Playing host to Cornell, M.I.T., and Princeton, the Crimson's first postwar crew opens its formal season today at 5:30 o'clock on the familiar stretches of the Charles River. The four-way regatta will take place over a 1 3/4 mile course from the M.I.T., boathouse to the West Boston bridge.

Coach Tom Bolles, hoping to maintain a record marred by only three defeats in nine years of guiding Crimson oarsmen, yesterday afternoon put his Varsity through a short workout in preparation for today's inaugural. "They look pretty good," he said. "In their last trial, the Varsity eight registered their best time of the season, but they are still a green crew."

Further hampered by the loss of stroke Torby Ross, who was laid low by German Measles, the Varsity will at least be competing under favorable weather conditions, promised as fair and cool with gentle, variable winds. The afternoon's competition will begin at 4:45 o'clock when Bert Haines' first and second shells of 150 pounders face M.I.T. and Tabor Academy on a 1 5-16 mile course. At 5:10 o'clock the Crimson, Cornell, M.I.T., and Princeton Jayvees will christen the 1 3/4 mile course.

To fill Ross's elide, Bolles pulled Lou Cox out of his Jayvee boat on Thursday. Cox, an ex-infantryman who holds the Purple Heart, stroked the Varsity shell once before earlier in the season, and was stroking the Jayvees when they beat the big boat two weeks ago.

Harrison Sanford, Cornell mentor, brings to Cambridge a tall, rangy squad whose average weight is an impressive 184 lbs. Luckier than most of his colleagues, Sanford boasts four former Varsity men in his first eight. Power and experience make them the team to watch.

Servicemen Stud Lineups

Besides Cox, six other servicemen will help propel the Crimson shell. None have seen Varsity service. Rowing number seven will be Bim Chanler, an exartillery captain in the ETO who held down the same spot in the undefeated Freshman team of 1942. Number six is Mike Scully, another Army man, with only a brief informal season behind him.

Paul Knaplund, in the number five position, an 185 lb. heavyweight nurtured on Wisconsin milk and eggs, spots four years to 22 year old Barrie White, former B-24 pilot, who rows ahead of him. Tom Haymond, number three, learned his business with the informal war-time crews.

Lew Bohn came back from three years in the Army to take over the second oar in the Varsity boat. Moving now more sedately than he did as a Navy night fighter pilot. Bill Cochran is bow man. Tom Grant, purple-heart infantryman, handles the Varsity megaphone.

Princeton is the only competitor tested so far this year. Last Saturday they trailed Pennsylvania and Rutgers by 24 seconds on Lake Carnegie. Not inexperience, but war-imposed inactivity plagues Tiger coach Deles Schoch, since his entire squad is composed of returning veterans. Dormant since 1943. Princeton crew was resumed last year on an informal basis.

Formerly the nation's only starboard stroked crew, Old Nasau has this year returned to more orthodox ways, will rely on outdistancing the opposition, not confusing them.

The Cornell visitors have made their headquarters in the Newell Boat House, while M.I.T. is entertaining Princeton. Both traveling teams will row in borrowed shells.