out before it reached anywhere near 10psi.

Just a tenner on amazon

I looked into rechargable or D-cell battery or mains/car electric pumps like above. They go on amazon from just £9.99, or even less for mains only or 4 x D-cell battery. These may be great for pool toys, air beds and other low-pressure items like slackrafts which just need a shape, not rigidity.
The Pumteck (left; £15) claims an obscure pressure rating of 4.5 kPa which sounds impressive but translates to just 0.65 psi or 0.045 bar. That is slackraft pressure; there is no worthwhile IK that runs such a low psi.

All these pumps do is save you the initial pumping which merely takes time (< 5 mins), not effort. The rechargeable ones will be spent in 10 minutes and then need hours of recharging. For a typical 3-psi IK you’ll still need some sort of manual pump to top off to full pressure; even more so a higher pressure DS IK.
If your back can’t handle a barrel pump (taller pumps work better for taller folk), consider a Bravo foot pump, but with any dropstitch IK there is no getting round the need for a high-pressure barrel pump or a very expensive SUP electric pump.

Tested: Anfibio Packrafting Nano RTC packraft review

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In a line
Super-light but sturdy packraft with a low-maintenance solution to in-hull storage.

Simple but well-detailed design
210-D fabric feels durable
Optional mini-hand pump works very well and can be deployed on the water
Holes easily sealed from the inside with a stick-on patch
Compared to TiZips, RTC is a simpler, lower-maintenance way to achieve in-hull load carrying
Raised floor lifts paddler, limits wear and may help limit yawing
Like most short packrafts, it’s not a joy to paddle on flatwater for hours
RTC will need care and may need practice to achieve a good seal
Floor is same thickness as hull, not double-weight, as is usual.

What They Say
Extremely light packraft with roll closure (RTC), which enables luggage to be stowed in the tube and thus offers higher transport capacity. Minimal pack size, 1kg light and robust enough for calm and tame waters allow combined adventures with increased payload. Price: €389

Out of the box

This pre-used Anfibio Packrafting Nano RTC came with an optional backrest seat (€57), the airbag, an optional mini top-up hand pump (€10), a strap and 3 patches but no glue or instructions. The latter appear online.
On the IK&P scales the boat alone came in at 1002g. The full seat adds another 237g with the horseshoe seat base weighing 135g. All the other dimensions in the image above closely match Anfibio Packrafting’s own data.

  • The rolled out Nano RTC
  • Thin TPU film layer to ensure a good seal

This is not your usual shiny-exterior packraft; the Nano’s coating is instead on the inside like the plain Nano SL model. The woven texture of the 210D nylon fabric still gives a sense of sturdiness which I can’t say I felt with the 75D Supai Flatwater and Matkat we tried a few years ago. Such perceptions are important when bobbing about in the middle of a breezy loch or tackling some light whitewater. Maybe it’s the black colour, but the Nano also managed to look bigger and tougher than the virtually same sized Alpha XC (left) we tried a year or two back.

The RTC is a new idea to Anfibio Packrafting, though I see the scantily described Rapid Raft in the US uses a similar closure. The Nano differs by being a more sophisticated design, with a broadly symmetrical hull made from just three pieces of fabric: hull top; lower hull and floor; inner ring. This adds up to just two long seams which ought to mean fewer chances of errors during assembly as well as less weight. Symmetrical also means you can have the closure up-front (normal) or at the back where, with just four folds rather than five, it creates an elongated stern which adds more buoyancy where most of the weight is and acts as a fixed rudder to limit side-to-side yawing endemic to packrafts. Payload is 135kg.

The RTC has an extra TPU film bonded inside to ensure an airtight seal, as long as you roll it up tight with no wrinkles. Providing it works, as a way of enabling in-hull load-carrying, I’d sooner put my faith in this than a TiZip which must be kept lubed and clean and dried properly to work well.
At the RTC-end you have four mounting tabs on the tube top. On this you can mount Anfibio’s DeckPack, as pictured below. Bigger exterior loads may also be more convenient here if your route includes many awkward portages where carrying the otherwise heavily loaded and inflated boat may be tricky. Otherwise, there’s a tab inside the hull to secure loads and keep them towards the RTC end.
You get seat mount buckles at both ends too, though I found the fully inflated seats jammed in well by themselves. There will be the age-old annoyance of the backrest flopping forward as you get in, but used RTC-sternward you can hook it upright to one of the tabs. This backrest design hasn’t changed since I had my first Alpacka Denali over 10 years ago. What is actually wanted is lumber support which is best achieved from strap-braced backrests, as in my Nomad, but that gets complicated.

