Champion Navy battles challengers Penn and Harvard in the world series of rowing tomorrow afternoon on the Schuylkill River in Philadelphia at 4:30 p.m.

As the only undefeated major crews in the East, these three eights will be rowing for the honor of being the best shell on the Atlantic seaboard and probably in the country. At stake will be the Adams Cup and Navy's string of 23 consecutive victories over the past three years.

Also rowing over the Henley distance of a mile and five-sixteenths will be the junior varsity and freshman crews from the three schools. The freshman race is scheduled for 3:30 p.m. The jayvees will row half an hour later.

Tomorrow's regatta will be the second time in three years when these varsity crews have gone into the Adams Cup race undefeated. Navy, current holder of the 19-year-old cup, has romped through all opposition this spring and set a record over the two mile Lake Onondaga course.

Except for two men, the middle crew is the same one which won the 1952 Olympics. It has been seriously challenged only once and that by the 1953 Harvard varsity in the E.A.R.C. regatta.

The Pennsylvania eight, averaging a solid 190 pounds, is stroked by former Canadian sculls champion Jack Guest and has won two major cups and set a regatta record on Lake Carnegie. It will have the advantage of rowing in home water tomorrow.

The Crimson oarsmen who will oppose these two powerhouses have won two regattas and turned in handsome time trials on the Charles. The crew average 187 pounds and will be stroked by senior Larry Brownell.

Princeton is the only common crew these three giants have beaten and on the basis of comparative times Navy has the edge. It beat the Tigers by eight seconds, the Crimson was six seconds faster than Princeton, and Penn was five seconds ahead.

In the junior varsity race, Navy's eight rates the nod over Penn and the Crimson JV's by sheer depth of material.

The undefeated Crimson JV crew, stroked by Len Wheeler, is unchanged so far this season except for the substitution of Tom Petterson for Bruce Martin at bow.

The freshman race features the Crimson Yardlings, with one victory to their credit, against weaker Penn and Navy crews. Stroked by Carlo Zezz, the big eight is experienced and has pushed the varsity in time trials.