During our sea trial, we hit a top speed of 25.4 knots on a fully loaded yacht, less food stores, with a pair of 3412 Caterpillars. On this particular 78, the owner chose to have the Cats "D" rated, reducing the horsepower from 1,350 to 1,250. This reduces the top speed, but provides a more economical cruising speed. According to Marlow, another 78 with "C" rated 3412s, has a top speed of approximately 30 knots. This impressive performance can be attributed to both the hull design and lightweight construction techniques employed in each Explorer.