sketchrbob
New member
Hi Everyone, This, and the following question will wind up my Compass Questions. Since many of you will not have had a sticking pivot, I will answer my own question.
A "sticking pivot" is a term describing a condition when the compass card no longer rotates on the pivot smoothly. It tends to hesitate at certain headings and actually hang there for a bit. When the condition becomes acute, the card may just stick at a certain heading.
The pivot is actually an osmium tipped pin which rests on a cup which is actually a commercial sapphire jewel. It is very hard and designed to last a long time. If a compass is dropped, the jewel may crack, or the pivot may become blunted. Also if there is a lot of vibration from the engine, over a period of time the pivot may become worn on one side and stick at the worn spot.
Once this condition develops the only solution is to replace the jewel and pivot. The next question is it better to buy a new compass or have the old one repaired? Compass repair shops will be able to answer this question. But in general the less expensive compasses will be cheaper to replace than repair. For most 5" compasses it is worth repairing. Most C Dory owners have the type that will be most economical to replace the compass.
You can check your own compass to see if the jewel and pivot are good by using a screw driver or a small magnet to pull the card out of position by a few degrees -- not over 5°. Remove the magnet and the card should return to the original setting. If it just sits there not moving then the pivot is worn.
So that is the story on sticking pivots. I hope none of you have them. But if you do you will know the story about them.
I have enjoyed sharing posts with many of you. Although I will not be posting new questions, I will be available for any of you who wish to contact me.
Thanks for your interest. Bob W
A "sticking pivot" is a term describing a condition when the compass card no longer rotates on the pivot smoothly. It tends to hesitate at certain headings and actually hang there for a bit. When the condition becomes acute, the card may just stick at a certain heading.
The pivot is actually an osmium tipped pin which rests on a cup which is actually a commercial sapphire jewel. It is very hard and designed to last a long time. If a compass is dropped, the jewel may crack, or the pivot may become blunted. Also if there is a lot of vibration from the engine, over a period of time the pivot may become worn on one side and stick at the worn spot.
Once this condition develops the only solution is to replace the jewel and pivot. The next question is it better to buy a new compass or have the old one repaired? Compass repair shops will be able to answer this question. But in general the less expensive compasses will be cheaper to replace than repair. For most 5" compasses it is worth repairing. Most C Dory owners have the type that will be most economical to replace the compass.
You can check your own compass to see if the jewel and pivot are good by using a screw driver or a small magnet to pull the card out of position by a few degrees -- not over 5°. Remove the magnet and the card should return to the original setting. If it just sits there not moving then the pivot is worn.
So that is the story on sticking pivots. I hope none of you have them. But if you do you will know the story about them.
I have enjoyed sharing posts with many of you. Although I will not be posting new questions, I will be available for any of you who wish to contact me.
Thanks for your interest. Bob W