This is for Rick Ellis (and others), answering the question he posted under "bilge bolts". This is also a copy of a response I gave to Ben Allen last year when he asked me the same question (I hope you don't mind me sharing this Ben). I also responded to a similar question that R.W. posted last year, and you can check that out in the archives, under "diesel conversion". Anyways here is my thoughts on the project: "Good questions. I have probably answered a dozen people over the years who had a similar desire, mainly associated with the older 25's. You have not mentioned cost, so maybe its a bit less important to you, within reason. Im guessing the cost/benefit ratio will be better for your relatively newer model O'Day, and this is a benefit for sure. Beyond that, your reasons are for safety and comfort for you and your family. And thats the best reason of all. Not only will a prop buried beneath the hull give you dependable thrust, but your charging capabilities are bigger, and there is no flammable fuel cans, amoung other reasons. Diesels are highly reliable. Fuel efficient, etc. Drawbacks are finicky fuel requirements (these can be addressed with proper filters), high weight to power ratios (although you are increasing stability), very costly to buy initially (but very low cost to maintain). You will lose storage room, that may not be a big issue, but you can always add extra shelves, and cabinets else where. I'm going to send you responses to a few individuals that I have archived at work. Most of your questions should be answered within them. I think you are limited not so much by the HP rating (10-12 hp sounds right), but more by the physical size of the engine. There is only so much room in our boats. I recently looked at a replacement for my engine (not that I'm planning), and Volvo makes a 12 hp 2 cylinder that would replace my 10 hp single cylinder. I would go 2 cylinder as it would be quieter, and less vibration as the cylinders would balance each other. I am very happy with my volvo (raw water cooled), but I would definetly consider Yanmar and Westerbeke. There is also another interesting diesel manufacturer called Beta that should be compared. Usually a quote would include the tranny too. It can be bought seperately, if you found a engine without one. Here is a parts list you will have to price out: Engine- includes controls, ignition, tranny, mounts (about 5 K new) Fuel system-includes tank, filters, water seperators, fuel sender guage (300) Electrical- extra starting battery, battery switch (250) Engine bed-you will have to construct this Engine box insulation, blower (in reverse to bring in more air)(300) Prop/shaft/cutlass bearing/strut support/shaft log/stuffing box or dripless system/ prop/shaft zincs/shaft saver?(2K) The biggest job will be to house the engine, and here is where you have to really apply your planning. You will have to recunstruct your counter/drawer area. What I did was to carry the counter around the corner, cutting off part of the starboard berth/settee. Don