Tag Archives: boston valve

Tested: Anfibio Alpha XC packraft review

See also: Anfibio Nano RTC

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The Anfibio Packrafting Store in Germany was one of the first Alpacka dealers in Europe, but now sells other brands of packrafts from China, Russia and the US. It’s probably the only ‘packrafting supermarket’ of its kind and in 2015 we group tested a selection of their boats.

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They also produce their own Anfibio branded packrafting gear, like the dry suit and inflatable jacket I use myself; the latter has become my go-to ‘pfd’ for tame paddles. In cooperation with MRS in China whose boats they were the first to import into Europe and whose design they’ve influenced, they’ve now added three lightweight Anfibio packrafts to their lineup of over a dozen boats: the Sigma TX double; Delta MX single and smallest and lightest Alpha XC which we tested here. I knew the XC would be too small for me so that job went to my g-friend who’s over a foot shorter and 40+ kilos lighter. It costs just €470 plus one type of seat or another.

Alpha symmetry
In a bid to keep costs down and make them the lightest in their class, Anfibios are all symmetrical, with identical bows and sterns and parallel sides. Unless it’s like their double-elongated Barracuda R2, a conventionally short stern can make a boat back-heavy without a balancing load over the bow, as right. Even my original, first-generation green Alpacka Llama had a fattened stern to compensate for this.

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This is why Alpacka’s now much-copied elongated stern from 2011 (my 2014 Yak, left) was such a clever innovation. It trimmed (‘levelled’) the boat by effectively positioning the paddler more centrally, and also acted as a skeg to further reduce the side-to-side yawing of the bow which short, wide packrafts are prone to. (It’s important to recognise this yawing is just an annoying left and right ‘nodding’ of the bow; people often confuse it with tracking (‘steering’ or going where you point it) which packrafts do better than some kayaks.

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Weights and measures **
After verifying the kitchen scales (1000ml = 1000g: √) the Alpha weighed in at 1822g out of the box; the bare boat was 1422g.
Interestingly, at 120cm the interior length is actually a bit more than my Alpacka Yak. At 185cm tall, I can sit in the Alpha with backrest deflated and with the same comfortable knee-bend as my Yak. Meanwhile, with legs flat on the floor, g-friend has some 15cm of foot room to spare up front.

Scout

Anfibio have missed a trick here. Assuming I’m at the upper level of average adult height and weight, and geef is at the other end, I think Anfibio could offer another model 10 or even 20cm shorter, more like Alpacka’s ultrabasic Scout (left); let’s call it an Omega XS.
There are many, many packrafts for people of my height or more, but very few for 5-footers if you take the view as I do, that in a packraft you want to fit snugly, feet pressing against the bow with knees slightly bent. Being shorter would make the ‘Omega’ at least 200g lighter and enable that snug fitting for the majority of shorter-than-me persons. Like a shoe that fits right, that means better control, comfort and efficiency and is one reason I choose to replace my original Llama with the shorter Yak. 

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Perhaps there are buoyancy issues in such a short boat which means tubes need to be fatter, speed suffers and you effectively end up in a slackraft. You don’t want that.
The 25-cm side tubes are the slimmest of the Store’s dozen-plus boats, but we both found the 32cm interior width, a bit tight for comfort. Slimmer hipped individuals will feel right at home. All this doubtless carefully juggled volume, length and width adds up to a recommended payload rating of just 110kg. That’s plenty for most folks who are lighter than me. The next-size-up Anfibio Delta MX weighs only another 225g but is rated at a massive 180kg.

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The hull is made from the 210D, single-coated TPU, sewn and heat welded (no glue). Most packrafts are made from this wonder fabric. I think the slight translucence of the yellow Alpha makes it appear thinner than my Alpacka Yak, but feeling the fabrics up, they’re very similar.
You’ll notice that, unusually, the taped join of the tubes is around the perimeter of the boat, not hidden under where the floor attaches to the hull.

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The floor is smooth, double-coated 420D TPU and feels tough without making the boat bulky when rolled up. The width of the heat-welding attaching it to the hull is little more than a centimetre in places. Perhaps putting the side tube join elsewhere eliminates a weak spot at the floor and reduces the need for excessive overlap, as with the 8cm on my Yak or the Longshore. As it is, we’re assured that TPU hull fabric will tear before a properly heat-welded join separates, but as with any packraft, I’d be careful putting too much pressure on the floor. “Get in bum first!” I had to remind my tester.

