Bubble in Brunton 70P compass

[josko]

The Brunton 70P compass on one of my boats's got a dime-sized gas bubble in the dome. It doesn't seem to be damaged in any way, and I don't think operation is affected. It was installed in '06 or '07.

Have other folks had this happen? Is there any way to get rid of this bubble? If not, should I replace the compass or let it be?

Edited September 4, 2014 by josko

[jason]

The Brunton 70P compass on one of my boats's got a dime-sized gas bubble in the dome. It doesn't seem to be damaged in any way, and I don't think operation is affected. It was installed in '06 or '07.

Have other folks had this happen? Is there any way to get rid of this bubble? If not, should I replace the compass or let it be?

I haven't had that happen, but I wouldn't be depending on it for a long trip.

[EEL]

Josko:

Ignore the bubble and paddle. It happens. If you have the right oil and tools you can add oil and get rid of bubble. I had a compass with bubble and it worked fine. That said, does cause doubt. I would only worry if bubble kept getting bigger.

Ed Lawson

[josko]

FWIW, Brunton is awersome - took it (10-year old compass) back, no questions asked, and they just senmt me a new replacement.

[Dan Foster]

I've refilled my Brunton deck compass twice now to get rid of the pesky bubble. Pressure changes throughout the years seem to cause compass oil to weep out of the fill hole on the back of the compass over time. Here's how to refill:

Remove the compass from the boat. Mine's installed with four small stainless wood screws into a plastic Tempest.

Flip over the compass and note the fill screw. It takes a small flathead screwdriver blade.

Go get yourself some white mineral oil, or stop by a marine chandlery and ask for 40-Weight Compass Oil, and make sure to get the Northern Hemisphere version - the spout should be on top. But the white mineral oil works just fine, and you'll get fewer weird looks.

Put the compass and the oil in the freezer for a bit to maximize the fluid density. Aren't you glad you took the compass off the kayak first?

Working above something that will benefit from copious amounts of spilled mineral oil (like a hardwood cutting board), flip over the compass, back out the fill screw, and inject mineral oil into the void. If you can get more than one drop in a time, you're doing better than me. There's no vent hole, so ideally you want a really narrow injection dropper to get the oil inside and still leave room for the bubble air to escape. Things went much smoother when I remembered I had a bunch of the little dropper bottles in the final photo. 

If you have a compass bubble you'd like to set free, I'm happy to pass along a dropper bottle full of mineral oil on a group paddle sometime.

[EEL]

While there are south and north hemisphere compasses, compass oil is different for north and south hemisphere use?

I have read the fluid used varies based on age and manufacturer of the compass.

Ed Lawson

[mhabich]

It’s actually the same oil with the label put on upside down. 

[Dan Foster]

Here's everything you need to know about the differences between Southern Hemisphere and Northern Hemisphere compass oil: (¡ʎluo ǝɹǝɥdsᴉɯǝH uɹǝɥʇnoS uᴉ ǝsn ɹoɟ) lᴉO ssɐdɯoƆ ǝᴉssn∀

Be aware that if you use anything heavier than 40-weight compass oil, your kayak will turn slower...

Edited April 15, 2022 by Dan Foster

[EEL]

Thanks for the tip.  My Bahiya has always turned slowly so during the Spring tune-up I will check weight of compass oil.

Ed Lawson