The Lun design had several drawbacks. One was that although the ground effect enabled it to fly at low altitude, in order to utilize the effect it had to fly as low as 1.5–3.0 m (5–10 ft) off the water due to its short wingspan, so it could not fly when seas were even mildly rough. Another was that the craft was only designed to use the ground effect principle, so it could not ascend to higher cruising altitudes.

I question how on earth this got past the whiteboard phase. If seafaring ability was the need, why not build this as a ship? If speed was necessary, why wasn’t this a true aircraft?