Two major problems made a redesign necessary. The preferred light weight medium-speed (locomotive type) Electro-Motive Diesel 12-567 diesel engines were not immediately available. Staff wanted more power and higher speeds if possible, which the EMD engines could have provided. However, the only engines available were very heavy steam reciprocating engines from frigates that had been cancelled. These delivered two and a half times the power of the diesels. So large were they that significant changes had to be made to accommodate them. Lack of welded construction facilities meant that the hull had to be riveted. This combination of heavy hull and heavy engines meant that speed was only 3 knots faster than the LCT (2).