Mercury’s Customer Service center frequently receives calls from engine owners seeking information regarding the speed they can expect from a certain engine on a certain boat. It’s a common request because specifications like this are typically available for automobiles and other recreational vehicles. Most people are surprised to learn that these specs are often not available for outboards.

The reason speed specs are typically not published by engine manufacturers is simple: Let’s say you have a 2,000-pound fiberglass bass boat with a 200 hp Mercury Optimax on the transom. The guy next to you has the same engine on a 4,000-pound party barge. Obviously, these two boats will produce very different performance and speed specs.

Many other factors affect boat speed as well, such as water conditions (calm vs. choppy), weather conditions (temperature), hull design, boat material (aluminum vs. fiberglass), prop (stainless steel vs. aluminum) and gross weight (you and a fishing buddy on the boat vs. you and nine college buddies and two coolers of food and drinks).

In the marine industry we measure an engine performance not by speed but by RPM at Wide Open Throttle (WOT). Each engine has a recommended RPM range that should be reached at WOT. For example, the 200 hp Optimax engine mentioned earlier should turn between 5,000 and 5,750 RPM at WOT. Regardless of what boat the engine is mounted on, it should reach this RPM range at full throttle. The boat’s speed therefore becomes a secondary factor.

However, if you really want a tangible spec on boat speed we recommend contacting the boat manufacturer. After producing an engine, Mercury tests it on two to three boats and records the performance specifications (which you can find on this website). Unfortunately we can’t test the engine on every boat available due to time constraints (although it would be a fun job, right?). The boat manufacturers, however, test most outboards on each of their boats to determine the optimal match of boat and outboard. Therefore, many boat manufacturers have specs regarding speed generated with specific boats and engines.