In the interest of "just the facts, ma'am":
From Kerry's own website:
February 18, 1966 Kerry formally enlists in the U.S. Navy
He goes to various stateside schools as everybody did.
June 8, 1967 Kerry reports to USS Gridley.
February 9, 1968 to June 6, 1968 Gridley spends time in the Gulf of Tonkin off North Vietnam, at Subic Bay in the Philippines and in Wellington, New Zealand.
returns to US in June.July 20, 1968 - November 1968 Kerry attends stateside school.
November 17, 1968 Upon completion of his training, Kerry reports for duty to Coastal Squadron 1, Coastal Division 14, Cam Ranh Bay, South Vietnam.
Early April, 1969 Kerry departs Vietnam.
So what you've got for his "tours" is
4 months on Gridley in the Gulf of Tonkin off North Vietnam, at Subic Bay in the Philippines and in Wellington, New Zealand, returning to US in June.
5 months total from sign-in to sign-out in Swifts.
Enough of this "did not, did so!" There's the facts according to Kerry himself.
Discuss.
dates in red edited to correct timeline by ~ 40 more days on Gridley while ship was stateside. There ya go Horn; good catch. <\edit>