In this article we will be discussing what a little "test and tune" can do for your ride. In today's economy it often makes sense to keep your existing boat and upgrade it via a re-power, re-rig, or in a lot of cases just dial in the setup. Many people aren't even aware that their boats may not be setup correctly, or that they can capture quite a bit more performance with some simple and relatively cheap modifications to what they already have.

We recently had a customer with a 28' Lavey Craft-Party Prowler come to Quality Performance in search of more performance out of his existing boat. The boat was equipped with a Mercury Racing 525 with a Bravo 1XR drive spinning a 24 pitch Bravo prop. This particular boat was rigged a SmartCraft SC5000 screen which is a great tool as you can have access instantly to all kinds of information including fuel consumption. The customers complaint was that the boat had a hard time rolling over onto plane, he had to keep the engine RPM at 3500 or above to maintain a plane, and finally that he was getting 1.2-1.4mpg in the mid range cruising speeds.

We went out and tested the boat and found that the boat would hit 64 mph at 5200 RPM yielding a 19% prop slip. When
we trimmed the boat it did not carry the bow or affect the attitude of the boat, but rather just shot a small rooster tail. Now that we had a baseline to start with, we took the boat back to QPM and removed the traditional XR lower, and replaced it with a Bravo III lower unit. We installed a set of 27 pitch Bravo III XR props and went to try it out again. The boat had improvement in overall performance and we managed to lower the prop slip down to slightly better 14%, but we also screamed right to the rev limiter at 5450 RPM at 60 mph. Again playing with the trim settings on the boat there was no noticeable change in attitude of the boat, and our rooster tail came to life at the touch of a button, this is telling us that the X-Dimension is set too high on the boat, this could also account for the high slip percentages.

Next we installed a two inch drive spacer to lower our X Dimension and go out to see how the boat reacted to it. Right off the bat there was dramatic changes! The boat now comes out of the hole with no problems, and acceleration in the mid range was noticeably increased. The prop slip has now decreased again to 11%, but we are still hitting the rev limiter at a slight increase of 62mph at 5450 RPM. One of the more notable side effects is now the boat is able to be trimmed as it should be. With increased trim it will now carry the bow, and our efficiency robbing rooster tail (in this application) has finally disappeared.

Armed with all the information we need we made our final change to the boat which was nothing more then a prop change. We took the 27's off and replaced them with a set of Bravo III XR 28's. The boat now goes 65 mph at 5400 RPM with a 9% Prop Slip! The cruising fuel consumption has gone from 1.2-1.4mph to an incredible 2.6-2.7mpg, just shy of double! The boat now has no problems getting on plane and can maintain a much slower planing speed (21 mph) because of the reduced slip, and increased leverage of the counter rotating props. The customer is extremely excited and feels as though he has a new boat, and can't wait to take it out next spring. The bonus is between the trade in value of his old lower, and the increased fuel savings, this upgrade will pay itself off in short order.

If you are wondering if there is room for improvement on your current setup, there almost always is a way to get more out of what you currently have. Feel free to give us a call or to see if we can help you dial it in! We have an extensive selection of props on hand, and our team has the tools and the expertise to often make some minor adjustments and yield major gains.

Rob Clarke
Quality Performance Marine

(written by RiverDave)