Hatch and manway

How to choose portholes, companionways and deck hatches for your boat

The choice depends on four main variables: function (ventilation, access, inspection or light), the size of the compartment to be housed, the material and the type of installation. Knowing the exact size of the deck opening is the essential starting point.

Fixed or opening portholes

Fixed portholes guarantee watertightness with minimal space requirements and are the standard solution for the side hull. Opening ones add the possibility of ventilating the below-deck area and are available in both round and rectangular frame versions. Lewmar, Gebo and Nautica F4 cover a wide range of sizes, from the small hull porthole to rectangular formats of 410×205 mm and larger.

Companionways and deck hatches

The companionway is designed for physical passage between the deck and the interior: it requires a sufficient clear opening and a robust frame. Low Profile (L.L.) models are flush with the deck, reduce the footprint and improve aesthetics; raised ones offer greater resistance to seawater. Lewmar Ocean, Gebo and Nuova Rade offer aluminum and plastic versions with standardized dimensions. Inspection hatches (inspection ports), on the other hand, are used to access technical compartments without human passage.

Measurements and compatibility

Before ordering a porthole or companionway, always measure the external frame size and the clear deck or hull opening. Manufacturers indicate both dimensions in their technical catalogs. For spare parts (gaskets, hinges, handle kits), it is equally important to identify the exact series — for example, Lewmar Standard series 2 or 3, or Low Profile — because components are not always interchangeable between different series.

Materials: aluminum, stainless steel and plastic

Anodized aluminum is the most common material for frames: lightweight and corrosion-resistant in marine environments. Stainless steel is preferred for hinges and hardware subject to stress. Plastic (ABS or technical polymers) is used for inexpensive inspection hatches and companionways, with good watertightness but lower long-term resistance to UV rays.

Accessories: blinds, mosquito nets and spare parts

Blackout blinds and mosquito nets are mounted internally on the porthole or hatch and are available in roll-up, pleated or panel versions. OceanAir (Dometic line) and Trem (Sunset Curtain line) are the most sought-after brands. For spare parts — sealing gaskets, hinge kits, coupling bars, latches — always check the manufacturer's original code: many Lewmar and Gebo items are available individually.