“The goal of UMPBA is to have as few rules as possible,” said UMPBA President Brett Seubert. “We want to grow this sport by getting more competitors and fans engaged. Our rules make the sport easy to understand and leave a lot of room for creativity.”
The UMPBA hosts a form of bracket racing, but instead of the brackets being organized by elapsed time (ET), drivers chose to enter a bracket based on boat speed at the end of an 800-foot course. If they exceed that speed, they automatically lose. The seven brackets start at 65 mph, and go up in 10-mph increments to the Unlimited bracket, for boats able to top 116 mph. Like any drag race, success is based more on quickness than top speed. A boat able to out-accelerate a faster competitor – or the driver with quicker reaction time at the start – may end up winning the race. Boat speed is monitored by a GPS unit that’s required to be in every boat, which can be inspected at the end of each run.
Boats and competitors are required to meet basic safety standards. Racing is open to boats powered by outboards, inboards and jet drives. Each event has 35 to 45 entries, according to Seubert, with 45 to 55 class entries as some boats enter more than one speed bracket. This is real “run what ya brung” racing, and in the slower classes it’s not uncommon for fast family runabouts and bass boats to enter.
“I have four seats in my Hydrostream Venom, and I use it as a day cruiser between races,” said Nick Petersen, Mercury Racing Propeller Specialist and Project Manager, who competes at UMPBA events. “My boat is powered by a Mercury Racing 250 XS, and I started in the 75 mph class, and have moved up to the 85 mph class. Once you get up to the 95 mph class, most of the competitors are running dedicated race boats with two-stroke racing outboards that can pull a lot of RPM. A Mercury Racing 2.5 outboard can run up to 9000 RPM, so they can rig a smaller-pitch prop for hole shot and still make top speed at the end of the run.”
The faster classes are dominated by lightweight 18- to 20-foot hulls produced by brands like Checkmate, Allison, STV and Hydrostream; with pad-bottom V-hulls and Mod-VP style tunnel hulls.
“Weight is the real key to quick acceleration,” explained Petersen, “and some of the really fast hulls weigh only about 400 pounds. They’ll have a very thin carbon fiber layup, a small fuel tank, and a single center-mounted seat. Add a lightweight outboard like a modified Mercury Racing 2.5 Drag, which can make 400 hp on alcohol fuel, and you’ve got a real rocket.”
In keeping with the simple-is-best approach, UMPBA events do not utilize electronic timing. Boats approach a “commitment buoy” and a starting line buoy together, about 50 feet apart. Racers are then flagged off from a starting boat located 30 feet beyond the start buoy. Judges and a camera are waiting in a finish-line boat at the end of the 800-foot course. Each class runs a double-elimination format.
“If a competitor suspects the other racer broke out of the class speed limit, he can ask to see that racer’s GPS for verification,” said Seubert. “There is a 2 mph breakout for each class, so racers have that leeway before they break out and are disqualified.”
A new feature on the way for UMPBA races is a custom Ambush SS 1756 safety/tow boat being built by Legendcraft Boats of Alexander, Ark., for the organization. The boat will be powered by a Mercury Racing 60R outboard with tiller steering. The 17-foot aluminum boat will be equipped with dive tank racks and a step-off transom for the rescue divers stationed at each race. The boat will also be used to set the course and as a tow craft for disabled race boats, according to Seubert.
The 60R outboard features a four-cylinder, 1.0-liter long-stroke powerhead tuned for torque by Mercury Racing. The WOT range is extended to 6300 rpm to maximize acceleration and enable more propping options. A single overhead camshaft cylinder head keeps the powerhead as light and slim as possible for less intrusion on the transom. The high-thrust gearcase accommodates a robust 2.33:1 ratio to handle up to 20 percent more prop-blade area than a standard gearcase, and is shaped to provide added lift aft to further boost hole-shot performance and confident handling at speed.