Lewmar Low-Profile Size 40 Flange Base Hatch. The sleekly designed Low Profile Hatch is ideal for use on a powerboat. Smaller ventilation hatches are a better fit for sailboats, while the larger sizes can be used as foredeck hatches on smaller to mid size yachts. Lewmar hatches feature Lewmar's unique sealing system allowing easy acrylic replacement. All sizes suitable for CE Area 2 (Deck, Coachroof, Cockpit and Transom).