  • Boston valve – ideal for packrafts
  • Horseshoe seat option
  • Clean seams all round

No you can’t inflate it by opening the RTC to the wind unless there’s a gale on, but it helps to fluff the boat out, and using the usual airbag, 5-7 scoops fills the boat, after which you top up the one-way Boston valve by mouth. If you find this a bit awkward, I find a section of half-inch garden hose works as a ‘blow-straw’. Or use the top-up hand pump (137g) to get maximum firmness. On the Nano it worked very well and for only €10 I’d say is a worthwhile addition for any Boston-valved packraft. More below.

“The RTC cannot be compared to the usual roll closures of simple pack sacks [dry bags]!” proclaims the website, and I can believe them. We all know that Ortlieb-like roll-top dry bags don’t have a proper seal; water will seep through and air will leak out. But the multiple rolling of the film layer, as well as the fact they’ve dared use RTC on a packraft, gives a sense of confidence. Time to get paddling and see if that confidence is warranted.

On the Water

Mid-September and it’s nearly 30°C: too good to pass by so I head for a short run up and down the Medway. Airing up at Sluice Weir Lock, I had a good feeling about the Nano, even if at 95kg I expected to be on the limit, as I was on the Alpha XC. The extra 6 centimetres all round looked enough to make a difference, and one way to help the trim (level) would be to run the RTC at the stern and as long as possible (four folds) while perched forward on the backrest seat option. In the end I didn’t feel the need to do this.

Once inflated by bag and topped up by mouth, I knew the Nano would need a damn good tempering today. A boat firmly inflated by hot ambient air will go soft once cooled in the water. Sure enough, after some splashing the Nano went as limp as a stunned trout. While doing this I was reminded of the indispensability of a bow line to manage a boat at the water’s edge. I hooked the metre-long strap through the RTC (left); better than nothing.
Back on the jetty I tried the two-way hand pump: 20 pumps firmed it up. After over a decade of proven hull integrity, it’s become the norm to top-up packrafts with mini-pumps and not by lung, raising pressures up to 2psi or more. This added tautness is what differentiates packrafts from slackrafts and has a huge benefit on paddling efficiency and satisfaction.

They say don’t overdo the pumping but how are you to know? A well-made packraft may well handle a massive 0.5 bar or more before it blows a seam, but assuming the Boston one-way valve can handle it, I think the mini PRVs I tested the other day would be a useful addition to packrafts. They cost only 4 quid and you just keep pumping away until they hiss, knowing the boat’s reached the valve’s purge pressure which cannot be exceeded. It’s like an in-built pressure gauge. Fitting one to the open-ended Nano (or any TiZip packraft) would be especially easy

I decided to try RTC bow first (it made using the DeckPack easier). Once in the boat I felt fine, though from the pictures it’s clear the trim looks nearly as back-heavy as on the Alpha. Too many pies. But on these recommended ‘calm waters’ that didn’t seem a problem.

Confident I wouldn’t wet myself, I set off 2km up river for Oak Weir Lock, passing some happy Itwiters on the way (left). Those things are everywhere now! Good on Decathlon for satisfying the huge demand this summer.
Within a few minutes it became clear the Nano had cooled further and needed another 50 pumps off a handy concrete slab below the steep riverbank. I also remembered that, unlike my IKs, low-floored/high-sided packrafts want the seat base pumped right up to give height so as to get the paddle over the fat sides.

Back on the move, speed and response increased dramatically, but not having paddled a normal-sized packraft for a while, I’ve forgotten how slow they are, topping out at maybe 2.5mph/4kph. Riverside walkers were outpacing me; normally it’s the other way round on the Medway, albeit heading downstream. Where noticeable, the current here is about half a mile an hour.
I took off to explore some mysterious side creeks which I’d normally shoot past on my downstream burn-ups, careful to avoid the many brambles which line the river here. There’s a perception that the Nano’s textured woven surface could snag a bramble more easily than a smooth one, but should that happen it would be easy to open the RTC and slap a stick-on patch on the inside: the best place for such a repair. The heat and dense, overhanging vegetation reminded me of a boat trip I took years ago up the remote Roper River in Australia’s Top End.



