One of the presents to the us and the boat was a new Garmin 421 color chartplotter. I wanted something compact to add to the pedestal guard, it is actually only about 2' from your nose when you are sitting at the helm station so you don't need a giant display. I had a spot all picked out for the mount, just under the loop of the guard, mounted on the SS cockpit table mount. Pefect! I snuck the whole thing down to the boat before wrapping it to make sure my measurements were accurate, did not pull out the mounting instructions though. I held the unit in place with the composite mounting bracket in place and was amazed to see the binnacle compass start to spin! An "oh shit" moment. It never occured to me that there would be an issue with the innards of a small chart plotter interfering with with the compass. After some trial and error I found that the interference would go away if the chartplotter was on top of the pedestal guard instead of under it so I wrapped it and put it under the tree. Upon review of the installation instructions yesterday morning, the safe distance from the unit to a compass turns out to be 26".

If it ever stops snowing here, I'll head down and check things out again. Maybe measure a little more exactly as well. I guess the good news is that I removed the compass cover before messing around and was paying attention.