Select to expand quoteMizzenmaster said..
So what's the best coolant for a Bukh dv20 freshwater cooled engine
Have you installed fresh water cooling on her Mizzen master? Any good quality coolant should be good Id say.
% wise Im not sure what is needed other than a general percentage
Much to Ciscos dismay 
( he does not know about it) yet Ive started fitting wheel steering
the first photo shows the helm fitted in place since then Ive stripped Andy's 69 old pedestal off his S and S 34 Thank you Andy very much and beefed it up a little to support the helm unit and I also altered its foot print to suit the H28 cockpit.
Its been stripped down since then Ive sanded the old gel cot off and have add a few layers of epoxy and matt internally and externally I wont be fitting the engine gauges there just start stop.
The cylinder gives me 9 inch stroke lock to lock and the helm unit two turns lock to lock . Ill be adding a hydraulic auto pilot into the steering system
Phil at Fleming Marine is making a mounting for the cylinder rudder bracket
HyDrive 105 helm unit plus the hydrive HD 150-9 cylinder will give me 2 turns lock to lock
