Suunto marine compass repair

In our 1999 Bavaria 50 Cruiser, both Suunto compasses (model F-116/Sail) started leaking mineral oil at about the same time. After doing some research, I found out that this was not an uncommon problem. Unfortunately no replacement parts were to be found as this is an older model (and also regarded by some as a sealed unit and not repairable).

The (repaired) compass

The general consensus seemed to be to buy new ones. But new units are expensive, and didn’t seem worth the price for how little use they get.

Luckily, using my 3D printer I were able to produce tools to make it easier to disassemble it, as well as designing a replacement for the broken bellow. Since disassembling the original unit requires a vise and special tools, I designed new parts to make it easier to reassemble with only a screwdriver. I also made a small holder for a red LED-light, as ours only had an old light bulb glued on.

Printed replacement bellow. These are printed in polyurethane, and are chemically resistant to mineral oil, very tough and flexible. They should last longer than the original part, made of much stiffer plastic that cracks.

Getting the old compass apart is best done by dipping the lower “cup” in boiling water for about 30 seconds to soften the plastic, and then placing it in a wise with the 3d printed tools. This way the cup is squeezed off the compass body, and will pop of rather easily when enough pressure is applied.

Compass in a vise (with older version of the tools)


Cup off. Add some paper bellow to absorb any oil spill.


Vise-tools for applying pressure to the cup.

After getting it apart, clean all parts before starting to assemble again. I rinsed them in water, and cleaned them up with lint-free cloth. To not touch the compass dial though, this is very delicate and can easily bend. Any white spots or discoloration on this that shows up when it dries are invisible when the compass is refilled, so don’t worry about them.

Then its time to reassemble. Putting the new bellow on, ensuring that it fits well, the newly printed part to ensure a tight fit is put on and tightened with a screwdriver, using A4 stainless screws which are not ferromagnetic.

New bellow in place


New part to replace cup. Easier to tighten and ensure a good seal than original part.

For replacing the old mineral oil, fragrance-free baby oil were used. A syringe were needed to get the oil through the small refill-hole. Filling the compass and refilling the syringe takes time and patience, so one can save some time by filling the compass nearly full before putting on the clear acrylic dome. Then the rest of the oil is filled through the fill-port, tilting the compass so one can get the last bubble of air out before replacing the seal.

Everything ready for compass repair


Refilling of compass using syringe

Turn it around some times to make sure there aren’t any small bubbles stuck under the dial or elsewhere. My experience is that very tiny bubbles will dissolve after a day or so in the mineral oil.

Two newly repaired compasses. The right one has some oil spill on the outside of the dome.


Mounted in the boat with new LED-holder.


Compass with LED light on

So both compasses are now good as new. Hope this can help other who have given up hope on these compasses.

Due to there being some demand for these, the drawings are available at thingiverse. Since printing these are rather difficult due to the very flexible filament (and not everyone has access to a 3D printer) you can now buy the complete kit from me


    1. Since you seem very knowledgeable in these compasses. Do you know how they are adjusted? Mine looks to be in great shape but it’s indicates incorrectly.

      Thank you

  1. HI, i also have a Suunto compas on a bavaria 37 that has lost its fluid.. Am about to dismatle it to try and replace the bello that i suspect is dammaged. i am intrested in one of your replacement bellows to repair the compass as spares are not avaliable as you alreqady know. Please let me know if you are able to post a replacement to me on the Isle of man where we are based. I look forward to hearing from you and my compliments on a great write up to this problem.

  2. Hello together!
    My suunto compass just lost almost all oil (bought the boot recently Bav 31 1999) i do not see any cracks on the below part and also no signs of oil where glas is connected with black plastic. Only place where stil oils is coming out is the lowest part , where is a hole. I ‘ve tried to check what is inside ,looks a rubber gasket or membrane. If I stick this hole with oil resistant glue (or clean it properly the surface) I think can refill the compass with baby oil..😉 Do you think it will be a solution or even if I do not see cracks or damag on the plastic this make no sence? Thx Mate-Hungary

    1. Inside the plastic cover there is a membrane, and these fail from old age. That’s why I designed and printed a new one. I do not think plugging the hole at the bottom will work, as a flexible membrane is needed to let the oil expand and contract due to temperature. I guess it will start to leak again after a few temperature cycles.

      1. Aah no I got it. And Your poliurethane materiel is flexible enough instead the original hard plastic + membrane inside

  3. Hello, I already dismanteled the compass so I only need the cup with clamp and the new LED. Wat would be the price for the set (without the vise for dismanteling) including postage to the Netherlands ??
    My tip : after filling the compass put it in the freezer for some hours , the liquid will crimp. Take it out of the freezer and fill-up the compass again. Repeat if nessessary. This will during normal temperatures cause an overpressure inside the compass wich is absorbed by the flexible cup. It prevents that during temperature variations the inside pressure becomes lower than outside resulting in air being sucked in the compass causing air bubbles. This is the exact reason why every compass has a membrane to keep the pressure inside on a steady level ( just like Your central heathing).

    Best Regards Bas ( Dehler 35 Cruising )

    1. If you place an order for the kit I’ll remove the vice-tools and throw in the LED for free.

      1. Hi,

        I just placed the order , hope I can save the compass with it , I will keep You updated….Bas

  4. Have you double checked the fluid type before giving advice? Many compasses use Isopar L which is a low viscosity hydrotreated heavy naphtha. Sounds fancy but not too hard to find in marine and aeronautical supply.

