Released after the Carleton MK15 and MK16, the MK15.5 improved on the MK15 by retaining its compactness whilst significantly improving the scrubber, pneumatics and analogue electronic controls. Enough parts were made for only 26 Mk15.5s. One of these is owned by the Vice President of Nissan Corp (A CABA Pty Ltd version of Australian Navy origin).
Available in limited numbers from Steam Machines (Peter Readey), CA, USA and CABA Pty Ltd, Sydney, Australia as the 'SM1600'. Fitted with Kevin Juergensen and Will Smither's control electronics they were of very limited availability with either 2.9 litre Inconel (non-magnetic and laser welded) or 2 litre composite spheres/cylinders.
A MK15.5 minus spheres at CABA Pty Ltd, Sydney Australia in June 2000
Manual injection of Oxygen into the loop via the right-hand pneumatic push-valve (thumb activated)
Al Wright skipper of Salutay trying a MK15.5 out in 2000 after which he surfaced and said: "slicker than slide..." which I believe means 'smoother than butter'