Some boats are fitted with undersize hatch lift components, leading to early failure. Lifters are rated by how many pounds they can push. You want them overrated. A 100-pound hatch, for example, should be fitted with a 120- or 130-pound lifter. The use of two lifters, with total power equal to one larger lifter, is a positive, since multiple lifters evenly distribute the stress on the hatch and its hinges.