In Bray et al, Mystic Seaport Watercraft, 2001, p. 74 there is a photo of Herreshoff 15-footers with the caption "Fiddler and others of her class racing in light weather. (Mystic, 1960.349.)"
Fiddler's sail number is E-11.
Other sail numbers on that photo are: E-12, E-5 (I think...), E-8 and E-4.
Looking at Steve Nagy's H-15 registry E-12 might then be #693s Endeavor, E- 5 #785s Flickermaroo, E-8 #519s Ranzo ex-Next, but who is E-4?
And did these five boats race together in or around Marion, Mass.? When?