Danforth Constellation 5" compass refurb and refill - unbalanced card?

[steveg_nh]

Hi All,

New to the forum, but so many of my google searches landed me here on the forum, I thought I would join and ask a few questions, but also contribute. I have a 1989 Viking 35 convertible powerboat. This off season I've undertaken a refit of my helm (gauges, switches, panels) including a light refurb of my original Danforth compass.

The compass is a 5" Danforth Constellation that worked great, no leaks, etc. But the compass ring was in need of refinishing and I wanted to update the light. Upon removal of the ring, I moved the dome a bit and introduced some air. I did some research and Viking Instruments in Kingston MA recommended I add Ritchie Compass fluid (Isopar L) to top it off, which is a more refined version of odorless mineral spirits, also having a higher flash point. I did this, and noticed a hazy greasiness on the inside of the dome, so I decided to clean it and flush the whole compass. I removed the dome, emptied all the existing fluid (which has a definite yellowish tint to it) and inspected.

I am confused as to what was in the compass. Seems too thin to be mineral oil, but also had quite a smell versus odorless mineral spirits. I have no idea if it was every replaced before. It did seem to mix quite well with the Isopar L though, so I’m guessing it is some type of mineral spirit or mineral oil/spirits mix. As a test, I filled the compass with straight odorless mineral spirits (the same viscosity of the Ritchie Isopar L fluid, and while I felt like the compass had less dampening, it worked well. But I did notice that I thought the compass card was a bit off balance, and slightly tilted. I wasn’t sure, but felt like it was a bit. Anyway, I drained it again, as I want to refill with pure Isopar L. It’s on order. I also had the ring redone and powder coated.


But I noticed the compass card, when empty, is definitely not flat. Seems like some type of magnetic pull on the card. If I put a screwdriver next to it, I can affect where the card is pulled down. So I’m assuming this is normal and when reinstalled in the boat, should all be balanced. I’m thinking the compass was calibrated or adjusted in the boat to level it out? Maybe I’m crazy? I am sure when it was full, and I thought it was unbalanced that there wasn’t any air trapped under the card.

So in short: Anyone know what a Danforth Constellation from 1989 had in it originally for fluid? And second, is this card behavior when empty typical? Here’s some pics of before and after, and a video of the card spinning while empty, using a screwdriver to pull on its magnetic field.



Video https://1drv.ms/v/s!ApXVAXLoAEY8xWNv...s9lXo?e=tx0a9I

Thanks

[steveg_nh]

Also too, since I can't edit and just add this to the first post, what is the best thing to use to clean and flush the compass before refilling it? I've read isoprobyl alcohol, other solvents etc. It definite has a greasiness/oil residue. I'm convinced the fluid in there was a mineral spirits/mineral oil mix. Has a definite smell too. Thanks

[GordMay]

Greetings and welcome aboard the CF, steveg.

Unless your compass is VERY old, it won’t be filled with alcohol. It will have been filled with odourless mineral oil/spirits, or a proprietary (Isopar L) type of similar fluid.

Viking Instruments acquired the entire inventory of Danforth and Aquameter Compass Parts, as well as the tooling necessary to continue manufacturing replacement compass parts from Rule Industries. They are the exclusive manufacturer and distributer of replacement Danforth and Aquameter compass parts and service.
Compass Oil ➥ https://www.vikingcompass.com/compassoil.html

Adjusting a Compass ➥ https://www.vikingcompass.com/adco.html

The standard factory overhaul on the 5" Constellation is $293.00, which includes complete disassembly, cleaning, repainting of the bowl and powder coating the top ring, replacement clear dome, gaskets, diaphram, oil and a two year warranty.
➥ https://www.vikingcompass.com/017.html

[Benz]

I bought a brand new Danforth Constellation in 2006-ish which had an unbalanced card.
The authorized Danforth repair shop guy told me "Just return the Danforth and buy a Ritchie. It's a better compass."
I did what he said.

[steveg_nh]

Thanks guys. The Danforth is original to the boat, and has been great. It's flush mounted so I don't want to modify the dash. Plus a new one of similar size is around $850. The compass is from 1989, and just felt like a thicker version of mineral spirits with an odor. Maybe there was no such thing as "odorless" in 1989, and that is what it is.



GordMay, thanks. The guys at Viking Compass are who I mentioned. They do great work from what I've read, but I didn't need the full $300 service. I got the compass ring powder coated locally for $50, and don't need any parts. It wasn't leaking.



So I'll just wait for the extra compass fluid and tie down screws I ordered from Viking Compass, fill it up, and see where I'm at. I would like to clean it out a bit though to get some of the residue off the card and stuff. Not sure of the best way to do that. The card balance is definitely just how the magnets are are being affected by the surroundings. As I move it around, it changes. I bet when it's in the boat, surrounding by all the stuff near it, it's level, as it's adjusted to that location. At least after doing more reading, that's what I'm expecting.

[taylormobile]

When I rebuilt my Ritchie compass about 15 years ago (don't own the boat now) I used the odorless mineral spirits which worked great. But I also pulled vacuum on the fluid before using to ensure no air bubbles appeared.

[steveg_nh]

Thanks. I managed to get it refilled without bubbles using the freezer method, but I drained it again since I decided to just go with the Isopar L. But I can't figure out why the card isn't sitting level when empty. Nothing was messed with, meaning any adjustments. I'm wondering if this is due to compensation that was done in the boat, but not being in the boat, the item that was having an impact on it isn't present, so the card is unlevel. I need to understand how these work a bit more, and will read up on balancing. I don't want to mess with it if I'm not sure.

