Steering (Magnetic) Compass

[Andrew]

Hi All,

Thinking of getting a new steering compass, (did the forum search first but there's almost not detailed info on the forum about this piece of navigation equipment.)


I'm looking for one that is:

large enough card to watch easily (esp in a rough sea)
Lubber line
outside reading card, (and top too..?)
Can take about 25 degrees heeling (and bobbing about)
Dampened card
red 12v light for night use (probably when its most needed)
Probably bracket mounted (where and how do you mount your compass, how is it?)
Economical price
What color card? (have seen blue ones, are these better than black?)
Cardinal points and/or 360 degrees?
bearings? lifespan?

David's described his compass on another posting, its a "Plastimo Iris 100" dual purpose steering and hand-bearing type with battery lighting . viewtopic.php?f=4&t=1121&hilit=compass

only after a steering compass for now, (see handbearing c"s below)

Also i have a small Suunto hand-bearing compass already (and use my red head torch light at night), it was from mapping work and is high quality, weather resistant and seems to do the job (but of course a dedicated marine one would be ultimate, like my Dad's 1960's navy rubber hockey puck one with a radioactive? light source..they didn't know much about cancer in the old days?!)
(also have a plastic flip top grid Suunto hiking compass - tried it, blue tacked to seat but its too small to read)
Both of these are land compasses.

I had a 3"?-4"? card, bracket mounted, domed glass, 12v red lit compass came with my my Hartley 16 and it was good (forgot the brand). Mounted on the 4" high hatch coaming, under the sliding hatch (perhaps not an option in I563? much narrower coaming)

Had a 4" card, c'pit bulkhead mounted, domed glass, 12v red lit compass (forgot brand) on my Endeavor 24. Also good.

Ozzie, you mentioned being blindfolded on moonless night (in an unlit bay?) and getting someone to spin the boat around a few times, then see if you have any idea where you are..that got me thinking! Disorientation is a real danger. At the moment i'm minimal with an $20 "Azimuth 100" (miniature, too small to steer by but ok to know if its N, S, E or W or between those cardinal points, won't go off of a 180 deg course change at least!)

It would be great to hear your thoughts and details about magnetic compasses, or ones you might prefer.

Plastimo, Silva, Ritchie, Azimuth, are some brands i've seen on the net and in boating stores.

Cheers

[Topaz Bill]

I bought a Plastimo bulkhead mounted compass and installed it on the starboard side cabin bulkhead in cockpit. It's totally useless for two reasons. I saved money by buying one without a light (silly), and the compass varies by plus or minus 30 degrees bepending on heading. I think this is caused by electrical interference with clumps of wiring behind it. It's a dilemma where else to mount it, the compasses on my Autohelm and Garmin GPS always concur with about 5 degrees, so I rely on them which is not a good idea.

[Andrew]

Gday Bill,

Thanks for your honest feedback. Looks like any compass might not like electrical current (electromagnet effect?) right near them.
I will try to keep my next compass away from the electrical box/fuses.

May have to remove any ferrous metals near the compass area, (eg battery hold down clamp..) They could cause compass deviation.

Yes, i'm definitely for a red light to see it at night, when its most needed. (Red wont impair night vision,)(but see Ritchies have green lights) 12v wired to cabin power for it too.

I used my red LED headtorch to see my barely visible 38mm compass, it works but is a sub-standard method. Nothing beats a well-lit compass as it becomes a kind of homing beacon for the eyes, rather than having to look around to find it all the time (then barely bothering to look for it).

[Andrew]

This one is very cheap, has 12v light. Azimuth 200 series .. https://www.roadtechmarine.com.au/compa ... s/p/MNA015
Its $30 at Road Tech Marine and $50 at Boating and RV (pays to shop around)
But wonder if a 65 mm compass card is big enough for I563 use?

