Magnetic Compass

[briansuddon]

The magnetic compass on the dash of my Rib was very accurate since purchase, however just recently it is 40-50 degrees out. Nothing has been fitted or altered to the boat during this time. Thinking that the compass may have developed a fault I bought a new one and on fitting, it is still out by the same amount. Thankfully money not wasted as I need a compass for another Rib that I am doing up. Does anyone have any explanation or know if they can be adjusted. It is a Plastimo offshore 75 flush mount compass.

[Last Tango]

Originally Posted by briansuddon

The magnetic compass on the dash of my Rib was very accurate since purchase, however just recently it is 40-50 degrees out. Nothing has been fitted or altered to the boat during this time. Thinking that the compass may have developed a fault I bought a new one and on fitting, it is still out by the same amount. Thankfully money not wasted as I need a compass for another Rib that I am doing up. Does anyone have any explanation or know if they can be adjusted. It is a Plastimo offshore 75 flush mount compass.

40-50 degrees isn't going to "adjust" out.

VHF extension speaker, handrail, different fuel tank, only on the trailer or in the water? Magnetic mounting screws?

Tried the boat at different locations in case it's a local anomaly?

Does the compass work ok when it's nowhere near the boat?

[Pikey Dave]

Originally Posted by Last Tango

40-50 degrees isn't going to "adjust" out.

VHF extension speaker, handrail, different fuel tank, only on the trailer or in the water? Magnetic mounting screws?

Tried the boat at different locations in case it's a local anomaly?

Does the compass work ok when it's nowhere near the boat?

[emoji106]+1 adjustment is good for around 5-6deg on a small cheap compass, which at the end of the day is a moot point on a bouncing RIB. Anyone who can maintain a straight course on a RIB, purely on compass alone is a better man than me.

[hobbit555]

Have you changed your belt buckle or phone or similar?

[Last Tango]

Originally Posted by hobbit555

Have you changed your belt buckle or phone or similar?

Handheld VHF in your pocket ?

Anything with a loudspeaker will have a powerful magnet in it and can still effect a compass at a metre plus away.

[boristhebold]

Originally Posted by Last Tango

Handheld VHF in your pocket ?

Anything with a loudspeaker will have a powerful magnet in it and can still effect a compass at a metre plus away.

I once went to install a sub woofer in my console, had the rib on a trailer and the sub woofer in my hand as I stepped onto a step ladder to climb into the rib, even on the first step of the ladder I could see the magnetic compass moving which was about 1.5m away from me, they are very sensitive, anything nearby could be effecting it.

If you haven't changed anything recently check the wiring inside the console, perhaps some wiring loom has moved or fallen down somewhere due to boat slamming etc which may be effecting the magnetic field.

[xpertski]

Just seen this thread and wonder if there is much merit in a fixed compass on a rib? Most will fit well within 1m of a stereo/ vhf, which would presumably affect the compass? Is it better to just have a quality hand held compass for when required?

[GuyC]

This was discussed not too long ago associated with a thread on console arrangement. I think the general consensus was that a fixed compass is useful for orientation purposes when there isn't any landmarks. The handheld comes into its own for specific bits of navigation.

As for the OP. Does it still point in a consistent direction if you rotate the boat? It sounds poorly to me but it would be worth seeing if you can replicate the situation with another compass.