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Fittings and finish
The Alpha comes with 5 taped loops with a pleasing textured Cordura finish to the patches. As other reviewers and the commenter below have mentioned, the three on the bow look too close together to securely lash down a load, far less a bike; the ‘triangle’ is too small and positioned over the domed bow. I also feel the fitting points are the wrong way round: you want the single central point at the front and the other two behind on the next panel back. Glue two here and you’ll have a stable, 4-point lashing base with another tab to spare.
I don’t really see the value of attachment points on the already over-loaded stern of a packraft, especially when it’s not elongated. I’d sooner load stuff centrally, under my knees and have a single loop here to hang shoes off or for towing.

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The inflation valve follows MRS’ innovation in fitting a Boston valve as commonly found on cheap Slackrafts (about the only useful thing on them). For a short, low-pressure boat like a packraft (as opposed to an IK) Boston valves are ideal.
A Boston valve has two caps; the bigger one opens the main port for fast inflation / deflation. On top of that is a smaller square cap; unscrew that to access the one-way mushroom/flap valve and top-up the boat by mouth. Both caps also have nifty swivelling attachment collars so you can’t lose them while also making the caps easy to turn. The whole set-up is so much better than my old-Alpacka style dump valve which you need to secure with a line which gets in the way as you try and quickly screw it up. It also eliminates the separate twist-lock elbow valve which never felt that solid and being small bore, are harder to blow through and get a good fill, unlike the 2cm-wide Boston.
The supplied air inflation bag (see video here) is a denier or two up on my flimsy Yak one which I often think is on the verge of ripping apart. I also like the fact that it’s a bright dayglo green; you never know when you might need a signalling device.

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The seat resembles an old-style Alpacka base with backrest, except that it cleverly attaches to the back of the floor with a single adjustable strap and buckle. Simple and effective; that is all that is needed to keep the light seat in place compared to my Yak’s OTT arrangement. You also suspect that the length of this strap may have been designed to enable a shorter paddler to position the seat a little forward so as to shove a bag behind it (below). Doing this centralises their weight and helps level off the trim to reduce yawing. We tried this idea on the water – see below.

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One thing I recall of a similar seat on my old Llama was the annoyance of the backrest flopping forward every time I got in (an elastic fixed that). Taller Alpha XC paddlers: consider saving €34 by ordering the plain seat base and simply lean on the back of the boat instead of using the €59 backrest version. That’s what I did briefly paddling the Alpha and it felt fine.

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As for build quality. With only my 2014 Alpacka to compare, all the taping and fitments are as neatly applied. The lack of tape over the floor panel join exposes a slightly uneven cut in places and, as mentioned, the welded band interface looked rather slim. As a result of all this weight saving the Store rates the Alpha’s durability accordingly, but it’s unlikely they’ve gone too far as Alpacka may have done with their short-lived Ghost.
Yes but what about the strap, you ask? Well that weighs in at 22g but is a good half-a-metre longer than it needs to be to cinch the rolled-up bundle (below), so some weight could be saved by snipping it.

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On the water
With light winds forecast, we picked an easy circuit with about 4km of loch paddling and a couple of short portages where we could carry the inflated boats. We often paddle together in the Seawave but I’m not sure if the g-friend has paddled a packraft since a quick go in my Llama back in 2010. So this would be a good test on how a beginner handled the Alpha.

Once the Alpha was inflated, geef went out for a spin to get a feel for the boat, then came back and went out again with my empty Chattooga dry bag behind the seat back (this bag seals 100% against air leakage – a true ‘dry bag’). No surprise: she yawed less and felt more in control sat more centrally.

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With another bag of stuff under her knees the boat sat almost level. Watching her paddle she still looked a bit low in the boat which interfered with a good paddling technique, so we pulled over and pumped the seat right up and I advised trying a high-angle paddling to clear the sides and get a fuller draw from the blades. As it is, on flat water no packraft is actually that satisfying to paddle – unlike a slick kayak there is no glide. The fun lies in the places they can reach and the ease of getting them there.

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We emerged onto the west end of Sionascaig loch (above) surrounded by the dramatic mountains of the Assynt, and turned south for the sluice. Being thorough, we tried sat right back without the bag one more time, but got the same high-bow yawing. Even with the bag I still observed some yawing, but as it was intermittent it could be down to my test pilot’s as yet unrefined packraft paddling knack, just as it can be trying to get a hardshell to go straight the first few times. Yawing is not tracking – this boat will go where you point it, but you’d imagine pivoting is inefficient. A bit like moving off from standstill on a bicycle, my Yak also yaws wildly as I set off, but settles down once there’s some directional momentum, nodding maybe six inches left and right.

