Glass manufacturers specify tempered glass as being four to five times stronger than regular glass. It is highly resistant to blunt and distributed forces and is more scratch resistant. The high strength of tempered glass is one of the properties that makes it suitable for the most demanding uses: in wind-loaded, high rise glazing, in overhead glass *, in stair and deck guard panels, in vehicle windows, in shower enclosures and even for table tops. However, very concentrated forces, such as hard impacts from pointed objects, will cause breakage into small, harmless particles.
Laminated glass has one advantage: the vinyl film between the two, untreated glass layers will hold glass shards together. In a vehicle windshield, it may even retain an unrestrained occupant, after a head-on collision. It might only chip with a hard rock hit on the highway, whereas tempered glass could break.
Boat glass is unlikely to suffer a rock hit or a head on collision so the 4 times higher strength of tempered glass makes it a much better choice.
*(The BS 6206 Architectural Standard involves a series of tests where a lead-filled leather bag weighing 45kg is dropped from varied heights onto a standard test safety glass panel. Class 1 (tempered) failed with over a 122 cm drop. Class 2 (laminated) failed with over a 45 cm. drop. Class 3 (wired) failed at 33 cm.)