I placed the Halo 20+ as far forward as possible on the T-Top, with a Scanstrut 6" Aluminum Powertower base, such that the M8 bolts for the Scanstrut were all "nutted" on the inside cavity of the T-Top. The cavity isn't very deep beyond the radio panel, so I had to move the 360° light to give room for the radar.
That part of the T-Top slopes downward going forward, so the radar ended up at the correct angle — it leans forward about 3° down at no-wake and about 3° up while on-plane — a perfect compromise. I originally mounted the radar with a Scanstrut 4° wedge to get me closer to 0° level on-plane, but that resulted in the radar picking up too many waves when idling slowly.
The fiberglass of the T-Top above the cavity is very thin, and very weak. It can't even hold my 360° light without significant wobble. Therefore, I built up an internal buttress (using HDPE and stainless steel fittings) that mates the bolts of the T-Top frame to the rear bolts of the Scanstrut. I also added a plate of HDPE to stabilize the mounting point of the 360° light. My buttress also serves as a bulkhead to mount the NMEA backbone extension and other wiring. (The main backbone is in the helm closet, and I also have a backbone extension at the bow for my Motorguide trolling motor.)
I'll eventually add a VHF radio with AIS up there, but I haven't gotten around to choosing a radio yet. Not only is the NMEA backbone up there now, but I also pulled duplex for the radio (and other T-top accessories) when I pulled the radar/Ethernet/power cables. Given how much of a pain it was to strengthen the T-Top for the radar and 360° light, my plan is to mount a fold-down VHF antenna to the rod-holder frame on the rear of the T-Top, and then just route the cable externally into the bottom of the T-Top. That'll also give me the required antenna-to-radar distance.
Speaking of pulling cable, the only channel available for the wiring is the starboard aft tube for the T-Top. The port tube is full stuffed with wiring for the 360° light and speaker cables. It was a b!tch to wire, because the thru-holes in the deck are about 1'' in diameter — much smaller than the tubes! Moreover, to access that starboard aft tube, I had to move the reverse-bucket servos; but that turned out to be a good thing, because the screws holding down the bucket servos were 100% stripped by the dumbsh!t Yamaha factory workers, so I was able to literally lift up the servo unit and move it aside by hand! Also, I discovered that half of the T-Top bolts were
not actually screwed into their fittings!!! Not to mention, most of the screws along the bottom of the deck "lip" have fallen out.
Oh, I should I also mention that I added vents to the T-Top. Where I live in FL, the humidity is nearly 100% most of the time, and when the temperature drops 20° at night, condensation builds up on any surfaces that have a temperature gradient. Every time I opened up the T-Top, the rear T-Top cavity had about 1/2'' of water pooled up inside of it — from condensation, not rain!!!
Radar coverage is fantastic at all speeds. I can see rain, other boats, and flocks of birds from many miles away, kayaks from half a mile, and even
bare pilings from a quarter mile! The majority of the time I go boating, I come back to my home port in the dark, which often means navigating around kayakers and other small craft fishing at night with only a flashlight or headlamp to identify themselves. Also, there are countless unmarked pilings on my way home due to bridge construction. So the radar is crucial for me.
Also crucial — a Simrad NSS 12 evo3s MFD to run the radar, along with the HS60 GPS compass so I've got real-time heading for the radar. The Go12 is totally inadequate for displaying Navionics SonarChart with radar overlay. (Heck, I used to run a Go7 XSR on my kayak, and the Go was barely adequate for running SonarChart and Structure Scan side-by-side! I now have a Lowrance Elite FS 7 on my kayak because the Go was so laggy.) I have the HS60 mounted on the T-Top just inside of the starboard outrigger mount, in the shadow of the radar. I opted for roof-mounting because I wanted to reduce the chances of losing heading-lock when I'm fishing under bridges. If bridge fishing isn't your thing, then I'd recommend mounting an NMEA compass or heading indicator like the HS60 closer to the waterline, so you don't get as much "smudge" when you're bobbing around in big waves.
I have the NSS 12 on an Ethernet network with the Go12 (you'll need to update the Go's firmware to do this) and radar, via a Lowrance NEP-2. Most of the time, I have the NSS displaying Navionics SonarChart with a radar overlay, using heading-up mode, while the Go12 is split-screened to show the HDI Echo image below the boat, and the Active 3-in-1 Structure Scan to the sides. The NSS is generating the 800 kHz A3-in-1 image for the Go12. (The transom-mounted A3-in-1 transducer is connected to the NSS, and the boat's Airmar HDI thru-hull transducer is connected directly to the Go12.) I
can set up the Go12 to display the radar, but it's far too laggy to be useful for night-time navigation.
I really should make a full post about all this.
Sorry to hijack your thread,
@HangOutdoors !