Jet Boat Reviews
Reviewed: October
Author: Barry Tranter
Overview:
PWC's (personal watercraft) are the most common jet powered watercraft but jet power suits all kinds of vessels. Safety is a huge plus, particularly in the smaller family runabouts and tenders, which operate around swimmers and the sporty handing of jet power is popular with watersports enthusiasts.
Find new Jet Boats for Sale
Jet Boats - Boat Review by Modern Boating
"Jet Boats - The Big Squirt"
For many people, waterjet boats are exemplified by those tourist boats that execute crash stops and high-speed spins in order to make their passengers scream. Or PWCs running in the surf, where their speed and manoeuvrability and lack of a prop make them ideal for their task. Or on TV where those V8-powered skiffs navigate tight channels at ridiculous speeds, and sometimes dump their passengers on the bank. This noisy, spray-ridden public face of jetboating is misleading. Commercial craft are big users of waterjets, but recreational waterjets also have number of advantages.
Safety is a huge plus, particularly in the smaller family runabouts, which operate around swimmers. “Women, especially, don’t like props,” says Jeremy Bycroft of Australian Marine Leisure. “They worry about the sharp bladed prop even when the boat is at rest.” Waterskiers, wakeboarders and swimmers can breathe easy when they are towed behind a jet.
There are other advantages. Most of the production boats listed here draw only 300mm of water. If in-water obstacles are encountered—ropes, pots, logs—the jet nozzle tends to ride up and over, rather than snag. Drive unit manufacturers claim that servicing the drive unit can be as simple as keeping an eye on bearing oil levels and watching for anode depletion. One claims that the owner can perform basic service on a beach, or anywhere with a bit of tidal range.
How do jets boat engines work?
Water is drawn into the jet unit through an aperture in the hull bottom, where an engine-driven impeller accelerates it and squirts the water out of the jet nozzle. Steering is controlled by directing the nozzle. reverse and neutral are affected by the deflector, which lowers over the nozzle. For reverse the deflector lowers all the way and directs the water thrust forward; for neutral it directs the thrust downwards. So for some manoeuvres you can set the throttle and forget it, controlling speed purely by deflector position.
Choosing a Jet Boat or PWC
As with a conventional drive system, a jet unit has to be matched to hull and engine. The boat’s operating speed is a critical factor as speed through the water affects the rate at which water enters the jet orifice, which is known as ram effect. Cavitation is a factor, as is the case with conventional propellers.
Manufacturers make the point that the power-to-weight ratio is a vital statistic. “The ability of a waterjet to absorb engine power throughout the speed range is more important than matching to engine power alone,” says UltraJet.
Jet unit suppliers would rather work with a new hull than an older one, as old hulls can be weakened by age and may need a lot of work just to bring them up to scratch.
Matching engine and drive unit to a hull can be a job for a naval architect
Jet Boats
Williams Jet Tenders
You see the Williams boats in the stern garages of superyachts. The range includes two 2.85m models, one called the 285 Jet (which has 72hp and does 35 knots) and the Turbojet (104hp and 42 knots). Each carries three adults and one child.
The 325 carries four adults and a child, the 385, five adults and a child. There’s a new 445, which will carry six plus one. All these are good for 42 knots, and the makers claim even the smallest will tow a waterskier.
For more information, contact Allied Marine
Sea-Doo
This is a very sporty range from BRP. Sam Heyes, Director of Sales for BRP, says the best sellers are the 150 and 200 Speedsters, which feature original layouts and dramatic styling. “They are original craft, not from the sea of sameness,” says Sam.
The Sea-Doo craft use Rotax four-stroke engines in various configurations. Boats are available with 215hp or 155hp, and the various models use one or the other, or double them up so boats can have 310hp or 430hp.
There are 10 models, divided into groups—Luxury Performance, Performance, Recreation and Sport, the latter including wake boats with ballast tanks.
The most comprehensively fitted-out is the Islandia SE, a recreational craft which features change room, freshwater shower, and Porta-Potti. “These boats are great for tow sports because they are safe and they have exciting handling. And there is always the jetboat thrill factor,” Sam says.
More information on Sea-Doo craft
Sugar Sand
Sugar Sand boats have quite traditional hull configurations, most powered by 200hp or 250hp jet units driven by Mercury’s OptiMax powerheads.
“Mercury has been clever,” says Jeremy Bycroft of Australian Leisure Marine. “By mounting the engine directly over the pump they have made a very small unit.”
The smallest in this range is the 4.26m Sting with 135hp; the biggest is the 7m Oasis, with 250hp.
All the Sugar Sands are quick. Most top out around 35 knots, though the Tango boats are claimed to run at 49 knots (56.8mph). The range includes wakeboard options. Jeremy reckons that younger buyers—perhaps those moving up from a PWC—favour the smaller boats. But the 18ft Mirage is one of the biggest sellers, and offers a choice of 200 or 250hp.
