Why Do Landing Craft Have a Lower Payload Capacity Than Standard Cargo Ships?

The physical basis of a vessel’s carrying capacity is displacement: the deeper the hull is submerged, the more water it displaces, and the more cargo it can carry. To maximize cargo capacity, standard cargo ships typically have a draft of 1.5 meters or more. Landing craft, however, must be able to drive directly onto beaches and navigate shallow waters, so their full-load draft is usually kept between 0.3 and 0.7 meters. Take a 9-meter aluminum landing craft as an example: a draft of 0.31 meters means most of the hull remains above the waterline, leaving limited submerged volume and naturally limiting the payload to just 3 tons. This is the first trade-off landing craft make to ensure they “can reach shore,” and it is a core design element that cannot be compromised. If most of your operations involve deep-water docks, a cargo ship may be more suitable; however, if you need to deliver cargo to a sandy beach without a dock, the convenience of a shallow draft far outweighs the loss of a few tons of cargo capacity.

Cargo ships typically feature round-bilge or deep-V hulls. These hull forms have a large underwater volume and low navigational resistance, making them suitable for long-distance, heavy-load transport. Landing craft, on the other hand, feature flat or shallow V-shaped hulls designed to ensure even contact with the beach during beaching operations and prevent the vessel from becoming bogged down in sand or silt. However, flat-bottomed hulls have a relatively smaller underwater volume; for the same length and width, their displacement is 15% to 20% lower than that of round-bilge vessels. This means that, for the same hull dimensions, landing craft inherently carry less cargo than cargo ships. However, the flat-bottomed design offers another advantage: it is less prone to grounding in shallow waters, and when beached, the hull distributes stress more evenly, making the structure safer. For users who need to operate frequently in the intertidal zone, this stability provides a tangible safety assurance.

The most distinctive features of a landing craft are the hydraulic ramp and bow door at the bow. This system is approximately 1.2 to 1.8 meters long, occupying a significant portion of the bow’s length. Taking a 12-meter aluminum landing craft as an example, the ramp system takes up 1.5 meters, leaving only 10.5 meters of actual usable cargo hold length. In contrast, a cargo ship of the same length does not have this system, allowing its entire length to be used for cargo. Although the ramp “eats up” space, it is essential for the landing craft to perform roll-on/roll-off operations. Without the ramp, vehicles and equipment cannot board or disembark on their own. For users who frequently load and unload heavy cargo, sacrificing a little cargo length in exchange for operational efficiency is well worth it. A customer who frequently transports excavators said, “The ramp takes up an extra meter, but it saves two hours of loading and unloading time—it’s a win-win no matter how you look at it.”

Cargo ships primarily navigate deep waters, where the hull is subjected to relatively uniform forces. Landing craft, however, must repeatedly beach themselves, requiring the hull bottom to withstand violent impacts with the sandbar as well as bending stresses when part of the hull is suspended while aground. Consequently, the bottom plate of a landing craft is typically 6 to 7 millimeters thick, with critical structural areas specifically reinforced. This additional structural weight further reduces available cargo space. Although aluminum landing craft are lighter than steel vessels, the increased deadweight resulting from the reinforced design remains a factor. However, this “extra sturdiness” is essential for the safety of beaching operations. As one veteran captain once said, “It’s better to carry one ton less cargo than to have the ship fall apart on the beach.” In commercial operations, safety and durability directly impact long-term maintenance costs and downtime losses.

Cargo ships primarily transport bulk cargo (such as sand, gravel, grain, and liquids), allowing them to fully utilize every corner of the hold. Landing craft, on the other hand, mainly transport roll-on/roll-off (Ro-Ro) cargo such as vehicles, construction machinery, and containers. This type of cargo requires space for loading and unloading lanes, securing equipment, and crew operation areas, resulting in deck utilization rates of only 60% to 70%. For example, a 10-meter aluminum landing craft with a rated load capacity of 4 tons will have very little room left for other large items after loading a pickup truck (weighing approximately 2.5 tons). This is not a problem with the vessel itself, but rather a result of the cargo’s characteristics. For customers needing to transport vehicles, the landing craft’s load capacity figure does not represent the actual available carrying capacity; we recommend using the vehicle’s dimensions to match the appropriate vessel type. We frequently assist clients with “loading simulations” to ensure every inch of deck space is utilized efficiently.

Returning to the core of procurement decisions: Do you need a ship that “carries a lot,” or one that “can reach the shore”? If the destination has an existing wharf, a cargo ship is undoubtedly the more economical choice. However, many islands, aquaculture farms, and construction sites simply lack wharves. Building a makeshift wharf there can cost as much as $200,000. Sacrificing “a few tons of cargo capacity” to save millions in infrastructure investment while gaining “point-to-point” direct logistics efficiency is a highly cost-effective proposition for small and medium-sized business owners. A resort owner in the Philippines calculated that the savings on barge fees and dock rentals over three years of using a landing craft already exceeded the vessel’s purchase price. Carrying a few tons less to earn more for years to come—that is the true business logic behind the landing craft.