# replace Atomic 4 with Yanmar YSB8



## russ1302 (Aug 23, 2006)

has anyone replaced an Atomic 4 with a Yanmar YSB8? I'm considering the swap in my newport 27, but I'm not sure if it's enough engine. Does anyone have any experience with the Yanmar YSB8, in a 27ft boat?

Thanks
Russ


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## mhfowle (Sep 13, 2006)

I have a ysm 8 on my 26ft. S2. It's very reliable and powerful. I think my boats weighs 5000lbs. It's easy to maintain and the parts are reasonable and redily available. Also Yanmar stands behind their pproducts and offer superior customer service, even on 30 yr. old engines.


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## okawbow (Feb 15, 2007)

I have a YSE8 in my Bristol 24. The boat weighs 5800 lbs. I use a 12", 2 blade prop. The motor pushes the boat near hull speed, but I've had trouble making good headway in very high winds and waves.


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## sailingdog (Mar 19, 2006)

Russ-

Why are you replacing the Atomic 4? Is it because the engine is having problems? Or is it because is a gasoline engine??? 

BTW, IIRC, Beta Marine may make a diesel that is a "drop-in" replacement for the Atomic 4.... and that would significantly reduce the costs of swapping the Atomic 4 for a diesel—since you wouldn't need to replace the engine mounts or prop shaft.


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## russ1302 (Aug 23, 2006)

I'm replacing the atomic 4 because it was siezed when I got the boat, and when I dug deeper, I found the valves are frozen and there is way to many rusted out parts to mess with.

It sounds like I should try to find some thing with a bit more power for my 6000 lbs boat. Or maybe just a different prop?

Thanks
Russ


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## sailhog (Dec 11, 2006)

Look at the Beta Marine drop-in replacement. They're a lot less expensive than the Yanmar, and are made specifically to replace the A-4. Good luck.


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## Valiente (Jun 16, 2006)

Beta (which are simply marinized Kubotas, from what I understand) have been getting good reports not just as a drop-in for Atomic 4s, but generally as reliable small diesels that are a shade more intelligently designed, particularly for the typical "lift off the companionway stairs" access option.

I never thought I would appreciate having an engine bay I can simply stand in, but I do, as the thought of hauling my engine anywhere but directly up is fairly depressing.

I think it's a shame that the "engine box in saloon" style has pretty well disappeared. I'm sure modern soundproofing techniques, careful venting, and other methods could make it work. Having the diesel in the middle of the boat not only makes sense (360 degree access), but puts the weight over the keel and closer to the CG. It also means the shaft and prop can exit the boat at a shallower and more useful angle.

But I digress.


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## russ1302 (Aug 23, 2006)

The yanmar is a good used engine, and would cost a fraction of the Beta Marine. The boat isn't worth the cost of the Beta setup. So I'm looking to find an engine and just freshen it up.

Russ


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## okawbow (Feb 15, 2007)

*Go for it!*

Many sailboats don't have motors at all. The 8hp Yanmar should push your boat well in most conditions. If you don't sail in areas with strong currents, you should be ok. Just treat the motor as an aid to sailing. I can't understand why some sailors go around the world without a motor, and some have to have 50hp on a 26 footer.


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## russ1302 (Aug 23, 2006)

I sail in the San Francisco bay, and there is a great deal of current in some areas. I will often motor for as much as 45 minutes at a time, in strong currents. So I'm thinking I'll go with a slightly stronger engine. Maybe the YSB12, or a 2 cylinder model.

Thanks
Russ


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## artbyjody (Jan 4, 2008)

You may find a cheaper alternative in changing props (ie: going bigger)... than merely replacing the engine...



russ1302 said:


> I sail in the San Francisco bay, and there is a great deal of current in some areas. I will often motor for as much as 45 minutes at a time, in strong currents. So I'm thinking I'll go with a slightly stronger engine. Maybe the YSB12, or a 2 cylinder model.
> 
> Thanks
> Russ


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## JohnRPollard (Mar 26, 2007)

Russ,

I'm pretty sure you want at least two cylinders for this application. Yanmar makes a few examples and we've had good service from the 2GM and 3GM engines in our boats. 

I am studying the Betamarine engines right now for a boat I'm considering building. I think the models you'd want to look at are the BZ482 (.48 liter displ, 2 cylinder, 13.5 hp) or the Beta 16 (.6 liter, 2 cylinder, 16 hp). If you want to bump up to 3 cylinders, the BD722 (.72 liter, 20 hp) is the same engine as the BZ482 with one more cylinder. The Atomic 4 mounting system is listed as a no-charge option for all these models on the price sheet.

One thing to study no matter which engine make you go with, is that the stated HP rating of the engine is usually not the continuous rating, but instead is the surge rating for short durations. So when sizing the engine, make sure it has a CONTINUOS rating that is adequate for your boat. I would think you'd want at least 13-15 hp continuous.

P.S. Edit, oops sorry, now see you don't want to spend the money on a new Beta. Somebody recently posted a link to a slightly used Yanmar 3YM (I think) engine listed on Craig's list (again, I think). It's located in Maine but the price was well less than half a new engine, so it might be worth investigating even with shipping.


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