sailorman
Well-Known Member
Best to fix the cause not treat the symptom
Bubble in compas
- Thread starter westhinder
- Start date
Seajet
...
Westhinder,
get a new compass !
Why do I say that ? Try having the compass - with a bubble I'd casually ignored - suddely go tits up at the same time as the ships' battery, in thick fog so no GPS or depthsounder either.
I'd left the backup GPS ashore and the depth contours were too indeterminate to try a spanner on a line, so the only choice was an uncomfortable night at anchor, having got away from the busy ship / fishing boat routes.
get a new compass !
Why do I say that ? Try having the compass - with a bubble I'd casually ignored - suddely go tits up at the same time as the ships' battery, in thick fog so no GPS or depthsounder either.
I'd left the backup GPS ashore and the depth contours were too indeterminate to try a spanner on a line, so the only choice was an uncomfortable night at anchor, having got away from the busy ship / fishing boat routes.
Elessar
Well-Known Member
good lesson in not ignoring it - it won't heal.
I'd fix it though (and have done successfully before) you yotties must have more money than sense.
Elessar
Well-Known Member
the fault is often the seal on the fill screw though. A 2p fix. It might not be, and you might have to replace it. But what on earth is wrong with trying. Back to more money than sense again methinks.
AntarcticPilot
Well-Known Member
Different makes of compass use different fluids, and there are issues of compatibility with seals, lettering etc. Put the wrong stuff in and you might well end up with cloudy liquid, or all the numbers on the card in a heap at the bottom of the bowl. You might also ruin the damping of the card; the viscosity of the fluid is fairly critical. So, while white spirit might be correct, so might medical paraffin, alcohol, and no doubt others. I would not refill a compass without specific information about the correct fluid to use from an expert.
Salty John
Well-Known Member
I agree with AP. I've refilled a Ritchie with mineral oil, but more modern compasses use mineral spirit and you have to be sure which is right for your compass. Spirit in an oil compass can dissolve the lettering, for instance.
Silva probably won't tell you what the fluid is, they want you to replace the compass. At one time you could send the compass back and have the oil filled capsule replaced - I'm not sure they do this anymore.
Silva probably won't tell you what the fluid is, they want you to replace the compass. At one time you could send the compass back and have the oil filled capsule replaced - I'm not sure they do this anymore.
JayBee
Well-Known Member
I have had professional advice in the past to the effect that purified kerosene (lamp oil) is an appropriate fluid for nearly all compasses.
However there is a strong possibility that this might not be the original fluid and a complete change would then be necessary to avoid bad chemistry and disastrous results. Many older Sestrel compasses were filled with an alcohol/water mix of .930 SG. and this was printed on the bowl of the classic hand bearing compass.
There was some good advice in an earlier thread to extract a very small quantity of the existing fluid into a test tube and add a few drops of the candidate top-up fluid to check for any reaction between the two.
I would be inclined to seek the advice of BPSC services or of SIRS.
BTW, a handy source of syringes with dispensing (ie non-sharp) needles was http://www.mehodeelectronics.com - now seem to out of business.
However there is a strong possibility that this might not be the original fluid and a complete change would then be necessary to avoid bad chemistry and disastrous results. Many older Sestrel compasses were filled with an alcohol/water mix of .930 SG. and this was printed on the bowl of the classic hand bearing compass.
There was some good advice in an earlier thread to extract a very small quantity of the existing fluid into a test tube and add a few drops of the candidate top-up fluid to check for any reaction between the two.
I would be inclined to seek the advice of BPSC services or of SIRS.
BTW, a handy source of syringes with dispensing (ie non-sharp) needles was http://www.mehodeelectronics.com - now seem to out of business.
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VicS
Well-Known Member
That could have been something I posted.
i suggested doing this. Firstly to make sure that the two do mix properly ... a mineral oil even paraffin, white spirit, lamp oil etc probably wont mix with an alcohol/water fluid. Secondly by watching carefully as they mix you might be able to determine if the refractive indicies are the same. If they are you wont see the two fluids as they mix and you will have almost ceratinly picked the correct fluid.
JayBee
Well-Known Member
Yes Vic, it was indeed your suggestion - some time ago and I couldn't remember.
JayBee
Well-Known Member
More on compass fluids here:
http://www.trademarklondon.com/page2/index.html
http://www.trademarklondon.com/page2/index.html
VicS
Well-Known Member
Very interesting.
The snags for the DIYer are degassing the fluid ... easy if you have a chemistry lab with a vacuum desiccator at your disposal.. otherwise a "vacuum chamber" is not the sort of thing found in most homes, and confirming that the seals won't be damaged by kerosene!
Incidentally I had the analytical chemists look at some barbecue lighting fluid some years back. They concluded that it was a refined kerosene. It would almost ceratinly have been suitable in place of lamp oil (which is often perfumed and coloured anyway) for compass topping but I cannot guarantee that all barbie lighting fuel is the same.
AntarcticPilot
Well-Known Member
Yes, I read that site as boiling down to "Don't try this at home, kiddies!"
