Our Sestrel binnacle compass is Roaring Girl's original, making a solid, beautiful object now 33 years old. When we had finished all our work in Ipswich, which included quite a lot of new electronics, we got the compass refurbished, and then swung. This is an arcane art, now practiced by a few specialists, and involves making sure that the magnets positioned around the compass are oriented in such a way that the magnet needle does indeed point due north, despite the nearby attractions of the engine block and other chunks of metal. We got ours done by the lovely Peter Garrod of Seath instruments
in Lowestoft and a fine job he did.
But several years later, the compass had fogged up. A horrible brown yuck, reminiscent of fluffy ear wax, coated the compass card. The dome had become dulled and semi-opaque. Altogether an unpleasant and (more importantly) unusable object.
We were not prepared to pay for a new one. Anything resembling our splendid old one would be prohibitively expensive. Besides, we have this astounding teak mounting, made for us as a generous civil partnership present by Chris Dean in Ipswich, and we don't want to tamper with it. And getting it refurbished here in Rome would be, if possible, very costly. So we took a deep breath and decided to tackle it ourselves.
We now have a gallery on this blog, and if you look at the album 'Compass Clean-Up' you'll see pix of this process. We've written it up at length, to help any other cruisers with the same problem.
Before we started, we had Plans B and C. We have a small binnacle compass, which we keep for use in the dinghy (though we never have used it) which we could dig out and use for a while. Or a cheapy one from a dealer such as Plastimo, might be slotted into the stand for this summer, till we either find a compass refurbisher in Malta or take it back to the UK.
With this security in mind, we tackled the job. First of all, we polished the outside of the dome. That had no effect at all on the legibility of the card or the brown yuck in the oil inside. So secondly, we opened up the small screw on the side, which is where little quantities of oil can be added to top up if a bubble has formed. It was immediately obvious that the oil was badly contaminated and merely adding or exchanging small amounts would make no difference. Now we were moving outside our comfort zone of previously achieved tasks. After a deep breath, we removed the collar around the outside of the dome, which contains the screws attaching the compass to its base. That made no difference to anything.
There seemed little hope but to drain out all the oil, and see if we could do any cleaning up inside. With trepidation we unscrewed the brass ring around the compass base and then peeled away the thick plastic diaphragm that holds the oil sump.
Very carefully we drained it all out into various containers. A short note here on compass oil. Some cruisers report success with various more common oils, in particular Johnson's baby oil. We have always tried to stick to the manufacturers recommended oil, which is an extremely fine grade with a high level of transparency which should not cloud or discolour in response to changes in temperature, and not weight the card so that compass motion is overdamped. (Note that different compass manufacturers use marginally different oils.) We carry a bottle of the stuff especially for dealing with bubbles. The whole compass holds about 1.5 litres. After draining the compass, we therefore had over a litre of mucky oil which we would have to clean up somehow if it was going back into use.
Before tackling that problem, we needed to clean inside the compass. Pip liberated two brushes from her mug-painting kit. Very carefully we brushed inside the dome and across the card. Although some of the earwax lifted and resettled, our strokes had no effect on the grime caked on the inside of the dome. Time for even bigger risks. We broke out the meths as the least damaging degreaser we could think of. Acetone would be very damaging to the plastic and rubber elements. A little dab on the brush and hey presto! The grime came away. The glass began to clear, and the figures on the card began to show. With great precision, Pip brushed away with the meths, gradually dislodging and removing all the yuckiness. This left us with a clean looking dome and card but knowing a lot of stuff was still inside.
We pondered the possible damage of methylated spirits to sealants and diaphragms. In the end there was little choice. We put small amount of meths inside and swilled it around, gradually draining it out. Of course we didn't have that much meths on board so in the middle of this we had to go out and buy some, which meant discovering what meths is called in Italian. (Alcool denaturato, thanks to Google translate!)
This left us with a clean compass, empty of oil and unusuable. We certainly didn't have enough unused oil to refill it, so we had to work out how to clean (or 'polish') the oil. We set up a wee filtration factory on our table top, on a handy bit of oil cloth. Step 1: run the oil through a filter made out of a (purpose-bought) small strainer and a double piece of 10-denier mesh (aka a cut up piece of tights). This is where the coffee filter papers, unobtainable in Italy, would have come in handy. Repeat several times, replacing the mesh if necessary. Step 2: Put a plug (a wine bottle cork) in the bottom of a Racor diesel filter and suspend it on a skewer over a clean container. Pour the first-filtered oil through the diesel filter, giving it time to soak through the paper. Repeat.
For the least mucky stuff this worked well and quickly. For the really filthy stuff, Step 1 was modified by adding kitchen paper into the strainer. This was great at catching scummy bits, but a lot of oil was wasted by soaking into the paper, so we reserved this refinement for the dirtiest oil.
Now we had lots of lovely clear oil and a clean compass, and the challenge of reuniting them. Could we find our small funnel? Of course not. After two hours searching we went out and bought about ten assorted funnels. Back on the boat, none of them fit into the screw hole designed for the job. An hour later the small funnel decided to surface, and after all that, it didn't fit either. Life on boats! Eventually we found a 2ml syringe in our medicine chest, the nozzle of which fit in the hole.
We re-seated the diaphragm at the bottom of the compass, sealing it on with black sikaflex. We then replaced the brass ring that sits over it. Those screws are really soft metal and we broke one in situ, finally sealing the hole with a copious dab of the black goo. Then we left it overinight for the glue to go off.
Time to begin. We lined up the nozzle, stuck the small funnel in the top and slow, slowly, slowly started refilling the compass. Eventually it began to fill up, and resemble a normal compass with a large bubble. As it reduced, we guarded our precious oil stocks. Once the bubble was the size of a large washer, we sealed everything up, and put the compass in the fridge. This is standard because the colder oil creates a larger bubble for gradual replenishment. Then when the weather is hotter, the oil expands, making the bubble vanish.
Over the next few days we have gradually reduced the bubble, and at the time of writing its diameter is about 3mm. We even have about 50ml of polished oil and another 50ml of unused oil left to gradually eliminate even that. The photo above was taken a day or so through these final stages. You can see the oil is beautifully clear. So long as the diaphragm and seals don't leak, we think the compass will see us through to Malta and a professional refurb.
We know the professionals will throw their hands up in horror. And we wouldn't recommend this process as a general habit. If you do need to set about it, you will need the meths, funnels, filters and containers we've talked about. And enormous amounts of kitchen towel: we got through at least two whole rolls during this exercise.