I have a 33ft Westerly dating from 1991 with an 18hp Volvo
Penta 2002 which I am contemplating replacing. It has been suggested I should fit a Beta 25hp. I'm erring towards a Beta 30hp or a
Perkins 29hp. I’m not as far down the line as you are but I have done some
research.
I also have a useful book that you might want to track down – “How To Install A New
Diesel Engine” by Peter Cumberlidge (Adlard Coles Nautical). You can get it on Amazon UK. It’s probably got more information than you need. But it’s full of diagrams etc and will help you along the way. I haven’t fully read it, but will be when I am further down the line.
I think you need to think about the following:
Engines and Parts
From my reading and
research, I have learnt that most
Marine Diesel Engines are marinised tractor, car or van engines. The more you know about what the base of the engine is, the cheaper and more plentiful the parts will be as you ought to be able to use the equivalent car or tractor parts in many instances. Beta engines are marinized Kubota tractor engines which are used all over the world. I have heard that Yanmar parts are quite expensive. I had to pay £150 for a short piece of replacement metal
water pipe on my Volvo
Penta which I thought was extortionate. Also check the cost of
oil and
fuel filters on different engine makes – they can vary wildly.
Engine Mounts
As per a previous post, these may need to be moved or re-inforced.
Gearbox and
Gearbox ratio
Does the new engine come with a gearbox? Or will you fit it to your existing gearbox? What is your
current gearbox ratio and what is the ratio of the new Engine gearbox? That may have an impact on your prop.
Prop
Which way does the prop on your
current engine turn? Most turn clockwise. Mine turns anti-clockwise. That means I will probably have to get my very good Brunton Prop re-engineered to turn clockwise which will add an extra £500 or so to my re-engineering cost.
Electrical/Ignition board
Does the new engine come with an Electrical/ignition board – the Betas do and you have choices there. Will the new board fit the space where your current ignition board is? Or will it involve some ‘cutting and pasting’ which will add to the cost.
Weight
What is the weight of your current engine? What is the weight of your new engine? If there’s a big weight difference, it may affect your sailing performance.
Alternator
What size is your current
alternator? What size of alternator does your new Engine come with? That may affect your
electrical system.
Your Old Engine
Don't forget that if your old engine has some life left in it, you may be able to sell it on once it's been removed.
Hope this helps for starters. The Peter Cumberlidge book will give you much more!