Nautilus Ed,
When we were first hunting for a P-323, we were only going to look at diesels. A number of friends convinved me that, if the rest of the boat met my needs and requirements, that I shouldn't dismiss it just because it has an A4.
They turned out to be right.
The A4 is a very well-supported engine, thanks largely to the efforts of Moyer Marine. Of the 40,000 originally built, 20,000 are still in service. And as of 2 years ago, Moyer is even casting new blocks, built right here in America. All parts are readily available. And there is a huge active user base on the Moyer Marine Forum. So when we found a boat that was in good condition, and well equiped, but with an original, un-rebuilt but well-running A4, we went for it, knowing that we could get parts and support, and even a fresh engine, if needed.
What I found was that the A4 is a dirt-simple, overbuilt, reliable beast that can be understood and kept running by an ordinary Joe with standard tools. It's based on 1940s-era tractor engine technology, but was designed from the ground up to be a sailboat engine. Keep it clean, feed it with oil & gas, and keep it from freezing, and it'll run for decades.
As it turned out, the PO had damaged it by improper winterizing the Winter before, but the damage was not apparent, missed by both myself and the specialist engine surveyor. Midway through our first season, without symptoms, it died beyond redemption with a cracked block! I did a lot of research on the possibility of repowering with a diesel, but determined that this was a LOT of work, as MANY systems are affected (fuel, electrical, controls, mounting, prop, shaft, v-drive, etc) and very expensive. The total, even with me doing some of the work, would approach what we paid for the boat. A rebuilt A4, on the other hand, would be a drop-in replacement. In an effort to trade money for time, I elected to buy a rebuilt short block from Moyer, and swap out the other parts from our first engine myself. I also took this opportunity to convert from raw water cooling to fresh water cooling, as this is the single best thing you can do for your engine (gas or diesel) to improve its longevity. My total cost, including almost $1000 for the fresh water cooling, was somewhere between $5000 and $6000.
So that's how I came to the A4 and why I stuck to it.
As for performance numbers, here's what I have.
After the rebuild, on flat water with no wind, I get a wide-open-throttle (WOT) performance of 3100 RPM and a little over 6.5 Knots. This is still under the boat's hull-speed of 7.04 kts, but I believe I'm still a little under-propped. I'm hoping to repitch the prop this spring.
But you don't really want to run there. It's not efficient and it's hard on things. Normally, I run between 2000 and 2400 rpm. At 2000 I'm doing 5 kts with no headwind. On the other hand, we've pushed into an 18 kt headwind and 3 - 5 ft seas on the nose, getting up to about 5 kts before the next wave would slam us down to 3.
Last summer, We did a 400 mile circumnavigation of the DelMarva Peninsula. There was little wind and we ended up motoring a large portion of the time. 71 hours over a one week period! Based on the engine hour meter and actual gallons burned, we averaged about 3/4 gallon per hour. With the P-323's large 30 gallon tank, this meant we were able to do the entire 140 NM offshore leg on less than a tank. Never even had to get into the jerry jugs we kept on deck. Others on the Moyer Marine forum report similar consumption rates when some effort has been made to tune the engine for efficiency.
Hope this helps. Let me know if there's anything else you'd like to know.
