New F-Rib 375 - Feeling Somewhat Deflated

[harrison]

Took delivery of new F-Rib 375 last Saturday - Yipee!
Unpacked Sunday, assembled, partially inflated (50%) tubes to let creases recede.
Fettled bunks on launching trolley to suit hull, inflated to working pressure of 0.25 bar Sunday evening. All OK so far.
Monday evening tubes felt soft, re-inflated to full pressure. Strange.
Tuesday evening same thing. All three tubes soft, down to between 0.14 and 0.16 bar! Checked pumps/gauges (2 battery, 1 bellows) all reading within 5% of each other. Oh Shite!!
Turns out the two over pressure blow off valves on the rear tubes are opening prematurely at around 0.14 bar. Not sure why front tube goes down, baffles will deform with pressure imbalance or their may be a relief valve in the baffle? I have no User Manual as yet....do any other owners have a manual?

Not a happy bunny at the moment as we're off to the coast tomorrow and I have an unusable boat. Also can't raise any body at F-Rib (SBS Ltd) by phone or e-mail....if you see this I'd appreciate a call! If I am missing something obvious, my apologies. If not, I need this sorting.

At the moment F-Rib 375 - 0, Aerotech 380 - 1.

Hope nobody else here has these problems.

harrison

[philpot]

Hi Harrison

I have the 330 and as it is still a bit like winter, I have not left the boat inflated overnight as yet. I know that the red over pressure valves must be shut as the design bursts the flap open when in an over pressure situation so it is vital that the flap is closed. This is the only reason I can think of your problem. I have Steve Bruce's mobile number and am happy to pass on your number to Steve if that helps.

Phil

[Paul]

Harrison, sorry to hear of your woes
Just to add to Philpot's post, when inflating mine in the showroom Steve told me that the rear side tubes must be inflated first, then the front tube to allow the baffles and pressure release valves to work correctly
I noted that when we deflated it how little air came out to the front tube due to the baffles doing their job.
BTW, I believe Steve is currently sailing/delivering a yacht over to France so that is possibly why communication is difficult at the moment

Paul

[philpot]

I think you are right Paul, I have just tried Steve and I got an overseas dialing tone so I ended it.

It is very important to inflate the side tubes first as Paul says which is opposite most sibs sequence for inflation. The manuals are in Russian and have not been translated into English as yet, as far as I am aware. It is something which I believe Helen is looking into.

Phil

[harrison]

Hi Phil / Paul,

Thanks for replies and advice, much appreciated.
I don't know whether you guys have inflated/tested your boats at working pressure, but if not I would advise to do so, as both the relief valves on mine are opening at around 0.16 bar. So unless I have two faulty valves it could mean they are rated at the wrong pressure, which may also affect more boats! I take your point about keeping the flap closed, but as this is not the air seal and air still leaks out very slowly when closed from the valve inside. It just slows down the air flow masking the problem.
I concur also on your advice to inflate the rear tubes first to set the baffles. I also follow the good practice of inflating the tubes in rotation to 50%, 75% and then 100% in order to preserve the integrity of the baffles...you never know when you might have to rely on them!
I've never had a boat with relief valves fitted, but you need to be able to run all tubes at full design pressure, as 90% of the boats performance is achieved in the last 10% of air pressure. It also puts more stress on the seams/joints if under inflated. Apologies for the sermon but I see so many 'soft' boats out there.
If the design pressure is 0.25 bar then I would have thought a relief valve should kick in at around 0.27 to 0.30 bar as this small amount of over pressure would not damage the tubes.
I have this evening received an email from Helen at SBS who has contacted Winboat for a solution...Watch this space!
So did nobody get a manual with their boat? ... that's a poor show, these are not cheap bits of kit!


I do sincerely hope your two boats are not affected.

harrison

[philpot]

I have not had the Frib inflated for more than about 5 hours as the weather has not been great for full days afloat but I have not been aware of any level of deflation although I confess that I have not put a gauge on to check.

I will be interested in your feed back from Helen

Phil

[Paul]

Thanks for that info Harrison and no apologies necessary for the 'sermon' required as I do the same inflation process
I'm sure Phil and I were both thinking of any possibilities that could be causing your issue.
When I get a chance I'll inflate mine and see if there's a problem with incorrect relief valves being fitted by the manufacturer and report back
Feel for your disappointment mate

Paul

[Paul]

Guys
Following on from the above I've had a chance to inflate mine and set the pressures at 0.25 bar/3.6 psi and the temperature 11 degrees Fahrenheit.
I've rechecked the pressures 14 hours later and the rear tubes are 0.20 bar/2.9 psi and the front 0.18 bar/2.6 psi, temperature 7 degrees Fahrenheit.
It's difficult to not let any air escape during checking but I'm confident that very little was lost in the process.

Paul

[philpot]

I suspect we are talking of simply an air temperature issue with the cold nights reducing the pressures. My garage is quite full at the present otherwise I would also inflate the Frib and leave it to settle.

If I was still working I would have inflated it and left it in the showroom overnight where the temperatures is not cold at night so that we could have checked it left inflated in room temperature in order to compare the two. I will have to think about that one, must be somewhere I can run a few tests.

Phil

[Paul]

Agreed Phil regarding the air temperature affecting the pressure differentiating on mine.
I re-checked the pressures after 24 hours and they're still at rear tubes 0.20 bar/2.9 psi and the front tube 0.18 bar/2.6 psi.
I've re-pressurised to 0.25 bar/3.6 psi and see what goes on

One thought though together with air temperatures when we use these high pressure pumps the air entering the tubes gets warm due to its compression so when the pump cuts out at the set pressure the air immediately starts to cool and therefore the pressure will drop anyway.
I've experienced pressure drops of up to 0.35 bar with air floor SIBs after using these pumps and the boat being in the water 10 minutes which is a 50% deficit

I do hope Harrison has been able to use his new boat over this Easter weekend and if there is an issue, it gets resolved swiftly for him

Paul