This flathead four cylinder engine was used in many
sailboats, 25 to 45 feet, from shortly after WW II to the early
eighties.  Production ceased in 1978, but Catalina Yachts had
bought a large number and used them until the early 80’s.
Many boats are still being enjoyed by the owners who are 
willing to take a little time for routine maintenance.

Many 27-35 foot sailboats can be purchased for less than
$10,000 with A4’s..  Often owners will call for a quote on a 
new diesel and are surprised when the total remove and 
reinstall (R&R) exceeds what they paid for their boat.

Some choose to have their A4 rebuilt for much less. 
Some choose to  install an outboard, a poor choice in my opinion.
The A4 can be an excellent, reliable auxiliary engine.  There are 
a few folks who do an excellent job of rebuilding A4’s (Moyer Marine, Nuclear Engine and a firm in British Columbia, Canada).  I have been rebuilding A4’s for about fifteen years now, selling and shipping them all over the USA and have many satisfied customers.

Atomic 4’s