“Battleship” is all wet. The film boasts a destroyer’s wallop of visual effects, but not enough brains to fill a dinghy. Its cliches-in-a-blender plot and clunker dialogue will disappoint anyone who hoped that basing a movie on a brand-name board game was a guarantee of quality.

Slavishly imitative of action hack Michael Bay’s cinema du boom, the story is essentially a moist “Transformers.” Responding to a beacon signal from Earth, extraterrestrial invaders send, of all things, a fleet. The ships look like big, angry metal water bugs and propel themselves by jumping a few hundred feet at a time.

You may wonder why an intelligence that could manage an interstellar space expedition would choose to travel in such a slow, inconvenient and bumpy manner once they arrive. Don’t. Looking at “Battleship” through the prism of logic will only induce migraines. These aliens can quarantine the Hawaiian Islands behind a force field that flattens jet fighters like June bugs, but do not outfit their command ship with bulletproof glass. They engage in combat by firing explosive projectiles that are no more accurate than pirate cannonballs. This is a big step back for aliens. Even in the flying-saucer movies of old they had an air force and death rays.

The invaders arrive off the coast of Oahu during a multinational naval exercise. Taylor Kitsch (fresh off the epic flop “John Carter”) tops the cast as Lt. Alex Hopper, a wastrel who has been only partly redeemed by Navy discipline. Hopper may be the most boneheaded action hero in movie history. When an alien skyscraper pops up in the azure waters, he decides to form a one-man boarding party, pounding on the dormant tower’s exterior and making the sleeping giant wake up grumpy. After the invaders sink two destroyers amid explosions, fireballs and bodies flying through the air, he declares, “I’ve got a bad feeling about this.” Roger that.

The film is mostly about muscular, macho guys in uniform (the main civilian is a weedy science dweeb Hamish Linklater, who’s cowardly and can’t drive a car). In an effort to provide balance, there are a couple of hot chicks. Swimwear model Brooklyn Decker, whose name sounds like a deli sandwich, plays Kitsch’s love interest, Sam. She is the daughter of Adm. Liam Neeson. He must not have raised her well: She gives Kitsch her heart when they meet in a bar, and he breaks into a convenience store to steal her a chicken burrito.

Also on hand is pop star Rihanna, who plays a spunky gunner; apparently Michelle Rodriguez was taking the week off. There are also — spoiler alert — some crusty old seamen whose know-how comes in handy as they fire up the museum ship U.S.S. Missouri and miraculously locate 70-year-old ordnance for its big guns. Somehow I found the alien invasion part easier to believe.

The hoo-rah for vets extends to the best part of the film, the performance by Lt. Col. Gregory Gadson, director of the U.S. Army’s Wounded Warrior Program. He plays a double-amputee Iraq hero whose prosthetic legs are perfect for kicking alien butt. With lines like “Let’s see if we can give the Earth one more day,” his role is a hazardous mission, but danged if Gadson doesn’t nail it. You probably won’t remember the interchangeable action sequences the next day, but this guy will stay with you.