Navman de-mister

Swifty · 09 February 2005, 19:50

Following a mention from Danny that it is possible to open the Navman and dry the insides out.

Well... Couldn't resist so I took a torx driver (T6) and opened it up

and left it to dry out. Had a quick look at the keypad membrane which is the most likely place water is getting in, but couldnt spot any obvious ingress. It seems well designed with rubber seals all around. Maybe it was humid in the factory when it was made.

I had a tiny sachet of silica gel which fitted perfectly so should keep it dry.

Will let you all know what happens. Am hopefully out this weekend up the Thames.

jwalker · 09 February 2005, 20:25

I hope you heated or otherwise dried the silica gel before you put it in, otherwise it will contain moisture. If there is a wee leak in the unit, unfortunately it will only work until the silica becomes moisture laden.

danny · 10 February 2005, 12:09

Swifty.

This equipment is gasfilled/closed in the factory. I Think that the problem starts later on.

Check your edges on the plastic screen. Mine had some very tiny cracks on the black side. Since I have replaced it with real glas, the glue closed that cracks.

Have opened it again this morning and will dry the silica very well.

Next problem is the percentage of moisture in the air. It's never 100% dry in your house but will be around 30 to 60 % wet depending on weatherconditions outside. I don't think that we will ever close this thing really dry.

Dan.

Swifty · 10 February 2005, 14:22

What it needs is an inert gas that I can squirt in. What about some tinned air for blowing out cameras etc, wonder if that would do the job.

Butane might have an adverse effect

on the plastic...

danny · 10 February 2005, 17:20

I wil try 99% argongas. It's used for welding SS and alu. Has no Oxygen and is an inert gas.
I've got it at my workshop. Will try to assemble the unit together in a gasfilled bag. Let's see if it works.

I thought that butane contained water. Maybe I am wrong.

Dan.

Rupert Bear · 11 February 2005, 08:47

Doesn't work, I did this with a VHF last year using high purity Nitrogen and it still steamed up after a short time.
I thought I was being clever doing it as well!

MeMe · 11 February 2005, 09:56

...the wrong way BUT - you guys are bloody nutters. Gas filled bags, butane - nitorgen - argon gas etc - Bloody hell - how do you know all this stuff

Scary Des · 11 February 2005, 10:07

Quote:

Originally Posted by Rupert Bear

Doesn't work, I did this with a VHF last year using high purity Nitrogen and it still steamed up after a short time.
I thought I was being clever doing it as well!

How did you get the air out before you put the nitrogen in

Ideally you would use a vacuum chamber and once you have pumped the air out you would replace it with an inert gas

By the way what is the other 1% in 99% nitrogen

Des

Meme, I’m sure you used to know all this sort of thing before you got a stripy boat, it’s a bit like going blond there is a direct correlation with brain cell count

Des

danny · 11 February 2005, 10:12

Quote:

Originally Posted by MeMe

...the wrong way BUT - you guys are bloody nutters. Gas filled bags, butane - nitorgen - argon gas etc - Bloody hell - how do you know all this stuff

Well... For me. I'm running a repair en rental shop for all thinkeble kind of tools. beside that we make all kind of custommade stainless steel and aluminium parts. Yes, also for Ribs like a-frames and small parts.
I don't really know that much but the guys here do.

Dan.

MeMe · 11 February 2005, 10:13

Rupert Bear · 11 February 2005, 13:45

I work for a Marine laboratory and use this stuff to fill housings before immersion

You don't have to use a vaccum pump, in fact you will probably brake the housing if you do. Just either do it in a bag full of gas or fill from one end and flush through the unit, then seal up.

danny · 11 February 2005, 13:59

Quote:

Originally Posted by Rupert Bear

I work for a Marine laboratory and use this stuff to fill housings before immersion

You don't have to use a vaccum pump, in fact you will probably brake the housing if you do. Just either do it in a bag full of gas or fill from one end and flush through the unit, then seal up.

What kind of gas do you use ?

Dan.

Scary Des · 11 February 2005, 14:29

Quote:

Originally Posted by Rupert Bear

I work for a Marine laboratory and use this stuff to fill housings before immersion

You don't have to use a vaccum pump, in fact you will probably brake the housing if you do....

Hang on you said it doesn’t work so why are you using it at work

If you are still getting misting which indicates that there is water present and that the gas you are adding is not replacing the gas (air) in the unit. The method I described is a method used in the aerospace industry and found to be a reliable method.

Quote:

Originally Posted by Rupert Bear

... You don't have to use a vaccum pump, in fact you will probably brake the housing if you do....

It would not break the unit because a vacuum is not absolute and is nothing when compared to the pressure exerted by pressure filling the until with gas.

Des

danny · 11 February 2005, 17:24

First I took an transparant bag. Made two hole, big enough to put my arms tight trough. Let somebody else put the unit in. and have him filled the bag up with gas.
I assembled the unit, and............ have put her in a bucket of water.
Tomorow will be the day to see if it worked.

Dan.

99% argongas and 1 % oxygen (dry oxygen).

We'll see.

codprawn · 12 February 2005, 00:59

I thought most things are nitrogen purged to avoid moisture!!!

danny · 12 February 2005, 08:51

Took her out the water this morning and first placed her on the central heating.
After 15 minutes beeing warmed up i've placed it in the freezer to see if any moisture took place on the the screen.
Non what so ever. Maybe it worked ?

Will place her on the boat and let you know if she will stay dry.

Dan.

Swifty · 13 February 2005, 20:01

Didnt test mine quite so hard, but after a full days use in cold conditions I can report the screen as fog free. Now just got to do the same with my so called waterproof radio. Wish Id bought an Icom now...

Ta ra.

gavin · 13 February 2005, 21:22

http://www.rib.net/forum/showthread....mo+navman+5600

http://www.rib.net/forum/showthread....mo+navman+5600

WHAT ABOUT RESIN FILLING THE UNITS
AS NAVMAN JUST PRETEND TO MAKE EM WATER PROF

Swifty · 14 February 2005, 10:59

Hmmmmm, thanks Gavin. Didn't find where the water gets in but it only needs a drop to make it mist up. Like you said, cant fault the electronics but sealing the internals would cause it to run accross the front of the screen. You would need to put a gasket around the edge, but you can bet this will start to fog up.

Never mind,

Tim'mers.

Rupert Bear · 15 February 2005, 13:37

Quote:

Originally Posted by Scary Des

Hang on you said it doesn’t work so why are you using it at work

If you are still getting misting which indicates that there is water present and that the gas you are adding is not replacing the gas (air) in the unit. The method I described is a method used in the aerospace industry and found to be a reliable method.

It would not break the unit because a vacuum is not absolute and is nothing when compared to the pressure exerted by pressure filling the until with gas.

The housings I am filling are watertight to 600 bar so you can take it as read they are truly watertight. I wouldn't be keen to try evacuating a unit as the 10-12psi air pressure would be enough to break things.
It worked for a while but basically moisture gets back in through the seals as it did before treating, the seals on the housings are not good enough to keep all moisture out when flexed.