Compass Glare Hood

[Foswick]

I wonder about this from time to time. Our boat has a binnacle-mounted compass. It has what is almost certainly just a glare hood that covers approximately the forward 1/3. No real mystery there. It is hinged (like an eyelid, kind of). I always assumed this was just to allow for adjustment for different lighting/glare situations. There are two things that make me scratch my head, a bit, though.

First, the hinge is loose and seems loose by design. That is, it does not seem that it is meant to stay in place in any position other than the resting forward position. It moves quite easily and gravity readily drops it down into that position. I do not believe the hinge just needs to be tightened, though that is possible, I guess.

Second, the hinge is designed to prevent raising the hood more than about 30-ish degrees. The shape of the hinge's recess prevents that, by design.

My best guess is that the hood is designed so that, if glare was hitting it just the wrong way, you could flip up the hood, read the compass, and flip it back down. That seems like a silly feature, though, when you could just as easily shield it with your hand if you needed to be holding the hood in place anyway. But, it is my best guess. And, the angle restriction might be that the design assumes there is no reason to move the hood any farther aft, because you couldn't read the compass if you were able to flip it all the way toward you.

This picture is kind of tiny, but you can see what I am talking about. Anyone know for sure, why it is designed like this?

 

[Joe]

Search "compass binnacle functions"

• Housing:
  .Opens in new tab
  The binnacle provides a protective enclosure for the compass, safeguarding it from weather, physical damage, and the ship's magnetic field.
• Gimbal Mounting:
  .Opens in new tab
  The compass is mounted on a gimbal, which allows it to swing freely, ensuring a stable reading even when the ship is rolling or pitching.
• ..........etc............

 

[Foswick]

Thanks Joe, but those links do not bring up related information, for me - just some sort of random Google search results that don't really pertain to my question. I think Google must be showing you something different than what I see when I click on them.

I am not unclear about the purpose of the binnacle or the gimbal mechanism of the compass itself.

What I am talking about is, specifically, the glare hood (highlighted in yellow below). It flips forward (blue arrow) up to about the position of the green line:

 

[lemoiney]

The hood is solely to hold a small LED for nighttime viewing. It’s never been clear to me why it pivots. My LED was green and I wanted it red so swapped it out. I picked up the replacement at one of my local chandleries. These fail quite easily, usually due to the reason the wire is quite fine and moving the hood can put strain on the wire/connection. Mine is always on and not visible during the day. You can add a switch, but that adds an extra point of failure. My LED is very small and dim and draws virtually no power.

 

[Foswick]

The hood is solely to hold a small LED for nighttime viewing. It’s never been clear to me why it pivots.

Ah! Mystery solved! Thank you.

I had forgotten that there are two little wires there. They were severed at some point in the boat's history and were just sort of tucked up out of the way. I can see how the pivot might be useful, then, to adjust where the light shines? I guess?

Anyway, ours does have a switch, but I am thinking about an upgrade that I might try that gets rid of those wires entirely. In the tradition of overengineering (which is kind of my thing):

1. Pull the hood off and make some room inside it.
2. Replace whatever light is there with an efficient red LED.
3. Install a small supercapacitor and resistor in the hood.
4. Install pogo connectors along the forward edge of the base housing and the hood.

This would allow me to power the LED directly from the base unit via the pogo connectors (no wire), when the hood is in the resting position. When the hood is raised, the capacitor will power the LED for 30 seconds or so. Returned to the resting position, the capacitor will recharge.

I like this idea because it allows me to just turn the light on/off directly from the base unit switch and use it normally, in this way. But, if the switch is off and I just want a momentary read, I flip the hood up slightly and the light comes on. No wires - probably a $10-$20 upgrade, all told.

 

[Tally Ho]

The hood is solely to hold a small LED for nighttime viewing. It’s never been clear to me why it pivots. My LED was green and I wanted it red so swapped it out. I picked up the replacement at one of my local chandleries. These fail quite easily, usually due to the reason the wire is quite fine and moving the hood can put strain on the wire/connection. Mine is always on and not visible during the day. You can add a switch, but that adds an extra point of failure. My LED is very small and dim and draws virtually no power.

It pivots so you can get to the 2 screws that are under there that hold the compass in the binnacle.


I think (but never really looked) that the light in my compass comes on when I turn on my running lights.

Greg

 

[Blitz]

What brand compass is that? I think you may be missing a piece for the hood.

 

[Foswick]

What brand compass is that? I think you may be missing a piece for the hood.

It is a Danforth Constellation. I don't think there is anything missing - nothing major anyway. What do you think might be missing?

 

[thinwater]

Just a quick Google of red vs. green for night vision. I think the current SOA is that green may be better for some tasks, because you can read detail better. The important thing, of course, is that it is very dim; the colors are not so magic that they work if bright. Very dim white light is recommended if color rendition matters (charts), after quite a few accidents were correlated to misreading charts under red light.

'Green and red light use in night vision settings is based on how the human eye and its photoreceptors respond to different wavelengths of light, particularly in low-light conditions. Green light is generally considered better for retaining night vision because our eyes are more sensitive to green wavelengths, allowing us to see finer details and reducing eye strain. Red light, while also helpful, is thought to affect rhodopsin (a protein in the retina) less and may be preferred for preserving night vision in very dark situations. '

So yes, red does not affect perifieral vision as much ... but if the detailed receptors in the center of the eye are required, green is better. Different receptor math.

 

[colemj]

I've had compasses with both red and white lights, but not green. The light level when on was so low that any effect on night vision didn't matter in any practical sense. Green is probably the same. They were all just bright enough to see the compass card numbers. The tiny indicator LED's on our switch panel are brighter than the one in the compass in terms of vision effect.

Mark

 

[Blitz]

It is a Danforth Constellation. I don't think there is anything missing - nothing major anyway. What do you think might be missing?

On my now vintage Aqua Meter Galaxy compass there is a plastic two part glare hood that folds down that is installed on the inside of the metal hood.

 

[jssailem]

Plastic protection...

 

[Foswick]

On my now vintage Aqua Meter Galaxy compass there is a plastic two part glare hood that folds down that is installed on the inside of the metal hood.

Interesting. There is no clearance for a second eyelid on mine.