SeaJay 4.85 Haven Sports with Yamaha F70
  |  First Published: July 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 a beer I’m talking about, though some of those early boats we headed out in were exactly that: cold and wet.

When you look at the alloy boats that are offered on today’s market you can have pretty well anything you like fitted as a standard option. 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 angler.

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

For a long time there has been a void in mid range four-stroke outboards in the 60-90hp range. 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 it ended up being a four-stroke that was too big and heavy for a 4.5m-5m boat or just a little under powered if you try and work up from the smaller horse powers.

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 restraints of the GFC, 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 that we have seen for a long time.

To be able 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 in the same horse power.

This new outboard not only fills a long time void in the market of single engines on boats but re-enters the market of twin rigged 5-6m mono hulls.

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

The combination of Sea Jays’ 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 just about the engine. Both offer features to make this rig outstanding and the perfectly balanced combination.

A safe haven

At 4.85m the boat is a size that isn’t too big for the estuaries, it’s ideal for impoundment work, and well as suitable for bay and inshore work. That pretty well covers a lot of common ground for an angler.

The hull is pressed alloy with 3mm bottom and 2mm sides so we see it as a little more solid in construction. The pressing of the sides and the hull also gives the boat a reversed chine, which delivers better stability at rest and most certainly improves the pick up and performance of the hull.

The transom is full width and height, so there’s no cut out section in the transom for the motor to sit down into, thus eliminating slop and back wash rolling up into the back of the boat in any sort of sea.

In doing so you end up with a full width pod across allowing you to walk from one side of the boat to the other with only a few cables from the engine into the hull running across.

Keen anglers can really enjoy that the entire cockpit can be dedicated to fishing and the accessories that are needed.

This particular model was a side console. Pedestal seat behind the console, another for the passenger and another couple of positions forward. All seats can be moved around or completely taken out if you wish.

For me a good fishing boat is one that has plenty of storage area that is out of the way and yet still easy to get to. Simple things like side pockets should never be underestimated in a boat, and as in this rig, I see them as essential.

The raised platform towards the bow section of the boat provides the perfect casting platform while below a substantial amount of storage is found with hinged lids in the carpeted deck.

A bit more dry storage in the side consoles and a second storage shelf in the transom and you are pretty well able to leave yourself with a good open deck area for a few of you to fish.

The under floor fuel tank holds 60L. I found a good average running speed in reasonable conditions was around 3500 rpm at a speed of 30km/h. You are not flogging the boat, engine or yourself and crew at this speed. Fuel consumption here was just over 8L/h, which is a comfortable six hours running at moderate speeds.

If you want to push it a little to 4500rpm fuel consumption is only 15L/h at 46km/h.

Yamaha’s Smart outboard

Having a good fuel-efficient boat and outboard makes all the difference. To help keep you in touch with the fuel management of the engine, Yamaha’s new digital network gauges can display all the relevant fuel information on your gauges; from litres per hour, fuel used, fuel left, range and trip gauges.

Given the fact that 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 safe guards.

Precise throttle control

All air entering the engine block of Yamaha’s new F70 four-stroke 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.

Maximum power and efficiency

Four individual compact electronic fuel injectors deliver the exact amount of fuel needed for optimum performance and economy. Controlled by the Engine Control Module via input from an array of on-engine sensors, their location just above the intake valves enhanced fuel atomization, resulting in more efficient combustion.

Hole shot acceleration

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 gear ratio, with specially hardened pinion, forward and reverse gears for increased durability.

More power, cleaner emissions

The F70 derives every bit of power available from the fuel by using Vapor Reduction and Vapor Burning Systems. By eliminating vapor from the fuel rail and re-routing it back to the Vapor Separator Tank, only fuel is injected in the cylinders for better combustion and power. A fuel vapor valve prevents fuel vapors from escaping to the atmosphere when the outboard is not running, and re-routes fuel vapors through the intake when the outboard is running. This helps achieve maximum fuel efficiency and minimum emissions.

Protection from the elements

The new F70 features a new outer cowling design with an intake air drain system, to easily and efficiently drain away any water that enters the cowling during normal engine operation. Incoming air is routed through a labyrinth of passages that help trap and drain water before it enters the engine’s intake, for maximum reliability.

Quiet, yet strong

Yamaha’s F70 four-stroke outboard has a Long Span Mounting System, which uses large specially-constructed rubber engine mounts placed as far apart vertically and horizontally as practically possible. This results in smooth and quiet operation with strength and durability.

Large water separator

All new F70 outboards feature a large, on-engine water separating fuel filter with a water sensor. Used in conjunction with Yamaha’s optional boat-mounted 10-Micron Water Separating Fuel Filter, it helps separate water and contaminants from the fuel before they can reach the outboard’s other filters and fuel injectors.

Dryer operation

Yamaha’s large anti-splash plate, standard on F70 models, helps keep water from splashing up between the leading edge of the outboard and the boat, resulting in a much dryer ride. Located on the front of the lower mid-section just above the lower unit, it excels in applications where the outboard is normally run deep in the water, such as pontoon boats.

Precise trolling control

By just 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 620-900rpm in 50rpm increments. This helps provide precise and consistent trolling speeds in wide array of conditions.

Stella Performance

On the performance of the boat, there’s nothing quite like jumping in a boat and casually pushing the throttle to ease you up on the plain. 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 where the hull starts to jump off the plain the torque of the engine and its 1L capacity just holds you from dropping off that edge; it’s ideal for slow work in rough conditions or heavier loads.

Impressive would be an understatement for Yamaha’s new F70hp 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:60lt under floor

Reads: 9189

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