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We clambered around the sluice (above) and sat down on a tiny beach below for a snack, then I went out for a quick spin in the Alpha.
At nearly twice the weight and of course without the dry bag behind, the boat was back heavy and very easy to spin. A light breeze was now blowing little wavelettes up the loch and powering on too hard, it shipped a little water over the back sides.

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I reached back and felt the horizontal tape line was below the water, but the Alpha was nowhere near as edgy as the Supai Flatwater Canyon II in which I dared not even breath in too fast. Yes it yawed more than my Yak but long, smooth strokes minimise that. I’d be more concerned in less calm water, but then I’m clearly on the weight limit for the Alpha. I probably could have done this whole circuit in it but it would have not conducive to relaxation.

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Through the shallow narrows we passed, arriving at the next ‘sluice’ at the end of the loch. It’s actually a runable two-foot drop if you take it fast. Like last time I came here, I wondered about trying it for fun, but chickened out. Beyond the pool below it becomes steep, narrow burn dropping to the next loch. So we tramped through the springy heather made crisp by over a fortnight without rain. We chucked the boats over a nasty wire fence then set off across the last little loch and the short walk back to the car.

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Bravo Alpha
Being a large person, the benefits of saving a kilo or two add up to not much in my overall packrafting mass. Therefore I don’t resent the weight of my Yak for its benefits in durability and functionality. But not everyone thinks like me. Adventure racers, canyoneers and something called ‘fast-packers’ focused on absolute minimal weights while undertaking short or easy crossings will love this boat. So too might a travelling cyclist or a light person who just wants a handy, inexpensive packraft for the odd evening splashabout rather than an expedition-ready heavy hauler. The yawing is something you can minimise with good technique or balance-out with frontal loads or weight shifting, as we did.
For the price of just €470 + seat, this must be the cheapest decent packraft around. No one likes excess weight but I know I’d feel more confident paddling a proper TPU packraft like the Alpha over Supai’s amazingly light but unnervingly skimpy alternatives The extra 700 grams I can save in peace of mind.

Anfibio Alpha XC at the Packrafting Store
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We also tried out the Longshore EX280 double. Read about it here.

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Skinning the Sevylor slackraft

See also:
Slackraft river trials
Slackraft sea trials

As promised, I’ve invested in a Sevylor Caravelle PVC dinghy. Cost: £34 delivered complete with pump, oars, repair kit, manual in ten languages and a box which is bound to come in useful one day. The heavy-duty Super Caravelle model, as modified by Narwhal, is out of stock in the UK until next summer, although an Intex Sea Hawk is the same thing and can be ‘skinned’ of its outer hull (as in the graphic, right) in the same way to make a lighter, narrower and nippier ‘PVC packraft’ – see bottom of the page. That’s the purpose of what is being done here, in case you’re wondering.

Pre-skinned and rolled up, the Sevy was about the size and weight of a proper Alpacka packraft, but awaft with that dizzying scent of PVC which takes you back to Mallorca in the late 1960s. Fully inflated, it’s too wide to take seriously, but it stayed like that long enough to enable the outer chamber to be surgically removed with a bread knife. Unfortunately, it’s on this outer chamber that the half-decent ‘high volume’ Boston valve is fitted – all the rest (2 floor chambers and the inner hull) get poxy, beach ball-style push-in valves which, in the latter case, take a while to inflate due to the pencil-thin aperture. Perhaps the Boston can be grafted onto the inner hull; what’s the worst that can happen? I’ll find out soon enough as it also took so long to deflate the remaining hull by squishing the push-in valve I decided to cut it out there and then and slap on the Boston valve from the trashed outer hull over the hole (above left). This was the first time I used MEK solvent to clean PVC. This stuff is pretty damn potent and ‘cleans’ the PVC a bit like paint stripper removes paint! Tellingly, it’s also known as polystyrene cement and has uses for welding too, so use it sparingly on PVC pool toys or they’ll dissolve before your eyes.

The squidgey little foot pump (right) is very light, but slow, especially when trying to get enough pressure into the main chamber for the slide-marker to move down and line up with the ‘A’ on the SevyScale™ (below left). This is a pressure guide so you don’t burst your new pool toy – easily done with thin, stretchy PVC and sharp words. But by chance the Sevy valve plug fits neatly onto the end of my K-Pump which is much quicker at inflating. The Alpacka air bag sort of screws into the Boston valve too, but you need a K-Pump to get max pressure.