This Silva 70P bulkhead mount looks high quality https://www.whitworths.com.au/silva-70p ... ad-compass

[Andrew]

Im thinking that the Silva 70 bulkhead compass with light fitting might be best bet

Read its online instructions, warning about away from anything ferrous or 12v wiring. Tested my location with handbearing compass,, and had 5 deg deviation. Its was mostly the VHF handset causing it, (magnet inside?) , so will remount its clip away from it.

[Andrew]

Thanks for tips, my boat is a similar overall situation with the wiring. So the best spot is likely the port bulkhead.

No-one in Tsv stocks "Silva 70P"(lit) so put a phone order in at Whitworth's Cairns. Its $140 for compass and $30 for light fitting. A bit cheaper than the competition's (Plastimo mini contest ~$300) Silva is a Swedish company, with marketing association with Brunton USA (high quality exy compasses) Silva outsourced manufacturing from Sweden to China a few years ago..

here's a link with more info https://www.theboatwarehouse.com.au/coc ... d-compass/

[Andrew]

Update on compass. Finally fitted my Silva BH compass to the port bulkhead (sorry only took 2 years to get around to it..better late than never http://teria563.blogspot.com/2023/02/compass.html no red-LED yet.

Also renewed my field compass another Silva, (the old one got a bit dissolved probably from HCL at work..!)

Here's a pic

Teria's Silva 70P bulkhead compass (can also deck mount)

(NB finally, after years, had to let microsoft upgrade my computer from windows 10 to 11, and suddenly can easily resize pic's to fit on this forum! )

[Peter T]

Hi Andrew, interesting thread. I also have been having thoughts regarding a compass. The wiring in my boat used to route through the port side, but I have completely re wired the boat. My battery is in the fore peak and I have the two heavy battery leads running through the keel section, up along the side of the centreboard lifting cord pipe to my power panel etc which is mounted on the inside of the starboard cockpit bulkhead. Charging cable from the Port side mounted outboard motor routes across the stern and down the starboard side to the switch panel. Also, the VHF aerial is wired down the starboard side to the aerial mounted on the Starboard pushpit rail with the radio mounted with all the other electrical stuff. I figured that this should leave an interference free spot on the port cockpit / cabin bulkhead.
This then just leaves what to do with the autohelm. Port side mounted leaves it close to the outboard but allows single person seating on the opposite side to the outboard and therefore nicely balanced port to starboard. If I mount the autohelm on the starboard side, then it's close to the aerial and charger cabling from the motor as well as taking up good seating space. What to do ?
Then, I also have a GPS / plotter/ compass mounted on the cockpit side of the electrical panel.
Do I need a separate compass ? Do I rely on the plotter ?
Will the plotter be effected by the electrical panel ?
It's all getting really hard to work out the best scenario. It reminds me that there is not a lot of separation space in an 18ft trailer sailer.
Then I thought of using a compass as used on steel boats with the steel balance thingies mounted each side of the compass so that interference from outside sources can be adjusted.
Thoughts please everyone

[Andrew]

Thanks for your detail on electrical layout in relation to compass positioning Peter,
Yes there's not that much space to play with.

I've kept the nearest electrics about 300-400mm away from my compass, hope this is enough (it's the VHF unit, and wires) most of the other electrics are on starboard side away from it.

Haven't got the autohelm dilema..yet.. though it would be a nice problem to solve one day . Huntingford helm impeder (from dinghy cruising) and experiment with bungy's etc for awhile.

http://teria563.blogspot.com/2022/09/se ... peder.html

My GPS chart plotter and sounder readouts are about 500-600mm away from compass. in an unusual location - on experimantal DIY step/seat at companionway. The plotter mount is below the compass to port, the sounder is below the electrical (spagetti box) to starboard (behind rectangle aluminium plate, perhaps a potential future instrument spot, it looks like it was a past location patched over)

Teria companionway and instrument layout (compass under alfoil sun cover)

[Watto]

Thanks Andrew.

I’ve been wanting to fit a compas to my boat and was wading through all that is available. I think the Silva looks the goods.


How does the illumination kit work? Is that installed to the inside of the outside. Couldn’t see it in the manual.