It's nearly impossible to create a ground effect vehicle that can't fly out of ground effect for a limited time. They need a significant amount of extra power

It's nearly impossible to create a ground effect vehicle that can't fly out of ground effect for a limited time. They need a significant amount of extra power to get out of the water in the first place, so there will always be more power available to climb out of ground effect. The maximum altitude would be limited, you wouldn't be able to climb over a mountain, or over clouds. Depends on the exact specs, but should be more than enough to clear large ships, or at least get the altitude to make it safe to do a steep turn.