Home‎ > ‎Case Studies‎ > ‎

S/V Raven

S/V Raven is a 1979 Vagabond ketch. After I obtained her in the fall of 2014 I began an electronics refit. The notes from this project resulted in this web page. 

Raven came with a new Simrad AP24 autopilot installed by the previous owner. This system consists of four components: the AP 24 Control Head (the thing in the cockpit you use to turn it on), the AC42 Autopilot Computer (also called the brain), the heading sensor (electronic compass) and the drive unit (which for my boat is a hydraulic ram but a smaller boat would have an electric motor).  When I took possession of my boat I did not know that these four components were hooked together with a fully functioning NMEA 2000 based system called SimNet. I thought it was just some type of random cables used to hook up the autopilot. If I knew then what I know now, I would have bought all Simrad components for the rest of the electronic gear on the boat. Read on to find out why. 

The AP24 Control Head next to a non-working depth and speed instrument that will be replaced. 

This is a standard SimNet seven way hub. The four cables runs to each component of the autopilot (head, brain, compass and ram). Note that unlike every other N2k network, SimNet does not need its own power. 

The autopilot brain is hooked up to the boats 12v power and in turn powers the SimNet network. Note that this autopilot computer does not accept SimNet or any other type of network plug. You must splice a data cable and attach the individual wires by screws. Not very user friendly!

This is the digital compass in the under the sole of the boat in the salon. 

This is the port side of the cockpit. The two instruments on the right do not work. 

My previous boat had Garmin electronics. I loved my Garmin system, but I decided to try something different so I would be a more competent sailor. You end up crewing on a lot of other boat, so there is a learning curve trying to figure out a new system. I began by buying a RayMarine radar package and wind instrument. 

Sizing in the RayMarine a7 Multi-Function Display to see if it will fit in this spot. The wood used in this panel is probably 30 years old and would be difficult to match if replaced with a different piece of wood. 

I made the new console face with a 1/4" piece of StarBoard, a high quality plastic lumber designed for marine applications.

 The finished product. Note that the Ray70 VHF is placed in the cockpit so the helmsman can monitor the radio. This radio receives AIS signals and displays them on the MFD via the SeaTalkng network. 

Raven came with a VHF at the chart table, which was removed. This is not an appropriate place for the VHF on a cruising boat. The person on watch in the cockpit needs to have access to the radio at all times so it is useful in an emergency. There are options to put a radio down below and an extension to the cockpit, but I decided this was not worth expense. Note that racing boats typically have large crews so you can station someone at the chart table to use the equipment there. Cruising boats tend to be sailed shorthanded so it is better to put as much equipment as possible in the cockpit. 

This standard 
SeaTalkng hub is placed inside the port console. Note that one end of the N2k backbone is terminated with the little blue plug. The other blue backbone line goes down below to an iTC-5 transducer to SeaTalkng converter discussed further on. The three white spur cables go to the VHF, the MFD, and the i70 Instrument Display (discussed later). 

The iTC-5 transducer to SeaTalkng converter is mounted in an electrical cabinet down below. This device's job is to convert NMEA0183 signals to NMEA2000.  Note that there are three SeaTalk cables, one red and two blue. The red one is for 12v power to the entire SeaTalk network. One of the blue ones goes to the SeaTalk hub that was previously shown. The other blue one leads to an In-Line Terminator which allows it to be used as a spur for the through hull DST800 depth sounder/speed paddle which is discussed in this video

The RayMarine anemometer on Raven's mainmast. This is the only device that uses the 
iTC-5 transducer to SeaTalkng converter. As of this writing in late 2015 RayMarine does not make NMEA2000 wind vanes, requiring the purchase of expensive converters such as the iTC-5 or the i60

This is the back of the RayMarine a7 MFD, the heart of the system. These wires are ( from left to right) are the proprietary radar data cable, the SeaTalk spur, and the power cable for the unit. The unused proprietary port on the left side is for sonar. 

A thousand dollars spent for radar and it won't do an overlay on the nautical charts! RayMarine insists on having a heading sensor (digital compass) data to perform this feat. Other manufacturers can do this trick with GPS data. It is not clear to why RayMarine has made the choice. The good news is that I do have a heading sensor on the boat. The bad news is that it is on the separate SimNet network for the auto-pilot system. Read ahead to see what I did. 

The versatile i70 instrument is a second mini multi-function display. It can show any data except for nautical charts. Since Raven is a sailboat I leave it in this wind mode. 

Both the i70 and the autopilot control head are designed to be daisy chained with other small instruments. I special ordered a SeaTalk to DeviceNet cable and a SimNet to DeviceNet cable. Then I was able to attach these two devices. 

Sweet success. The radar overlay works. Daisy chaining the wind speed indicator to the autopilot let my chartplotter access the heading data. 

A proprietary data cable and a power cable must be run to the radar. The data cable attaches directly to the back of the the MFD. A modern radar unit produces too much data for an NMEA2000 network. 

The back to of the Ray70 VHF. From left to right the connection ports are the antenna, remote microphone and SeaTalk spur.