Designing Yanmar Repower Rejuvenates Sentimental Bertram 39

Outsider 1
A boatie with a keen eye will instantly recognise Outsider as a classic vessel.  This fully imported and rare boat, the Bertram 39 Sport Fisherman “Widebody”, was built by the Bertram Yacht Company in Miami, Florida in the mid 1970’s.

Peter Smith and his father Warren bought the boat in Perth in the mid-90’s and used Outsider extensively for family boating.  Mike Giles of Diverse Engineering looked after Outsider for nearly 20 years.

Peter Smith bought out his father when Warren “retired” from boating.

Peter thought about selling Outsider a few times, but over the 20 years, he and his father had fixed, replaced or upgraded just about everything.  Buying another boat would be inheriting someone else’s issues and there were, of course, plenty of sentimental reasons for keeping Outsider.

The problem was the engines.  The original engines fitted by Bertram in the US were a pair of beefy V8, naturally aspirated diesels.  They were heavy at about 1,250 kgs each and only developed 270 hp.  They were noisy and leaked oil.  Peter and his father had each engine rebuilt over the years, but no matter what you did, they were still old engines, requiring continual maintenance and they were a limiting factor for the boat.

Performance was also pretty ordinary.  At wide open throttle Outsider made around 15 knots.  Fuel consumption was high, limiting Outsider’s range and making her expensive to run.

The owner, settled on a fresh pair of Yanmar 6LY3AM-STP marine diesel engines.  These were fitted with Yanmar transmissions, the KMH61A with a 2.04:1 ratio.
Outsider 2
Yanmar’s 6LY3-STP engine is a turbocharged, direct injected, intercooled, 24 valve, in-line 6 cylinder displacing 5813cm3 to produce 440mhp (324 kW) at 3300rpm.  Weighing in at only 640 kgs (without gearbox) the 6LY3-STP deliver industry leading power-to-weight Yanmar diesel performance.

The Yanmar 6LY3 features a high-technology electronic control and display system that monitors all engine operations from fuel management to twin engine synchronisation, gear shifting and diagnostics.

“The re-power project went very smoothly,” said Mike Giles.   “We completely stripped the engine room and replaced all the wiring, fuel system, transmissions, prop shafts and so on.  We ripped a lot of 1970s gear out of there and replaced it with modern systems.”

The upshot is an overall weight saving of just over 1,000 kgs.  The majority of the weight saving is attributed to the Yanmar 6LY3 engines being so light.  At 718 kgs each with
transmission, the pair of Yanmars contributed most of the weight savings from the refit.

The power benefit of the Yanmar’s 440 mhp over the old 270 hp V8’s, delivers a collective power gain of a massive 340 mhp, albeit pushing 1 tonne less weight. Understandably the performance boost is impressive.

Whereas as Outsider used to get to 15 knots, now top speed with the Yanmar 6LY3 engines spinning at 3,300 rpm, is 29.5 knots almost double the previous WOT setting.  Throttle back to a comfortable cruise speed of 20 knots and the big, beamy Bertram 38 performs brilliantly and efficiently.

“The owner is so happy with the family boat,” Mike Giles said.  “He is hugely impressed with the way the boat performs that he is now enjoying it on extended trips with his own family.”

This is a boat that has been totally transformed by the Yanmar repower.  With the Yanmar 6LY3 engines installed she is faster, lighter, quieter and much better on fuel consumption.

Peter says that he now has a boat that does twice the speed using half the fuel.
Outsider 3
Following the Yanmar re-power, there is considerably more room in the engine room.  The installation envelope on the Yanmar 6LY3 is such that the 6 cylinder in-line engine is
noticeably narrower than the old V-8 diesels.  The Yanmars are also a little shorter too.

“Outsider has come the full circle and with the new Yanmar engines on board, she will still be going strong in another 30 years time.”