Fitting 4.8 psi PRVs on a Gumotex Seawave

Seawave main page
General article covering PRVs
Updated Summer 2016

yaldingMy current Gumotex Seawave is a well spec’d IK for my sort of inshore paddling and occasional touring, especially as it’s factory rated to run at a higher-than-usual 0.25bar or 3.6psi (normal is 0.2 on Helios, Palava, 410C, etc). That means greater rigidity which adds up to less longitudinal sag caused by paddler weight (who, me?!) and also better glide. My previous Amigo and Incept both ran an even higher 0.3 bar, and it’s said that this Gumotex can also be pushed to that sort of pressure on the side tubes without risking damaging the structure. Factory hull pressures are set on the conservative side, perhaps to limit warranty claims.
Like all the Gumboats I’ve owned, the more vulnerable I-beam floor chamber has a factory-fitted PRV, presumably set at 0.25bar/3.6psi (confirmed below). PRVs are important here as if an IK gets hot (typically out of the water on a sunny day) internal air pressure can increase to the point where seams can separate or the boat can blow. If separation happens to an internal I-beam in the floor it will balloon up and make for a very difficult repair. I would not meddle with the factory-set PRV in the Seawave’s floor.

PRV-PalaverIn a discussion with a French Gumtexer, he suggested that Gumotex use the same orange dot  0.243 PRVs in all their boats, irrespective of the stated official rating – either 0.2 like most or 0.25 like the Seawave. He sent me a photo of his 2016 Palava floor PRV (right) – orangey-pink, same as my Seawave and classified by Ceredi as 0.243. Officially the Palava is a ‘normal pressure’ 0.2 bar canoe. Upshot? Your Gumboat’s floor may be rated at higher pressure than you think or officially stated and you’d assume the tubed sides can handle at least as much pressure. Then again, kin the table below Ceredi state the orange PRV  will open between 0.21 and 0.243 so perhaps we all just need to calm down a bit.

PRVs use springs set to purge air before it reaches structure-damaging levels. Then again, my Amigo had no PRVs at all so you assume Grabner were confident their floor construction was solid enough to handle occasional neglect. But I’ve been caught out before and always try to ensure a boat remains in the cooling water when moored up on hot days – even getting up to throw on a cooling splash as the sides tighten up like a drum.
Guatemala, Fuego volcano, Strombolian eruptionLike most IKs with single side tubes, my Seawave had no PRVs in the side tubes as the rounded profile can handle higher pressures better than a flat, ‘lilo-like’ floor. However, if you’re planning to run them over-pressure as I am suggesting, that could be risky. The answer: fit PRVs in the two side chambers – just like my Incept. That way you can safely leave you IK out of the water in the tropics, go and hike up a volcano (planet Earth’s ‘PRV’) knowing that all three chambers on your IK will harmlessly purge any excess pressure. Sure, when it all cools again the boat may be saggy, but better a quick top up with the K-Pump than pulling bits of shredded Nitrilon out of the palm trees.
cereditable
Ideally I was looking for a PRV set at a reasonable one third over the factory figure of 0.25 bar – i.e.: something around 0.33 bar or 4.8psi.

Well-known IK valve-makers Leafield and Halkey didn’t make anything matching my needs (or don’t sell to individuals). The Seawave’s valves are stamped ‘Ceredi Italy’ and once I managed to track them down online, I saw the same Ceredi 6600 PRV series came in options including Red 4.78 psi or 0.33 bar, (left and below). In the UK they were a special order via IBS and cost £35 a pair posted.

prvcolours

I admit that the colours look pretty close
but it’s pinky-orange for the OE floor and red for my 0.33s

Fitting the valves

Tools and time needed
grabtoolGumotex inflation valve removing tool (fits Ceredi PRVs also). Right;  £12 on ebay