Note: Sugar Sand production in the US stopped recently, but Jeremy expects a change of company ownership will see the boats back in production.
Mercury Jet Power
Mercury Marine offers a range of jet drives and outboards, which are particularly suited to shallow water boating applications such as navigating rivers and fishing spots. Their OptiMax jet drive engines have no gear case or propeller extending below the hull, so they pass over obstructions that could limit conventional propeller driven outboard engines.
How do they work? Water is drawn into the unit through the intake grill by an impeller, driven directly by the engine driveshaft. The water is then forced at high pressure through an outlet nozzle, creating thrust that drives the boat forward. To obtain reverse, a gate lifts into position over the outlet re-directing the pressure stream in the opposite direction.
Every Mercury Jet Drive is equipped with a self-draining cooling system for improved reliability. They utilise a patented XK 360 aluminium alloy with low copper content to provide the best material to protect against corrosion. All exposed fasteners, shafts and impellers are stainless steel, and multiple self- sacrificing anodes are used to further protect the Jet Drive.
Mercury Jet Drives are protected against corrosion, even if left in the water, and backed by a three-year corrosion failure warranty.
The recently released two-stroke Direct Injected OptiMax Jet 80 and OptiMax Jet 110 outboard engines offer an excellent power-to- weight ratio when compared to competitive four-stroke jet drive outboards in their class.
This makes them ideal for shallow-water running conditions typical in jet applications. The 1.5L OptiMax Jet 80 outboard engine is based on the 115hp OptiMax and has a three-star CARB rating. The 2.5L OptiMax Jet 110 outboard engine is based on the 150hp OptiMax and has a two-star CARB rating.
There are more powerful options in the Mercury jet engine range, including a 200 and 250 OptiMax M2 jet drive and a 240 EFI model. Less powerful options include a two- stroke 65hp outboard and four-stroke 40hp and 25hp outboard models.
Drive Trains
Mercury/Mercruiser
MerCruiser is unique in that the company produces integrated engine and drive systems. Because the engine and jet form a single unit Mercury claims to save up to 475mm of space in the boat interior since the drive shaft, usually situated between engine and jet, is eliminated. MerCruiser does four diesel-powered units and two with petrol. The diesels are a 1.7L and 2.8L fours, and a 4.2L six. They range from 116hp to 250hp. The petrols are a 4.3L six and 5L eight, the former producing 240hp, the latter, 260hp.
Sport Jet units as used in the Sugar Sand boats are from the Mercury stable. These are outboard powerheads mated to 184mm- diameter jet units; they come with 240 EFI, 200 OptiMax and 250 OptiMax engines.
Mercury in the US offers outboard motors with jet drives where the gearbox and prop would be on a normal outboard.
For more information contact Mercury Marine: www.mercurymarine.com.au
Ultrajet
Drivetrain Australia is the agent for UltraJet, whose units are made by a company based in both Britain and the US.
Most of Drivetrain’s business is with commercial craft, including ferries, workboats and military craft. The company can accommodate recreational craft—they supply the jets for some of those tourist-scaring craft mentioned above—but for owners wishing to fit a jet to a new hull, or adapt an existing hull, a naval architect would probably be involved.
UltraJet units come in eight stock models with impeller diameters from 250-575mm, with four or five-blade impellers to match marine diesels from 300-1700hp, 224-1268kW. They are intended for one, two or three unit installations; in case of the latter, the centre unit doesn’t have steering or reverse capability.
The company’s website gives an excellent guide on how to choose a jet unit to suit a specific hull. For more information, contact Drivetrain Australia: www.drivetrainaust.com.au.
Hamilton
Hamilton has been involved with waterjets since the early 1950s, when Sir William Hamilton produced a development of an American jet unit.
These days the New Zealand company manufactures waterjet units and associated controls. There are two model ranges: the HJ group includes eight models running impellers from 215-400mm in diameter, to power craft from 6-20m in length; and the HM Series includes seven models with impellers from 420- 1000mm diameter, for craft from 18-60m long.
Peter Iredale, product manager for Wiltrading (distributors of Hamilton Jet in Australia’s south-eastern states) says that most of their work is on commercial craft but they do some recreational boats. Do they retrofit older hulls? “We have done it successfully but we also encourage people to seek good advice before working on older hulls because often there are hidden problems within the hull and the job becomes too difficult.”
However, in 2000 Wiltrading retrofitted two fast tenders for the superyacht Arctic-P, replacing surface drives, and both were a success. Eight years on, the boats’ engines have since been ‘uprated’, retaining the Hamilton units.
“We offer lots of advice,” says Peter. “In effect, we are involved in a partnership with the owners, as it’s in our interest to make sure everything works properly.”
For more information about these models contact Hamilton Jet: www.hamiltonjet.co.nz; or Wiltrading www.wiltrading.com.au.
Review supplied by Modern Boating
Buy Modern Boating magazine online and save!
Click on the cover to subscribe today!
Like this review? Why not share it!
Like this review? Why not share it!
