Help replacing compass

[vlbaysailor]

We need to replace the compass on our 2007 42' catamaran. The existing compass is a Plastismo offshore 105 that has leaked out all its fluid. I have a couple concerns with replacing this with the same model
1. That model specs say for boats to 30 ft. The compass is mounted about 10 feet forward of the stern. I don't know the technical issues which drive sizing for compasses, but I am assuming the placement forward vs a standard mono is why this compass was installed OEM??

2. The compass has no visable damage, but has leaked all its fluid prior to us purchasing the boat. Since we don't know how long it's been without fluid, we are not sure it is fixable. I have never had a boat compass fail at 10 years of age. Do we think this is just an anomaly for the brand, or should I look at a different brand.

Any advice is appreciated.

Thanks
Vicky

[jt11791]

Compass size is a matter of convenience. How far from the helm is it, and how good are your eyes? Get one big enough that you can read it easily from the helm.


Plastimo makes good compasses, Ritchie is the other major brand. I might try repairing what you have, if you can find the leak, refilling it is not a big deal.

[foggysail]

Originally Posted by vlbaysailor

We need to replace the compass on our 2007 42' catamaran. The existing compass is a Plastismo offshore 105 that has leaked out all its fluid. I have a couple concerns with replacing this with the same model
1. That model specs say for boats to 30 ft. The compass is mounted about 10 feet forward of the stern. I don't know the technical issues which drive sizing for compasses, but I am assuming the placement forward vs a standard mono is why this compass was installed OEM??

2. The compass has no visable damage, but has leaked all its fluid prior to us purchasing the boat. Since we don't know how long it's been without fluid, we are not sure it is fixable. I have never had a boat compass fail at 10 years of age. Do we think this is just an anomaly for the brand, or should I look at a different brand.



Any advice is appreciated.

Thanks
Vicky

I would look for a rebuild kit. Last year I rebuilt the Ritchie mounted on our boat. Not a bid deal. The oil used in them is similar to or in fact mineral spirits.

An interesting thing about my Ritchie along with another Ritchie that came with my old sailboat. My present compass has a deviation chart that would let one believe the thing was almost perfect. IT WAS NOT as checked with my GPS numerous times. Whomever paid for the correction got @#$%! What I did to correct the compass was to move it to a flat surface off the boat, plywood in my case. Next I took a bore sight to a known object that I could relate to on a chart so I knew the angle I was pointing at.

Next I rotated the compass body and adjusted the tuning magnets to set the card’s angle to that pointing at that known object. Took some time but I easily was able to get it so that regardless of the degrees of rotation of the compass body, the card remained pointing at that known object which was also tracked my chart angle.

My compass now tracks my GPS; did the same thing years earlier for my sailboat’s compass.

[Jim Cate]

What I did to correct the compass was to move it to a flat surface off the boat, plywood in my case. Next I took a bore sight to a known object that I could relate to on a chart so I knew the angle I was pointing at.

I don't quite understand your correction method... the corrections that you make are specific to the compasses location on the boat with all its stray magnetic fields. Doing it off the boat does not seem to accomplish this.

Perhaps I misunderstand what you did...

Jim

[foggysail]

Originally Posted by Jim Cate

I don't quite understand your correction method... the corrections that you make are specific to the compasses location on the boat with all its stray magnetic fields. Doing it off the boat does not seem to accomplish this.

Perhaps I misunderstand what you did...

Jim

Jim-

There was no magnetic interference what so ever to the compass itself from its location mounted on the boat. So the compass card should have remained pointing at where ever magnetic north happened to be. But when I rotated the compass body, the thing the compass was mounted into, magnetic north changed by +10 degrees to -5 degrees.

Most inexpensive compasses DO NOT have correction magnets which in my opinion is good! So if you have a compass with correction magnets it must be tuned by swinging the entire boat.....if there is a magnetic interference to the compass caused by something on the boat.

Because there is/was none where my compass was located, rather than swing the entire boat, I just rotated the compass itself and made the adjustments to keep the card’s magnetic north constantly pointing in that direction.

Sure, I could have just replaced the compass with a less expensive model without built in tuning but still expensive. What I have now works just fine without the huge errors it originally had.