Magnetic Compass: red, white or black

[Bigjim]

I just bought an older boat which has a really old compass. The glass is very cloudy the fluid is down and it's hard to read during daylight, but it's almost impossible to do so at night.

The current compass has a red card. Replacements come in red, white and black.

Anybody have a good reason to pick one over the other? My experience has only been with white on black. I can't judge the red card, because the compass is in such bad shape. The local West Marine, doesn't have any compasses on display so there's no way to see them for myself. But even if I did, it wouldn't tell me what's best in bright day or blackest night or during storms.

Thanks

[Jim Cate]

Before you give up on the old one, try cleaning/polishing the dome with an appropriate plastic product. A bit of elbow grease will likely make a huge improvement in clarity. Auto supply houses offer kits for cleaning the plastic lenses over headlights, and that willl work ok.

Fluid can usually be added, but consult the mfg to determine exactly what fluid is used in your compass... not all the same stuff.

As tp the color of the card, I've had both red and black base cards, and both work just fine IMO.

Jim

[noelex 77]

The idea of the traditional red card was to help preserve night vision. With modern red led illumination, white numbers on a black background are perhaps even better in this regard and also offer better daylight visibility, but check it has red illumination preferably with adjustable brightness if you plan to do much night sailing.

[UNCIVILIZED]

My only experience in 40-some years of sailing has been black cards, with white numbers/lettering, & red illum. And I'd think that a compass with a red card would be tougher to read with red illum., especially as there'd be less contrast between the card & the writing. However, you might try walking into a shop which has the whole menagerie of colors, drape a couple of blankets over your head & the compass, & then illuminate each with both red, & green lighting, after letting your eyes night adjust under the blankets.

There are some other illum. colors besides red & green that don't wash out your night vision, but those are the 2 most common. And it really, really does pay to have a way to adjust the brightness level on your compass & instruments, otherwise it's easy to lose a lot of your night vision, knowingly or not. Especially say if it's foggy, which tends to make a lot more light reach your eyes at the same brightness setting than on a dry night.

[Neptune's Gear]

you can clean up the cloudy lense - its plastic, right? (very old ones sometimes glass, so shouldn't be cloudy) . So, you can use a headlight restorer pack from an auto store, or just plain cutting polish and a rag, or better yet a polishing machine at low revs. High revs gets too hot and marks the plastic. In extreme cases, you can even sand the dome with 600 grit wet and dry, then 800, 1000, and then polish the dome as above. The domes are thick, and will take lots of polishing! They come out like new :-)

[foufou]

The domes are also replaceable. I bought an older compass with crazing and was able to buy a new dome for very reasonable price. The manufacturer recommended fluid which in my case was odorless paint thinner. As was mentioned not all fluids are the same

[Bigjim]

Although it's really old, I'm not a fan of the red card. The light inside the current one is not red and I did not see an adjustment for any of the instruments.

All the instruments on board right now are old analog devices. The lighting in all of them is muted white. There seems to be a red crystal around the edges of the wind and speed log but the white light sneaks out anyway. I'd just as soon replace them then try to refurbish any.

I was just looking for some recommendations on color. Adjustable lighting is definitely a good idea. Twilight is the real problem with most dials and displays.

[Time2Go]

Originally Posted by Neptune's Gear

you can clean up the cloudy lense - its plastic, right? (very old ones sometimes glass, so shouldn't be cloudy) . So, you can use a headlight restorer pack from an auto store, or just plain cutting polish and a rag, or better yet a polishing machine at low revs. High revs gets too hot and marks the plastic. In extreme cases, you can even sand the dome with 600 grit wet and dry, then 800, 1000, and then polish the dome as above. The domes are thick, and will take lots of polishing! They come out like new :-)

Before and after pictures of my DIY
headlight restore. 20 dollar kit from Walmart
Took about 5 minutes a lens
Cheers
Neil

[Bigjim]

Originally Posted by Time2Go

Before and after pictures of my DIY
headlight restore. 20 dollar kit from Walmart
Took about 5 minutes a lens
Cheers
Neil

I read that you have to polish the lens or it will return to the original condition.

The fluid level is low. Do you know how hard it is to top it off?

[Wotname]

Originally Posted by Bigjim

I read that you have to polish the lens or it will return to the original condition.

The fluid level is low. Do you know how hard it is to top it off?

Sometimes easy, sometimes hard!

Unfortunately if the level is very low and the compass is very old, it is hard more often than not as the seals may well be hard and brittle and break when disassembled.

Make sure you keep the old fluid as this might be the only way to work out what new fluid to get.

IME, the most common fluid is clear (white) kerosine usually just called compass oil. Some very old units will use alcohol or alcohol and water. The alcohol is usually either Isopropyl alcohol or ethyl alcohol.

More info here Compass Fluid

Note that they recommend de-gassing but that is not always easy to do on-board so most do not do it and accept that there will be a bubble forming sooner or later. A poor mans way to de-gass the fluid is to warm it (carefully - it does burn) and shake or stir vigorously before using it.