GROTON, Conn. (AP) _ The U.S. Navy Saturday launched its 10th Trident nuclear-powered submarine, the USS Pennsylvania, as police arrested dozens of anti-war protesters.

''This ship is part of the strongest military deterrent force ever assembled,'' Rep. Joseph M. McDade, R-Penn, said at the launching at the Electric Boat Division of General Dynamics Corp. ''This boat allows us the luxury of having no doubtful engagement.''

The Pennsylvania, after it is fully equipped and outfitted, a process that normally takes at least a year, will be the second ship in its class to carry the more accurate Trident II missiles. Each of the 24 missiles carries 10 nuclear warheads.

The boat, which was christened by Marilyn Kay Garrett, wife of Navy undersecretary H. Lawrence Garrett III, will have a crew of 154.

The Ohio Class Trident submarines are the largest and most powerful in the Navy fleet and are the heart of the U.S. sea-based nuclear deterrent. The boats measure 560 feet long and displace 18,750 tons.

The program was initiated in 1974, with the first ship, the Ohio, commissioned in 1981. Congress has approved funding for 15, of which eight are in service.

Fifty to 75 anti-war protesters demonstrated at the shipyard, and Joan Cavanagh, a member of the Coalition To Stop The Trident, said 32 people were arrested after they lay down in front of the gates.

A dispatcher with the Groton City Police Department said more than 20 people had been arrested on disorderly conduct charges as of Saturday afternoon and would be released on their own recognizance.