Understand the Basics of Jet Boats
If you’re a first time jet boat shopper, it can get confusing, understanding the different terms and descriptions used to explain jet boats. Here’s a preview of features, terms and characteristics that apply: (You can quickly 'jet' to a particular section by clicking on the following highlighted terms - Inboard Jets, Outboard Jets, Impeller, Cavitation, Deadrise "V", Hull Thickness, On Step, Wooldridge Jets the 4-Wheeler of Boats)
Four Stroke Inboard Jet: Wooldridge offers Chevrolet V-8 inboard jet power. The actual jet pump is mounted inside the boat, with the water intake through the bottom.
Wooldridge Boats prefers Hamilton jets for their V-8 inboard jet models.
Hamilton inboard jet pumps come with different pitch impellers to match up correctly with boater needs and the motor selected.
Pump selection is critical for optimum jet boat performance and Wooldridge specializes in coordinating boat, motor & pump combinations to suit individual customer needs. In most instances, the Hamilton 212 is the unit of choice, as it offers a broad range of performance benefits in big rapids and extreme shallows, in glacial, sandy and challenging rocky river conditions.
These pumps will offer optimum handling and control through the RPM range, a better reverse than other pumps and use the most durable impellers of stainless steel.
Two Stroke Inboard Jet: Wooldridge offers the Mercury Sport Jet for the sportsmen who want a smaller, lighter inboard jet package.
Outboard Jet: Outboard jets are an extremely popular power choice for jet boats, particularly those in the 16-23 foot range. Major outboard manufacturers offer outboard jet motors as standard issue now. During the early years they were created by simply replacing the propeller gear case with a jet drive.
Whether this outfitting is done at the factory or at Wooldridge, these motors all use the same Outboard Jet Drives, designed and produced by Dick Stallman at Specialty Manufacturing.
Stallman pioneered the outboard jet drive, has been good friends with the Wooldridge family and Wooldridge Boats from the early development of the jet. Stallman’s 2nd outboard jet, the oldest in existence, is displayed in the showroom at Wooldridge Boats.
The function of the outboard jet is simple, an impeller draws water up through the grill in a jet foot, spins it at high velocity then shoots it out the stern to push the boat. There’s a "bucket" on the rear of the jet drive to divert water and provide reverse and neutral.
The factory outboard jet motor is usually downrated to account for the 30 percent loss of power when going from a prop drive to a jet drive. Thus a 150hp motor with jet is labeled on the cowling at the factory as a 105hp, a 115hp is labeled as a 80hp jet, etc.
Impeller: The impeller is actually the driving force that sucks in water and accelerates it to high velocity to power the boat. Whether inboard or outboard jet powered, aluminum is the least preferred material as it is the softest and most prone to damage.
Wooldridge Boats uses stainless steel impellers in most cases.
Glen Wooldridge, president of Wooldridge Boats recognized the need for a more durable outboard jet impeller in the early 1980’s and subsequently developed the stainless steel design. These are a four-bladed configurations for maximum pumping power and performance gains, particularly on the higher horsepower models. The Wooldridge four-blade Stainless Steel Impeller provides such massive improvement in acceleration and load hauling ability over aluminum, it is the common way they are outfitted now.
Cavitation: By all jet boating standards, Wooldridge Boats with properly serviced and maintained Jets and Impellers don’t cavitate. That’s the truest indication of a premiere jet boat which is designed from the bottom up as a coordinated unit. Listen when jet boats are running for that sudden and distressed change in engine RPM’s. When a jet motor cavitates, it is sucking air. Performance is reduced and it’s even possible to damage the motor if it free revs without load.
Deadrise, "V": Basic hull design is a major factor in jet boat performance. The evolution of Wooldridge jet boats has resulted in 9 to 12 degree’s of "V" at the transom, in configurations that assure feeding the densest, cleanest water to the jet for optimum performance. A flat hull results in cavitation, too much "V" slows a boat down and compromises handling. Wooldridge measures "V" by the correct standards, as "deadrise", the angle on only one side of the hull.
Hull Thickness: Hull thickness is only one standard by which a jet boat hull can be correctly evaluated. Hull thickness is very important, but structural support is equally vital. Wooldridge engineers structure with hull thickness to provide optimum strength, weight and performance. Wooldridge has proven the effectiveness of this combination over decades of boat building. Wooldridge Boats are built with aluminum ranging from 1/8" to 1/4" and our hulls are guaranteed for life to the original owner. See details in the factory warranty.
On Step: Common term used to explain the point that a jet boat is planing. It’s important in evaluating boats, because how quickly a boat gets "on step" reveals the coordinated function of power and design. Obviously it’s critical that boats get "on step" quickly in shallow-water situations. Wooldridge Boats are recognized world-wide for their quick planing ability.
There are more strange terms and terminology's associated with jet boats. If you hear a term you don’t understand, ask your Wooldridge Boat Company representative. They’ll be happy to explain!
Wooldridge Jet Boats: Premier ‘Four-Wheelers’ – Here’s Why!
When you think about Wooldridge jet boats it’s easiest to imagine them as the four-wheel-drive models of the boating world. Many of Wooldridge jet boats will run in a scant 4 inches of water. They’ll tackle brawling rapids and zig-zag through a shallow log strewn obstacle course on command, for the experienced and capable driver.
Performance in a jet boat means much more than simply making horsepower. It means converting it into the most efficient water pumping operation possible...at every potential boat attitude in the water.
The making of horsepower is the easiest of the three. Pumping efficiency can be enhanced with optimum impeller selection.
It’s that last mention that identifies the winners and losers in the jet boat performance. Because inboard jets draw water in from the bottom of the boat, they’re the easiest to work with.
Different story with outboard jets. They’re located at the transom, with their intake off the stern. Hull design is critical to keep the outboard jet pumping efficiently....at every potential boat attitude in the water.
That has very little to do with the motor, it has everything to do with boat design, and feeding "clean" water, the densest water possible, to the jet pump, enhancing efficiency and boosting power.
Wooldridge Boats began extensive experimentation on this decades ago, first identifying the increased performance with a slight V in the bottom of the boat, designing and fine tuning hulls to best feed the outboard jet.
Then in the late 1970’s and early 1980’s, Wooldridge began intensive experimentation with a tunnel, to enhance "clean" water flow to the pump, minimize side slippage on hard cornering, raise the intake to be less apt to hit the jet foot in shallow running and enhance overall handling and jet performance.
It took more than a year of intensive development to fine tune a tunnel design that evolved into state of the art performance and was ultimately patented.
Again, because so much of outboard jet performance is based on feeding the intake clean water, a properly designed Wooldridge tunnel is essential to feeding the jet in all on-the-water postures. The Wooldridge tunnel also acts as a skeg and enhances steering control, providing the ultimate in aggressive handling situations.
A poorly designed jet tunnel, or a tunnel which does not complement the design and performance of the hull (size and shape) can negatively affect boat performance.