Hello to you all from Southland, New Zealand I am planning the construction of a very small motor vessel that is capable of making passages offshore. I've located the plans of a suitable design, 26' LOA, 23'LWL, 9000lbs Displacment, with auxilary sailing rig. The plans call for 10 to 20 Hp, I think these would have to be continously rated "real" horses!! From what I've read something like the Sabb 18 Hp model 2H with variable pitch gear would have been ideal ... however it is no longer avaliable. In a boat this size one by necessity lives in very close proximity to the engine so it seems worthwhile to go to some trouble to get a civilised engine solution. By this I mean the quietest and most vibration free engine available, relegating considerations such as weight to a secondary status My experience with one and two cylinder engines ie all the current 10 - 25 Hp range is that they are extremely noisy and vibrate like hell no matter what "science" is applied to the installation. I understand (though am sceptical) that the Sabb and other counter-balanced engines can be much better. Modern high speed diesels with their continous rating obtained in the 2500 - 3000 rpm range are also extremely "busy" and arn't as easy on the disposition as heavy low speed type diesels at 1500 - 1800 rpm. I would be grateful of your thoughts on my above opinions, and seek your consideration of the following questions: 1. Are a particular number of cylinders ( ie 1,2,3 or 4) inherently more vibration free, do any of the counter-balancing systems have a big advantage (eg the Sabb)? 2. Would it be possible to produce a smoother engine by "de-rating" a 3 or 4 cylinder model (eg de-rate the 3 cylinder 35/38 Hp Izuzu to 20 Hp)? What are the considerations in this approach apart from cost and weight? 3. I've read that there are different design/construction considerations for engines that are intended to run intermittantly eg as a yacht auxillary, and those designed for continuous use eg on a passage-making mv. These differences are clearly apparent when comparing big engines like the Gardners and Catapillars but less so in smaller engines. Any opinions? Sorry about the long post but these question are burning a hole in my old "grey-matter" and people with sufficient experience to answer them without resort to bulls--t are very rare! Thanks - Foster Price