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Blair · 06-28-2009, 05:19 PM

Thanks guys - not immediately concerned with the issue of 'swinging' the compass to correct for variation due to extraneous metal-related forces nor geographical deviation in that similar context. I have the deviation card -somewhere! That's another story perhaps.

As mentioned I am able to correlate with the GPS on various headings and can adjust/record variation and deviation as in 'swinging'. My query really is that I have seen people with "Northern Hemisphere" handhelds and being told that the imbalance of the needle when used in the far South can cause a 'catching' of the needle which tilts quite a lot and whether this 'extra' error causing factor could also be apparent for Northern fluid filled compasses? Intuitively I think not as the range of tilt in a fluid filled compass seems far greater than the needle has in a slim handheld but I thought I would ask the wise ones.

By the way Kiwi, I can agree that magnetic compasses on a bouncing fizz boat are very much a fall back system these days especially with GPS.

I admit that I have gone over the Kaipara Bar quite deliberately, no accidental crossings as yet, and that it itself is an adventure even in decent conditions - up to 10 metre breaking Tasman Ocean SW swells and 6 knots of tide if you were otherwise stupid about weather or don't pick your tide times! I think the wreck tally at the Graveyard/North Head was something like 100 ships in a 100 years until it was closed as a NZ port of entry. Reputably the biggest harbour in the Southern Hemisphere but no lights or official nav buoys at all these days - good fishing for the good keen bloke/sheila though.

06-28-2009, 05:19 PM	#13
Blair Registered User Join Date: Mar 2008 Location: Kaipara Harbour Posts: 61	Thanks guys - not immediately concerned with the issue of 'swinging' the compass to correct for variation due to extraneous metal-related forces nor geographical deviation in that similar context. I have the deviation card -somewhere! That's another story perhaps. As mentioned I am able to correlate with the GPS on various headings and can adjust/record variation and deviation as in 'swinging'. My query really is that I have seen people with "Northern Hemisphere" handhelds and being told that the imbalance of the needle when used in the far South can cause a 'catching' of the needle which tilts quite a lot and whether this 'extra' error causing factor could also be apparent for Northern fluid filled compasses? Intuitively I think not as the range of tilt in a fluid filled compass seems far greater than the needle has in a slim handheld but I thought I would ask the wise ones. By the way Kiwi, I can agree that magnetic compasses on a bouncing fizz boat are very much a fall back system these days especially with GPS. I admit that I have gone over the Kaipara Bar quite deliberately, no accidental crossings as yet, and that it itself is an adventure even in decent conditions - up to 10 metre breaking Tasman Ocean SW swells and 6 knots of tide if you were otherwise stupid about weather or don't pick your tide times! I think the wreck tally at the Graveyard/North Head was something like 100 ships in a 100 years until it was closed as a NZ port of entry. Reputably the biggest harbour in the Southern Hemisphere but no lights or official nav buoys at all these days - good fishing for the good keen bloke/sheila though.