Chapter 2 engine installation.
The boat's transom is uniquely built to accommodate 30" shaft outboards. The smalles t30" outboards are 225hp, making the repower a very expensive proposition. Plus, as its intended use as a survey/workboat, did not require a 50 knot top speed. After much deliberating, we decided to design a custom bracket based on stock (off the shelf) structural aluminum angles. The bracket would offset the engines from the transom about 18", while providing a 5" inch drop I mounting position to fit 25" shaft outboards. Then 115 hp 4stroke Yamaha's were installed. Trial runs with 3 crew, full gas, 2 foot seas is 32 knot top speed and a 21 knot cruise at 4600rpm. Motors are not giving full rpm's so it may benefit from a drop in prop pitch. However, we are satisfied with current performance. Motors are not counter rotating. Pictures to follow .