Scubapro’s MK11 first stage has been around for a while now, but the latest version, coupled with the C370 second stage released in December 2017 provides an excellent entry-level option for the travelling diver. The classic Mk2/R195 combo, much loved by dive centres around the world is still available for the lowest of price points, but the Mk11/C370’s versatility and performance far exceeds that of the Mk2/R195, with an RRP of only £24 more.
Mk11 First Stage
At just over 60mm in height, the Mk11 is one of the most compact regulators around, with the DIN version weighing in at just 490g (710g for the INT version). Despite the low profile, it still manages to fit two HP and 4 LP ports onto the fixed barrel. The Mk11 is of an air-balanced diaphragm design and bears the EN250 stamp for cold-water use, however, the chamber is not dry-sealed and it doesn’t have the anti-freeze coating present in the Mk25 or Mk17 regulators. Dedicated cold-water divers will probably be looking at a higher-spec regulator in the first place, but the Mk11 does cover all the temperatures that a recreational diver is likely to encounter.
Port placement has the HP port situated in-between and forward of the LP ports. This is not unique in the world of regulators but I’m uncertain if the claim of port positioning ‘for optimal hose routing’ is applicable. Depending on how you orient the regulator and to which LP ports you connect the second stage and LPI hoses, the ‘standard’ recreational setup means that the inflator hose is either above or below – but always behind the HP hose. A fellow diver remarked that they thought it looked to be set up ‘backwards’ and while I agree – I much prefer my HP port to be well below the LP port for ease of routing – the port location is really not a problem.
Two of the four LP ports are labelled ‘HFP’, or ‘High Flow’ ports – delivering 15 per cent greater airflow than the other two, regular ports. I’ve never really been convinced as to the merits of HFPs as a selling point. They sort of imply that the other LP ports are sub-standard, in which case why have them at all? All of Scubapro’s latest models of the higher-spec’d Mk17 EVO, Mk21 EVO and Mk25 EVO have ports that are all HFP, so what’s the difference?
In reality, not very much. Airflow to the diver is limited by the second stage, not the first. The Mk11 has an advertised airflow rate of 5,500 litres per minute; the C370 second stage at 1,600 litres per minute. What benefit the High Flow ports do have, however, is that they help to reduce the breathing effort from the second stage. This could be a lower specification or older, unbalanced second stage without an air-flow adjustment control.
I did notice, for example, that with my primary second stage connected to the ‘regular’ LP port, and with the C370’s air flow control wound down to the bare minimum (and the Venturi assist in ‘predive’), that it did feel that the regulator was ‘overbreathing’ (ie the breathing effort was getting slightly harder) after an extended (ie 50 minutes) bit of huffing and puffing against some current at Big Brother in the Red Sea This problem was immediately dismissed by increasing the C370’s air flow control, and I tested my octopus (an older second stage from a different manufacturer), which was connected to the HFP port, and the airflow felt immediate and clear. In my opinion, this configuration is better than having the primary on the HFP and the alternate on the LP, as if anybody ever does need to breathe from the alternate, there is a good chance they would already be huffing and puffing.
The key word here is ‘slightly’. In all other circumstances, I found the combination extremely comfortable, even with the ‘airflow’ through the system at its absolute minimum. It’s worth experimenting between the different ports to determine which suits your particular setup best. But overall the compact, lightweight Mk11 is an excellent first stage, easily allowing for a standard setup, plus wireless transmitter plus drysuit inflator.
C370 Second Stage
Also compact and, at only 190g, the balanced C370 primary second stage is very lightweight, yet without sacrificing anything in terms of build quality. It is a very solid design, feels extremely robust, and has a little more versatility than some other available second stages. The purge button is large and rubbery and thick gloves would be no impediment to its use. The Venturi lever operates with only a tiny amount of adjustment and the airflow control knob operates through almost three complete turns, giving plenty of adjustment to the air flow control. The exhaust tee is one of the most firmly attached I have seen to date, although I felt that if it were a little bit wider, there would have been fewer bubbles in my face.
When airflow adjustment is available on a second stage, I like mine wound down to the bare minimum. I have no particular reason for this other than I like it that way, perhaps a hangover from many years ago when I was working to bring my air consumption under control and timing my breathing patterns, and I preferred feeling as if I was pulling the air out of the regulator, rather than having it pushed into my mouth. Before anybody comments on the daftness of that idea, I will also point out that it’s purely psychological, has very little basis in mechanics or fluid dynamics – but it sort of worked for me, and that’s why I like it.
The only downside, as mentioned, was the ‘overbreathing’ that happened after pumping against the current (unnecessarily, in my opinion, dear dive guide) for the better part on an hour. This would have been less of an issue if I was in better shape than my current, sedentary self, but as per above, winding open the airflow adjustment knob a single turn sorted all that out and – remember – I had deliberately set it as low as possible, and connected the secondary to the LP port on the first stage. (It’s worth pointing out that I still got more than an hour’s dive time from a 12l tank, despite the huffing and puffing, and and that no doubt was largely thanks to the regulator). In all other respects, it functioned just the way I like a regulator to function and, dare I say it, reminded me (most of the time) of the differently-branded ‘Legendary’ regulator that is the mainstay of my personal gear.
Verdict
Overall, I like this regulator combo a lot. I don’t love it as much as my personal, ‘Legendary’ regs but there’s not a lot in it. I would prefer it if the Mk11 first stage had its ports arranged slightly differently on the barrel, but the C370 is an impeccable second stage and there is absolutely nothing to fault it. One significant advantage that the Mk11/C370 has though, is the price tag. At £229 it is one of – if not the – least expensive balanced diaphragm regulators on the market. Technical and dedicated cold-water divers will be looking higher up the list of specifications but as an all-around, lightweight, recreational travel regulator, the Mk11/C370 is an excellent choice.
Mk11 Features & specs
- Fittings: Yoke or DIN
- Balanced diaphragm
- Marine grade brass barrel
- Environmentally sealed
- External intermediate pressure adjustment
- Cold Water: Yes
- Ports: 2 HP, 2 LP, 2 HFP (High Flow)
- Weight: 490g (DIN), 710g (yoke)
C370 Features & specs
- Air balanced valve for smooth inhalation effort at varying depths and supply pressures.
- Compact rugged fibreglass reinforced nylon casing and new exhaust tee.
- A new poppet and lever allow the design to maintain the same overall size as the C350.
- Stainless steel frame on the front cover with the Scubapro C-Series signature.
- User controls include a diver-adjustable inhalation effort knob and coaxial Venturi-Initiated Vacuum Assist (VIVA).
- Large purge button, excellent for thick gloves.
- Super-flow hose features an oversized bore that allows more air to flow on each inhalation.
- Compact Hi-Flow mouthpiece improves airflow as well as mouth comfort, fitting all mouth sizes, from smaller to largest.
- Weight: 171g
Scubapro MK11 / C370 RRP: £229
