Rebalancing Compass for New Zone

[Reefmagnet]

I have a brand shiny new compass that came with the boat that I just purchased. The only problem is it was purchased overseas and is obviously not balanced correctly for my current zone as it sits tilted at rest. The compass is a Silva 1000. Does anyone know if it can be rebalanced economically?

[btrayfors]

Originally Posted by Reefmagnet

I have a brand shiny new compass that came with the boat that I just purchased. The only problem is it was purchased overseas and is obviously not balanced correctly for my current zone as it sits tilted at rest. The compass is a Silva 1000. Does anyone know if it can be rebalanced economically?

I'd ask the local dealer:

Fiskars Australia/NZ
39-41 Fennell Street
Port Melbourne
Australia
Tel: +61 3 8645 2400
australia@fiskars.com
newzealand@fiskars.com


or the manufacturer, Silva in Sweden (terrible website, but you can find their contact info if you try).



Bill

[GordMay]

I don’t believe it’s practicable to re-balance your compass for zone 5, covering Australia and the southern oceans; but, as Bill suggests, I'd ask.

Most compass makers balance their compass needles for 1 of 5 Geographic Zones.
The needle of each Silva Compass is counterbalanced (centre of gravity is below the pivot point of compass needle) for a specific Magnetic Balance Zone. The compass is intended to work precisely, only within it's designated Balance Zone.

[boasun]

IF you are high latitudes your compass may be dipping... because the magnetic poles are in the earth and as you near the poles the compasses will dip and point downward toward the poles... A natural occurance. And as you near the equator the compass will be level with the earth.

[Jim Cate]

Originally Posted by Reefmagnet

I have a brand shiny new compass that came with the boat that I just purchased. The only problem is it was purchased overseas and is obviously not balanced correctly for my current zone as it sits tilted at rest. The compass is a Silva 1000. Does anyone know if it can be rebalanced economically?

G'Day RM,

I can't speak specifically about Silva compasses, but some years ago I had a Danforth binnacle compass rebalanced by an independent marine instrument service in Auckland. The price, including a new dome was far less than a new one at that time. We had them balance it for the "equatorial" zone, and that seemed to work in all the following areas that we cruised in that boat.

In our case, the compass was balanced for the San Francisco area, and by the time we were at about 25 degrees south it started hanging up, and before we reached New Zealand it was totally frozen in place. Interestingly, some fellow SF area sailors who were in loose company with us had a Ritchie compass which did tilt a bit but continued to function all the way. So, it seems that some designs are more susceptible to dip errors than others. If you have to replace the compass, you might keep that in mind!

Cheers,

[GordMay]

Silva reduced the needle dip tendency by placing the centre of gravity below the pivot point of the needle. Also, the needle of each compass is counterbalanced for the middle of the magnetic zone where it may be used. Hence, you must change the needle to change the compass’ operational zone.
Silva designates Zone 5 as “MS”.

[Jim Cate]

Originally Posted by GordMay

Silva reduced the needle dip tendency by placing the centre of gravity below the pivot point of the needle. Also, the needle of each compass is counterbalanced for the middle of the magnetic zone where it may be used. Hence, you must change the needle to change the compass’ operational zone.
Silva designates Zone 5 as “MS”.

Hmmm...

Gordy, it seems to me that all compasses must have the COG of the card/needle below the pivot point, or else the card/needle would just tip over and lie there whining about the unfairness of life in a bowl!

I think the issue is to have the card (usually not a flat card anymore, but some sort of 3 dimensional structure) designed so that when the inevitable tipping occurs it doesn't hang up.

I believe that the usual practice is to simply have tiny weights placed on the card to counterbalance the dipping force experienced in the normal zone of operation. Moving those weights to a new position is what the folks did to our Danforth compass in NZed.

Cheers,

Jim

[Reefmagnet]

Hey thanks for all the info guys. Fortunately the compass still works at the tilted inclination (FYI it tilts left side down and to the back - it's a bulkhead mount style). I think a new one is something around $250 so I guess it would be worth spending a few bucks to get it fixed and Jim it does have a hub-cap style card so I'd imagine it is balanced with weights along the rim. Anyone know of someone in Australia that does this rebalancing sort of thing?