ChathamSailor
Active Member
Is neatly £400 the charge for a compass adjuster? If so is it not cheaper to just buy a new steering compass ?
Compass Adjuster
- Thread starter ChathamSailor
- Start date
Star-Lord
Well-Known Member
Alan Hopton did mine in Falmouth for a fraction of that! It was in 2015 but.
thinwater
Well-Known Member
A new compass must be adjusted to the boat (mag field unique to the location on the boat).
That said, it's not that hard to do yourself. Read the instructions. Traditionally, you go out and motor back and forth on some measured ranges, at 90 degrees. Remember, you are adjusting the compass to the local earth field, not to a GPS course, since they are not the same.
davidaprice
Well-Known Member
Arthur Ransome describes the process, called 'swinging the ship', in "Racundra's First Cruise". He used a special round wooden dolphin which he found in Helsinki harbour: the boat is moored to the dolphin and warped round to face each heading (which the compass adjuster determined by pointing the boat at known landmarks ashore). The dolphin he used is gone, but another is still in existence just off the end of our club's jetty, here you can see it in Google Street View: Street View · Google Maps . I must say I've never seen anyone using it.
ChathamSailor
Active Member
I have done this and produced the card, but the errors are large, hence the need for magnets which I cannot do.
johnalison
Well-Known Member
I did this once, over 40 years ago. I bought a small book with a catchy title something like ‘Compass adjustment’ and learned about the different coefficients that needed to be corrected. Although a proper adjustment is clearly a complex and skilled business, in practice you only need to correct for the two coefficients that are maximum at N-S and E-W to get a satisfactory result.