perjantai 27. maaliskuuta 2020

Compass repair.

So, todays topic is compass repair. In Avance 245 as in many other boats, you can find main navigation compass embedded in the side of the cockpit, as a bulkhead compass. I kinda like the looks of it and functionality since it is always there, big enough and clearly visible especially in a smaller boat like this.

Unfortunately it is also pretty vulnerable to external damage due to placement. this paticular compass is Suunto B-110. Good and trusty one that has not been manufactured in.. over 20 years? So no spares are available. When we bought the boat, seller informed us that is has been cracked during docking last autumn. As you can see, main window is severely cracked and all oil has leaked out. 

Basically there are not many options. Something needs to be done. Replacement with a new one is a no brainer in most cases, but finding a replacement one that would fit the installation hole turned out to be a challenge. At least if one is not ready to lay down plenty of cash. And I am not. And since it looks kinda nice and is original I thought I would give it a go to see if I manage to actually fix the thing. No spareparts are available so this requires some serious trickery. 

First, uninstallation. this is what compass looks like from the inside. There is a metal cover that prevents hits on the back of the compass and makes it look nice and neat on the inside too. Some say that it also prevents thermal disortion and cracks caused by temperature difference between outside temperature and inside temperature. Who knows if this is true?

Anyway, cover needs to be removed. Use a fitting screw driver and try not to loose the screws. you will need them later. Also unscrew the 4 screws from the outside that are the ones actually attaching compass into bulkhead. Now you should have something like this in front of you: 

Undo electrical wires that are attached to compass light. Then, depending on the installation, you should be able to push the whole thing out. If installation is tight and jammed use a screwdriver or similar and a hammer to tap the compass out by giving hits on the black metal frame on the sides evenly on all sides. No hits on the center. It is the weak part. 

If all goes well, you should have a compass in your hand now.

That looks really sad. 
Just in case my repair fails, I measured the diameter of mounting hole in case I need to go shopping for a brand new one. That seems to measure about 125mm. 

In case your compass is not as broken as this one and just need a bit of filling up, this is the screw you need to open and add oil under the rubber cover until it is full. there is no need to try pushing the oil inside plastic ball itself, there are 2 holes in the compass enclosure and oil will find it's way inside. Also the space between inner closure and this rubber thing is supposed to be filled with oil. It is made of rubber to allow oil to expand doe to temperature changes. Sort of an expansion chamber if you will. 

Sorry for not having pictures from disassembly, i kinda forgot to take them. But basically open all the 6 screws and raise locking ring which holds rubber part in its place. pry out the rubber without ripping it and everything should fall apart pretty nicely. Check the condition of all inner parts. They should move freely. and try not to mishandle whiskers that are inside. They are pretty delicate.

Main window here is the biggest problem. From my modelling days I remember that superglue is awesome. Cyanoacrylate can creep into tiny cracks and glues plastic pretty tightly. Just remember to wash all oil remains out to secure good bond and let everything dry thoroughly.

Few words of caution about superglue. I used quick attack. It glues skin in seconds. So work cautiously. It also has cyanide in it and in this instance we are using it liberate amounts. So you WILL have fumes that are toxic. So ventilate and try not to breathe fumes. They are pretty strong and make your eyes sting. 

Also, do not blow on glue to make it dry faster. Cyanoacrylate reacts with moisture in 2 ways. It indeed dries faster but also shifts color from transparent to white. Moisture from your breath is enough to do this and this is something you want to avoid. 

Start adding liberate amounts of superglue on the INSIDE if the window, on the cracks like you would be painting over them. If you want to, you can slighty try to wiggle and bend window to allow cracks to open up a bit if they are big. work through all the cracks. Glue is pretty running and starts to get thicker as it dries. To avoid pooling of puddles, keep moving and rotating cup in your hand to allow glue to spread evenly.

In my case glue started to turn white on the areas that were not covered in glue. This also sometimes happens due to fumes that glue itself is emitting as it dries. So I decided to grab a piece of paper tissue (strong one) and give the glue a slight wipe. Spreading it on every part of the window. It might not turn out as totally even and you will most likely see some stripes of glue here and there. That does not really matter as you will see later on. Allow glue to dry properly. 

Once everything is dry again assemble compass back to way it was. Remember to put inner sphere in the same position it was originally. One hole should be on the lower part and another one naturally in the back, where filling screw is.  

Personally I added some epoxy glue under locking ring before I screwed it back on. Partly because 2 of the crews were so jammed that I had to cut them in order to get the thing disassembled. And partly because one part of rubber was pretty brittle and left a small opening and I wanted to seal it properly. Epoxy id goof filler since it becomes hard and as a gel-like it fills gaps nicely. 

Again, let glue dry well in case you used any. 

Time to fill the compass again. this is the part you will need to follow if you are just adding oil to compass that just has some fluid missing. In Suunto B-110 there is mineral oil. Nothing special. Basic lamp oil works perfectly. You could possibly also use ethanol. But I use oil since that this compass originally had. to get the oil in, make a small funnel from baking paper and slowly pour oil between rubber back and inner sphere. Keep checking oil leven low and then. It takes in few dl of oil. I did not measure. And you will have spillage so have some tissues at hand. Once compass is full screw the cap screw back in and wipe everything clean.

 So now you should have something that looks like this. If you see big bubbles in spheretry to roll compass in your hand in such manner that you can sneak bubbles out from the sphere on the expansion chamber side out of sight. Looks nicer that way.

Then it is time to mount compass back on it's original place. remember to clean all contact surfaces before assembly to make sure you have good coupling. I recommend adding a dab of marine caulking between bulkhead and compass to avoid water seeping under compass and from there inside hull. Add crews, connect lamp wires and back cover and you should be good to go again!

Like so, still mising installation screws. 
 And behold! Good as new. Now, regarding those small cracks and uneven spread of superglue on the cracks. If you look at the picture below you can see that filling compass with oil actually makes smaller cracks and uneven glue drips mostly disappear. Optics are amazing, eh?

Good as new. Even though from year 1987. 
As an epilogue I must admit that in this case also the magician is a bit amazed in the trick. I was fully prepared to go shopping for replacement. And still I am a bit cautious to see if that superglue, even if dried out completely before filling, makes some strange reaction with lamp oil and either dissolves or just chips off from plastic window leading to leaks. We will see and time will tell. If that happens I can always replace the whole thing. :)

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