You are going to all sorts of advise and as always, the opinion of the reply is always best. Troll around some 4x4 forums where you will obtain very good hints like install a catch can. Now, my own experience is this, my SM has a TMD22A installed, this is a Turbo version of the Volvo built by Perkins. Incidently, these are believed to be in most taxis around London. With the older Autoprop which is lubricated by sea water, I cruise under power only at 6 knots at 2000 rpm, the speed of course varies depending on sea conditions. I don’t bother going any faster as this seems to be a very comfortable temperature for the engine. On such a trip I will open her up to full 3000 rpm for about 5 minutes, prior to entering my destination, allowing the temperature to drop back to normal. I motored ALL the way from Noumea to Bundaberg in perfectly calm conditions with the engine purring away all the time at 2000 rpm. I have experienced trial drag races with another boat of 8 knots at 3000 rpm in glassy conditions up in Hitchbrook Island without running over a Croc (I think) and it will not get better so I am happy. However, I have ditched the Autoprop in favour of the spare fixed prop since this seems to run smoother but not quite the performance but I still maintain that 2000 rpm. It’s a cruising boat.

Best regards

Barry & Robyn

Tradewinds III SM # 171