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Freitag, 19. Oktober 2012

gear test: Raymarine ST 40 BiData



Well, after nearly 25 years of service my good old VDO log reached the end of its lifetime. The instrument is corroded and worn out through the effects of sun and water drips in the casing.
So last winter I installed the Raymarine ST40 Bidata. You might wonder why I chose a Bidata and not a simple log?



 Well, I operate a NASA Target Sounder. It works, but I´m not quite happy with it, because if you have a small air bubble in the ”coupling oil” which sometimes happens on a rolling boat, then it can lose its readings. And, according to Murphy’s law, this tends to happen exactly in that moment when you go through  a shallow and narrow passage.

The installation of the Bidata instrument was quite easy, apart from  the fact that you have to drill two holes in the hull. I installed the sounder in the front section, i.e. before the keel. The log is installed next to the old log beside the keel. The manual recommends the installation of the log in front of the keel. But a couple of years ago I installed a NASA log in front of the keel and I didn´t get a reading from it except when I ran Geronimo by engine at a speed of 4 knots and there was no wind-drift at all. I don´t blame the NASA log for this, but it seems that the flow in front of the keel is somehow different for a Delanta 80 from what they have tested. The old VDO  log is installed next to  the keel and it works, so why search for a new spot that works if you already have one, right? 

You might be wonder why I  I haven´t kept the NASA log . The simple answer is, because the instrument was damaged in a winter storm. I guess something must have hit it, because the casing was broken and water had gotten inside, which the electronics took exception to. 

So what I like about the Raymarine log is that there are two flaps in the mounting unit you put through the hull, which should close when you have to remove the transducer, such as if it´s bunged up with something or algae have become tangled in it.That is a really nice feature. How often have you nearly flooded your boat, because the transducer was stuck and you really wanted to know the speed again ? I lost count of the number of times and while recently, since I have started diving, I rather  liked the idea of gearing up, diving down and giving it a good scrub, it’s not all that pleasant early or late in the season. ;-). I was actually lucky this year, because the transducer didn’t get stuck this year, and sadly / fortunately  I didn´t have to try the double flaps. 

Also note that it is recommended that you don´t paint the sounder transducer. Oops… 

After wiring everything up and once Geronimo was back in her natural element  (It always seems wrong  to see a ship on dry land) it worked. For accurate measurements, you  have to calibrate the log, and here is something odd:  Sometimes it “forgets”  the calibration factor. I’m still not sure why this happens, but it is quite easy to put it back in, just follow the instructions in the manual. 

Using the Bi Data instrument is quite satisfying. I normally run it at the setting where the speed is shown in large digits and the depth in small ones. However, when I navigate on a 5 or 10 m line,  I switch it to the display mode where the depth is shown in large digits instead. 

The Bi Data gives you the following information in the speed menu setting:

  • ·         Current speed
  • ·         Maximum speed
  • ·         Average speed
  • ·         Log
  • ·         Trip
  • ·         Water temperature

The depth menu gives you:

  • ·         Actual depth
  • ·         Minimum depth
  • ·         Shallow alarm
  • ·         Deep alarm
  • ·         Anchor alarms (shallow and deep)
  • ·         And an offset

I have been using the BI Data now for one year and I´m very happy with it. Apart from the minor snag  that sometimes I have to calibrate the log ( usually after I haven’t used it for more than two weeks). It has a compact display and it is perfect for every small boat. Also, you don´t need an extra fuse for the night light.
For its price (around 300 €)  you get a very good piece of equipment.

As I mentioned in my review of the Raymarine ST40 Wind, there is also the new I40 series of instruments. It seams that the I 40 series gives you the same data as the ST 40. It offers you now red backlight, the ST 40 has a green backlight.


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