As I think that told you last time you asked this question, I seem to recall three different roughly 38 foot Seafarers, the first two were built in Holland (I think that at first one was built by G. DeVries Lentsch boatyard in Holland for Seafarer), and the third design was built at Seafarer in Huntington, New York.
If I remember right the original Dutch built boat was a Phillip Rhodes design, the second was a Bill Tripp design and the third was a design by McCurdy and Rhodes.
Phillip Rhodes is deceased, but I believe that some of his work is in the Hart Maritime collection at M.I.T. and the bulk of the rest is at Mystic Seaport Museum in Mystic, Connecticut, USA. http://www.mysticseaport.org/index.c...F3190696B4438F
If your boat is the second 38 foot Seafarer the design was called a Javelin and that boat was a William H. Tripp Jr design and some of the drawings can be found on this website http://www.javelin38.com/
. This design was only available as a sloop and yawl, but not as a ketch.
The third design was by McCurdy and Rhodes and they are still in pactice and you should be able to reach them at McCurdyRhodes@aol.com
Have you tried these sources....?