Our controllers have been used in a wide variety of electric boat projects. The 4QD-200 and 4QD-300 are particularly popular for cruising on the inland waterways, and have also been used in electric outboard conversions.
The 4QD-300 has been used as part of a diesel electric hybrid drive system on a 40′ catamaran, and a number of boats in the Electric Boat Association use our controllers, have a look at this post on our blog.
Marine use can be hard on electronics, and high currents can be sustained for long periods. For reliability we recommend using a full H-bridge controller without relays such as the new Pro-360. This model includes a display that shows voltage, current, and controller temperature. With an optional sensor it can also show motor temperature.
We now have water cooled and air cooled heatsinks for the 4QD and Pro-360 controllers which will allow operation at high currents for extended periods. They can be retro-fitted to existing controllers if required.
We have a section in our knowledgebase related to electric boat issues.