[CarinaPDX]

Compasses are built to operate in a range of latitudes; the compass you buy in Canada is different than the same brand and model in Australia. The difference is the weighting of the compass card. The card (or needle) is attracted to the north pole, but we do not live in a 2D world, so the pull has a downward component that changes as we move around the sphere of the world. The weighting is chosen so as to counter this pull for the designed operational range of latitude. When used elsewhere this weighting can over- or under-compensate and cause the card to have a tilt to it. If your boat were built in Australia or New Zealand (and the compass bought there) the compass card would be severely tilted when in North America. This is probably not what you are seeing, but is a possibility and is worth remembering for future cruising.

Greg

[GordMay]

Originally Posted by CarinaPDX

Compasses are built to operate in a range of latitudes; the compass you buy in Canada is different than the same brand and model in Australia...

Unless you buy a "Global" compass.

Magnetic Zone Balancing

Compasses generally have one of two balancing solutions:
One is a two [or more*] zone system, with a northern hemisphere zone, and a southern hemisphere zone (with zones overlapping several degrees).
The other is a single global system, with one needle, balanced to work anywhere on Earth.
Check with the compass manufacturer, or a knowledgable retailer, if you intend to use your compass during a trip in another part of the world.

Your safest bet, would be to buy a quality global compass, that can be used in all regions.
However, I don't know if they're made in binacle versions
Handheld Global Compasses [Silva & Suunto]
➥ https://www.thecompassstore.com/globneedcom.html

Because the dip angle is of no navigational interest, the "global" compass is made so that it can rotate only in the horizontal plane.
This is done by different [proprietary] methods, that have a double system, pivoting the magnets, and the needle separately, but coupled, allowing the needle to stay parallel with the compass capsule, while the magnet tilts with the vertical component of the earth’s magnetic field, without pulling down the needle.
The global compass can then work effectively at all latitudes [except very near the poles], without specific compensation for dip.

* For example, Silva [for one] has divided the earth into five magnetic zones. MN - Magnetic North, NME - North of Magnetic Equator, ME - Magnetic Equator, SME - South of Magnetic Equator, MS - Magnetic South.

The Earth’s magnetic field runs parallel to its surface, only at the Magnetic Equator, which is the point halfway between the Magnetic North, and South Poles.
As you move away from the Magnetic Equator, towards the magnetic poles, the angle created by the vertical pull of the Earth’s magnetic field, in relation to the Earth’s surface increases gradually.
This angle is known as the dip angle.
The dip angle increases in a downward direction as you move towards the Magnetic North Pole, and increases in an upward direction as you move towards the Magnetic South Pole.

[Jim Cate]

Originally Posted by CarinaPDX

Compasses are built to operate in a range of latitudes; the compass you buy in Canada is different than the same brand and model in Australia. The difference is the weighting of the compass card. The card (or needle) is attracted to the north pole, but we do not live in a 2D world, so the pull has a downward component that changes as we move around the sphere of the world. The weighting is chosen so as to counter this pull for the designed operational range of latitude. When used elsewhere this weighting can over- or under-compensate and cause the card to have a tilt to it. If your boat were built in Australia or New Zealand (and the compass bought there) the compass card would be severely tilted when in North America. This is probably not what you are seeing, but is a possibility and is worth remembering for future cruising.

Greg

Greg has this correctly described. And FWIW, our previous boat had a Danforth binnacle compass, purchased in California by the PO. Worked fine until we were approaching New Zealand for the first time. As we progressed southward, the compass card tilted more and more from the horizontal, until if finally seized up and failed to move at all! This was long before GPS, so it was fortunate that we had other compasses on board. Once in NZ we took it to an adjuster who rebalanced the card for the local dip angle and all was well again. And again, FWIW, a fellow San Francisco based yacht with a Ritchie compass had no such trouble.

Now, as to the observation that the card is not horizontal when the bowl is empty: I suspect that when full, the little weights that balance the card displace a bit of fluid and thus loose some of their weight. The balance was adjusted so the card was level when the bowl was full... and so, when empty the balance changes slightly and the card tilts.

Jim

[steveg_nh]

Thanks all. I did read about northern vs southern hemisphere compass adjustments. But this compass is right where it's always been, in the north.



I am happy to report that the tilt is mostly solved. I took the compass apart for a thorough cleaning prior to refilling. The old fluid was definitely much more viscous than Isopar L or odorless mineral spirits used today. It was a blend of oil and spirits I believe, as it did mix fine with OMS and Isopar L. But thicker and much more oily. Anyway, there was some fluid just hanging on the tabs of the lubbers line pan assembly causing it to tilt. Once thoroughly cleaned of all the old fluid, it's sitting flat again, or maybe just a hair off level, which to Jim's point, likely resolves when it's full.



Pretty simple but amazing device actually, and cool to get in there and find the diaphragm (which was perfect) and give it a good but delicate cleaning. The rest of the Isopar L I need will arrive tomorrow so I can fill it up again. Thanks for everyone's help!

[steveg_nh]

Just wanted to come back to this for some quick tips. The compass looks great, card is balanced, etc., but I can't get one last teeny tiny bubble out of the darn thing! I tried the freezer trick, with the compass and extra fluid in there overnight, and this little bubble keeps eluding me.



Will it pop as the fluid warms up to room temperature? Thanks!

[steveg_nh]

Actually got this sorted out. Did the freezer trick again and got the last tiny bubble out. Installed the new light and the refurb is complete. Very happy with the results.

Thanks for the advice and humoring me with all my questions. Great forum.