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  1. #11
    Join Date
    Aug 2016
    Location
    Me in Cowes, boat in Quiberon
    Posts
    462

    Default Re: Yanmar 3YM20 or Beta 20?

    Replaced my 3GM30 with a 3YM30, different world with the new one - quiet, powerful and economical, plus old one out, new one straight in with no fuss in a couple of hours.
    The alternatives I looked at all needed quite a bit of work to fit

  2. #12
    Join Date
    Oct 2002
    Location
    Plymouth
    Posts
    8,680

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by Trident View Post
    .....

    Any feedback is gratefully received


    It was no contest for me because all of the class were fitting one type of engine so, with one eye on resale value, there was only sensible solution. Think about where, in the fullness of time, you may want to dispose of the boat; in the Med and elsewhere, a Yanmar might possibly have the edge, in the UK, or States, then Beta comes more into the picture.

    As suggested, check out spares. I just replaced my Beta stainless high rise exhaust which was a little over £200, the Yanmar equivalent seems only a tiny bit more expensive. However Yanmar engine feet must be gold plated whilst the Beta ones are pretty common across the range and come in at c £35 each.
    Last edited by doug748; 08-11-19 at 16:13.

  3. #13
    Join Date
    Dec 2018
    Posts
    18

    Default Re: Yanmar 3YM20 or Beta 20?

    I have recently bought a Moody 27 that came with a 4 year old Yanmar 3YM20.

    The engine has performed fine during the one season I have had it.

    But there have been two problems.

    1. The rev counter stopped working, and when I asked the company who fitted the engine about it they said "Yes, the engines are susceptible to that problem"

    2. I've got a suspicion that it does vibrate rather too much. I have just noticed that two battery switches (see photo) attached to a bulkhead in the engine compartment have cracked, and I guess this must be due to excessive vibration.

    I don't know whether these problems are because of my particular set up, or whether they are common to the design.
    image0.jpeg

  4. #14
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    20,985

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by CJ1 View Post
    I have recently bought a Moody 27 that came with a 4 year old Yanmar 3YM20.

    The engine has performed fine during the one season I have had it.

    But there have been two problems.

    1. The rev counter stopped working, and when I asked the company who fitted the engine about it they said "Yes, the engines are susceptible to that problem"

    2. I've got a suspicion that it does vibrate rather too much. I have just noticed that two battery switches (see photo) attached to a bulkhead in the engine compartment have cracked, and I guess this must be due to excessive vibration.

    I don't know whether these problems are because of my particular set up, or whether they are common to the design.
    image0.jpeg
    The cracking is more likely to be due to over-tightening.

    In my experience, give a plastic fitting to a typical auto or marine mechanic with a screwdriver or spanner and you will end up with a cracked fitting.

    Richard

  5. #15
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    36,955

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by Trident View Post
    Weirdly the Yanmar now comes with a 125Amp Alternator which seems huge for a 21 hp engine so I was actually thinking of seeing if they could do a smaller one like a 65...
    It most probably won't make any difference, in terms of overloading the engine, unless you have a huge battery bank. Batteries will only accept a certain amount of charge, regardless of the theoretical capability of the alternator. Having a higher-rated alternator can be a distinct advantage, as it will usually provide a reasonable charge current at lower revs.

  6. #16
    Join Date
    Mar 2018
    Location
    Aberaeron
    Posts
    1,789

    Default Re: Yanmar 3YM20 or Beta 20?

    I’d go for the Beta everytime, I fitted my last boat with a Beta 10 which performed fantastically over the 20 years that I had the boat, my new boat has a Beta 14 which is just as good.
    The guys at Beta are also great to deal with.

  7. #17
    Join Date
    Mar 2009
    Location
    UK, Hamble
    Posts
    582

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by Trident View Post
    I need to repower and will get one of these - I can get both at so close to the same price that its not a decider and they have 1 hp difference in power and 4 ft lb more torque to the Yanmar but for 0.2L / hr greater fuel consumption - its a bit more fuel but again not enough to go one way or the other.
    Unless you actually use the extra 1hp (i.e. run flat out) you will not use the extra 0.2l as it corresponds to the fuel required to deliver that extra 1hp.

  8. #18
    Join Date
    Sep 2012
    Location
    Currently at anchor in the Med
    Posts
    549

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by ithet View Post
    Unless you actually use the extra 1hp (i.e. run flat out) you will not use the extra 0.2l as it corresponds to the fuel required to deliver that extra 1hp.
    The fuel consumption difference is based on a direct RPM comparison - the Beta and the Yanmar make the same power almost exactly at 2000 rpm but the Yanmar uses 200ml more fuel there BUT makes 4 ft lb more torque so is putting more power in to the prop for that fuel which means of course in the real world I may get the same boat speed at slightly lower revs with the Yanmar so the difference is probably not a major issue in the real world

  9. #19
    Join Date
    Mar 2009
    Location
    UK, Hamble
    Posts
    582

    Default Re: Yanmar 3YM20 or Beta 20?

    Quote Originally Posted by Trident View Post
    The fuel consumption difference is based on a direct RPM comparison - the Beta and the Yanmar make the same power almost exactly at 2000 rpm but the Yanmar uses 200ml more fuel there BUT makes 4 ft lb more torque so is putting more power in to the prop for that fuel which means of course in the real world I may get the same boat speed at slightly lower revs with the Yanmar so the difference is probably not a major issue in the real world
    Yes, in the real world your prop curve would be well below the max power curve at 2000 rpm so the difference is negligible as you say. In theory you could fit a slightly higher pitched prop to the Yanmar to get the slightly lower revs.

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