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Old 06-08-2014, 11:45   #1
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handheld compass- magnetic clip-on errors!

I just finished a 7 day practical course after previously completing a shore based day skipper theory course. When doing fixes on the boat using a hand held- eye level compass my results were way out with cocked hats up to an inch wide! Pretty embarrassing and frustrating until it was figured out that my magnetic clip-on frames made it impossible to use a compass sighted close to my glasses.

I'm extremely myopic,so taking off my glasses isn't an option. I need to get an arms length hand held compass, but the reviews I've read on a couple of models are not positive.

Does any one have one they would recommend?

Cheers, Foz
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Old 06-08-2014, 12:05   #2
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Re: handheld compass- magnetic clip-on errors!

Changing specs may be the best option there are lots of compasses on a boat (autopilot, HH, steering, binoculars) The earths magnetic field is quite weak and even small magnets have an effect at suprising distance. High power neodymium magnets can have a far reaching effect despite their small size. You have to be very careful where you put the specs or clip ons down. There are plenty of prescription frames in Stainless steel, or even better titanium.

Anyway the Autohelm personal compass is the best I have used. It is used at arms length. Sadly they stopped making them about 15? years ago, but they seem to last forever and they still appear on ebay or similar. A HH compass is a great tool and is very under used these days. It is worth getting one that works well.

I use mine almost daily and I change the batteries every 3 or 4 years whether I need to or not.
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Old 06-08-2014, 12:38   #3
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Re: handheld compass- magnetic clip-on errors!

Foz,
Congrats on your course completion as a first step towards proficiency in coastal navigation. The best compasses are the "hockey puck" style and secondly the hand held line of sight compasses that you refer to in your above description. The former are definitely better and more accurate than the latter, but with a little practice you should be accurate with the other style. Our first major ocean voyage down to the Virgin Islands during the age of Loran was completed with a dedicated DR track, charts, ship compass, standard binoculars and the least desirable handheld compass with the floating ball on a handle and two sight lines. We made every passage successfully and found every anchorage we sought. Although it is far more difficult to navigate coastally than offshore, you really don't need exact precision to a few feet/meters(as is afforded with GPS) if you use your sea sense and eyes in relationship to your chart. With practice, you'll be surprised how close you will be able to plot a fix in relation to a GPS fix. And, if the electric god fails, you will be able to happily continue your cruise in the path of the great mariners of the past. Good luck, good sailing, and happy navigating.
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Old 06-08-2014, 20:19   #4
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Re: handheld compass- magnetic clip-on errors!

I've had good results with the basic davis type that you hold at arms length. Got to give them time to stabilize and not rotate too fast from bearing to bearing or lower the unit, and then raise it again. Only about 5 degrees of accuracy, but satisfactory with some decent fixes if you are sensible. And the puck type although it should be more accurate the results dont seem much better in the real world. The ones we use are like this one.

http://www.austinkayak.com/products/...g-Compass.html

I think the plastimo iris 100 looks better but its much more expensive.
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Old 06-08-2014, 20:43   #5
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Re: handheld compass- magnetic clip-on errors!

Thanks for the feedback. When I next change my specs out I'll not add the magnetic clip on sunglasses. In the meantime I'll look out for some of the recommended handheld compasses.

cheers foz



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Old 06-08-2014, 20:55   #6
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Re: handheld compass- magnetic clip-on errors!

Uhh, Foz, on all the magnetic clip-ons that I've seen, the magnets were on the clip-on part, not the base glasses frame. Dunno if yours are the other way around, but possibly just removing the clip-on part whilst taking the bearings would cure the problem.

Perhaps, perhaps not, but worth checking!

Jim
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Old 06-08-2014, 21:04   #7
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Re: handheld compass- magnetic clip-on errors!

Jim. It seems mine have pretty powerful magnets in the frames. They are also transitions so I wasn't wearing the sunglasses add ons(only use them when I'm driving). The frames change the reading anywhere from 15 to 60 degrees. I tried to work out a deviation for them but it wasn't consistent! My prescription is about -10.5, so I'm pretty lost without them. I have contacts for swimming and sports but don't usually don't keep them in when I need to do any reading, because then I need to put on reading glasses. Growing old can be a pain!






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Old 06-08-2014, 21:56   #8
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Re: handheld compass- magnetic clip-on errors!

I'm a gadget guy. I like and use an app on the iphone/ipad called compass eye. Free and works a treat at arms length as it uses the camera on the phone
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