Tag Archives: Gumotex Solar 410C

Gumotex Solar 410C – the new Sunny

In 2017 the Solar 410C became the Solar 3


The Solar 410C was a step up from the short-lived, fixed-seat Solar 2 (below). The price in the UK with two seats and a skeg was £470.
It became for all intents and purposes the new Sunny, because the old discontinued 405 Solar and Solar 2 (below) were usefully long touring boats ruined with fixed seat designs: either the original space-wasting thwarts (at least they were replaceable) or worse still, Helios-style fixed seats in the half-coat (Lite Pack) Solar 2 – the pits!


Luckily, the Solar 410 ‘C’ (for ‘Convertible’) has two or even three seats which can be removed and one re-installed the other way round to make a big, single seat kayak with lots of room for stuff – nice. You also get adjustable footrest pads (see here for a lighter and simpler idea), the usual half-arsed cargo net in the back, and the usual floor PRV too. Gumotex never seem to mention this useful feature, but of them I am a big fan.
If not included, the black plastic skeg might be extra (and is worth getting). On the 410C you don’t need a skeg-mounting patch at both ends because unlike a Sunny, you simply move the seats forward or back on the D-rings, not turn them the other way. In the unlikely event your 410C doesn’t have a skeg patch, it’s not so hard to glue one on.

The stats for the Solar 410C are 4.1m long (Sunny 3.85m); 80cm wide (Sunny 77cm), weight 17kg (Sunny 16kg) and payload no less than 270 kilos (Sunny 180kg). With pressure still at 0.2 bar/3psi, that looks to be quite a jump in payload for just a little extra volume. If you can imagine three hefty adults sat in the new 410C, that equals 270 kilos – the slightest wave will surely swamp the boat.

But one thing I do wonder with a 410C (and why I got a Grabner instead, even at nearly twice the price), is that with my weight I suspect the longer hull would sag even more than the Sunny. This was why I moved on from the Sunny after many years, although here I discuss ways of getting around that flaw

Gumotex Solar 405/ Solar 2
The original, pre-2007 Solar 405 (below) was similar to a Sunny of the time but longer. Unfortunately it used space-wasting thwarts (fat air cushions) for seats. For that reason a Sunny was always better solo touring choice at the time.

The post 2007 ‘Solar 2s’ (right) became even less versatile: horrible fixed seats like the Twist and Helios may give great support, but along with fixed footrests it all means it can’t be set up optimally for solo paddling without chopping it all out.

As on all post-2007 Solars for a while, only the outer wet surfaces were coated, and then the Solar 2 was dropped in favour of the broadly similar but more popular Sunny MkIII, the semi-decked 3.8-metre Helios II (also with fixed seats and decking) or even the shorter Twist I. By 2013 the 410C set things straight again and that soon became the Solar 3 which is still around today.

Gumotex Solar 300 improvements

They don’t make the Solar 300 anymore – it’s been superseded by the lighter Twists, although the similar full-coat, white-water Safari is still made All these Gumboats and a few others may benefit from the footrest mod as described below, as might bigger Gumboats which both use a similarly mushy footrest pillow.
Our Solar dated from 2006 and although (or because) it doesn’t get used much it still looks like new. And it’s lost no air to speak of lying in the garden for over a month (can’t say the same for my Incept K40).


But the seat/footrest arrangement is poor, like all Gumos from that era. The seat pivots at the right angle base as you lean on it, because the top edge is attached to the bottom edge instead of the actual boat, like any sensible IK. You lean back, it lifts up – no good. I messed around a lot with my old Sunny before I got smart and simply glued some D-rings onto the top of the hull sides, which Gumo started doing soon after. This way when you lean back or brace against the footrest, you’re locked to the boat and so get more drive.

The pillow thwart footrest is OK, but I ditched that at the same time on my Sunny to use a small Otter box. For the Solar, the g-friend is short and can’t reach the footrest pillow even set right back.

I glued on a pair of big D-rings with Aquaseal (hopefully bonding PVC D-rings to the Nitrilon hull) to the top of the hull sides to provide a fixed point to tension the seat back. And I removed the footrest pillow and replaced it with a bit of sawn-off four-inch drain pipe, tapeing the pipe ends to limit any rubbing against the hull. The seat straps were sewn into a loop and clipped to the D-rings.

This mod will improve bracing in the Solar: the bane of all IKs (and SoTs for that matter) which without bracing are like paddling a log. The footrest (the tape goes through a slot under the pipe) can easily be moved, even when inflated and will transform the Solar which is a nippy IK. The next step would be to fit thigh straps as found on the current Safari – then you can do cool stuff like this – but for the use our Solar gets, the current improvements will do.

Recently I also glued on the later style skeg patch to take the plastic fin. No more faffing about with butterfly nuts and bolts and bits of bent alloy. The patch costs £12 and so does the skeg, which I also fitted to my Grabner Amigo.


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 suit higher pressures and are needed for dropstitch panels. In America they’re called ‘military’ valves.
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.

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.


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.

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.

Another good idea are TRIB airCap live pressure monitors so your boat doesn’t end up like the Seawave left (actually an unexplained internal rupture while in the water).
These TRIB solar-powered gadgets replace the valve cap on bayonet-type inflation valves like Halkey Roberts or Gumotex. One fitted securely an LCD display displays your pressures in psi, kPa or bar, a bit like TPMS for cars and motos. And like TPMS, you can even set a bleeping alarm at anything up to 20psi / 1.37bar.
You need to make sure the seal is good and air is not slowly leaking out, but you can also use them as simple digital pressure gauges: twist on, measure and remove. Once fitted, you can watch as pressure drops after you put the boat in the water, and then seeing it rise out on a hot river bank. If I kayaked in a hot country (ie: not the UK) they’d be a simple alternative to the faff of installing PRVs. TRIB airCaps cost $40 in the US and the same in £s in the UK. The ribstore sells them.