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Posts: 3
Reply with quote  #1 
Hi, I have an Offshore 8 metre with a 9hp Farymann engine. The engine is very old and a bit under powered. I wondered if any other owners have replaced their engine and if so what engine options are out there, that will fit in the tight space. All help and advice would be greatly appreciated.


Posts: 107
Reply with quote  #2 
Have a look at the yanmar range, very robust reliable engines

Posts: 186
Reply with quote  #3 
Hi, when I underposed mine Mk.II Nantucket to mayor overhaul, including the whole replacement of engine/shaft/propellor, I choosed a Beta Marine 28, 3 cyl, 1005 cubic
centimetres, w.heat exchanger. Basically it is a Kubota, marinized by British Beta. :
A very reliable, simple, silent, rugged, lightweight, low consumption & emissions.
          Ciao, Guido.==

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Posts: 8
Reply with quote  #4 

Replaced the ancient 9HP with a 14HP Yanmar 2YM15 the moment I bought my Halcyon 27 Clipper. For the waters we go it was the right choice between, I think, a 12HP replacement and the more powerful 3YM20.

It is said newer engines weigh less for more power. Might be but a more powerful engine still weighs more as an old underpowered one. Moreover, more power means the cylinders are bigger hence one gets a bigger engine onboard and less space onboard to manoeuvre around the beast for maintenance. Less space, more heat production in the confined space...

While originally the engine could be reached via a hatch in the cockpit the engineer who put the new motor in closed the (leaking) engine hatch and provided "access" via the removable staircase in the boat or (sort of) via the lockers in the cockpit.

Fuel efficiency might have been enhanced in newer engines they still need their juice and unless you find space onboard to add a tank or put in a bigger one the fuel supply will come from the tank designed for the original engine.

We did not increase our fuel tank capacity but monitor the time the engine runs closely and have had to refill the tank while at sea (at night).

The 2YM15 does come with an hour-counter but lacks (besides a fuel gauge) a decent engine temperature probe (just a red light and a warning sound when actually overheated). We intend to patch that up with a BBQ dual-probe device attached to the engine with heatsink gel and monitored via Bluetooth. Should do the job. We also sometimes remove while sailing under engine for longer stretches the staircase so the engine heat can disperse.

The 2YM15 has served well. Only in extremely strong currents like when getting into Cardiff marina against the powerful tidal current in the Bristol Channel we needed to lower the outboard engine to give an additional 4HP to get us moving.


Replacing an old and certainly an underpowered engine is a good idea. Adds to the safety onboard. The 2YM15 provides 80Amp electricity. Great when one has upgraded the electronics onboard as well. Replacing the engine of an existing boat comes with additional issues; like fuel tank size, weight. ... I do think the investment was well worth it.


This is an interesting article related to the matter: http://www.ybw.com/forums/showthread.php?376626-Yanmar-why-does-anyone-buy-the-2YM15-instead-of-the-3YM20




Sailing the Nomad.


Posts: 186
Reply with quote  #5 
Good evening to all members.
     When replacing/heart transplanting engine, mine was a 240 Kos. Volvo Penta MD2B, 25 hp.-without heat exchanger- that is to say a full contraddiction in terms by the way a Diesel engine requires high running temperatures to work correctly.
- For what about fuel consumption, question simply lays in a simple as strict formula that is : grams per hour horsepower. Trick lays in efficency; so, we will can do :
- Improve engine w. higher burning temps (heat exchanger)
- best if we couple it to an air supercharger(compressor) for the simple reason that one mole of diesel oil requests 800 moles of air to properly burn. As we know, such arrangement is obviously expensive and not available on engines of less 30/35 hp.
- Betamarine 28 hp. weights 100 kos. less (the volvo flywheel) because fairly better running w. 3 cyl. firing at 120° rotation instead 180°w. 2 cyl.(extremely alternate: big vibration:heawy flywheel to damp such a disturb).
- Xtra power is not a luxury but only more safe and less fuel consumption.:in normal conditions I use the engine  just 1/3 - 1/2 power, w. a fuel consumption around 1.5/1.75 litres per hour, w. clean hull, giving me an average speed of not less than 5.5 Kts.==
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