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Shearwater Predator and Heinrichs Weikamp OSTC 2N
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Below is a list of links to the main pages about my yacht, Catlypso and My Yachting Adventures:
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    Shearwater Predator and Heinrichs Weikamp OSTC 2N Computers
    In 2012 Kelly and I purchased new dive computers. These were the first new computers we had purchased for well over 15 years. Kelly got hers in February 2012 just before we went to the US for the Gabe Watson trial. She decided on the Shearwater Predator OLED PROT-SA. I got mine in June 2012 and I purchased the Heinrichs Weikamp OSTC 2N.

    Both are similar computers, in that they support (in one form or another), nitrox, trimix and closed circuit diving. They have the same screen but that is about where the similarities end. The following detail each of the computers.


    New Model is Shearwater Petrel, smaller but very similar.

    Shearwater Research is a Canadian company that produces only dive computers (including a CCR HUD) . There are four computers, but in reality they are all the same one, just with different activated software and two have an external Fischer PPO2 connector for rebreather use.

    The base unit is the Predator OLED PROT-SA. The cost is about A$1145 (same in US or Canadian dollars roughly). It is quite a large and bulky computer,but it looks like it would handle any rough treatment it was given. This is the one Kelly purchased.

    Kelly's old computer was a Tusa computer that she had owned for 15 years. I think that it was really a rebadged Suunto. It was not a bad computer, had user replaceable battery (cheap from Jaycar) and pretty simple. However, as far as I was concerned, it had two problems. The first was that it was far less conservative than my Aladin computers on the first dive and then, far more conservative on a second dive.

    Also, when we went to Vanuatu in 2007 and were diving the SS President Coolidge for two weeks and in 2011 when we went to Chuuk and dived the deep wrecks there, it spat the dummy and went into a sort of error mode. It did this when we had been doing a lot of deep repetitive diving and then, when doing a deep dive (about 60 metres), it started flashing Error. Even though it did this, it still sort of worked, giving decompression stops but also blinking ERROR for the whole time. Not great when this happens. Luckily Kelly had one of my old Aladins that she could trust and refer to.

    In the end, the Tusa started rebooting itself in the middle of a dive or just shutting down. It still seems to be working today, but we became very distrusting about it. We ended up purchasing the Predator from the Australian distributor as we could not find it anywhere else at anything but the same price (A$1145). We got it just before our trip to the USA in February 2012 when we were attending the Gabe Watson trial. That way we were able to claim the GST back. I think the price ended up about AUS$950 as we purchased two computers (one for a friend).

    Shearwater PredatorShearwater Predator
    The Shearwater PredatorA side shot of the Shearwater Predator

    Note that there are four models, the PROT-SA, PROCT-SA, PROT and PROCTE. These are in increasing capability and cost. The features below are only for the PROT-SA. The PROCTE is over $1800.

    Features - Shearwater Predator PROT-SA

  • Screen: 6.1 cm (2.4") OLED colour display (organic light-emitting diode)
  • Screen brightness: Automatic
  • Screen colours: Colour for text can be picked from limited range
  • Screen flip: Can flip so it can be read the other way
  • Size: 87.5 mm x 81 mm 44 mm
  • Weight: 0.4 kg
  • Date and Time: Yes and time can be seen during dive
  • Temperature gauge: Visible on front screen
  • Switchable between metric and imperial: Yes
  • Algorithm: Buhlmann ZHL-16C algorithm with user set gradient factors (Google what this is if you do not know)
  • Deco stops: one shown on front screen, rest shown (I think) on next screen
  • Time to Surface: Shown
  • Maximum depth: 137 metres (450 feet)
  • Gases: 5 different gases, any combination of oxygen, nitrogen or helium (open circuit only)
  • Closed Circuit: No, but can do with the purchase of a code
  • Better gas indicator: If a better gas is available, indicates this
  • Auto on: Yes, but does not seem to record till about 2.5 metres
  • Auto off: Yes, but not for 30 minutes
  • Dive planner: Yes, including estimated air consumption
  • Log book: Yes, including graph, 20 hours of diving - dive log number can be set
  • Fast ascent indicator: Yes
  • Menu operation: Two Piezo-electric Switches
  • Downloadable: Yes, via Bluetooth using software and a Bluetooth dongle supplied or other software (eg DivingLog)
  • Upgradeable: Can be upgraded to the PROCT-SA which is closed circuit rebreather compatible - costs $200 more
  • Firmware: Can be updated easily, but not many new features
  • User Manual: Supplied on disk, but has the four different models included in the one manual but can sometimes be a little confusing as not everything is fully explained
  • Power: 1 x SAFT LS14500 3.6 volt Lithium 2250mAh AA size user replaceable battery (costs about AUS$16 each but you can get on Ebay for as cheap as $5 each when buying four)
  • Battery life: Said to be 100 hours on medium brightness - Kelly has changed a few times, probably gets more like 60 hours of diving
  • Web Site: http://www.shearwaterresearch.com/pages/3722/introducing-the-shearwater-predator
  • So what is it like?

