Compass Swinging

[Nick2]

My boat has been used soley on the non tidal Thames by last owner for the last four years although I have a 5 year old deviation card for both compasses.

Should I have them adjusted again before setting to sea ?

Sorry to sound extra thick but think I should know.......

Nick

<hr width=100% size=1>Just can't understand why I'm not allowed to bring my new dinghy into the house.....

 

[BrendanS]

Nick,

once you get out on the water, swing it yourself, and you'll see if there are any major discrepancies. If it needs adjusting, that's the time to get an expert in.

Checking it yourself isn't difficult if you understand the basics, and will be very good practice to see if you really understand the concepts you've learnt in theory.

If you or the previous owner have made any changes to electrics or installed any lumps of ferrous metal (generator etc) then it may well need swinging.

If you haven't read up on the theory yet, try it against your GPS first. Just travel in a straight line on GPS and check against compass and deviation card, repeat this at various headings. Make sure the GPS is set to magnetic. Not a purists method, but will show if there are any major errors.

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[Gunfleet]

<<Checking it yourself isn't difficult if you understand the basics, and will be very good practice to see if you really understand the concepts you've learnt in theory.
>>
How will he know? If he's wrong he'll just drown.

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[BrendanS]

Nick is very sensible and safety conscious, and if he's in any doubt, I'm sure he'll ask for advice.

Most motorboaters don't need to have deviation down to one degree or less, as it's near on impossible to steer a course to anything other than the nearest 5 degrees. Purists will disagree, but practical experience says otherwise.

GPS 'swinging' will show any major difference that needs to be checked. If that is the case, it's not that hard to swing the compass by traditional methods if you want to do it that way.

If the compass needs adjusting, I'd get a pro in, unless you are happy to spend hours fiddling.


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[Gunfleet]

Sorry Brendan, my reply had some levity and didn't need the serious response you gave. My mistake and apologies

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[BarryH]

Re the adjustment. I've a Ritchie Explorer. On these there's 2 recessed brass ssrews set at 90 degress to each other. The instructions for the adjustment are fairly straight forward. I adjusted it myself in about 30 mins. Then checked it against gps and handbearing compass in the dinghy.



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[Guest]

Am not trying to be unhelpful or unfriendly, but if you dont know how to check your compass (and assuming that's indicative of your general level of boaty knowledge) then you shouldnt be going to sea for your own sake.

Get yourself on a training course. Yiu'll get much more satisfaction out of your boating and you might well save your neck.

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[Nick2]

Thanks for the advice which I shall follow.

Nick

<hr width=100% size=1>Just can't understand why I'm not allowed to bring my new dinghy into the house.....

 

[Nick2]

I certainly do know how to check a compass but unsure as to whether the swinging bit is within my capabilities. I appreciate your sound comments but should emphasise that I have done my Dayskipper theory and will be undertaking my practical during my very first sea trip with this boat - Just in case you think me a total looney!

I am taking this all very seriously indeed but wanted to check I have it sorted in my smallish brain

I really do hope not to sink...........

Nick

<hr width=100% size=1>Just can't understand why I'm not allowed to bring my new dinghy into the house.....

 

[Observer]

Compass swinging in order to prepare a deviation card is not too difficult if you have somewhere to go to take true bearings (transits are typically used I believe). Compass adjustment may need more expertise. I've never done either, but think I understand the theory of the former although putting it into practice is another matter.

If you do want to have it done professionally, it will cost £130 ish (or that's what I paid in December). Let me know if you need a name.

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