How to drive a 100mph ski-race boat

You can take Todd Kelly out of Mildura, but you can’t take Mildura out of Todd. Nor his brother Rick, or the whole Kelly clan who call this Murray River town their home.

So it’s no surprise to find the Kelly Brothers, best known for their Supercar racing, have a passion for waterskiing. After all, the summer temps average more than 30C in Mildura and a big river runs through it.

What you mightn’t know is just how deep this love of boating flows in the Kelly Gang. Nor might you appreciate what’s required to drive a 100mph (160km/h) ski-race boat with a reworked Supercar engine.

We can now enlighten you about these things after Todd risked life and limb to let us behind the wheel of his roaring 725hp Nissan V8-powered Force 21 skiboat Mojo and share in that other passion in life.

When we caught up with ace race driver it was prior the Southern 80, the biggest ski-race event in the world held annually on the Murray, where the Kelly family has held records and is competing again this year. Naturally.

"We love boats," Todd says, waving his arms around at his 'man shed' in the outer Melbourne suburb of Chelsea.

The room is stacked to the rafters with race cars, race bikes, race boats and jet skis. There is a fridge with cold beer, one coffee cup in the sink, but it’s otherwise spotless. His planes can be found in a different hanger.

"We’re born and bred in Mildura. Rick and I have a heap of toys," he adds, straddling a Kawasaki Ultra LX jet ski upon which he plans to ride across Bass Strait. You can read all about how Todd Kelly will ride a Jet Ski to Tasmania in this separate story.

THE KELLY GANG’S FLEET
Todd admits the Kelly fleet is a bit ridiculous. Last count was 22, as long as you don’t include father John’s massive Murray River houseboat! But can you really ever have too many boats?

The Mildura-based line-up ranges from a punt with an 18hp Tohatsu outboard to a classic 17ft Syndicate wooden boat, a 21ft Connelly Craft with a 350hp Mercury Verado to a Malibu wakeboat, from a 24ft double-cockpit timber Hacker Craft replica to three race boats (the Super Class hull is up for sale if you’re interested), plus two jet skis, a party punt and two 6L Nascar ski-race engines.

But it's the Force 21 with the bored-out Nissan V8 that we’re here to talk about. Mojo is the ski-race boat proudly boasting Todd’s engineering work-of-art. At the Southern 80, Rick drives in place of John these days, with Todd skiing behind in tandem doing 100mph. It’s a brotherly love thing based on trust.

"It doesn’t matter if it's a car, a motorbike or a boat, speed has big consequences… Life can change in a tenth of a second," Todd says.

And with that things just got real.

Meantime, if you want to read about the building of Mojo and the Kelly’s custom Nissan engine them see our

That’s a good thing given that Todd’s normally hanging out the back on a 250-280ft rope and a single ski doing the ton (160km/h). The extra waterline length is also a good thing given I’m about to have a crack at driving this machine.

"In the curves, it’s easy for the skiers, so the driver must power ahead. We have to pick our lines in relation to the boat. You really need to focus on the boat and you must ski inside the wash, that’s the ski-race rule," Todd says, explaining how he keeps out of the bush in the Southern 80, which traverses more than 120 river bends along the 80km of the Murray between Torrumbarry and Echuca.

But we’re not skiing today. We’re getting behind the wheel of Mojo to feel the kick of that very special 5.2lt Nissan VK56DE engine, tuned and optimised, as it pulls 8500rpm.

The engine is coupled to a Mercury V SSM race sterndrive and custom 1.53:1 gearbox spinning a 23in x 14in left-hand rotation prop. The engine has a FNR shift, but that doesn’t mean much once you slip off the trailer, head to the start line, and knock it in gear.

To drive this boat, you need both hands on the (custom) steering wheel, your right foot on the foot throttle, and your left foot on the foot trim. It’s all about the trim, which goes from 1-9. More throttle equals more speed. More trim gives you even more speed. Then you are flying Kelly style.

DRIVING LESSONS
We tow the rig to the National Water Sports Centre outside Melbourne. I’m pulling on my fire-retarding race suit, gloves, shoes and socks, and race-red helmet with inbuilt communications.

"You need to work up to it. It’s like anything. You need to build up to it. You don’t just sit in the seat and drive at 100mph. Normally you’d do a season or two in an 80-85mph outboard class and then work up to inboard ski racing, Todd says.

Romeo that. I’m aiming for a modest 70mph, but let me tell you from a lifetime of driving and testing production pleasure boats that most boats transform above 60mph.

It’s about then that they begin to take flight, need to be driven, usually to correct chine walking or that worrying rocking moment. This is the skill of the high-speed boat driver and, as Todd says, it’s doesn’t come without loads of practice.

HITTING 100MPH
Mojo has a Motec race-management software system that monitors its key functions much like a race car.

Todd starts the Nissan V8 with the boat on the trailer, as the engine has closed cooling, then warms it up to 80C over about 10 minutes. Some squirts on the throttle bring a Supercar cackle that commands attention.

The old guys racing model yachts nearby pull OMG faces. But they ain’t seen nothing yet.

We launch, Todd drives, he pulls 100mph down Bangholme Straight at the National Water Sports Centre.

As if stuck by lightning, life instantly changes. From 80mph to 100mph your vision tunnels and the world takes on a surreal quality almost like cosmic travel.

The roar of the V8 and water pouring out of the stainless-steel pipes adds to the drama, as your brain processes the multitude of sensory inputs. It’s a fascinating state of mind, unfamiliar and dangerous to most of us.

But neuroscientists have found that elite race car drivers experience something called the ‘bullet time' phenomenon where time appears to slow. This is a time-learnt skill that allows Todd to make vital decisions (using enhanced visual information processing) that separate him from me.

So while 100mph feels ridiculously quick, Todd seems totally relaxed and in his element.

With a subtle correction of the wheel, milliseconds before each chine dip, he keeps the hull on even keel. That pre-emptive, intuitive skill doesn’t come to rookies, I’m afraid. It's learnt.

"So no safety straps Todd?" I ask, fumbling around behind my back.

"Mate, if it goes pear shaped, you want to get out of it," Todd replies.

"But this is a longer boat and a fair bit safer than an outboard," he adds, trying unsuccessfully to quell my nerves.

To compensate for the V8 engine weight and extra hull length on Mojo, the composite F21 hull was built as light as possible. That also has consequences when you add 725hp. I know that. So does Todd.

"Driving the boat at speed is more like driving a plane. There’s not a lot of boat in the water. It’s crazy but controlled," Todd reassures me, my heart quickening.

Of course, the thing that amazes you is the acceleration. Not off the mark in this Nissan boat so much as from that transformative 70mph-plus mark or from about 6000rpm onwards. I hesitate going much further, with a case of over trim on one run (the foot trim is highly sensitive) and a bit of chine walking on another.

KNOW YOUR LIMITATIONS
Approaching 80mph I call it a day, with Mojo and our lives intact.

Todd is a first one to admit he’s not a great passenger. Besides, another the thing about driving a fast boat: know your limitations.

Todd, now 37, knows he won’t race Supercars forever but he will never stop boating. We return to the ramp and the old boys in the model yacht squad are catatonic.

"I also enjoy family boating with my two kids aged 9 and 11," the motorsports gun says.

Family boating? Now that’s something I can do well. We make tentative plans for a weekend on the Murray with the Kelly clan.

Meantime, look for Mojo among the 220 boats racing at the Southern 80 at Echuca/Moama from February 10-12. It’s the world’s biggest water-ski race with the world’s top drivers…. for whom I now have new-found respect. More at southern80.com.au.