Testing the newly glued on Boston valve, the boat was losing air, but it didn’t look like the glued-on valve was at fault. As it happens the bath was full so a check revealed a tiny, half mil hole near one of the seams underneath. I’m fairly sure I didn’t jab the boat with the knife while skinning it, so it must have come like that or my carpet is sharper than I think. Lesson: test all chambers in your cheap pool toy before running a coach and horses through the warranty by attacking it with a knife – that’s if you can be bothered to send it back instead of dab some glue on the hole, should it also be faulty.
The oars are mere fly swatters as previously noted. It’s possible they could be joined together into a packrafting paddle, but why bother; there are decent Werners and Aqua Bounds under the bed so the oars can join the scrapped outer hull at the local dump.

It has to be said, once skinned it’s 36″ (91cm) wide, 60″(152cm) long, and no more than 12″ high at the bow, so there doesn’t look to be a heap of buoyancy left over for the likes of bloated boaters like me, but the floor also holds air unlike an Alpacka so a spell on a river will reveal all. As mentioned, if it’s enough to stop me sinking, I may invest in gluing a spare sheet of tough nylon onto the base. It may add weight but will make the Caravette unstoppable; that’s unless a sharp-clawed bird lands on the deck or it gets splashed with MEK.

With half a dozen attachment points cannibalised from the outer hull and glued onto the stripped-down packboat with some Bostik 1782 (right), it now weighs 1550 grams; about half the weight of my current Alpacka Yak and about half the volume once rolled up. So compact, it could even make a flat-water towing platform for the Yak – for carrying a bike for example, as I’m not sure it would so easily fit on the bow, especially with camping gear.

River trials will follow shortly, or I may well head straight out to Rannoch Moor for an overnighter with Intex chum Jon who lives up there – see the vid above from last summer. He has also been inspired to skin his SeaHawk 1 bloat into a purposeful packslab. Might be good to take the Yak as a spare up there; if Loch Laidon freezes up round the edges the ice spikes might be too much for our pool toys.

Slackraft river trials
Slackraft sea trials

Inflatable Kayak and Packraft Valves & PRVs

Pumps are here
Installing high-pressure PRVs
Testing unbranded mini PRVs
Fixing a leaking PRV

The best inflation valves for an inflatable packboat aren’t the bungs you find on an airbed or an old Semperit. Nor the thin, twist cap stems off a Feathercraft Java or an old Alpacka.
What you want are one-way valves. Like a car-tyre valve, one-way operation as well as a secure seal are the key, so what pumps in doesn’t push back or escape when you remove the inflation hose. Found on cheaper IKS and packrafts Boston valves are simple and effective for lower pressures. More below.
What I call raft valves (left) like Halkey Roberts, Leafield or whoever makes your boat, suit higher pressures and are needed for dropstitch panels. In America they’re also called ‘military’ valves.

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With raft valves you either push and twist the button clockwise to lock open (deflating). For pumping up, push lightly and turn anticlockwise so the button springs back up to seal. This closed ‘button up’ position is the best way to transport an IK too. To lose a little pressure (say, the boat is getting hot in the sun) just jab the valve core button, same as on a car tyre.

Many raft ​valves are now ‘push-push’ (graphic left) which work like a clicking biro so are even easier to use. I always refit the cap seal straight away to keep water and grit out of the mechanism.

Two raft valves. On the left the collar goes inside the hull, the valve body screws into it tightly and the dust cap goes on top.
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I’ve found these valves reliable on all my IKs, although this Gumotex 410C owner didn’t. Once in a while – or after the boat is new – you may want to check the valve is screwed tight against the fabric with the valve spanner, right. They’re also useful for removing the valve (or a PRV; see below) should it play up.

When it comes to inserting the inflation hose, a simple push-fit plug as shown below left can work; just jam the adaptor into the valve body and it usually stays in place while pumping. It looks cheap but on a Gumotex at least, works fine. With higher-pressure boats like Grabners and Incepts and some Gumotex (as well as dropstitch boats), the jam-fit can blow off so you’re better off using a bayonet fitting (below right) which won’t pop off as pressure builds.

Low-pressure valves for packrafts

Alpackas and even Feathercraft used to use crappy, soft plastic twist-lock oral stem valves (below left) which you could never be sure were done up just right and which didn’t take well to pump nozzles. I suppose they were a step up from blow-up airbed plugs (below) which are still found on cheap IKs.

