Worth changing bulkhead compass?

[eddystone]

Last October I came up Southampton Water/Itchen in the dark - first time I had done any night sailing for probably close on 20 years, point being before I needed reading glasses. I couldn't make out the compass reading (standard bulkhead Plastimo thing - red card) at all; not an issue at the time as I knew my way home but I thought I'd better get a new compass before any significant passage at night. The plastic dome is a bit cloudy but I find the card perfectly readable by day. However on Googling I found an old thread that suggested that if your near sight is bad then it's just an inherent problem. I generally use 2.5-3 strength reading glasses for anything up to 1 metre away but my normal long sight doesn't kick in until maybe 2-2.5 metres distance, i.e. I have a problem in the mid-zone. Do you think a brand new compass would through clarity of the dome and better illumination have significantly more acutance? just wondered if anyone else experienced similar problem.

 

[Tam Lin]

Varifocals?

 

[Hadenough]

Varifocals?

Are a pain in the **** unless you like nodding your head like one of those things in the back of a numpty's car! and on a boat where distance, height, depth, are so important are IMHO a liability.

 

[Tam Lin]

Are a pain in the **** unless you like nodding your head like one of those things in the back of a numpty's car! and on a boat where distance, height, depth, are so important are IMHO a liability.

They work for me!

 

[sailorman]

They work for me!

Yep took to them like a duck to water, make sure that the lens is deep enough to allow better graduation

 

[neilf39]

I agree varifocals are great. No nodding, closer things are normally lower down so you just glance down and look through the right bit of the lens. Works for my compass and plotter...

My multifocal contacts don't have the same degree of flexibility so if I use those I compromise and have it so one eye is fully adjusted for long distance and one eye is set slightly under corrected so I can read at normal distance but only just and need -1 reading glasses for close up. Multifocals also take your brain a bit of time to work them out.

It's a toss up between these as I like having clear vision at all distances, but it is so much nicer not wearing glasses, especially if its raining.

 

[Binman]

Yep work for me to, once you get used to them, it's more moving your eyes up and down, not your head as well.

 

[andygc]

that suggested that if your near sight is bad then it's just an inherent problem.

As you age your accommodation decreases - that is, the range over which you can focus - it's a result of the lens in the eye becoming stiffer. Hence the problem of your arms getting longer when you read (so you wear reading glasses). Add to that the effect of ambient light. In bright sunlight your pupil contracts so you have something akin to a pinhole camera -your range of accommodation will be at its best. As light levels fall your pupils dilate. Your ability to focus degrades because you lose the pinhole camera effect and light is passing through a greater area of lens, so any optical errors in your lens become more significant. This effect is, obviously, greater the darker it gets. A better-lit compass will be easier to read, but at the expense of interfering with dark adaptation. Some form of reading glasses is probably the answer. Some people love varifocals, some never adapt to them. If you have good distant vision you don't need them and you could try half-moon readers which you look over most of the time. You'd need to choose a strength that suits the distance at which you want to read the compass.

 

[James_Calvert]

.... Do you think a brand new compass would through clarity of the dome and better illumination have significantly more acutance?

I have replaced one of my pair of old Plastimo bulkhead compasses because it sprang a leak. I was so impressed with how much easier the new one was to read, particularly at night, that I'm going to replace the other one as well. The new one has much sharper definition between the white numbers and the red background.

One thing you could check first: the older model has two bulbs, a backlight as well as one in the front. Could be one of these has failed and contributing to your problem?

If you do replace it, be aware that, although the new Plastimo compass should fit in the same hole as the old one, the hole might still need a little dressing with a file if it wasn't cut exactly to the template in the first place. Turned a 5 minute job into somewhat longer in my case.

 

[lw395]

The clouding of the compass body can possibly be polished out with a fine metal polish like duraglit or even solvol autosol, farecla perhaps?
The illumination can be improved.
However the best answer might be a digital compass mounted at a better distance?
I have one of the little tacktick ones for dinghy racing, they are great but not illuminated.
I have an app on the hudl which is a great compass display....
Probably cheaper than buying a compass. World's gone mad....

 

[AntarcticPilot]

Just a note about distant vision.

