OptiMax 250 Pro XS with Big Tiller

OptiMax 250 Pro XS with Big Tiller(click image to enlarge)

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OptiMax 250 Pro XS with Big Tiller 'amazing'

Mark Nissen might have been in business for only about a year, but he's already known for creating high performance sports and spear-fishing boats… and his new Chaos Cat 520 is only going to build his reputation.

The 5.2m purpose built aluminium catamaran has been tearing through the water off Mission Beach, North Queensland - where Mark is based - powered by an OptiMax 250 Pro XS and controlled by Mercury's unique Big Tiller.  'I've only had the boat in the water for a few hours but everyone who's seen it tells me it's amazing," Mark said.  "With the OptiMax 250 Pro XS, the power-to-weight ratio is phenomenal. We've been cruising at 45-50 mph (72-80 km/h) in one-metre seas.  "Some might say I've overdone it with a 250 motor but I wanted to see what was possible."

By changing his current 23 pitch propeller to a 25 pitch Mercury Laser II prop Mark's confident he can hit 65-70 mph (104 - 112 km/h).  "But the fuel economy is amazing as well, which is why I chose this engine in the first place. I've gone for a long run and fuel consumption was less than one litre per nautical mile, and that's into 12-15 knots of wind," Mark said.  "The 200 litre tank means we can go 100 miles (160 kilometres) off shore for spear fishing."

Big Tiller
When he was building the boat, Mark wanted tiller control to allow more room in the craft but he wasn't sure about matching a tiller to an outboard as powerful as the OptiMax 250 Pro XS.
"I thought it might be too sensitive, but it's brilliant. The feel and control you get with it is just perfect. Whoever designed it has got it just spot on."

The Big Tiller was designed with a ergononomically-friendly, easy to use tiller handle with integrated shift, trim and throttle controls located within easy reach, along with user friendly adjustment knobs which allow for easy modification of the tiller handle angle, throttle handle and valve tension making it very easy to operate. The power steering option (not available on 40-60efi FourStroke models) allows for effortless use for long periods of time without causing fatigue to the operator.
It was created specifically for high horsepower Mercury and Mariner outboard engines;

  • 75 to 115hp FourStrokes,
  • 75 to 250hp OptiMax engines, and
  • 135 to 200hp four-cylinder Verado engines with SmartCraft Digital Throttle & Shift (DTS).

The Big Tiller has proved very popular in commercial applications across a broad range of outboard sizes, particularly as it allows full engine functionality. DTS power steering is available on all four-cylinder Verado outboards and OptiMax engines with DTS. The system allows for adjustable steering pressure with the touch of a finder and has zero engine feedback through the tiller arm.

Sea Patrol
Mark's Chaos Cat 520 has already caught the eyes of some great ambassadors - the people behind TV's popular Sea Patrol series.
"We went out for two days scouting for new locations and they said some great things," Mark said. Keep an eye out for one of Mark's six metre catamarans in an up coming episode, and they are now looking at using his new creation as well.
At the moment, Mark says the Chaos Cat 520 is purely a demonstration model. And it surely is - demonstrating Mark's ability to build a great boat, the power and fuel-efficiency of the OptiMax outboard, and the fantastic control provided by Mercury's unique Big Tiller.

The OptiMax, Big Tiller and accessories were supplied by the crew at Tully Boating World

Chaos Cat 520

  • Mercury 250 Pro XS OptiMax
  • Mercury Big Tiller with power/hydraulic steering
  • Length 5.2m, width 2.2m, max hp 250
  • Fuel 200L (Bermuda fuel tank)
  • Lenco trim tabs
  • Garmin 500 GPS combo, GME flush mount cd/mp3/af/fm stereo, flush mount speakers, GME gx600 VHF radio
  • Spear gun locker
  • Custom Rex marine fittings (switch panel, grab handles, fuel breathers, fuel filler)
  • Targa/folding canopy
  • Rae-line bucket seats
  • Chaos Cat custom alloy trailer
  • Freshwater tanks
  • Ballast tanks
  • Deck wash
  • Electric motor mounts