    Kelly loves it. She now has the ability to set the computer for Nitrox (which we now use for all boat dives in Sydney) and also a much larger screen. I have used it on a deep (48 metre dive) and found it excellent to use. As it has Gradient Factors (GF) as the only decompression algorithm, it is a little more conservative than the Uwatec computers. Kelly has decided to use a setting of 30/85 after a lot of experimentation. I have also set my computer to this as well and deco times are within a minute of each other.

    It is very easy to read and understand, although the bulky size can make it a bit harder when you are donning your BCD.

    Downloaded Dives

    The software to download the dives, Shearwater, is very basic. Kelly is happy with this, but I would want more probably. It is easy to download using Bluetooth.


  • A very solidly built computer
  • A reputation for working well
  • Easily read
  • Battery user replaceable and relatively cheap
  • Bluetooth means no opening of case
  • Cons

  • Much larger and heavier
  • More expensive
  • Need to purchase upgrade to closed circuit
  • Battery not rechargeable
  • One friend has had problems with his Predator which was using batteries about five times as fast as it should have been. He had it repaired/replaced.


    Now replaced by OSTC 2C.

    This is one of the newer computers on the market. It is made by Heinrichs Weikamp, a small company in Germany. It is run by the owners and gives excellent before and after sales service. The computer uses the same screen as the Predator but in a much smaller package, half the weight and far less bulky. The big advantage of the OSTC 2N is the OSTC itself. OSTC stands for Open Source Tauchen (Dive) Computer. This means that the code for the computer is readily available and in fact, if someone was game and capable enough, they could add in features to the computer. The OSTC 2N is basically a repackaged version of an earlier computer, the OSTC MkII.

    I have only ever owned Uwatec computers. My first one was an Aladin Pro which I got in 1991 (I think) and which was stolen in 1994. I then purchased an Aladin AirX. While this was a brilliant computer for its time, it had very poor quality control and I had three (or four?), all replaced under warranty. For the last replacement I was given a newer AirZ (for the cost of a battery I think). Back in the 90s, I would guess that 90% of the people I dived with used Uwatec computers.

    I used this till about 2009 when I purchased a Uwatec Aladin Smart Pro second hand off eBay. This has Nitrox, but was basically still the same as an Aladin Pro. As this will need a battery change shortly ($255 I think), I decided to get a new computer instead. While I thought that Uwatec computers were the leading computers through the 1990s and most of the 2000s, they have lost the plot and are not producing what the consumer wants now (funnily, this is when they were taken over by a US company, ScubaPro). They are also too expensive.

    Heinrichs Weikamp OSTC 2NHeinrichs Weikamp OSTC 2N
    The Heinrichs Weikamp OSTC 2N A side shot of the Heinrichs Weikamp OSTC 2N


  • Screen: 6.1 cm (2.4") OLED colour display (organic light-emitting diode)
  • Screen brightness: Two settings
  • Screen colours: Colour for text and other parts of screen can be picked from large range
  • Screen flip: Can flip so it can be read the other way
  • Size: 80 mm x 68 mm x 32 mm
  • Weight: 0.2 kg
  • Date and Time: Yes and time can be seen during dive
  • Temperature gauge: Visible on front screen
  • Switchable between metric and imperial: Yes
  • Algorithm: Buhlmann ZHL-16C algorithm with or without user set gradient factors or with conservatism
  • Deco stops: one shown on front screen, more shown on next screen
  • Time to Surface: Shown
  • Maximum depth: 120 metres
  • Gases: 5 different gases, any combination of oxygen, nitrogen or helium plus one configurable during dive
  • Closed Circuit: Yes, fully supported
  • Better gas indicator: If a better gas is available, indicates this
  • Auto on: Yes with user set depth for this
  • Auto off: Yes (user settable time)
  • Dive planner: Yes, including estimated air consumption
  • Log book: Yes, including graph, 40??? hours of diving - dive log number can be set
  • Fast ascent indicator: Yes
  • Menu operation: Two Piezo-electric Switches
  • Downloadable: Yes, via USB cable using software supplied on net or other software (eg DivingLog)
  • Upgradeable: No as this has all features for closed circuit as standard
  • Firmware: Can be updated easily, with many new features implemented regularly
  • User Manual: Printed version supplied and on-line versions available when firmware upgraded - it is however not 100% complete in what it covers
  • Power: Rechargeable Lithium-Ion replaceable battery (can only be changed by manufacturer but they say this should not been needed for most people - cost is €29 plus mail)
  • Battery life: Said to be 40 hours on maximum brightness
  • More than 60 customer functions that can be turned on or off or adjusted by user
  • Web Site: http://www.heinrichsweikamp.com/#/de/ostc_2n/
  • Cost