• Narrow-bladed knife
• Water pump/lock channel pliers
• 30 mins

Short version
• Choose your spot and cut a 37mm hole in each side chamber – Ceredi suggested 35mm was not enough
• Remove the side chamber’s main inflation valve with the tool
• Squeeze the PRV’s back collar through the bigger inflation valve hole, shuffle it over to the 37mm hole and screw on the external part of the PRV by hand
• Reassemble the inflation valve and clamp down both valves with the tool
• Fit push-on caps to the PRVs
• Pump up and check for leaks – maybe retighten some valves with tool

prvvs.jpg

Long version I chose to fit the PRVs close to the inflation valves and at about the same level. There are mysterious markings on the inside of the Seawave to aid symmetrical positioning (Pic 2, below). HadronI used a narrow-bladed knife and of course took care to gather up the hull skin so I wouldn’t inadvertently puncture the other side of the side tube. I assumed the 37mm hole would be big enough to take the back nut. When it wasn’t I was a bit flummoxed. Now I had a gaping hole in my boat but performing a Caesarian on my Seawave was an unpleasant thought.
Luckily two brain cells dropped into my Hadron Collider and it occurred to me the main valve’s hole might be bigger. It was – just – but one valve was extremely hard to undo. I wondered if it had mistakenly been glued in or that the plastic valve removal tool would snap. When the other side undid with less effort I knew it had to be possible.

Another problem is that the internal collar or nut is only 10cm deep (pic 4, below) and so was hard to grab through the hull fabric. Until I realised this, I was grabbing the inside part of the outer valve body which screws through the collar from the outside. Trying to ‘unscrew’ the valve body from itself is like trying to pull you head off –  eventually  the valve tool would break. Another ‘Higgs boson’ moment came over me and I realised that by chance the two valve holes in the boat were close enough for me to get some water-pump pliers in there, grab the back collar and finish the job (pic 6, below). After that, no more problems. One thing I noticed while doing all this was the unseen protective patch on the inside of the hull opposite the inflation valves to limit wear and rubbing between valve body and hull when the boat’s delated. Nice touch, Gumotex ;-)
I did all the valves up as hard as possible with tool and hand, and in a year have has no problems. On a hot day in the sun I can hear the high-pressure side PRVs hissing away. The gallery below shows the job in chronological order.

Now it’ll be good know that should I doze off as the tide ebbs away, I won’t be rudely woken by an exploding boat.

smoko

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16 Responses to Fitting 4.8 psi PRVs on a Gumotex Seawave

  1. Warren King says:

    Hi Chris,

    Great website – thanks for the great info. I live just north of Brisbane in Australia. I’ve got a C2 which I picked up used on Ebay and am visiting Vancouver in Sept and pick up a new Seawave there (can’t wait).

    I installed a couple of PRVs in my C2 recently and was able to squeeze the back of the Ceredi PRV sideways through the 37mm hole with a bit of effort and persistence (I was struggling to remove inflation valve so gave it a go).

    I tightened with the tool and holding the back with my hand as best I could from outside the tube. To my surprise, the first one was airtight first try and the second one just needed a bit more tightening. I’ll try the same with the Seawave and let you know how I go.

    This might help someone who has trouble removing the inflation valve.

    Thanks again for the great info.

    • Chris S says:

      Thanks for the info Warren. You will love your Seawave. What is a C2, a Gumboat?

      • Warren King says:

        No worries Chris. Sorry, I meant K2 not C2. People do get a laugh out of seeing “K2” on the boat – it does get along ok for a whitewater boat (my wife and I get about 5km/h out of it over 10+ km on flat water but the tracking is a challenge) but FAR from the speed of the K2s most people think of.

        Certainly looking forward to the Seawave.

      • Chris S says:

        Yes, thought you might have meant K2. Nearly bought one once – a serious, high-end (and high-pressure) WW IK, but they wanted 500 quid.

  2. Rob Math says:

    Thank you for such an excellent website Chris. It’s such a help for someone like me who is just getting into iKs.

    Have you encountered any anecdotals of running other Gumotex boats overpressure?
    I have a Twist and I would love to add PRVs to the side tubes but perhaps 4.78psi PRVs might be pushing the nitrilon light too far?

