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The Atomic 4  

April 11, 2013. Anyone who has sailed in the 60s and 70s has probably had one of these engines - including your webmaster in his O'Day 27.

Jim Oppy is thinking about repowering WISP with one. Here are his emails - consolidated and edited


Re - researching motors. I can't justify a $7-10K (inboard diesel) motor but have fixated instead on an Atomic 4. They are too big heavy and powerful but they make up for that in initial low cost and overall performance. I had an Atomic 4 in a Cheoy Lee and it was remarkably quiet and reliable. Used ones are plentiful and reasonably priced. I'm leaning in that direction. 

I have safety concerns about a gas inboard. I had a blower arrangement on the cheoy lee, and the starting procedure included running the blower for a full minute before starting. It also had a fuel petcock that had to be manually opened when running the engine, and closed when not. I still had concerns and remember wanting a diesel instead of the gas motor. But I recently went sailing down in Annapolis on a Pearson Vanguard equipped with a rebuilt A-4 from Moyer Marine. Quiet, smooth reliable power. No diesel stench. Low initial price for re-powering compared with any diesel I've been able to find (that I would want). 

As for safety, I still have qualms about gas engines in boats. However, I would imagine the overall incident rate of accidents from accidentally ignited gas fumes is low. Anecdotal experience tells me it never happens to reasonably prudent mariners. There are a TON of boats out there with A-4's in them, and I've never heard of a single one blowing up (except for reading about it happening to someone else). I am OK with using gas engines aboard, especially for less than half the price of a comparative diesel. 

It would be fun to make an electric direct drive motor, like this http://electricboatmotors.com.au/?page_id=37 I am sure McMaster-Carr has all the parts one would need, except the shaft and prop itself. 



Here are a couple of Atomic 4 websites that are worth checking out


http://www.alberg30.org/maintenance/MechanicalPropulsion/Atomic4/ (see reader comments as well)





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