My 2019 goal was to install a new below deck autopilot on our Catalina 36. I had a lot of time to source the parts and no real time line, so I really took my time to try to find the best deal on the parts.

The main choice to replace Hotel Catalina ST4000+ wheel pilot was the lack of reliability as soon as condition was a bit challenging. Also the idea to have an autopilot able to follow a sail point was very appealing!

At the end I am very happy with my choice to upgrade to this B&G system, since the setup we completed few cruises with different wind and sea conditions. The autopilot was always performing perfectly in heading or in wind mode. I really advise B&G technology and most importantly their support team, through facebook messenger, email and phone.


Total cost: ~$3,529 + miscellaneous parts (epoxy, fibreglass, drill bit…)

  • B&G nac-3: $1,100 –|344|2028687|2028716&id=3467058
  • B&G drive unit t1 (used): $1,000 –
  • Simrad controller (used): $99 –|344|2028687|2028714&id=3470315 – $270
  • B&G precision 9 (used): $450
  • B&G rf25 nmea 2000 – $240
  • Edson tiller bronze: $400
  • Drill bit:
  • B&G bluetooth remote: $240


Timeline & Cost

This is how much each part costs me. I am sure I missed a lot of costs like plywood, epoxy and hardware.



autopilot – installed compass precision 9 (used)



autopilot – nac 3 head unit setup



autopilot – t1 ram



autopilot – edson tiller



autopilot – wiring (power + n2k)



autopilot – bilge paint on the shelf area for the tiller arm



autopilot – cut hole in navpod for autopilot controller



autopilot – install rudder sensor rf25n



update triton2 firmware



autopilot completed!


Wiring Diagram

s a wiring diagram, I mostly built it to be able to communicate with B&G when I had some questions about the wiring of the T1 RAM. B&G was very helpful across the complete process.

B&G Compass precision 9 install

to figure out where to set it up, honestly I should have checked with a compass there was not too much variation in this specific spot. Especially with the big fuel tank next to it. I calibrated the precision 9 a couple of times in adding the corresponding offset through the B&G setup tool.

AF1QipNir8PLKWxZAsDJ1hO5bX0dpWm9gvRYTF717GzJw1536 h2048 1AF1QipM3CYSa1XW0rdd0pczRlrvO4YVXwPX2pwH8DkHjw1536 h2048

B&G NAC-3 Head Unit

g special about this effort, except I realized later about the amount of power it would require and the fact I had to add a relay to avoid burn out the dedicated panel switch for the autopilot.

Next I had doubts how to connect motor-sol1 and motor-sol2. B&G documentation is not very helpful… Same for the drive engage…

After I asked for excellent B&G support on facebook messenger! It doesn’t matter, you can connect either way. Just for motor-sol1 and motor-sol2, you need to swap if it turns the wrong way.

AF1QipPQK5wQBXG6rykgpkkkCZiFwY6pMZnNSgz7lGBiw1536 h2048AF1QipPbcpk37FlAkUUDN79OEfn0hC1OuJnzkzSLeVd0w1536 h2048AF1QipNNV2tm8 iuHsPItfD1YIIqRyGOI0qbNzrKu4hlw1536 h2048AF1QipOrcIppKqLGaF8YM5fx1Y0ezcB4pigYvZOvNjmew1536 h2048AF1QipNO7kRHbUhdawQz6 yeqzqvUTuP4et pE7rrww0w1536 h2048AF1QipMeDG2HTfKchcmDKcpGiU8k4eqCmQMM HNH6buw1536 h2048 1AF1QipPFgS3 eR f0ZvUwJwYjeOlmJn5DP96 TQ4laO8w1536 h2048


B&G T1 Ram Install

build a shelf to fit the hydraulic arm:

The T1 Ram has one tip to get it off from his base, all the tools came with the setup.

AF1QipPiN4nyWLcuEcBWu1BXmC2 t5AP3rinoF05Y i w1536 h2048

AF1QipOhdDoEBMY6fd30kU80MavFswei em9hV3A5w3zw2048 h1536 1AF1QipOViPS4d7E1Z2MdvdZ2bpFxrY5njq1MopW2obHbw2048 h1536AF1QipMzbA7 7XIXuPRu7p dsmUP14Y1  MBYMH 54Idw2048 h1536AF1QipNGovyVoNUE50qEaIJLFy3MTeSsOg2HpUz1JyNjw1536 h2048AF1QipMKjAawsIsijuBM64vsrZ 2LNCZIBVSpGyV7PbOw2048 h1536 1AF1QipMXxJHEUMh5kyMHFmEVtwNiZLvQkL7K71NZYWyiw2048 h1536AF1QipOZssAKGcCjol7no59t2AiG19DXYgYpQlFzc0Rkw1536 h2048AF1QipMv7KUU czf2YTXpkddDSE FZVX E 7QnKuzWssw1536 h2048AF1QipM5rrYKvVxgIeyHdON7QsHEz38FJyC FzYcdZLmw1536 h2048AF1QipO30Q8PDFNxONy6LNz0AaboFklQKo3oVuRLmvH5w1536 h2048AF1QipPT04rVQxk99O2RcgBe6Xzb n Mu6uNGHZBwLDvw1536 h2048AF1QipNApz1eYEjJf9F8iklix g 13UPb4DASMVe66pGw2048 h1536

Edson Tiller Arm

th the build of the base for the T1 RAM were the most intimidating. This one actually was easier than expected.

