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Gisborne shark chaser Boyd McGregor has just one piece of advice if you are "lucky enough" to come across a shark while out at sea.

"My advice is just enjoy the experience. ... even if a shark attacks you, you're probably not going to know about it anyway," says Boyd.

After hearing one of Boyd's fishing tales about how a shark nearly ate his 120hp outboard motor, we arrive at a spot in the vast Bay of Plenty about 25km off the Whakatane coastline.

It's a serene place which ticks all the boxes for shark viewing. A change in water colour from greenish to blue shows where the shark's food supply of albacore tuna is likely to run, and birds - which chase the fish - and the reef structures provide the clues Boyd and first mate Warren Veall seek.

The pair set a fragrant, nauseating berley trail, which lingers in a greasy trail on the sea surface.

Within minutes, a 2m mako shark picks up on the emaciated fish trail and scent. Its ominous arrow-like shadow darts under the boat triggering a strange feeling in my stomach very different to the magic things an enormous pod of dolphins did to my heart just moments earlier.

Undeterred and excited, Herald dive maniac and photographer Richie Robinson and I jump in to the 2.5m x 2m aluminium cage alongside the boat - reassured by Boyd that despite it not having a roof "there's no way mate" that the sharks can get in.

The water is warm - not from my own efforts, either - and I'm armed with a tiny metal rod "for protection".

Our wait for our first underwater shark glimpse is compounded by big doses of adrenalin.

And then it happens.

Like a performer late to his own show, the mako emerges from its sea curtain metres from the cage.

Its black, emotionless eyes are fixed firmly on the both of us and we inch back in awe and initial fear, but there's no frenzied attack on our cage.

The shark simply glides past us. The zen-like moment is altogether beautiful, exhilarating, unforgettable and profound as the shark circles the cage and boat.

As my heart pounding subsides, I'm starting to believe an American tourist who the day before told me her experience with the sharks was the most at-peace she had felt.

A short time passes and five more sharks fade in. A blue marlin slides quickly in and out of the picture, but there's no feeding frenzy over the bait, which floats in limbo all around us.

A couple of drunk-looking 3m blue sharks continuously snap at the boat's outboard motor - one even tries to tear it away, supporting Boyd's earlier story. Comfortable in our setting, we open the cage trap door allowing Richie the chance to take some paparazzi-like close-ups.

The sharks don't seem to mind too much, until the 3m mako slams his torso into the cage, rattling it violently.

We surface, feeling that sharks have been ripped off by a poorly-managed public relations campaign.

ENGINES ARE 'PREY' EVEN SHARKS FIND HARD ON THE TEETH

Boyd McGregor and some mates were trolling for yellowfin tuna off the Gisborne coast a few years ago when all of a sudden the motor started making strange noises.

It was then they noticed "a bloody big shark" thrashing, with the entire propeller in its mouth.

"When we got to shore we saw it had been bitten and crushed in its mouth," said Mr McGregor, who has been in the shark-chasing business since 1998.

"It gave us a fright so I went and bought a gun. I had it ready to take out and I got bullets and filled the end with silicone."

His claim form for his mangled motor to a disbelieving insurance officer simply read: "shark attack".

Department of Conservation shark expert Clinton Duffy said sharks were attracted to outboard motors because the metal generated an electric field similar to that of a living animal.

Last week, a group of four fishing friends in the Hawkes Bay watched a 3m mako shark have a go at their motor.

Mr Duffy said sharks had jelly-filled receptors on their snouts which detected small electric fields as well as subtle changes in temperature.

When metal is placed in seawater, it reacts with the salt ions to produce an electric field that sharks can mistake for prey.

The shark-attracting electric field is created by an anode used to prevent corrosion in seawater.