I don't think there is a written spec, a few inches of airspace is what they recommend. If you are mounting it vertically it will shed heat a little faster.
You are over thinking it. The prop is behind the transducer anyway, but if you can stay 20" away from it I think you won't have any problems. If you are unsure post a picture of your transom and I'll let you know.
Sorry I meant Woody not creekwood, too much wood around here. Your observation about right of way is dead on. It's just a coincidence. The difference between course and heading will be significant if the effects of set and drift are significant. If they are not the difference won't be much. The...
I don't think you have a source for heading info. The Rn300 GPS is a source for position info, and course info from that. Heading requires a heading sensor.
No there isn't. The sizes are considerably different now, and the newest raymarine Axiom MFD's do not have an easy way to hook to the older Sea talk 1 accessories. Sorry.
Kevin if you already have the Garmin cable end and just need to go to Ray end you just cut it off and splice it. I'll get you a part number. If it's a new install, Chris and I both recommend the mix and match and raymarine end. I'm sure there was an error in translation.
Is the E140 and raypilot on the seatalk network? The raypilot has 2 connections on the back for seatalk1. Hopefully one goes straight to the E140. The other one should go to the course computer. This is not mandatory though.
Kevin that sounds like a pretty solid plan. I wouldn't connect the current P79 with a mix and match. Just cut the end off and go direct with the raymarine end. Get the mix and match for the new one.