Preparing your electronics for a race
Wednesday, June 28, 2017
Marine electronics can play an important part in achieving success at a sailing competition, and with the Round the Island Race in association with Cloudy Bay fast approaching, we asked Will Sayer, one of Raymarine’s Senior Mechanical Design Engineers and Winner of the 2016 SORC Round the Rock, how he gets his boat ready for race day.
Will, what are the main checks you would recommend people do in advance of an important race?
I would double-check that your boat’s electronics are giving accurate readings. Remind yourself how your depth transducer is calibrated, waterline or bottom of the keel. This could be the difference of between running aground at zero meters or the depth of your keel. The tide and corresponding water levels play a big role in the Round the Island Race so don’t get caught out.
Make sure you have double checked the Depth Tx calibration and that your crew know what it is too. Know what the tide times and heights are of all possible close quarter locations and what clearance to expect. It’s important to cross refer the GPS position from your Chartplotter against water depth to confirm your position and make allowances for swell/ waves to ensure you do not strike the bottom when in close quarters.
You can check the calibration through your system set up or calibration menu – once the transducer calibration is set, make sure no-one in the crew attempts to modify this – it is the skipper’s responsibility alone.
As each Instrument will have slightly different calibration access, read the manual beforehand and familiarise yourself with how to change the calibration. The basic calibration works the same however, a +ve figure represents a WATERLINE offset (distance between the transducer position and the waterline), so the display will read actual water depth (can be cross referenced to the charted depths directly as a simple double check on positional accuracy). The -ve figure represents a keel offset (distance between the transducer position and the bottom of the keel) so the display will read the depth below the keel and gives a simple indication of how much water is actually beneath the keel.
And, Will, what happens if my instruments are not showing anything?
If your instruments are showing dashes rather than numbers on the master display (the display connected to the transducer), it is likely the instrument is not communicating with the transducer or the source of the data.
I would recommend that you check your transducer cables are undamaged and securely connected. Make sure the junction boxes do not have loose or poor connections, or that there is any corrosion or Verdigris on the connectors.
And, if the master display is showing the data, but the repeaters are showing 0.0, I would check your SeaTalk cables or data cables throughout the network. There could be loose connections, a short circuit corrupting data in the network, or it could be a faulty instrument that is not transmitting or sharing data. You will find it helpful to break the system down into smaller segments, test each section and isolate the offending section to diagnose more fully.
It’s a really good idea to plan ahead. Should the numbers stop appearing partway through a race, make sure that you know where all the junction boxes and connections are located on board. This will ensure that you will be able to quickly look for the weak points and get the basic system operational again.
Is there any general maintenance you would advise?
Getting accurate depth and speed data is vital, so I would recommend making sure that the corresponding transducers are clear of weed and barnacles. The easiest way is to locate the transducer.
You will need the speed transducer blanking plug, supplied with the unit. This is located next to your removable hull transducers. Always use the bung supplied if removing the paddlewheel insert.
If you clear any debris from the paddle and give it a spin, this will help make sure readings are being made. Then replace it in the housing; make sure the paddlewheel is facing the correct direction. Your depth and speed may use two transducers. If so, check both.
Replace the transducer in the housing, making sure the arrow is in the direction of travel and don’t forget to replace any pins. It is good advice to replace the paddlewheel and shaft at least every two seasons, more frequently if the water is silty or there are lots of barnacles and marine life evident.
I would always check the security of the masthead wind transducer and check all electrical connections. Identify all cable runs through the boat and the locations of all connections, junction boxes, transducers and joints. What’s more, ensure all cable runs are supported and secure any loose wires which may get tangled with other equipment.
Will, could you offer any advice on checking heading readings?
I always check the reading against a traditional compass, as I can then know the difference and adjust the on board compass to be closer to the traditional one during calibration setup. The electronic compass sensor is usually connected to the autopilot on board and so calibration is via the autopilot control panel.
If you check the compass readings against several known transit bearings, this will help you to gauge accuracy. The compasses display MAGNETIC information, whereas your charts will identify bearings in TRUE. Ideally you want the same reading throughout the system.
I would also advise all guests and crew of the location of the compass, to ensure no metallic equipment or magnetic sources are located anywhere near. This could be radios, mobile phones, tools, clothes hangers etc.
Finally, anything you can do with a Multifunction Display if you have one?
If you have an MFD aboard, I would always check that the COG, SOG latitude and longitude, and course made good is all reading well and giving sensible readings. You can check position displayed on the electronic chart by closing on a prominent navigation mark. I would also cross reference with depth of water and any convenient transit bearings too, to confirm your confidence in the accuracy of the position as displayed on the electronic chart plotter.
We hope you find these race preparation tips useful, but if you are unsure, please consult your manual which you can download at http://www.raymarine.com/view/?id=10125, or contact our service department (http://www.raymarine.co.uk/view/?id=1154) who will help as they can.
Final point to remember; never rely on one source of data. Always confirm the information from other sources too and always pay more attention to what you can see, rather than spend all your time looking at charts, LCD displays and computer screens – the eyeball is the best sanity check ever invented!