The Bertram 35 is a modern classic and is regarded by many as an all-rounder that is hard to better, even 40-plus years since they were originally in full production. Just as happily put to work as a sport fisher as it is a family fun station, many Bertram 31’s and 35’s in Australian and New Zealand waters are looking for their next lease of life from new engines. The Western Australian-based Bertram 35 Long John Silver was recently repowered with new Yanmar 8LV common-rail diesels, a move the owners couldn’t be happier with.
With a hull and cockpit design almost as famous as its namesake, (the vessel is called Long John Silver), this 1987-built Bertram ticked all the boxes for Chris and co-owners Simon Govey and Stephen Warne as a leisure vessel and fishing platform – until engine failures and parts issues on its original petrol V8 engines presented an ultimatum.
“After our third tow home from engine failure, we really had to decide whether to upgrade the engines or get rid of the boat,” admits Chris.
Not an unusual predicament for many owners of boats this vintage. It can also be a problem that is hard to find a workable solution for as well. Until now!
Yanmar 8LV – a repowering godsend!
The Yanmar 8LV series of common-rail high performance diesels provide an option for vessels like the Bertram 31 and 35 that is as close to perfect as a repower can get.
As the leader in their class in power-to-weight, the 8LV is Yanmar’s V8, twin-turbo, mid-revving dedicated marine diesel that offers variants from 320 to 370 horsepower.
Long John Silver was fitted with the 8LV320 (320hp @ 3,800rpm) and these compact diesels compliment the engine room space easily. “There’s lots of room in there with the new Yanmars,” says Chris.
More space in an engine room is good news for any boat owner, making maintenance and daily cruising checks all the easier on these already easy-to-maintain Yanmars.
Owners of the 8LV will first notice the smooth and quiet operation of these 4.46litre displacement V8’s, along with the stunning acceleration response inherent in their intercooled twin-turbo design.
Weighing in at just 435kg, power-to-weight is a standout, along with clean operation that includes IMO Tier 2 and EPA Tier 3 certification. There’s never been cleaner V8 diesel horsepower on the water in fact! A proven solution for shaft and jet drives, all 8LV models are fully compatible with Yanmar’s ZT370 sterndrive for vessels utilising a leg option.
Changing engine brands is rarely a plug-and-play exercise however and Chris had his work cut out for him in doing the repower in the most economical way possible.
“We wanted to keep the gearboxes that come with the Yanmars (1:1.67 ratio, slightly lower to the previous engine’s 1:1.89 gearbox ratio), and we upgraded the shafts to high-tensile but kept the original prop’s,” he explained.
The engines’ mountings were upgraded, with the only other significant customisation required being a change in floor thickness above the Yanmars to account for their slightly taller stance, (catering for their 86mm X 96mm bore and stroke, dimensions that help deliver Yanmar’s famous torque abilities).
“Initial tests showed an almost perfect match between the Yanmar 8LV’s and the existing prop setup,” Chris said, “all we had to do was get the propellers altered by a few millimetres on the tips and load ratios were spot on.”
Outstanding fuel savings – and better speed
Well known for exceptionally–built structure and deep V hulls, the Bertram 35 tips the scales at just under ten tonnes and delivers good seakeeping abilities. Planing hulls that can handle a sea can be hungry for horsepower, but the Bertram shines under its new Yanmar power.
Sea trials and the few hours on-water since installation are showing a better cruise speed, (up from 20 knots to around 22+ knots) and brilliant fuel savings.
“The twenty knot cruise speed under the old petrol V8’s would be using more than 110 litres per hour combined,” Chris said. “So far the Yanmars are showing consumption of only 70 litres per hour combined, so I’m very happy with that.”
Chris says he is still getting used to the Yanmar’s new electronic controls at the helm, but impressed with their functionality. “It’s like having to completely relearn how to drive the boat in some ways – the electronic controls are very good though, very easy to operate.”
The 8LV Yanmars also deliver better control of a vessel in some respects because of their wide rev range. These common rail engines deliver a rev range from 550rpm through to a maximum 3,800rpm, enabling easier manoeuvring and stunning top end performance.
The Bertram now delivers a WOT speed of nearly 30 knots, a sprint that most older Bertram owners would be envious of. Carrying around 1,300 litres of diesel onboard, Long John Silver’s legs will be much longer under her fuel-efficient Yanmar repower.
“Another advantage is that the Yanmars talk directly to the new Raymarine electronics we installed so that all engine systems can be monitored on that system too,” Chris said.
Yanmar’s 8LV series are in fact as clever in their compatibility with other onboard systems, (including full NMEA connectivity), as they are with their own internal power delivery.
The 8LV Yanmar even sports a high capacity 180 amp alternator as standard – enough to keep all onboard electrical power needs catered for with ease. The Yanmars can also cater for up to three electronically controlled stations with Yanmar’s VC10 Vessel Control System and are available with joystick control options for either twin shaft (JC20) or sterndrive (JC10).
