Engine Tests: 2014 Yamaha F115B and F175A

Fifteen years is a long time in the outboard-engine world. It has taken that long for Yamaha to update its long-standing 115hp four-stroke outboard from the F115A -- the first EFI four-stroke for the Japanese-engine giant -- to the all-new F115B, a smart new-generation four-stroke outboard that is now officially the lightest in its class.

The other big new release is the Yamaha F175A, a new four-stroke outboard in the Hi Power range that fills the gap between the long-standing F150 and the newer F200 with Digital Electronic Control (DEC) released last year. In fact, the F175A is based on that same 2.8-litre 200hp outboard block, only it hasn’t got DEC but rather manual cable throttle and shift in a move aimed to keep costs in check.

Given the significance of these two new Yammies, your BoatPoint and boatsales crew wasted no time winging it north to Couran Cove Island Resort on the Gold Coast to put the engines through their paces. There was a good range of testing platforms and full marks to Yamaha for avoiding the temptation to fit maximum horsepower donks and instead going for everyday pairings. 

However, Yamaha Australia can't release pricing until the end of March, 2014. We'll update this story then. Meantime, there's a lot to report...

First up, the F115B was fitted to a SeaJay 5.1 Striker side-console plate-aluminium boat, exactly the kind of rig you would use for inshore barra, bass and bream fishing. With a 4mm plate bottom and 944kg hull weight, plus four batteries for outboard and electric motors, it was no lightweight. But punching above its weight, the SeaJay has the seaworthiness to fish offshore, too.

The new F115B was also fitted to a CruiseCraft 530 Explorer, a cuddy cabin boat flaunting the Brisbane yard’s famous fair mouldings. The 530 is an ideal crossover family and serious fishing rig in an easily managed size range.

In a dual set-up, the F115B found its way on the transom of a NoosaCat 2400 HT Sportsman, a serious offshore platform that might also have commercial applications.

Not to be outdone, the new F175A was teamed with another impressive CruiseCraft, this time the 625 Hard Top that we tested late last year with a pre-production Yamaha F200 four-stroke outboard.

Based on the same block as the F200, this F175 is a very nice match for the 5.7-6.0 metre trailerboat class. We’re told local boat manufacturers such as CruiseCraft have been asking for a 175 for some time. There was also an AMM 7800 Tournament plate-tinnie with twin Yamaha F200s available for testing.

Compared with the old F115A with a 1.74 litre displacement, the new F115B has an altogether new-from-the-ground-up 1.83 litre block with a bigger bore for more torque.

For this writer, who owned an F115A for some years, the benefits in hole-shot derived from the improved power-to-weight ratio were certainly noticeable on the CruiseCraft 530 Explorer.

Yamaha claims 0.7 seconds faster acceleration for the F115B over its predecessor in 0-60m tests on the back of a Skeeter TZX 170. We’ll take their word for it but, as mentioned, we felt the hole-shot has improved over the F115A with which we were intimate.

On the technical side, a new throttle-body system has been credited with the crisp acceleration, while a knock sensor has been fitted to ensure the F115B, which runs on regular unleaded, has the ability to detect abnormal combustion and sound an alert.

But in terms of the all-important weight, a lot of credit was given to the new single-ram power-trim-and-tilt unit in place of the previous multi-cylinder system. Those who launch their boat off beaches might also appreciate the faster trim operation.

In this day and age of electronic accessories, just about everyone will welcome the high output 35A alternator at wide-open throttle (WOT) but, more importantly for those who troll, the 28A down low at 1000rpm. Class-leading recharging, claims Yamaha.

Next comes economy. According to the official data, the F115B is up to 20 per cent more fuel efficient from 2500-5200rpm (measured in terms of litres per kilometre but converted to nauctical miles below) than the F115A it supplants.

“Significant improvements” have been made in the all-important 3500-4000rpm eco rev ranges. Yamaha Australia says the fuel efficiency figured conveyed below using the F155B were achieved and documented after local testing by Yamaha on the CruiseCraft 530 Explorer using a wide range of propellers.

In respect of propellers, the Yamaha Shift Dampening System (SDS) and a soon-to-be-available compatible stainless-steel props (late 2014) will offer super-smooth gear changes just like the higher horsepower sister Yammie outboards.

At 5900rpm, according to Yamaha, you get a top speed of 34.61 knots, while cruise of 21.81 knots at 4000rpm has the F115B covering 1.31 nautical miles or 2.43km per litre. Based on 95 per cent of the 140 litre fuel capacity, the SeaJay has a range of 174.4nm or 323km over about 8.5 hours running at 4000rpm

From a subjective point of view, there was a little bow lift during hole-shot but this heavy plate-alloy side console soon flattened out to a comfortable cruise, producing a nice motion through an admittedly calm Broadwater. Certainly, mid-range power when throttling up from around 3800-4200rpm to 5000-5500rpm is a feature across both this new 115 and the 175hp Yammie

Interestingly, the CruiseCraft 530 Explorer (not a lot heavier at 1640kg for the rig) wasn’t far behind the SeaJay in respect of speed and range. Yet the fibreglass cuddy was in a different class for fit, finish and fishing/family comfort.

