Atomic 4 - SailNet Community
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post #1 of 27 Old 06-30-2013 Thread Starter
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Atomic 4

Hello All,

Seems every time we almost find that right first boat, new questions/concerns arise. There actually 3 boats in our sights...1975 Northern 29, 1981 Mirage 27, both of these have atomic 4 gas with sail drive. The third is a 1979 Mariner 28 with a Yannmar Diesel. The Northern and Mirage are completely equipped the way we had hoped for and are around the same price range....7k. The Mariner needs a few items we had hoped for, but has the diesel engine and looks great and I know I can get it for 5k.
My main concern is the Atomic 4 gas with sail drive. Both owners have regularly maintained their engines?

Can you comment please, I look forward to your advice.


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post #2 of 27 Old 06-30-2013
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Re: Atomic 4

I haven't seen a A-4 coupled to a sail drive before but, I've got a 40 year old A-4 been rebuilt once if well maintained they are a solid reliable engine. and all parts are readily avalible.
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post #3 of 27 Old 06-30-2013
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Re: Atomic 4

Same experience as CorvetteGuy. 1000s of miles on my 1965 A-4. Just maintain and use the blower. If you end up with a A-4 you will find this forum, Moyer Marine Atomic 4 Engine Rebuilding and Parts ,as well as sailnet helpful. Dan S/V Marian Claire
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post #4 of 27 Old 06-30-2013
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Re: Atomic 4

My A4 is fine

In all reality the fact that it is a diesel or the A4 does not matter much the condition is what matters

The boat should look like this as we need to understand what you mean by saildrive as they were not used on A4s

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post #5 of 27 Old 06-30-2013
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Re: Atomic 4

Not a fan of gas engines, when diesels are so available. Many seem to like their A4s though.

From the sounds of it, however, you will not get the $5k boat to match your satisfaction with the $7k boats for the difference.

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post #6 of 27 Old 06-30-2013
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Re: Atomic 4

Originally Posted by Kalina-Lona View Post
atomic 4 gas with sail drive.
If it's gold/bronze/copper color it's an Atomic 4 (atomic bomb) gas engine - lots of these around and outfits established as quality rebuilders (have never seen one with a saildrive either)

If it's not it's an OMC Saildrive (snail drive) - basically an outboard motor power head with no casing installed inboard, coupled to a stationary lower unit leg - considering the age and rebuild parts are increasingly harder to find

I'd weigh the cost of the extras you are looking to add to the diesel powered boat compared to an Atomic 4/OMC engine rebuild/replacement, and also consider the age and condition of the features existing on the gas powered boats that may need replacing.
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post #7 of 27 Old 06-30-2013
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Re: Atomic 4

I'm with tommays - VERY unlikely you're looking at an A4 with a saildrive. It's most likely a standard shaft and propeller arrangement. I wouldn't rule out an A4 in your price range. Overall condition is more important.
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post #8 of 27 Old 06-30-2013
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Re: Atomic 4

My previous boat, recently sold, had an A4. They are good, solid, simple engines. One advantage is that the A4 is a lot quieter than most diesels. The gas fumes thing is no different than carrying propane. Follow proper procedures, and maintain the system, and it's no big deal.

The major downside of A4s is really just a reality about gas vs diesel: diesel is roughly twice as efficient. If range is not an issue (not going long distances, into areas where fuel is hard to find), then the A4 can be a fine engine. If range is important, go with diesel.
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post #9 of 27 Old 06-30-2013
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Re: Atomic 4

Where do I start first? First and foremost, the A4 is very reliable, extremely efficient, easy to work on, rugged, and cost efficient. When it comes time for total replacement, you could install three A4s for the cost of a similar HP diesel.

As for diesel being more fuel efficient than gasoline - not when you compare HP to HP. I'm pushing a broad-beam, 15,000-pound plus Morgan 33 O.I. with a 30-HP A4 gasoline. I get about 9 MPG at 1,800 RPM and cruise at 6 MPH on calm water. I have a friend with a similar boat, a Morgan 321, powered with a 3GM30 Yanmar Diesel. The boat weighs less, has a narrower beam and his fuel efficiency and speed are not as good as my A4. And, when it comes to repairs, the cost of replacing that Yanmar is out of this world.

Some folks believe that gas engines are all dangerous because of the possibility of explosion. If 6 decades of being on the water, and having owned 17 boats, spending an average of 70 or more days every year on the water, I have yet to PERSONALLY witness a single boat fire directly attributable to a gasoline engine - not one. I've seen two dozen fires directly related to electrical short circuits, and two diesel explosions. And, none of those fires were aboard sailboats - not a single one.

If you can find a good boat at the price you want to pay, I wouldn't worry whether or not it had an A4 or a diesel engine, as long as it the engine has been well maintained and in good condition.

Good Luck,

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post #10 of 27 Old 06-30-2013
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Re: Atomic 4

If all you want the engine for is to push you in and out of the marina then an A4 is fine.

However if you want to use it for long periods of upwind motorsailing then I would go for the diesel.

You don't see many A4s in the Eastern Caribbean.
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