Now best used on inflatable seats and the like, they’ve been superseded by similar one-way stem valves (below right) with a light spring closure easily openable by lung pressure. They’re a bit trickier to deflate: you have to depress the ‘X’ with a finger while squeezing out the air. The one below right is actually on a buoyancy vest.

Boston valves is a generic name for a one-way valve long used on cheap IKs as well as slackrafts and have now become common on packraft hulls. Note they’re widely copied and not all may be identical, like well-known branded IK valves.
The square top cap screws onto the round valve body which itself has a knurled edge to easily unscrew from the hull port (below right). Here you attach your air inflation bag or open to quickly dump the air when rolling up.

Ideally suited to low-pressure boats like packrafts, they use a simple rubber ‘mushroom’ valve on a stem (above middle). Once the main valve body has been screwed back into the hull, unscrew the square cap to finish the inflation process by either topping off by mouth or with a hand pump.

A one-way Boston-type valve eliminates the need for the old separate stem valve and the whole assembly has swivelling plastic lanyards so nothing drops away when unscrewed.

Pressure release valves (PRV) for some IKs

I’ve learned the hard way to be careful and not let an IK get too hot when out of the water. On a hot day you can feel the more exposed sidetubes tighten like a drum. This of course happens to be good for rigidity and paddling efficiency but isn’t good for the seams or an I-beam floor or the sewn seams of a cheap shell&bladder IK.

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The floor tube on my old Sunny had a pressure release valve – oddly it’s something rarely mentioned in the specs, even on current Gumboats. It’s there to protect the I-beam floor which could rupture inside under pressure (I-beam floors explained here).
The valve is set to purge (open) at a certain pressure when the air inside heats up, expands and pressures rise. With Gumotex it is 3psi or 0.21 bar. It means an IK can feel a bit soft on a cool morning following a hot day; don’t worry, you don’t have a leak, it just purged some air when hot yesterday and in the cool air make sit a bit soggy. A quick top up is all you need to do.
The handy thing with a PRV is that it makes a good guide to how hard you ought to pump up the other chambers of the boat without PRVs when you don’t have a pressure gauge. At whatever pump effort the floor PRV starts hissing, that’s the same or a bit more pressure to put in the side tubes which usually don’t have PRVs.

As mentioned, the air in an IK can also get cooled, for example when pumping up on a hot day and then putting the boat in a cool river: a normal scenario. Cold air contracts (loses volume/pressure). Because you want the boat to be as rigid as possible, after initial inflation it’s worth topping up again once the boat is in the water; splashing helps cool the sides.
Topping up, or tempering as it’s called, optimises rigidity and with long, 2psi boats you need all the rigidity you can get. Conversely, pumping up your boat in sub-freezing temperatures then putting it on water which actually ‘heat’ it up, though this is a much less likely scenario.

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PRV leaking from the sides not through the valve.
Needs tightening with a special tool; a common necessity
with hastily assembled new IKs.

My higher pressure Incept K40 had PRVs on all chambers which meant you could confidently leave it in the Sahara and it would safely purge then feel a bit soft once cooled down back in the water. Picture above: Incept PRV test with the protective cap removed and purging correctly through the centre.
Below: a PRV being resealed after leaking from the edges (left). This was because I failed to check tightness after buying the new boat, as recommended by the manufacturer. (My Gumotex IKs never needed such tightening or checking in years ownership.)
I ended up also fitting sidetube PRVs to my Gumotex Seawave to run higher pressures and the be able to leave it pumped up and out of the water for months at a time.
Like any valve, PRVs can leak due to grit on the seal or a weak or sticking spring. Grit is not so unlikely when you think they can’t have a cap and have to sit on the floor of an IK, with water and sand occasionally swilling in and down into the body. Try removing the cap and blasting it out with air and maybe give the spring a squirt with 303 (UV protectorant). The best thing is to remove the PRV with the same valve tool, inspect and clean the sealing surfaces and reinstall.

Oddly, my Grabner Amigo had no PRVs at all and neither do the latest Holiday models and a few other Grabners, even though all run higher than normal 0.3-bar pressures. One presumes Grabner are so confident in their construction they’re not needed, despite the warnings above.
It should be included with the boats, but if your pump has no gauge, Grabner do pressure relief adaptors to fit on the hose (left) which purge at 0.3 bar, so dispensing with faffing about with a handheld pressure gauge. It’s a good idea.