Yea for the 1942 Navy!

Somehow we knew that President Reagan would bring back the battleship. After all, he is partly responsible for the rerun of a lot of old movies on television. So why not a nostalgic fighting force?

The battleship New Jersey was first commissioned in 1942, so it is no wonder President Reagan modestly declared at the recommissioning ceremony, ''Our status as a free society and world power is not based on brute strength.'' Amen to that. It probably is the most appropriate thing to say while standing on the deck of a 40-year-old battleship.

Thousands of people toured the ship at that time. It was reliably reported that hardly anyone mentioned the smell of mothballs. There were a few lifted eyebrows, however, when the President said, ''Providing an adequate defense is not cheap.'' A lot of officials had just finished bragging that, at $326 million , the New Jersey is the cheapest way to bring a floating Navy up to strength. At least up to the strength it was in 1942.

There is much to be said for these old dreadnoughts which first began about 1906. Considering the state of the American economy, rebuilding old battleships and reviving other older forms of combat may be the best answer to the arms race. Some of that old stuff served the United States very well. President Theodore Roosevelt had high praise for the battleship. And also for the US cavalry which did such a great job going up San Juan Hill in Cuba. We haven't been able to get into Cuba since. Later, it proved to be one branch of the service which always arrived in the nick of time, as old movie fans well know.

It probably would not cost too much to rejuvenate the cavalry. Especially since it wouldn't require a lot of that electronic equipment for guidance and so forth. It might even be possible to mount two Exocet missiles on each side of a horse like saddlebags. One could argue that horses are not steady enough to be missile-launching platforms, but they could be trained to sit down when the missiles were fired.

All in all, there is much to be said economically for a return to simple gunboat diplomacy - showing the flag in foreign ports. Laying a random shot from 16-inch guns across the bow of some of those smart-aleck pirate boats based in North Africa might not be amiss, either. Incidentally, those 16-inch guns toss a hunk of metal about the size of a Toyota, if such a comparison is not too suggestive.

No one knows all the answers. Maybe the 40-year-old New Jersey has a lot of brand-new secret weapons on board. A very reliable source states there are some improved Gatling guns recently installed.