Spinning a 16in stainless-steel prop, top speed according to the Yamaha data was 34.3 knots at 6000rpm, with optimum cruising at 4000rpm giving 21.0 knots for economy of 1.22nm or 2.26 km/litre and a range of 162nm or about 300km from 95 per cent of the 140-litre underfloor tank.

Also spinning 16in prop, and on the second hole mount as with all these test boats, the F115B  was an albeit modest fit as a twin installation on the NoosaCat 2400 HT Sportsman. This cat is an evolution of the 6.7m hull with new extended running surface and chines to support the weight of higher horsepower outboards (twin 150hp outboards are a common match).

With the twin F115Bs, top speed was 33.64 knots at 5900rpm, according to the official data. Yamaha says the cruising range is 207nm/384km at 3500rpm doing 17.5 knots and reeling in 0.68nm or 1.26km per litre. Independently we recorded 21.4 knots at 4100rpm cruise for 35.3 litres per hour and a safe range at those revs of about 195nm. Low-speed plane was noted at 3200rpm and 13 knots.

The empty cabin structure did create some increased resonance on the NoosaCat with these otherwise quiet F115B outboards, but some cabin lining might help this issue on what is a seaworthy and surprisingly flat-turning cat.

Among the technical highlights is a balancer system for smooth operation, three engine coolers needing less oil than some competitor’s 175s, and a high-output alternator giving 50A at WOT and 22A even at low idle. Economy in the 3700-5700rpm rev ranges is marginally better than the F200, we’re told.

Common features of the F115 and F175 include: Command Link for multifunction dash engine-data display including fuel usage; the Y-COP key-fob immobiliser security system; new rakish cowling designs and a modern, compact inline four configuration. A water-detection alarm on the integrated fuel filter will be welcome by travelling trailerboaters refuelling in less populated areas.

We were smitten by the Variable Trolling System on the F115B and this F175A that, with a press of the MODE button on the multifunction dash instruments, lets you adjust idle up or down by 50rpm increments from 600-1000rpm and 650-900rpm respectively.  For that may well mean more time for your lures or livies in the strike zone.

Nathan Nichols, a director from the eponymous family that founded CruiseCraft, let leak that a 595 Explorer HT will be released in April this year that will perfectly suit this new Yamaha four-stroke. “We’ve been asking for a 175 forever,” he added.

Spinning a 17in prop, we hit a WOT rpm figure of 5500, which is a bit below the desirable 5800rpm-plus, so a smaller 16in prop will be fitted in future. The initial propping was done with half fuel load and a couple of people, but our tests were run with three aboard and a bit more fuel.

According to the official data, top speed of 40.12 knots was previously recorded at 5700rpm WOT, with the most economical setting of 4000rpm returning 25.72 knots (47.65km/h) for 0.99nm or 1.84 kilometres per litre and a 227nm (420km) range from 95 per cent of the boat’s 240 litre underfloor tank. From 4000rpm to 5500rpm there was noticeable midrange throttle punch as with the F115B.

Using the Lenco trim tabs, which come standard on the 625 with Hard Top to ensure the boat stays on an even keel in all conditions and crosswinds, we easily held a 3300rpm low-speed plan for 18.35 knots cruise.

Using the Variable Trolling System let us change from 2.15 knots at 650rpm to about 3.25 knots at 900rpm at the press of a button. At 3000rpm, the F175A automatically switches back to normal idle and throttle operation.

A turnkey package from the CruiseCraft factory, the 625 HT (weighing about 2 tonnes on trailer dry) has been a big hit in the hot Hard Top market, where Nichols says the bigger sister ship, the 685 HT, is the best seller.

We also drove the 685 HT on the Yamaha test day, with a pair of the old twin F150As but also a revolutionary Optimus 360 docking joystick from SeaStar that let you berth singlehandedly. A boost button powers-up the outboards to counter strong wind and current.

The Optimus 360 docking joystick cost a whopping $18K or thereabouts, making it an option for those who want to tick all boxes.

Meantime, back aboard the 625 HT, the fully spec’d rig with Lowrance HDs12 was valued at about $105,000 as a terrific turn-key package. It was just a delightful family-and-fishing rig with the F175A and the signature CruiseCraft five-star finishes.

“We had the best six months in five years of production,”Nichols told us, adding that the trailerboat market is converging on the 6.2-6.8m bracket, with buyers meeting in the middle after coming back down the range and also upsizing. One 605 they recently sold had $55K in Furuno gear aboard, pointing to the highly spec’d nature of trailerboats today.

The improved acceleration was noticeable, along with mid-range grunt, and the refinements add to your trailerboating pleasure. The new-generation F115B looks smart, compact and calculated and, as a class leader in terms of weight and recharging, the new engine answers a lot of demands placed on outboards today. Look for a F130A version later this year.

Using the same block as the F200, the F175A is more of a gap-filler than a revolution like the F115B. Pricing will determine its appeal compared with the F200 with Digital Electronic Control for plug-and-play or bolt-on-and-go-boating use.

But with better economy from 3700-5700rpm on the CruiseCraft 625 HT and capital savings compared with the F200, the new F175A holds sway. After all, any outboard that lets you go further for less just has to be a winner these days.