Is this true? Why did it change into a sitcom then?

I heard about this a few years ago, I believe the original title was Seven Against the Sea.

yes, that was the original title. Some site (I think it's tvparty.com) has or had an article about it that also had some clips from it.
Gene L. Coon-the producer of "STAR TREK"-turned it into a sitcom. It was seen as a segment of an anthology show called "Fred Astairs Alcoa theater" or something like that. Ernest Borgnine played McHale, but I don't think any of the other castmembers were in it. (Tim Conway and Joe Flynn OBVIOSLY weren't-could you see those two in a drama???:lol: )

...was as an hour-long dramatic pilot (produced by John Champion), which was "burned off" on "ALCOA PREMIERE" (aka "FRED ASTAIRE'S PREMIERE THEATER") on April 3, 1962. Somewhere between the pilot's production and ABC's rejection of it as a weekly series, MCA/Revue decided to "convert" it into a half-hour comedy [which ABC and sponsor Procter & Gamble bought], with Edward J. Montagne, formerly in charge of "THE PHIL SILVERS SHOW", as executive producer [which led some in the industry to refer to the show as a "briny (Sgt.) Bilko"]. Only Ernest Borgnine and Gary Vinson continued from the original pilot. Montagne added Tim Conway, Joe Flynn, Carl Ballantine, Gavin McLeod, and Bob Hastings, as well as Yoshio Yoda as prisoner-of-war "captive", "Fuji" ("Oy, vey!"), and changed the situation from the crew of a PT boat trying to survive on a Japanese-held island during World War II....into that of a conniving PT boat commander, and his equally larcenous crew, "living the good life" inbetween missions on a South Pacific island during World War II while trying to avoid being caught by their blustery commanding officer [sounds like "Sgt. Bilko", doesn't it?].

:tv:

1962? I thought it was 1960 or 61.

ONLY BORGNINE,THE ACTORS WHO PLAYED WILLY AND CHRISTY WERE ON THE ORIGINAL PILOT. I HAVE HAD THIS PILOT FOR 3 YEARS OR SO-COMPLETE, AND IT IS VERY INTERESTING TO WATCH. A MUST SEE FOR ANY FAN

Can the original poilt be seen on the dvds or youtube or somewhere?

i have it on dvd-it is really good