I am in the position of having to change out the navigation electronics in my 1985 Hunter 31. The original instrument was the NAV 5 system from SR Instruments. It included a cockpit display mounted up near the cabin vents and a cabin display mounted near the navigation desk. I’m planning on going to Raymarine ST- 40 instruments, specifically starting with an ST-40 depth/speed bidata display, cockpit only. Perhaps I’ll add wind at a later time. The installation will require running the transducer cables from the existing thru hull locations to where the display will be mounted. The depth thru hull is located in the cubby under the V-berth, and the speed thru hull is located under the sink in the head. I assume a good portion of the new cable run will be under the sole of the boat. My questions are: 1. The old thru hulls required a 2 1/8” hole. The new Raymarines require a 2” hole (the flange in nearly 3”. Is there any problem in mounting the new thru hulls in a slightly larger hole? 2. Does anyone have experience running wire under the sole of this boat? There is a fiberglass strut which extends the width of the boat near the entrance to the head, and another at the entrance to the galley. How do I wire through or around those? Does the floor need to come up? Any advise regarding snaking these wires would be greatly appreciated. 3. Where is a good place to mount the new display? I am considering the bulkheads on either side of the companionway. They appear to be hollow with about 1 ½” of space between the inner and outer walls. Can the wires run down through the hollow area and then into the electrical panel wall and finally into the floor? Has anyone done this? Is there a better location I have overlooked? Any help would be greatly appreciated. Paul I.