Back out on the main channel and heading upstream, after a while it took some effort to move the Nano along, with the tell-tale bobbing of a soggy slackraft. A squidge of the sides showed they were soft again. More tempering needed or a slow leak, probably from the inexpertly sealed RTC. I hacked on and at Oak Weir jetty and got my weight over the bow to push the RT closure underwater. A couple of tiny bubbles popped up occasionally, but they may have been just trapped air escaping the folds.

The picture above makes it appear worse than it was, and being a hot day on cold water, I felt one more tempering may do the trick. I often have to do this with my bigger Nomad; which takes a good few minutes on the water to fully cool on a hot day. I did my best to check for tell-tale bubbles elsewhere, but anything easily spotted would have seen the boat droop in minutes.

I realised the seemingly redundant hand pump hose was actually ideal for topping up on the water. I reached behind and carefully undid the upper cap of the Boston valve (you don’t want to undo the main valve…), pushed on the pump hose nozzle and gave it another 50 jabs + 10 for luck (about 8-9 litres). With the Nano taught again, I couldn’t resist hopping out and sliding back down the shallow Oak Weir canoe chute which the Nano took in its stride. This boat could easily manage river riffles; the caveat would be too much scraping in the shallows. The exposed fibres can probably take some rubbing but it’s the coating inside that counts. I wonder if spraying a slippery coating (303 Protectorant springs to mind) on the undersides may help reduce possible wear.

I’d asked for the backrest seat option to push my bulk forward off the overloaded stern, but comfort, or a relaxed all-day paddling posture, will take some experimenting. With the unusual raised floor and seat base pumped right up, the now higher backrest had less to lean against so I tipped backwards. I should have tried deflating the seat base a bit.
Even at my height (1.82m) I can still stretch my barefoot legs flat out, when in fact a bent leg is better for paddling. So you might want to fit Antibio’s footrest (as I use on my Nomad), shove a bag or shoes up there, or better still (for trim), put something behind you to act as a thicker backrest and centralise your weight (as we did on the Alpha). However you achieve it, a solid back–to-foot brace improves paddling efficiency which means it takes longer to get tired.

  • Trim not too bad

Running back downstream to Sluice Weir felt like it took half the time, and I got there with the boat still firm. I do wonder if wetting the inner film surface provides a better seal, just as licking a suction cup before sticking it to glass. One to try next time.
I also noticed that for a short, wide raft, the Nano barely yaws left to right. Besides my fine technique honed over the years, the profile of the raised floor may help the side tubes ‘bite’, like ice skate blades. Or it may be the subtle protrusions (below) under each end of the boat which my 2.9-m Nomad also has and which are said to have a skeg/keel effect.

Either way I was confident I’d survive the sporty Sluice Weir chute, catching only a cupful of water as I hit the frothing base. With that ticked off, I paddled over to the portage jetty crawled out and aired down. Being a black boat on a hot day, the Nano dried itself off in no time.

Packing the boat up, I checked for seepage into the RTC when it had been submerged for a minute or two. As expected, water crept along the textured outer nylon surface but the inner film was dry, though as Gore Tex will tell you, air can pass where water can’t. If that was the issue, not just heat, I’m sure getting a good seal is a knack that can be acquired.

=

Conclusion

Providing they can handle the added pressure of a hand-pump, I wouldn’t be surprised to see RTC-type closures becoming more common on packrafts. Using zippers for such a critical seal always seemed a bit dodgy to me, though I’ve only read of them playing up.
Besides that novelty, the sturdy 210-D Nano makes a great crossraft at a price that’s competitive with the thinner Supai boats. It’s very light, compact (3 litres rolled up), comes fitted with enough useful tabs and can be paddled RTC-stern to level off the trim, if needed. Seats are quite a lot extra, but you can sit on your gear, and for a tenner, the little pump is a no-brainer to get the most from your boat. And if the Nano’s RTC arrangement is not for you, choose the conventional Nano SL costing about 15% less. Either could make a great entry-level packraft or an ultra-light crossraft.

Testing unbranded mini PRVs

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See also:

IK valves and PRVs
Fitting 4.8psi PRVs to a Seawave

  • Mini PRV on the right

I fitted over-rated 4.8psi Ceredi PRVs to my Seawave’s side tubes a few years back. I like the idea of not having to worry about the boat getting hot in the sun (and exploding), just as much as gaining some extra rigidity by fitting PRVs rated a little higher than recommended side tube pressures.

