Yanmar and Beta

[Guest]

I intend to replace a 30 year old MD2B Volvo engine (~25hp) with either a Yanmar or Beta Engine in an Ohlson 35' (relatively heavy displacement yacht). Both do a 3 cylinder 28HP, and Beta do a 4 cylinder 35HP

1) Which brand is better?
2) Should I go for the extra HP and cylinder in the Beta engine?

Thanks for your help

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[johnsomerhausen]

I have no expoereience of the Betamarine, but it is based on the Kubota engine which has a very good reputation and has been marinized by various firms; Beta is supposed to be one of the better ones in this respect.
I've had a Yanmar 2QM15 (15 HP) on a 36 ft steel boat (displacing 7 tons +) and I fopund it quite adequate for the job, so a 28 HP engine would seem more than sufficient for a 35 footer.

john

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[Twister_Ken]

PBO?

Don't know, but was intrigued by a bit about changing engines in one of the current mags where a too-powerful engine was put in which made the boat heavy to steer (excessive prop wash on rudder). Try and catch that article if you can (to be continued next month). Was it PBO?

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[Samphire]

I have a Beta 4cyl 50hp in a 9ton displacement yacht and am delighted with it .
I'd go for the Beta as the extra cylinder makes a smoother engine, and I think although the Ohlson is a slippery shape and easily driven the extra power is worth having.Also agree with comments about Beta being a good company to deal with.
Samphire.

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[Aeolus_IV]

Hi,

We changed a MD2B for a 3GM30F last year - worked a treat - but a couple of "gotya's" if you go down this route:

Prop for MD is LH, prop for 3GM is RH

Check max prop dimentions you can swing, then work out which prop is right for your boat, then pick your gearbox ratio to suit

Don't bother trying to re-use shaft, although it is probably 25mm which is OK - the taper for the prop will probably be odd by modern standards. Apart from that this is a good time to fit a rope cutter if you've not got one.

On the good side, we managed to install the 3GM without rebuilding the whole engine bed - by either using alternative mountings or (as we did) by taking out some of the spacers on the supplied mounts you can drop the engine enough to allow a pair of steel angle iron beds to be fabricated so that these can be bolted down onto the old MD2B bed, then the 3GM bolted down onto this. The alignment is good - but we installed a flexible couple between the gearbox and shaft to remove any doubts.

If you go for the fresh water cooled 3GM (the F version), then the last "gotya" is the raw water pump which is under the engine - the intake and outlet pipes seem to foul the new engine bed - this is easily over come though - turn the pump through 180 deg and change the hoses with suitable replacemnts (ie large diesel fuel quaity pipes), and all is OK.

As a final safety factor we have installed the exhaust riser on the engine to elevate the point at which the water is injected into the exhaust - a factor on our boat as the engine is installed quite low in the boat, so the exhaust outlet and sea water level is a little too high for comfort.

Your old MD2B is probably not generating the power it used to (25HP when new), so I'd say that going for an engine significantly larger than this would be unwise. The 3GM although "only" 28HP does have a lot of torque, and is a much friendlier engine - I'm very happy with ours after nearly a year.

As for power - our 32 foot boat weighs in between 5.5 and 6 tons, and this engine with our rather small 15"x12" prop (the biggest we could physically fit) - pushes us along at just under 6 knots with about 2800 rpm on the engine.

Hope this helps,
Regards, Jeff.

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[jeanne]

We did a great deal of research before changing our engine in a heavy displacement 12 ton boat. The Yanmar was our first choice as it is the only engine dedicated to marine use...BUT....it is not an easy engine to service. The latest design has an overhead cam and needs specialist advice or tools. They themselves said that they were disappointed by the sales. I suspect that the design is the problem. Most other marinised engines can be dealt with by anyone with a knowledge of land based agricultural machinery! This was important for us as a major engine problem in the back of beyond or even in some civilised places would mean that help is available. (not that we're expecting that....)
As another of your posts says, the Beta is based on the Kubota and these are popular engines worldwide, so spares are easy to find. The major thing about Beta is that they build the engine when you order which means that they can build in any mods necessary eg they changed the side for the exhaust on ours, put on a larger alternator in a different position and some other minor things to make it fit into our existing space on our existing bearers. They couldn't have been more helpful and we got a huge amount off as we had a Hurth gearbox on the shelf and they fitted that. Also a generous 30% discount off the list price. They are always at the end of a phone or if you are near them, as we are, you can go and discuss to your hearts content. The engine is also a lot cheaper than the Yanmar. Don't forget to plan for delivery cost if you are going to fit it yourself. We collected ours. We used the money saved on the gearbox to fill up with spares, and they were very helpful about that too.

The engine is more than we hoped for, is quieter and considerably more powerful than our previous 22hp.

Hope this helps
Best wishes
Jeanne

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[Twister_Ken]

Point of information

The Yanmar is not the only engine built solely for marine use. So is the Bukh, which offers a 2 cyl <A target="_blank" HREF=http://www.writeforweb.com/twister1>Let's Twist Again

 

[silverseal]

As another subscriber has mentioned, the Beta is based on the Kubota range of small diesel engines, used in things like small diggers and even larger ride on mowers, industrial compressors, charging sets and even roadside lighting units used when roadworks are in place. Hence there are a lot of spares and they tend to be more competitive than some other makes of "marine engines". Why should a replacement thermostat be about £15 from one maker when another charges £62, and they are near identical?

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[jleaworthy]

Re: PBO?

Also saw the article referred to by Twister Ken. I think they kept the same prop shaft when they changed engines and the more likely explanation of the heavier steering, I think, is that the prop is now a lot closer to the rudder than it was before.

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[Guest]

Re: Point of information

But for a 2 cylinder engine why is it so heavy? 210kg against 150kg for the 28hp Betamarine and 27hp Yanmar.

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[roger]

I bought a Beta recently. The staff are extremely helpful and know their products. You will have to get spares from them as there are few spares agents around (especially in the Baltic). However spares delivery is fast. My engine was delivered to Gothenberg for £80 so costs are low.
They can provide special feet for awkwardly set bearers. So far (3 years) mine has been excellent.

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[vyv_cox]

Re: Point of information

Dimensions, too. I replaced a Bukh 20 with a Yanmar 27. It's about half the size and the boat sat noticeably higher in the water after the change.

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[Twister_Ken]

Re: Point of information

>But for a 2 cylinder engine why is it so heavy?<

Built to last? Big flywheel and counterweights to give smoother running?

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[vyv_cox]

Re: Point of information

If only they did! My 3-cylinder Yanmar is far smoother than the Bukh was and the counterweights, being gear driven, seem to add noise and complexity. The flywheel is definitely big but I'm not sure how much it contributes to smoothness. There's no doubt that more modern engines without massive flywheels seem to be perfectly OK.

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