JayBee
Well-Known Member
Degassing the fluid is probably a bit OTT. 
FWIW I have successfully refilled a couple of completely dried out WW2 RAF compasses with Bartoline colourless lamp oil from the local hardware store. They needed to be topped up once or twice after standing for a short while. No problems or bubbles after a couple of years gathering dust at home.
I used nitrile O rings, not available to the original manufacturer, to replace the old knackered seals.
FWIW I have successfully refilled a couple of completely dried out WW2 RAF compasses with Bartoline colourless lamp oil from the local hardware store. They needed to be topped up once or twice after standing for a short while. No problems or bubbles after a couple of years gathering dust at home.
I used nitrile O rings, not available to the original manufacturer, to replace the old knackered seals.
westhinder
Well-Known Member
Thank you all very much for your interesting and useful replies.
The verdict from the repairer is that the membrane needs replacing before top-up, but a Silva 125 is not repairable: the thing is moulded plastic, so the membrane can not be replaced. Buy a better one, Sir.
Before I shell out, I will give it a go and top it up with clear lamp oil. I'll let you know the result.
The verdict from the repairer is that the membrane needs replacing before top-up, but a Silva 125 is not repairable: the thing is moulded plastic, so the membrane can not be replaced. Buy a better one, Sir.
Before I shell out, I will give it a go and top it up with clear lamp oil. I'll let you know the result.
Lucky Duck
Well-Known Member
Just had a very efficient exchange of e-mails with Barry regarding this problem and unfortunately the Silva 125 is a sealed unit so is unlikely to be repairable if the bubble if too large. Cheapest replacement I have found is £230.
Edit - Just seen that I am a bit too late!
CreakyDecks
Well-Known Member
You're not a coarse fisherman then Vic? You can buy a pump designed to prepare pellets as bait at any fishing tackle shop for about a fiver. One would be perfect for de-gassing the amount of liquid used in a compass!
macd
Well-Known Member
Maybe if the fix works, it's a good idea to keep the bubble as back-up for your spirit level.
antaris
Well-Known Member
Oh god the compass issue!
I bought two boats in my life so far and both had their compasses leaking on me about 2 months after purchase.
So I went dot the dissadembly route - twice.
Used baby oil for both. The first lasted a season - and then emptied itself over the electrics. Then I changed it... could not possibly find a replacement diaphragm.
The second one has just been fixed and I am wating for time to prove me right. I basically plastered the whole back with epoxy glue and left a (hidden) bubble in the rear compartment to take all the changes in volume due to temperature variation.
But above all...I was totally freaked out when I was advised to use a flammable liquid in a potentially leaking item on board. Having had th experience of the (failed) first fix, there is no way I am having white spirit pouring all over the deck - worse, still, via bulkhead hole, into electrics...
Baby oil it is for me, albeit a bit viscous, and it gives you a smoother baby skin
.
Will replace if it fails...
I bought two boats in my life so far and both had their compasses leaking on me about 2 months after purchase.
So I went dot the dissadembly route - twice.
Used baby oil for both. The first lasted a season - and then emptied itself over the electrics. Then I changed it... could not possibly find a replacement diaphragm.
The second one has just been fixed and I am wating for time to prove me right. I basically plastered the whole back with epoxy glue and left a (hidden) bubble in the rear compartment to take all the changes in volume due to temperature variation.
But above all...I was totally freaked out when I was advised to use a flammable liquid
in a potentially leaking item on board. Having had th experience of the (failed) first fix, there is no way I am having white spirit pouring all over the deck - worse, still, via bulkhead hole, into electrics...Baby oil it is for me, albeit a bit viscous, and it gives you a smoother baby skin
.Will replace if it fails...
westhinder
Well-Known Member
A quick update: Kelvin Hughes Rotterdam tell me a Silva 125 is not repairable. The Dutch importer tells me it has to be sent back to Sweden, will cost nearly as much as a new one and will take about two months.
So I have decided to give it a try myself: I have topped up the compass as best I could with clear lamp oil. The bubble is all but gone, merely 2-3 mm is left. I can see no trace of a difference between original fluid and top-up. Time will tell how it reacts to temperature changes.
If/when the bubble returns, I will have to replace the compass. I'll start saving up now, as I have found that a quality compass which is also repairable costs an arm and a leg.
So I have decided to give it a try myself: I have topped up the compass as best I could with clear lamp oil. The bubble is all but gone, merely 2-3 mm is left. I can see no trace of a difference between original fluid and top-up. Time will tell how it reacts to temperature changes.
If/when the bubble returns, I will have to replace the compass. I'll start saving up now, as I have found that a quality compass which is also repairable costs an arm and a leg.
saltylegs
Well-Known Member
heres a link to a previous post that I left. I had used Barotine clear lamp oil and that was 2 years ago. 1 still ok the other has a bubble starting but should be ok for another season and will get topped up as needed.
http://www.ybw.com/forums/showthread.php?330545-Clouding-inside-compass-dome
http://www.ybw.com/forums/showthread.php?330545-Clouding-inside-compass-dome