    In Australia you can only purchase from a dive shop that I prefer not to name. I am not sure of the price. You can also buy direct from Heinrichs Weikamp in Germany. The cost was €662 - AUS$868 (delivered). The delivery was via post (even though it shows as DHL) and it took about 14 days to be delivered.

    So what is it like?

    To date I have done well over 200 dives with it. A lot of the dives were only to about 18 to 20 metres, but I have also done many deeper than 25 metres. I have also done about a dozen in excess of 45 metres. The screen is extremely clear and bright, even in clear shallow water. I found it no problem to read at all. In addition, the numbers that are important are very large. I have used for Nitrox dives as well. I have it set for gradient factors using 30/85.

    On the decompression dives I have done to date, I did multi-gas dives and set it up to use 100% oxygen for decompression on some dives and a 50%+ mixture for others. Arriving at the set depth the computer suggested I change to the better gas. This was quite easily handled. Note that the Predator also does this.

    The computer has so many features that can be turned on or off as you need them. I have set things as I think I might want them, but I am sure that I will change some as time goes by. Nice features are a stopwatch, the ability to set a marker that can be used to record an event (visible in the downloaded profile), Future TTS (Time to Surface) which can be set for x minutes and gives you an idea what decompression you might have x minutes time, ascent/decent rates for alarms, different decompression algorithms, with user set levels of conservatism and more.

    From what I can see, how I have it set up the decompression is very similar to my Uwatec computers. When on I used it on the 27 metre dive, the no deco time was within a minute of two of the Uwatec.

    Downloaded Dives

    There are a few free software applications that can be used to download the dives. One is JDiveLog. This software is reasonable, and I started using it but then changed to Subsurface which is a lot better (and also free).


  • Cheaper
  • Smaller
  • More features
  • Closed Circuit as standard
  • Easily read and understood
  • Rechargeable battery
  • Cons

  • Battery if it fails not user replaceable
  • Need to open USB cover to download dives and recharge

    This is a hard question to answer. Both are extremely easy to use and read underwater. Both have heaps of features. If you are a tech diver just using oxygen and nitrogen mixes, then either one would probably be suitable for you. If you want to do trimix diving, again, either one would appear to be as suitable as the other. It probably comes down to the price.

    If you have a CCR and do not want sensor integration, then the Heinrichs Weikamp OSTC 2N is probably better as it does everything at a much cheaper price. If you want external sensor integration, then the Predator PROCTE is the only option, although you could purchase the PROT and upgrade later.

    No matter which one you choose, you will probably be happy.


    Both computers worked perfectly till early 2016 when they both encountered identical problems. First, the OSTC started having intermittant problems with the left button not working, or at least, working only when it was tapped very hard. This then got worse till it required about 10 or more hard taps before it would work reasonably okay. Some months after this, the Predator started having a similar problem with the left button, but it would not work at all unless tapped hard. Within a few weeks, it stopped working at all.

    I contacted both companies. The OSTC could be replaced with a brand new one for a very discounted price of €432 (AU$626 at that time), with me keeping the old one. So far I have not taken up this offer as I can get it to work before a dive by tapping it lots (I did later take it up, but it lasted less than 7 years before it too died).

    The Predator could have the buttons replaced with plastic ones by sending it to New Zealand. I posted it off and about three weeks later it was returned repaired. I had thought that this was going to be free, but it cost AU$225 plus the cost of mailing to NZ.

    To be honest, I am a bit disappointed with both companies as it is obviously a fault that is common (I know some others who have had the OSTC fail the same way). In 2023, I now have a Shearwater Perdix and a new Garmin Descent G1 Solar.

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