I bought a pair of unbranded Chinese PRVs off eBay (<£9 posted – about 30% of Ceredi/Leafield prices) to consider for my next IK. Some sold on eBay don’t even mention the purge pressure! These ones did: 4psi or 0.27bar, just a bit over the 0.25 of the boat I have in mind.

Out of the bag, the quality of the molding looked no worse than a Ceredi. I was a bit surprised they’re smaller than usual PRVs, (the listing gave these dimensions), but what does it matter as long as they work.
I worked out a way of testing them by removing the backing ‘nut’ and screwing the ‘male’ PRV housing onto a rubber motorcycle throttle grip. The other end of the grip I jubileed to the barrel pump nozzle.
Pumping the pump, the pressure built up and PRV ‘burped’ suddenly at an indicated 0.4 bar. But as my manometer needle zeros at 0.1 bar and not zero, we can probably subtract that 0.1 and call that 0.3 bar which is 4.34psi. Close enough to 4psi. Now I can fit these PRVs with confidence.

The hole which must be cut in the boat to fit this valve is 24mm ø, but to get the back nut inside the hull you’ll need to go in via the larger inflation valve aperture. So cut the PRV hole close to the inflation valve. Once loosely screwed together, the knurled outer housing can be tightened with some wrench or another.

  • Accounting for manometer error, the PRV burped at 10% more than claimed, which is pretty good.

MRS Nomad S1 – a few mods

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MRS Nomad Index Page

After paddling around in the S1 I can see some ways of improving it. So I did.

Replace the inflatable backrest with a plain foam backrest. The backrest which came with the boat had already been repaired twice and, unless it’s at the back of a packraft, who needs an inflatable backrest anyway? It’s more about support than weight-bearing comfort, like a seat base. As on my Seawave, a foam backrest (£12 on eBay; 200g) does the job and is one less thing to blow up. The press-pivot clips from the old backrest fitted on easily, and even though it only has 4 straps, not 6, it works fine. I trimmed about a foot of excess from each strap.

nomanewseat

I bought some mesh zip pockets about 6” x 10” off eBay costing next to nothing from China. I zip-tied one to the back of the backrest. A handy way to ensure the airbag, K-Pump adapter and a couple of zip ties are always in the packraft.

mrsfootrest

I fitted an Anfibio footrest cushion. You lose some inflating time there, you gain it here but the Nomad’s seat is too far from the bow for efficient bracing, even for me, and moving the seat has its limits.  I’ve since found the broad flat resting edge makes a more comfortable footrest than having them jammed in the bow. For flatwater I may not even need the thigh braces.

nomafootrest
nomappump
kpumpmini

Top-up pump. The Nomad’s large volume takes a lot of tempering (topping up) to get it firm, but I can only do so much by lung. With a bit of hose on the end, the £3 pump (left) should have enabled a higher pressure, it’s the same one Alpacka were selling with some boats at one stage. But it didn’t work – or would take forever. I think it just hasn’t got what it takes. By comparison, my bulkier K-Pump Mini also with a hose nose (below), effortlessly packed in enough air to firm up the Nomad like a drum. So if it’s that important, the K-Pump it will have to be.

nomazips

Quicker detach seat base. I replaced the knotted-in laces with long, thin unzipped zip-ties threaded through the holes to make the seat easier to remove for land use or for drying and cleaning the boat. Any similar plastic wire-like thing will do, as long as there is no puncture risk. But it’s still not clip-off easy. I have a better idea.

2bags

I replaced the blue MRS airbag with a brightly coloured Anfibio one. Visibility is the rationale: because packrafts lack somewhere to stash this important item (but see below), with a neon green bag I’m much less likely to forget it when packing up (done that before). It could also be handy to wave as a rescue aid if stuck on a stormy skerry in the North Atlantic (not done that yet).

For the same reason I stuck some hazard tape on the skeg. I also threaded a reusable zip tie through a hole in the back so it can be securely attached to the boat when packing up, but in fact, unlike my IKs, on the Nomad a skeg is not essential to make it track well.

mrsskeg

I added some sidelines; handy handles when manhandling the boat, and also useful to tuck in the paddle securely across your lap while controlling a sail. Or course having the mounting points pre-fitted makes all this much easier.

Pumps for inflatable kayaks and packrafts

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Updated January 2023

See also:
Inflation valves and PRVs
My PoV on electric pumps for IKs
Tested: Flextailgear rechargeable packraft pump

Your inflatable packboat needs a pump to take form as well as to top-up once on the water. These functions may be best performed by two different pumps. It seems the era of the folding bellows footpump (left) is over and even low-pressure IKs now come with some sort of barrel pump.