Go slow to drill in the rudder post, if you ask yourself, it’s empty in the middle, so don’t worry, just be very patient, drill very slow speed and push hard at the same time.

This operation is way easier than expected.

AF1QipPksFgzn5ufwyNSMCOrFzGTghBvhS1tj1URVUsTw2048 h1536AF1QipM8Qd9lgHbUiledKzb6q CVtvC3CgZalVEayFYnw1536 h2048AF1QipOqmyRKaIF0nEHe Z2 3GjMn534X617mngneujgw1536 h2048AF1QipPK4Gq4 Gco84kYEdzcP4Ng  0U0ypjtvrAPWWnw2048 h1536AF1QipNGovyVoNUE50qEaIJLFy3MTeSsOg2HpUz1JyNjw1536 h2048 1AF1QipOT4pi6KSAdzclNI80iAFyxz7cSE1XA1vZS6UxXw1536 h2048AF1QipPekCHYp OqSYx471duihrpe9aulefpgdB zLamw1536 h2048 1AF1QipP9LsRw081Ze5tpaqC0kbLuU74jS96QH4IEZ USw1536 h2048 1


  • Most of the power wires were concentrated from the DC panel to the NAC-3


  • The NMEA2000 network connection were concentrated in 3 points around the backbone:
    • Navigation Desk:
      • Bluetooth remote
      • Zeus 2
    • Galley: Precision 9
    • Aft Water Tank:
      • NAC-3
      • Rudder Sensor
    • Helm:
      • Autopilot Controller
      • Triton 2

Autopilot Controller

se my old navpod to fit the controller there. Very good support from B&G again to ship me a bezel.

AF1QipO7vbL6oGoUD 2sf9aEkc 7LDb7tIZkzrHoNaU0w2048 h1536

B&G RF25N rudder sensor

Sensor base: HDPE 1/8″ ($13.38)
  • Rudder Stopper: HDPE 1/2″ HDPE (High Density Polyethylene) Sheet, Opaque Off-White, Standard Tolerance, ASTM D4976-245, 0.500″ Thickness, 12″ Width, 24″ Length ($18.54)
  • AF1QipOQ82fCOnZ8S0ZASU9RPy1nFOD0ih2OEy3EhRjJw1536 h2048 1AF1QipMbkqpbSJa7KFNLsSxm 86Eh2oSFmbP QFDWi5Iw2048 h1536AF1QipPcR4Lc9mi6mIQUROhW7VcnCLzhsXzcz0GLW4x7w2048 h1536AF1QipPvs8rAkJrW8oQnD4KLd1th8GHFTIX31neN6Q34w1536 h2048AF1QipOVUZIYIlx0FQbRLDJa yADcAGPnEMnDScc1ipNw1536 h2048AF1QipNjBUHRjIoOXCEVh476 lgUZv9qYyocK uHFF Tw2048 h1536 1AF1QipN3npkmyT2u i5CQGGlsA8iDQU8kUgcTxwuIAtVw1536 h2048 1AF1QipO3odLlWXejVxcg TO owSqRHypxSQ AMH0xEW9w1536 h2048

    Rudder Stop modification

    hment-id="3675" data-permalink="" data-orig-file="" data-orig-size="1200,1600" data-comments-opened="1" data-image-meta="{"aperture":"0","credit":"","camera":"","caption":"","created_timestamp":"0","copyright":"","focal_length":"0","iso":"0","shutter_speed":"0","title":"","orientation":"0"}" data-image-title="AF1QipPvs8rAkJrW8oQnD4KLd1th8GHFTIX31neN6Q34=w1536-h2048" data-image-description="" data-medium-file="" data-large-file="" loading="lazy" width="1200" height="1600" class="wp-image-3675" src="" alt="AF1QipPvs8rAkJrW8oQnD4KLd1th8GHFTIX31neN6Q34w1536 h2048 1" srcset=" 1200w, 225w, 768w, 1152w, 696w, 1068w, 315w" sizes="(max-width: 696px) 100vw, 696px" />AF1QipMDWNhCXNsuy1JP4hfy4YlCrTlF7PqwVh5ToKrRw2048 h1536

    Firmware update and calibrations

    several update and calibration phases during this setup.

    AF1QipMCEAiC9fPO9jKhy2T8Fk8Wqx  AqMQkrv01tRnw1536 h2048


    Remote Setup

    s to set up the B&G remote, again thank you B&G for their support during this process.


    /" target="_blank" rel="noopener noreferrer">

    This was my 2019 project, way more work than expected but it works great! 🙂

    0 0 votes
    Article Rating
    Notify of
    Inline Feedbacks
    View all comments