    1. I couldn’t source Isopal L locally, so I went with baby oil (mineral oil) that had been suggested at other forums. It has worked perfectly for my two compasses. Other brands/models might differ and everyone should check before they pour liquid into theirs. I’ve only tested my 3D-printed parts with baby oil, not with Isopar. According to the material datasheet ( it’s resitance to naphtalene is “fair”. So I cannot be sure that it’ll work as well as with baby-oil.

  5. Thank you for this web site
    How is the baby oils reaction in wintertime.
    Will it freeze ?
    Best regards / Oskar

  6. Hi Njal,

    recently, I bought your fantanstic repair kit, and it worked really fine. Thanks a lot for this solution for a really nasty problem.

    As I said: Everything went fine, but now, after having the repaired item resting on my desk for several days, I detected a tiny, but clearfly visible oil leakage THROUGH THE BOTTOM of the yellow plastic part. There is neither a mechanical damage to be seen (even not with a magnifying glass), nor can it be from hidden oil spill somewhere on the compass – I washed it thoroughly several times, but the leakage is still there. And I can provoke the spill when putting some soft pressure on the mebrane: then you can see where the oil comes through, but – as I said – there is NO visible damage or such.

    BTW: I used just common, but high-class baby oil.

    I could imagine, that there was a small printing error, which caused a tiny, not visible micro-hole in the material? Or do you have another explanation? What would you suggest to repair this?

    Very best regards from

    Ralf Remensperger

  7. Hi Njal,

    just to make the story complete:

    It really looks like that the leakage came from a micro-size printing error in the first bellow, which was not visible at all. But after all, a hole of 0.01 mm is not detectable by eye, but is enough to let the damned baby oil seeping through …

    Anyway: You sent me another bellow for free, which solved the problem. Now my compass is tight, no leakage anymore, everything is ok. Thanks again for your reactivity and support!

    Cheers from Ralf

  8. Hello,

    I suffered from exactly the same problem as described above by Ralf. I even tried to seal it with some oil resistant sealant but it did not hold up.

    Kind regards

  9. Hi everybody,

    Just an update on the leaking bellow I wrote about earlier.
    Njal sent me a new one free of charge on short notice and now it’s been OK for 3 weeks.
    No signs of any leaks so I’m pretty cofident it will work.
    Thanks Njal for your support!

    Best regards

    1. Thank you for the update. I’ve upgraded the printer to get a more consistent print, and printed a test rig to pressure test them so hopefully this won’t happen again 🙂

      Thank you for your patience!

  10. Hello !
    I have a Suunto compass which is leaking totally empty. I have disassembled it from the boat (Bavaria 31, 2001) and tried to fill it up in order to find the very leakage point. I have seen your pictures about the process and the spare parts you have made, and I was on the brink of ordering the kit, but I’m not sure if my compass is exactly identical to yours. I cannot find any model number. I seems that splice between the bellow and the housing is somewhat different. Since there is no option for attachment here, I would need an address to send a good photo separately. I appreciate your intention to help remedying products in stead of bying new ones.

  11. Hello,
    Thank you very much for your Suunto Compass bellow replacement kit.
    It’s a great idea !
    I send you an order today for one kit.

    Best regards

    Jean-Yves (from France)

  12. Heisan
    Jeg bestilte et slikt repsett fra deg 26.4.22, ordrenr: 462 og monterte det i hht deres beskrivelse.
    Alt virket veldig greit og fint, men så ser jeg nå at i løpet av vinteren så var kompasset igjen bare halvfullt…?

    Jeg har nå demontert det og ser ved nøye studering ikke noen nevneverdig grunn til lekkasje…
    Men jeg ser en brun flekk i bunnen av den gule beholderen.
    – Kan dette være årsaken til at kompasset lekker?
    – Eller har du andre teorier på hvorfor oljen lekker ut?

    Mvh Karl Edvard

  13. Hello,
    Very well done. Impressed with your doing!
    I have another nice suunto compass that is a bit dirty inside, lack of light and missing liquid creating a bid air bubble. I did not think about baby oil but some “de-natured” white spirit also called “desaromatisé” WSp for refill. The compass is “white lock” I do not know dimensions
    I will try to dismantle it and revert to you hoping not to break anything.
    Looking forward

  14. Hi Njal, greetings. I’m trying to process an order for our Suunto binnacle compass repair kit but it’s not going through (PayPal) – please can you kindly confirm it is still possible, and that you are able to supply?
    Many thanks,
    +44 7773 377558

  15. Hi There. I live in Melbourne Australia. Recently my k-14 model compass has been malfunctioning. It does not rotate freely and is sitting off its level axis. There are no leaks or airbubbles. Do you have any advice fir me.

  16. I’m attempting to print this myself. What size and length stainless bolt did you use exactly?

    Many thanks.

    1. M3 bolt, 20mm. Use stainless steel (A4), ordinary steel is ferromagnetic and will affect the compass. Good luck 🙂

      1. Hi Njal, you might have seen that I messaged you last month as I’m really keen to acquire one of your kits for my Suunto steering compass. Your e-shop didn’t seem to be working, please can you come back to me when you get a moment? Many thanks, James

  17. It seems you have cracked the repair of these lovely compasses. In my case since I have taken my Boat to warmer climes the oil seems to be escaping slowly.

    Is there anyone using your techniques and parts who could refurbish my 2011 F-116/Sail?

    In an ideal world in the UK but Incan mail it to anywhere in Europe

  18. Hello,

    I have been trying to find a place to get a new F116 compass, but turns out its harder than I thought, probably impossible.

    Is there a way to send the compass somewhere to get fixed?

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