Joffrey Caused the Bridge of Ships

“Mother promised I could have the Whores.”

When Joffrey commanded the trebuchets to launch the Antler Men into Blackwater Bay, they hit the ships, or overshot them, but did not splinter them as boulders would. Aboard the bridge of ships, Tyrion sees a naked man splat on the deck. Then, running out of Antler Men, the Three Whores throw boulders again and the bridge of ships is ripped apart.

“A naked man fell from the sky and landed on the deck, body bursting like a melon dropped from a tower. His blood spattered through the slit of Tyrion's helm. Stones began to plummet down, crashing through the decks and turning men to pulp, until the whole bridge gave a shudder and twisted violently underfoot, knocking him sideways.

Suddenly the river was pouring into his helm. He ripped it off and crawled along the listing deck until the water was only neck deep. A groaning filled the air, like the death cries of some enormous beast. The ship, he had time to think, the ship's about to tear loose. The broken galleys were ripping apart, the bridge breaking apart.”

- ACOK, Tyrion XIV

Since stones break the bridge apart, stones would have kept it from forming.

But if Joffrey hadn't caused the bride of ships, Tyrion would have. Before Tyrion entered battle, he sent a command to the trebuchets. He redirected them to target the beach, at the men clambering out of the water.

“Bring my compliments to Ser Arneld and ask him to swing the Whores thirty degrees west.” The angle would allow them to throw farther, if not as far out into the water.

- ACOK Tyrion XIII

The bridge of ships would have been Tyrion's fault, where this order followed. However, this is when Joffrey objects, saying Cersei promised him the Whores. Tyrion allows it:

“It was as good a time as any; flinging more firepots down onto burning ships seemed pointless. Joff had the Antler Men trussed up naked in the square below, antlers nailed to their heads. When they'd been brought before the Iron Throne for justice, he had promised to send them to Stannis. A man was not as heavy as a boulder or a cask of burning pitch, and could be thrown a deal further. Some of the gold cloaks had been wagering on whether the traitors would fly all the way across the Blackwater. “Be quick about it, Your Grace,' he told Joffrey. “We'll want the trebuches throwing stones again soon enough. Even wildfire does not burn forever.” - ACOK Tyrion XIII

The men selected to fire the trebuchets turn out to have been better at knowing what to target than their commanders, especially Joffrey who preferred to entertain himself by making men suffer than see his throne defended.

This has to be a critique of command by noble know-nothings.