    • Chris S says:

      Glad you like the website, Rob. A mate just added Leafed C6 PRVs to an old LitePack Twist, but 3.25s (£16 ebay) – about what a Twist is supposed to run normally. I would have thought the sides of a single sidebeam IK are less prone to over-pressure damage than an I-beam floor (or twin beam side, Like incept), but then pankanels’ experience with his seawave side blowing shows it can happen. Still, I bet the pressure was a lot more than 4.8 before it finally blew.
      In the end it’s a gamble meddling with manufacturer’s recommendations, but they are probably set on the safe side because of people like us and also the risk of passive over-pressureisation (like pankanel’s). And yet my old Grabner Amigo ran similarly high pressures and had no PRVs at all.
      You can fit manufacturer’s rated pressure PRVs in the sides to avoid accidents like pankanel’s, or you can take the chance and fit slightly higher rated PRVs in the sides as I did to benefit from a stiffer boat which is still protected from over-pressure. I would never meddle with the floor PRV.
      Your Twist is factory rated at 3psi while my Seawave is rated at 3.75. So 4.8 is a bit of a leap for a Twist but 3.25 Leafield sounds just right. No harm in doing that to protect your boat if you live in a hot place.

  3. Gareth Lane says:

    Excellent project Chris, am using my Seawave in Greece at present and has been amazing just knowing it’s not going to explode on me. On a slightly different note do you know the PSI rating of the floor PRV just mine seems to be contantly letting out air to the point the floor goes squashy, had it in the swimming pool and sure enough it’s letting out air – the two I’ve put in the side chambers are of course fine :-) Do I need to do a a replacement on the floor or do they sometimes get stuck? Anyway of fixing it? Thanks any help gratefully rcvd!

    • Chris S says:

      Hi Gareth, never happened to me but they can get stuck with a grain of sand embedded in the rubber seal. If you have the tool take it apart, clean and inspect. That should do it and if not, I guess you need to replace. Make sure it’s leaking out the valve not the sides – if yes that just means it needs tightening down. One of my other IKs need that once. I imahgine in greek heat they’re all purging away quite a lot. Chris

  4. pankanel says:

    I would recommend that all seawave owners should follow your example-solution with the prvs.
    I left my seawave one hot noon, in a sunny Greek beach (without prvs). Even though I had relieved some pressure from the boat, the result was one of the side chambers to burst. One of the seams opened and I had to paddle 9 kms with one chamber less.
    I repaired it myself and retrofitted prvs. Unfortunately it opened again (even with the prvs) in exactly the same spot. Which is now a weak spot. I will have it repaired by a professional and hope.

    • Chris S says:

      Sorry to hear that pankanel. I also once ruined a (near new) IK once. Left in the forest on a hot day but there was a gap in the trees… BANG! (x 3).
      In that case it was a Feathercraft bladder boat – easily replaced with new inserts. Fixing a burst Gumotex would be very tricky. The PRVs I used at .33 bar – about a third higher that the .25 bar rating for the Seawave. I assume the round side tubes can handle a little over-pressure, certainly better than the I-beam floor. Hope you manage to fix it.

      • pankanel says:

        Fortunately the professional help gave the solution and the boat is fixed and working perfectly with its prvs. Its been used and left on the beach a lot this last month, with temperatures reaching 40 C. With no problem. And the prvs opening constantly.

        I would also like to comment on the K-Pump Mini. I was looking for something compact and bought it from an online shop in Poland. When I first saw it, I was disappointed. It looked small for the job. Like a very fat version of my bike pump. But when I used it I was
        astonished. Side by side, it inflates the boat as fast as my high pressure Bravo foot pump or an electric Bravo foot pump. Using an extension I made using a little garden hose, some duct tape, and three of the included adaptors (vinyl tubing, boston adaptor, universal adaptor), I can now inflate the boat very fast, standing up, or even in the water. It is the best pump I have ever seen. I Imagine the bigger models will do miracles.

      • Chris S says:

        Good to hear a happy ending, pankanel. I also just rolled my boat up after three months inflated. Rarely got to even half of 40° but always a little top up needed after a sunny spell which means the PRVs are purging nicely. And like you say, the K-Pump Mini works great with an IK.

  5. Gareth Lane says:

    How is the seal on the PRV’s have you had any issues ? Thinking of doing this project before the Summer. Thanks

  6. Vitaliy Reznikov says:

    Much Thanks for great reviews, ideas and how to’s!!!
    Just want to get your opinion on PRV valve placement.

    What do you think of position pressure valve on internal side of the tube with slight down angle to prevent valve water build-up?

    Much thanks for excellent resources and experience sharing!!!

    • Chris S says:

      Hello Vitaliy – yes I thought about that but decided it was not so important when you think that water will more often collect in the original fitted floor valve.
      On the sides as I have it – much less chance.

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