The
Skjold design is a
surface effect craft, constructed of
glass fibre/carbon composite materials. Buoyancy is augmented underway by a fan-blown skirted compartment between the two rigid catamaran-type hulls. This provides an alternative solution to the planing hull/vee hull compromise: the air cushion reduces wave slam at high speeds while presenting a low-drag flat planing profile at the waterline. To ensure stealth capabilities,
anechoic coatings of
radar absorbent materials (RAM) have been used in the load-bearing structures over large areas of the ship. This strategy leads to significant weight saving compared to the conventional construction technique of applying RAM cladding to the external surfaces. The ship's profile has a faceted appearance with no right angle structures and few orientations of reflective panels. Doors and hatches are flush with the surfaces and the windows are flush without visible
coaming (edge of window aperture) and are fitted with radar reflective screens. The vessels are additionally protected by the Rheinmetall
MASS sensor / decoy system. The final design was changed compared to the prototype
Skjold, which itself was rebuilt to the new specifications. Most notably, the vessels use 4
gas turbines combined by
Renk COGAG gear units built in a lightweight design. The smaller gas turbines rated 2,000 kW turbines are used for cruising speed. For sprint speed a second, larger gas turbine is combined providing a total of 6,000 kW to the waterjet on each shaft line. Two MTU 123 cruise diesel propulsion units used previously at loiter speeds were removed. The foredeck was strengthened to accommodate the addition of a
76 mm Otobreda Super Rapid gun. The hull material was produced by a different method to improve strength and minimize vulnerability to fire. The bridge saw some changes, including an upgrade to six weapon systems control consoles. In 2020, the Norwegian Government decided to further upgrade the
Skjold-class vessels, partially to compensate for the loss of the frigate
Helge Ingstad. The upgrades of the four ships would take place between 2020 and 2024, permitting the
Skjold-class to remain up-to-date through to 2030 when replacement vessels were envisaged under terms of the government's defence plan. In February 2026, contract was signed for upgrade of the fire control radar and electro-optical sensors for four vessels. The radar upgrade is to ensure capability to deliver precise fire with the 76 mm gun, while the new electro-optical sensors will improve the vessels’ ability to detect and track targets at sea and in the air, including smaller and fast-moving objects such as drones. ==US Navy==