I have had cataract surgery in both eyes, and have good distant vision but no power of accommodation whatsoever - that is, I can't change the focus of my eyes, as I have artificial plastic lenses in places of the natural ones. I can legally drive without any correction, but do wear glasses with a very small correction for distant vision - it makes the difference between good vision and excellent vision.

The remaining depth of vision is quite sufficient for me to see objects further than a couple of metres away clearly - in other words, I can see perfectly well for all objects more than about 2 metres away. I can read large print between 1 and 2 metres; for example, I can read the instruments on the car dashboard perfectly well while driving.

I don't use varifocals; I prefer to use separate reading and distant glasses. I have no problem at all reading the instruments on Capricious (including a bulkhead compass) at a distance of 2-3 metres from the steering position.

I'd suggest that as long as the OP's distant vision is properly corrected, there should be no problem seeing instruments, even with no capacity for focusing at all.

 

[eddystone]

Just a note about distant vision.

I have had cataract surgery in both eyes, and have good distant vision but no power of accommodation whatsoever - that is, I can't change the focus of my eyes, as I have artificial plastic lenses in places of the natural ones. I can legally drive without any correction, but do wear glasses with a very small correction for distant vision - it makes the difference between good vision and excellent vision.

The remaining depth of vision is quite sufficient for me to see objects further than a couple of metres away clearly - in other words, I can see perfectly well for all objects more than about 2 metres away. I can read large print between 1 and 2 metres; for example, I can read the instruments on the car dashboard perfectly well while driving.

I don't use varifocals; I prefer to use separate reading and distant glasses. I have no problem at all reading the instruments on Capricious (including a bulkhead compass) at a distance of 2-3 metres from the steering position.

I'd suggest that as long as the OP's distant vision is properly corrected, there should be no problem seeing instruments, even with no capacity for focusing at all.

Yes varifocals are not feasible for me, given the rate I lose reading glasses it's Sainsbury's ready readers - I don't think swapping with low dioptre glasses say +1/1.5 helps in the "dead" zone beyond near reading distance but before normal vision kicks in. However post above suggests a new compass may be much more readable - I'll look into the tick tack idea as well.

 

[eddystone]

Had a look at Raymarine tacktick micro compass - looks very neat piece of kit especially the dual angle, 20mm high digits and solar power - I wonder if it's illuminated for use at night? Also wonder if any issues mounting fluxgate compass close to existing magnetic one.

 

[lw395]

Had a look at Raymarine tacktick micro compass - looks very neat piece of kit especially the dual angle, 20mm high digits and solar power - I wonder if it's illuminated for use at night? Also wonder if any issues mounting fluxgate compass close to existing magnetic one.

The Tacktick micro is not illuminated. Well mine isn't. It only has a tiny solar cell.
Conventional wisdom is that two compasses should be a metre apart as a rule of thumb.
BTW, it's not a fluxgate, there is a moving compass card in there.
That might mean it does not work too well heeled over a lot?

There are other electronic compasses, KVH did a nice one, and there are those that tie into your instrument network.
But I think a B&G system with a display on the mast is quite a few ££££.
But it is IMHO the best thing.....

 

[Iliade]

2.5-3 Diopter lenses imply a more than subtle level of presbyopia. A big digital display 3m from the helm would probably work, as might a dirty great big red LED aimed at the existing compass, but I fear the only real solution is a new compass and good reading glasses.

I find cheap ready readers suffer with water splashing and salt encrustation when I really would like to read the compass (or more likely, the GPS) such that I may soon consider a single contact lens. A short and a long range contact lens arrangement works well for one of my crew, while the varifocals I bought are utterly hopeless!

P.S. Anyone want a pair of varifocals? 0d to +1.5d both eyes, Police frames, Crizal photochromic, anti-scratch, anti-fog, anti-alien-invasion lenses. Cost ~£500 in UK. Bought for £100 in India. Blooming hopeless! £30 (for the frames)

 

[William_H]

OP should first try to polish and clean up the plastic dome of the compass. Motor factors may have a plastic polish sold for rejuviating plastic headlight "glass'.
Eye focus can always be enhanced with brighter ilumination. So try to fit a bright light for the compass with a dimmer to you can hopefully keep some night vision.
These 2 approaches may avoid buying a new compass. good luck olewill