You'd want to look at various "max" ship designations, which are based on various dimensions: overall length and beam, draft, and height above waterline (generally to accommodate bridges). These correspond to various canals and harbours. E.g., "Panamax", "Suezmax", and "Chinamax".
The tallest ship I'm aware of is the Pioneering Spirit, a catamaran / split-hull oil-platform service vessel, originally conceived as being built on two supertanker hulls. Given its mission, it might actually operate in the vicinity of the Irish Sea.
The maximum designated naval architecture stated vertical dimension standard I'm aware of is Suezmax, with a 68m (223 ft) air draft, shown in this Wikipedia article: <https://en.wikipedia.org/wiki/Cargo_ship#Size_categories>. (There are standards with unlimited air drafts as well, but I suspect most ships will fall within bounds of the largest stated.)
Oh, and another option would be for a tunnel-bridge hybrid, as with the Øresund Bridge, with tunnels to either side of Beaufort's Dyke and a bridge spanning that portion. I'm not aware of that being proposed though I suspect someone's thought of it. This would make for unlimited ship height through the passage overall. The Øresund span's clearance is 57m, FWIW.
The tallest ship I'm aware of is the Pioneering Spirit, a catamaran / split-hull oil-platform service vessel, originally conceived as being built on two supertanker hulls. Given its mission, it might actually operate in the vicinity of the Irish Sea.
The maximum designated naval architecture stated vertical dimension standard I'm aware of is Suezmax, with a 68m (223 ft) air draft, shown in this Wikipedia article: <https://en.wikipedia.org/wiki/Cargo_ship#Size_categories>. (There are standards with unlimited air drafts as well, but I suspect most ships will fall within bounds of the largest stated.)
Oh, and another option would be for a tunnel-bridge hybrid, as with the Øresund Bridge, with tunnels to either side of Beaufort's Dyke and a bridge spanning that portion. I'm not aware of that being proposed though I suspect someone's thought of it. This would make for unlimited ship height through the passage overall. The Øresund span's clearance is 57m, FWIW.