No ordinary tinnie and motor
  |  First Published: December 2010

Once upon a time a tinnie was a tinnie. Sure, there were a few different brands to choose from, but all that really mattered was that it was cold and wet. That’s beer I’m talking about, though some of those early aluminium boats we headed out in were also cold and wet.

When you look at the alloy boats that on today’s market, you can have pretty well anything you like fitted as standard.

This is a big advancement in Australian boat building and I do believe the way we fish these days and where we go fishing has had a lot to do with the evolution of boats, tackle and the anglers themselves.

Just as having the right fishing reel matched to the right rod to make a nicely balanced outfit, so too does matching the right outboard to the right boat combine to make a potent fishing tool, and with so many choices along the way it’s not an easy task.

For a long time there has been a void in midrange four-stroke outboards from 60hp to 90hp. Sure, there are a few about from various manufacturers but they are generally de-tuned from larger engines or beefed up a little from smaller engines.

Either way, these ended up being four-strokes that were too big and heavy for a 4.5m to 5m boat or just a little underpowered if you tried to work up from the smaller horsepowers.

The problem has been that outboard manufacturers just haven’t been able to build a lightweight four-stroke with enough grunt in this mid range. Given the constraints of the global financial crisis, manufacturers haven’t been overly keen in pumping too much into development.

At least that’s what we thought until Yamaha released what can only be described as one of the most significant advancements in four-stroke outboards for a long time.

To produce a fuel-injected 70hp four-stroke outboard with a 1.0L capacity that is lighter than any other four-stoke engine in its class is a remarkable achievement. But at 120kg it’s also lighter than even fuel-injected two-strokes of the same horsepower.

This new outboard fills a long-time void in the market for single installations in an extremely popular boat category in this country and it also reopens the option of twin rigged 5m to 6m monohulls.

If you have ever been under the perception that all four-strokes were sluggish and heavy, think again.

The combination of Sea Jay’s new 485 Haven and Yamaha’s new F70 is one of the sweetest little rigs I have ever been in. It’s not just about the hull or the engine; both offer features to make this rig outstanding and a perfectly balanced combination.


At 4.85m, the Haven isn’t too big for the estuaries, it’s ideal for impoundment work and is suitable for bay and inshore work. That pretty well covers a lot of common ground for a majority of Aussie anglers.

The hull is pressed alloy with a 3mm bottom and 2mm sides, so it’s a little more solid in construction. The pressing of the sides and the hull also give the boat a reversed chine, which delivers better stability at rest and most certainly improves the pickup and performance of the hull under power.

The transom is of full width and height, so there’s no cutout section for the motor to sit down into, thus eliminating slop and backwash rolling up into the boat in any sort of sea. So you end up with full-width pod across allowing you to walk from one side to the other with only a few cables intruding. Keen anglers will enjoy the entire cockpit.

This was the side console model with a pedestal seat for the skipper, another for the passenger and another couple of positions forward. All seats can be moved around or removed.

To me, a good fishing boat has plenty of storage out of the way and yet still easy to get to. Simple things like side pockets are essential.

The carpeted casting platform has substantial storage below and there’s a bit more dry storage in the side console and a second storage shelf in the transom. That pretty well leaves an uncluttered open deck area.

The underfloor fuel tank holds 60L. I found a good average running speed in reasonable conditions was around 3500rpm at 16 knots (30kmh). You are not flogging the boat, engine or yourself and crew at this speed.

Fuel consumption here was just over 8L an hour, which offers a comfortable six hours’ running at moderate speeds for a range over 90 nautical miles.

If you want to push to 4500rpm, fuel consumption is only 15L/h at 25 knots (47kmh) for around 100NM range.


Having a fuel-efficient hull and outboard makes all the difference. Yamaha’s new digital network gauges can display all the relevant fuel information on your gauges, including litres per hour, fuel used, fuel left, range and trip gauges.

If you also run a GPS, which will tell you the distance to your fishing spot, it doesn’t take much to work out how much fuel you are going to use to get there, so there’s no excuse for running out of fuel.

Yamaha’s F70 also introduces numerous technological advances and safeguards.

With its precise throttle control, all air entering the engine is routed through a single throttle valve, to ensure the precise amount of air necessary for optimum power and fuel efficiency. It then enters each cylinder through individual long intake tracks, which are pulse tuned to provide air at the precise volume and timing for maximum density and power.

Four compact electronic fuel injectors deliver the exact amount of fuel for optimum performance and economy. Controlled by the engine control module via input from an array of engine sensors, their location just above the intake valves enhances efficient combustion.


Yamaha’s F70 provides outstanding hole shot and acceleration, thanks in part to an advanced sensor that allows maximum safe ignition timing and a gearcase featuring a high 2.33:1 ratio. There are specially hardened pinion, forward and reverse gears for increased durability.

The F70 derives every bit of power available from the fuel by using vapour reduction and vapour burning systems. By eliminating vapour from the fuel rail and rerouting it back to the vapour separator tank, only fuel is injected into the cylinders for better combustion and power. A valve prevents fuel vapour from escaping into the atmosphere when the outboard is not running and when the outboard is running reroutes it through the intake. This maximises fuel efficiency and minimises emissions.

The F70’s new outer cowling can drain away water during normal operation. Incoming air is routed through passages that trap and drain water before it enters the engine intake.

The engine has its own water separating fuel filter with water sensor. Yamaha’s boat-mounted 10-micron water separating fuel filter is optional but in this day and age of water-attracting ethanol fuels, adding the external filter makes sense.

Pressing a button on the digital network gauge tachometer or the VTS switch on the optional multifunction tiller handle, the operator can adjust the engine’s trolling speed from 620rpm to 900rpm in 50rpm increments. This helps provide precise and consistent trolling speeds.


There’s nothing quite like jumping in a boat and casually pushing the throttle to ease you up on the plane. Hit the throttle hard and the boat jumps to attention and shoots out of the hole. Ease back and it’s just a quiet purr behind.

Even at low revs, when the hull starts to jump off the plane, the torque of the F70 just holds you from dropping off that edge; it’s ideal for slow work in rough conditions or toting heavier loads.

The word impressive is an understatement for Yamaha’s new F70 outboard and I’m sure we are going to see more advancements in the line using this new technology, which is good news for us all.



Sea Jay 485 Haven Sports

Max Hp:80hp
Fuel:60L underfloor

Reads: 4041

Matched Content ... powered by Google