Air cooled diesel with hydraulic drive

[DoubleEnder]

My boat is in the shed though hopefully coming out soon. I've been idly musing and wondering about 'the next boat' while waiting and paying.

The next boat is some time off I hope, so this is in the completely spurious category. The next boat will be small, maybe 20-23 feet, easy for ageing old crock to handle alone. But it would be nice to have inboard rather than outboard power. I have seen a couple of boats for sale with what is described as a single cylinder air cooled diesel driving a centreline prop through a hydraulic drive.

Both these boats are one-offs, not series produced. Both have narrow beam and limited space. So I can sort of see the rationale. But surely this arrangement would be diabolically noisy? Does anyone have any experience of such an arrangement? Unlikely I guess.

I think I would maybe look at one of those little Dolphin petrol engines, but realistically I guess it's an outboard, if space is tight. I know that Yanmar makes a single cylinder marine diesel, perhaps that would be more bearable.

My own boat has a luxurious, velvety Beta 20, 3 cylinders and smooth. But it's a custom install and the amount of sound insulation is quite limited. That is plenty noisy enough.

Maybe by the time I'm doing the swap the battery problem will have been solved and I can go all electric. . . . .

 

[Tranona]

Air cooled engines are generally horrible. Our old club launches had aircooled Listers which were very reliable but you needed ear plugs. The one saving grace was the warm air coming out of the vents. Very comforting when doing winter series rescue boat duties!

Avoid any small petrol inboards apart perhaps for a Vire. The Yanmar 1GM is an excellent engine overall as is a 10hp Beta. However, few boats that small will have inboards. Size is generally not a barrier to single handing. It is the design and layout of the boat that is more important than size and I personally find a bigger boat easier than a small one as (depending on design) it is more stable and things happen more slowly. A good reliable inboard and good low speed handling are important if you have a fixed berth.

 

[LittleSister]

My previous boat originally had an air-cooled Ducati diesel. The first owner had fitted the boat out (very nicely) himself, and later told me he had bought that engine as it was on a special offer at the time but, after installing it, the first time he started it he realised it was a mistake. Despite little use, it had been replaced by an intervening owner before I bought her, so I never witnessed it myself.

 

[William_H]

Just musing like OP. However I would consider outboard power if I could get a suitable size in electric start 4 stroke perhaps with hydraulic tilt and fit it to a slot in the transom. ie not hung out on a bracket and not in a well but half way between. Twin rudders would be needed. olewill