A plastic-bodied barrel or ‘stirrup’ pump is light but bulky so not something you’d want to tour with. They’re usually used for pumping up high volume/low pressure things like whitewater rafts, lots of IKs or kite wings. Some pump on both up and down strokes to fill your boat faster, but as you reach higher pressures they automatically or manually switch to downstroke-only inflation to reduce the effort. They work best on flat, firm ground where you can stand on the stirrup plates and get stuck in. The excellent Bravo 4 RED Kite pump below (newer ones are blue) is still well under £20 and will pump up an IK in 5 minutes.

sw05

I got a Bravo 6 with my Seawave once but found it hard work – who knows why. The cheaper Bravo 4 does claim to be an ‘R.E.D’ (‘reduced effort device’) and I can confirm this isn’t some gimmicky acronym. The other port on the Bravo’s handle can be used to suck air from an IK so it rolls up good and flat; you can see creases forming in the hull as you suck it down.

I left my Bravo 4 RED at home one time so bought a Sevylor RB2500G barrel pump (below left) for a tenner. Same size as the Bravo barrels, it did OK for the awkward topping-up of my Semperit’s lilo plugs. It came with push-fit, lilo-plug and bayonet adaptors and sucked as well as pumps. But pumping up my Seawave from flat was exhausting towards the end: I actually got out of breath and had to rest! Morale of this fascinating anecdote: get a Bravo 4 RED and the right adaptor for your boat.

Not all barrels have a built-in pressure gauge which is obviously dead handy in getting the right pressure without needing to faff about with a separate manometer (see below). It’s worth an extra tenner to get a built-in gauge, especially with DS boats. Or fit an inline adapter manometre: see below.

sevypump
Cheapo Sevy barrel – tiring
pump-kpump
Handy K-Pump Mini for topping up on the water
kpump200

The K-Pump Mini (above right) is a handy top-up pump or compact 600-g travel pump. It took 15 minutes to fully inflate up my 14-foot Seawave; the push-fit nozzle works on any IK with one-way spring valves. You have to press and hold the nozzle against the valve. Using it a lot one time, I got the feeling it might break something or wear out the seal (which needs regreasing once in a while). I’ve also used the K-Pump to top up my Nomad S1 packraft which was too big and long to inflate firmly with just its airbag. Fuller review of the K-Pump Mini here. They’re hard to find in the UK, the very long, and slim US-made K-Pump 200 (above right) may also be suited to higher-pressure dropstitch applications.

Packraft mini-pump for topping up IKs

Another idea from Seawave-user Jason, is adapting a packraft mini-pump (left) for topping up. It may take a while but he says it’ll reach 4.5psi eventually. Less bulky and much cheaper than a K-Pump, they’re actually for footballs and the like, so you can find them on eBay for a tenner.

Left, the Bestway Air Hammer is an ‘upside-down’ barrel pump which comes in three sizes and costs from just £6 on eBay. If you don’t want to paddle with your full-size barrel pump, the smallest Air Hammer could work as a compact top-up pump like the K-Pump, but a tenth of the price. The one on the left came with a ROBfin and was rated at 4psi.

High-pressure pumps

More and more IKs now feature super-rigid, high-pressure dropstitch hulls – either just floors or the entire hull which runs 2–5 times higher pressures than regular IKs. Your old Bravo footpump will blow its brains out trying to reach a typical 7-10psi.
Barrel pumps with long, slim bodies, as opposed to the shorter, stockier examples above, put out less volume (DS IKs have less volume anyway) but can more easily attain higher pressures. It’s something to do with the ø of the pump face x the stroke. You don’t necessarily need a super high-pressure iSup board pump.

Left: Bravo Alu RED from £16 • Middle: Bravo 110 >£40 • Right Itiwit (Decathlon) £20

Some of these pumps may be double action. At a certain psi they become single action (downstroke only). I believe the Bravo Alu 4 RED (0.8 bar) works like that. Or they have a switch to do the same and help attain higher pressures. It works. Whatever pump you get for your DS IK, make sure it is rated to comfortably exceed your DS boat’s pressure rating.

