Friday, March 6, 2015

Rearranging the mast top

The arrangement of poles and instruments at the very top of the stack is called the "stinger".  Or at least that's what I call it, mostly because I heard someone else call it that and I thought it was a great name.

Here's the original arrangement.  It worked fine except for one problem.  The Sat Compass is all the way aft.  It's got a good clear view of the sky which is good.  The various devices are show in the picture.

Original stinger arrangement

 The problem is that it hangs out near the exhaust stack, and when there is a tail wind the soot and heat gets blown up towards the compass.  In the picture below you can see the sooting on the underside.  We had a couple of times when the compass locked up on us, and both times we had a strong tail wind and there was a lot of soot.  The theory was that the device was overheating, so I wanted to get it away from the exhaust.

Sooting suggests we are too close to the exhaust stack.
In the new arrangement the sat compass has been moved forward.  It's equally clear of obstructions, and now well away from the exhaust.  The secondary GPS and weather sensor are on the two side "horns".  I eliminated the XM weather.  The lightening brush still needs to be reinstalled, and it will go aft since it doesn't care about heat from the exhaust.

New stinger arrangement

Doing this was actually a royal pain in the ass.  The N2K cables for each device thread through the stinger and down the stack.  And they only come out through the top, so two of the three had to be pulled all the way out, then snaked back through, and down the stack.  This also included removing the connectors at the lower end, then reinstalling them after re-routing.  But now it's done.  One more thing off the list.

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