OSTC Mk 2 Dive Computer – Gordon Mackie
I was lucky to get my hands on a pre-release version of the OSTC (Open Source Tauch Computer) in time for a planned trip to Scapa Flow as this would give me 6 days of air, Nitrox and Trimix diving with varied deco gases to test out the OSTC alongside my VR3.
When penetrating wrecks at 40m plus on mixed gases, the most important thing is clarity of information and the OSTC Mk2 gives you exactly that. Clear depth and deco information, good no stop information followed by clear deco depths and times. I tested it out in straight Buhlmann ZH-L 16 and also in Gradient factor mode, adjusting the min and max factors to set deep stops. The unit performed really well and in either mode, the surface time was almost identical to my VR3 and a Suunto.
FIRST IMPRESSIONS
The Mk2 comes in a sturdy reinforced neoprene case which holds the computer and the USB cable that is used to load firmware updates, download dives to the log book and also to charge the rechargeable battery. The case is a solid, well moulded plastic construction and the wrist strap is a simple flexible Velcro strap that is easy to put on and stays tight when your suit compresses. The screen has a very tough borosilicate glass front and the buttons are large, flush mounted piezzo electronic switches that can be easily used with 5mm gloves and cold hands.
The OSTC is also unique because the software is completely Open Source, you can rewrite it, alter it and write new and individual programs for it. All upgrades are available free from the manufacturer’s website and installation is simple using their BootLoader software tool. But don’t panic! You don’t need to be a geek to own one, you can just use it out the box and only install updates from the manufacturer. The computer has an active discussion group and any queries can be made direct to the designer Matthias and he is frighteningly fast to respond back. He has taken the Linux approach to dive computers. And as Linux needs a computer to run on, the OSTC processor is the tool to run his Open Source software. Unlike other computers, mathematical models can be upgraded or changed as decompression theory evolves.
THE DISPLAY
I must say that the display is one of the best OLED displays that I have seen. In surface mode it is clear and bright but underwater it is astounding; I was doing deco at 9m and divers at 6m reported that they could read my display. My eyesight is not good and even with prescription lenses I struggle to read most computers in poor visibility. The OSTC has large white on black characters and it is as bright as some lamps that I have used.
USING THE UNIT
This is simplicity itself, pressing either button or reaching 1.6m will switch it on and it will immediately start displaying dive data. There is a dive mode menu that you can select underwater to show your decoplan, select gases to switch to, display the current tissue saturation graph or change brightness. The gas switching is logical, select and enter gases from the list and you can alter one of the 5 mixes on the fly as well.
Pre dive, the computer is really intuitive and easy to use. I did not need to open the manual, the menu is simple and user friendly.
4 deco algorithms are available :-
ZH-L16 Buhlmann Open Circuit
ZH-L16 Buhlmann Closed Circuit
ZH-L16 Buhlmann Open Circuit with Gradient Factor Extension (deep stops)
ZH-L16 Buhlmann Closed Circuit with Gradient Factor Extension (deep stops)
You can also run in gauge mode or even select Apnea for free diving.
Just about every variable can be adjusted in the setup menu – gradient factor max and min, thresholds for warnings, alarms etc. Some are mandatory and must be in place, others are to allow user customization and flexibility without compromising safety.
The unit gives you clear dive history summary with drill downs and you can also download your dives. They offer a couple of free log tools, I used Dive Log 4 and found it to be very user friendly and easy to use.
The USB charging is a real benefit. No more flat batteries and trying to change batteries in wet, salty conditions. I found that 4 hours from flat gave me a full charge that will last for 6 hours of diving. When charging, you get a regular single flashing red LED that changes to double flashes when the unit is 95% charged.
SUMMARY
The OSTC Mk1 has been seen as a “Techie Diver” computer and was not seen much in Sport and recreational diving circles. The simplicity, price and ease of use of the Mk2 make it a very good choice for anyone diving recreational Nitrox or Trimix. The lack of a Fischer connection for CCR is intentional. The soon the be released (and more expensive) DR5 is designed for the CCR market and it has 3 cell monitoring via a 7 pin Fischer socket.
The OSTC Mk2 is available in the UK from Deep Ideas. The retail price is £620, which is very competitive for a fully featured Trimix computer of this standard.
SPECIFICATIONS
The OSTC Mk.2 does not have a Fischer connector and only Fixed SetPoint CCR with 3 Setpoints is available.
- Open Source Firmware with full schematic of the hardware
- 5 Preconfigured Trimix gases + 1 Trimix configurable during the Dive
- Fixed SetPoint CCR (Three Setpoints + 5 Bailouts)
- Excellent PC Software Support with JDiveLog and Divinglog
- 40 Custom Functions
- User replaceable Li-Ion Battery with coin-slot battery cover
- Battery life > 30h at maximum brightness in Divemode
- Charges via any USB Port within 4 hours
- 2,4" (6.1cm) OLED Display
- Two additional status and warning LEDs
- 4mm highly scratch-resistant borosilicate Glass display
- Electronics completely encapsulated, no airspace left to crush or flood
- Two Piezo-electric Switches, usable even with extra thick gloves
- high-tech flex-velcro wristband
- 70 x 65 x 29 mm (width x height x depth)
- Weight 160g
RETAIL INFO
Dealer
Deep Ideas Ltd
www.deep-ideas.co.uk
info@deep-ideas.co.uk
Manufacturer
Heinrichsweikamp
www.heinrichsweikamp.net
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