Left: Kokopelli Nano pump ticks all the boxes: fold-out feet, screw-off handles, switch for one-way pumping as pressures increase, manometer in the handle.
Right: twice the volume Bravo Alu 4 with auto one-way switching (so it says). The bayonet valve nozzle on the Nano keeps the valve open and so is for live (constant) manometer readings. With the push-fit (non-bayonet) adapter on the blue pump suited to Boston valves, a manometer only reads as you pump and push open the valve. Both are better than soggy footpumps.
What I call ‘raft’ valves

Bayonet nozzles for ‘raft’ valves.
Who would have thought there’s something to be said about bayonet nozzles? Well there is. There are two types: plain (below right, Gumotex) and crossbar-peg or detent (left, Bravo). Both need soft spacer washers to fit snugly against your boat’s raft valve, but the small peg inside the green one will press open your valve stem as you connect it.

You will notice a similar peg on car tyre inflation hoses and also on a hand manometer (below). A manometer can’t get a pressure reading without this peg partially opening the valve as you push it on. A nozzle with a peg/detent means that:
a: you’re not pushing the valve spring open each time you pump (easier pumping) and
b: if your pump has a manometer you will get a constant/live reading as the pressure climbs which is the point of having a built-in manometer. The Bravo one goes from 3 quid; search: ‘Bravo Adjustable HP Valve adapter’.
The only drawback might be that you need to remove a pegged nozzle carefully with Push-Push (Gumotex) valves. Normally a little air escapes as you do this, but if the valve doesn’t spring back closed, air will rush out. Turn slowly then pull away briskly; you’ll get the knack.

Pressure gauge (manometer)
Until I got a Grabner which has no PRVs but ran a relatively high, 0.3 bar (4.3 psi), I never bothered with a pressure gauge (manometer, below) and just pumped up by feel. A lot of people do this. Since then, I ran a Gumotex Seawave and fitted PRVs to all chambers. That meant I still didn’t need a pressure gauge to get the right pressure; I simply kept pumping until each PRV hissed: the boat was then at operating pressure. My Seawave 2 was left stock (no side PRVs) so I have got into the habit of keeping a Bravo manometer with the K-Pump Mini and checking the sides at each paddle when I top up. I have checked this manometer against the floor and it measured 0.25bar which matches with the PRV rating, so I think it’s pretty accurate. Try and get a model with a range of no more than 1 bar (as below left) as that is the range you’re working in. At the moment, Sea Mark Nunn sell it in the UK.

amigauge
Bravo manometer: from 13 quid and accurate
Adjustable screw/peg to push open the valve

With high-pressure DS IKs, you probably want a pressure gauge as the boat will perform best at the right pressure which may be higher than you’re used to.

Add a manometer to a barrel pump
I’ve had a couple of 0.8 bar rated Bravo 4 Alu R.E.D barrel pumps over the years, including with my Zelgear Igla IK to (a typical DS pressure). In the UK they go for under £20 without a gauge – a real bargain for a powerful and smooth acting two-way pump. The next similarly rated Bravo barrel with a gauge is nearly fifty quid. That’s inflation for you.
The good thing is you can now buy the long lost SP90B inline adapters with a manometer in the UK. The manometer screws into the black plastic adapter which has the male and female bayonet fittings to attach to the 3 Alu’s pump hose and the handle.

Bravo SP90 B adaptor.
Finally in the UK!

Packraft Pumps

Packrafts used to be inflated with a featherlight airbag which came with the boat. A nozzle on the bag screws into the boat’s valve and you scoop air into the bag (easier with a breeze) and ‘bear hug’ it to cram the air into the boat. It’s takes about ten scoops to inflate a boat this way, then unscrew the bag nozzle and quickly screw on the valve without losing much air.
Next, you top off by mouth: the firmer the boat the better it rides. In the video below (speeded up x 15) from walking up to a beach with my paddle in my pack, to loading up and paddling away took 8 minutes.

Things have moved on: most packrafts now have one-way Boston valves which makes topping up much easier. And for those who don’t have lungs like Luciano Pavarotti, you can use a light and compact mini handpump (below) to top up and get the boat good and firm.

Firm boats paddle better but like IKs, a packraft that’s been firmly inflated by hot ambient air on land will go soft once cooled in the water and will need more topping up. The pump above has a hose which means with a Boston valve-equipped packraft, you can top-up on the water, if needed. A good packraft should hold air for days at a time, but don’t leave it fully inflated and out of the water in the hot sun. The air inside heats up and expands, pressures rise and the seams will get strained.

A mini handpump is very handy to get a good fill into your packraft. But now there are tiny rechargeable electric pumps which will do the job of the air bag. More here.

Mini electric pump