I’m planning to replace the Yanmar 2GM20F engine as it is underpowered for a 335 and also 23 years of age.
I’m considering a Yanmar 3YM30 or alternatively a Beta Marine 25 or 29.
What 3 cylinder engines and propellors(!) are currently in use for Parker 325/335,
I have a 15” VariProfile propellor which I hope can be used.

The latter 335s were fitted with either 3YM20 or 3YM30 when they were built.
Both good engines I believe. The Beta also has a good reputation in the UK and Beta Marine are said to be good people to deal with.

Parkers fitted quite a lot of KiwiProps, We have had two on different boats, they seem to work well and last.

Martin
335/50

Hi Dirk

I replaced Blue Moon's original and underpowered engine with a 3YM20 and it think it is plenty powerful enough - 6.5 knots in flat water, nice and smooth, not too noisy. It has the same footprint as the original Yanmar (a 2GM something) so dropped onto the existing mountings. The propeller is a 3-blade Featherstream which I love - and was glad not to have to pay for!

Peter

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Completely agree with all of Peter Dann's post. By coincidence we have an identical setup. The 20HP is quite sufficient and the Featherstream is a dream - no problems with going from ahead to astern, and the difference in going astern (and stopping) is great for confidence. But you lose the prop walk ;-)
But it would be interesting to hear from those who have the 30hp Yanmar. And I do hear good things about the Beta, but if you already have a Yanmar upgrade to the 20.

Best Wishes,

John Clack

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WE HAD A NEW BETA 25 ENGINE ADDED TO ARENARIA LAST YEAR AND SO FAR SO GOOD. ITS LOVELY TO HAVE MORE POWER THAN THE OLD YANMAR 20. THE ENGINE JUST FITS INTO THE SPACE VACATED BY THE OLD ENGINE WITH NO MODIFICATIONS NEEDE, ALTHOUGH THE GEARBOX WAS A LITTLE TIGHT. WE DID NEED NEW MOUNTS AT THE SAME TIME. WE ALSO HAVE A FEATHERSTREAM PROP.
ANNE AND DENNIS KELL

Hi Dirk,
I have the old Yanmar 3GM30. You have to cut a corner off the engine mounts to fit it. This doesn't seem to cause any problems but then I have an aquadrive which absorbs some of the engine vibrations.
As Peter Dan has been round Britain with his new engine he is well placed to comment. My engine does not produce more speed than Peter's in flat water. But then it is 22 years old. I don't know if a new engine would be any better.
If I replaced my engine I would probably choose the same as before as I understand I would have to recalibrate the feathering propellor if using a different horsepower engine.
You can have higher output alternators as an option so that is worth investigating. If they will fit.

Mike

Thanks for reminding me Mike - yes I had the higher output alternator fitted - 125A if I remember correctly.
I've attached the fuel combustion curves for the YM20 and 30 which make interesting reading. I was looking at these when I was deciding between the 20 and the 30.
When we were on the French Canals - flat water, 5~6kn limit - I was getting better that less than a litre per hour, although that was the 2YM16 ... A tribute to the Parker's sleek hull.
See attached curves and enter your cruising revs.
Regards,

John

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John,

That is interesting. I generally cruise at 2200 revs as it is quieter and produces 5 knots in flat water. According to your chart that is 2.2 litres an hour which coincidentally I have always worked on as someone told me that ages ago.
When I go flat out against the tide it manages a sustained 2700 revs, but not much more as it is an old engine. This is 4 litres an hour which I did not know. I had no idea it used so much. If that is true, it might make more sense to have the 20 horsepower engine. It would be interesting to know how many revs it produces flat out. Over to you Peter!

Mike

I forgot to say Dirk that I have a Max Prop original feathering propellor which is similar to the Featherstream I believe. It is superb. I do get quite reasonable prop walk to port in astern. Not sure why John doesn't with his 20 horsepower engine. I wonder if Peter gets it?

Mike

Thanks for those graphs John, and the one for the 3YM20 bears out my experience over the three years around Britain. I usually cruise at around 2,600rpm which gives 5.5 kts in flat water and does indeed consume 2l/h as the graph says it will - how reassuring! The engine will happily run at full chat and 6.5 kts+ if you need it to but my usual 'full power' option is just over 3.000 rpm which ups the speed to over 6kts if you're in danger of missing a lock gate or closing time at the pub. In reality I was more likely to use this for any length of time when motoring into wind and waves, when fuel consumption really does go out of the window, so I don't have figures for it.

Incidentally I did monitor fuel consumption and engine hours carefully because my fuel gauge gave up the ghost long ago. Since the dipstick is messy I just log my engine hours and know that when I get to 32 I really need to find a fuel pump as somewhere between there and 40 I will run out! It was noticeable how even just a few sustained instances of 3,000rpm made a huge difference to the level of diesel, and the chart bears that out too - 50% more! My spare carn(s) got a lot of use...

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