Hi Chelsea, been a few days writing govt policy papers ... one does what one can to live.
In answer to your immediate question - and in doing this we may achieve the apparent limit - I would never use a solution that involves anything other than Windows when the problem is more than 24 hours offshore.  That way you can set up downstairs and upstairs solutions with Expedition potentially separate i.e. installed independently on both devices and having the possibility of GPS input separately.  Sure, 6 hour race, who cares if the iPad doesn't behave properly?  Walk downstairs or use your phone w Navionics.
And yes, I'm accustomed to wet boats whose electronics are dodgy after a year or so .... generously.
Try PM'íng again if you wish.  Campbell Field definitely has a greater wealth of experience in these things than moi.

Kite, there is certainiy an error there.  As Barne suggests, do speedo and compass calibrations as a first step.  Until they are in good shape, nothing else matters.
Presuming this to be a recent problem, also find your compass in the boat and check it isn't loose and no metal has mysteriously been placed near it.

Phil
That utility exists within the KND suite, and very nice too ..... however I find a waterproof notepad and pencil more robust and flexible.

In simple hardware terms, I can vouch for running Expedition over a NUC, my home desktop is a NUC Extreme Ghost.  Waterproofness would be an utterly different issue, I dunno about taking one to sea.

As Campbell is in the middle of the Atlantic right now, I wouldn't expect a quick reply.