Yanmar Repower: Bertram 46 Battlewagon - 07/08/2009
The Bertram 46 was the offshore convertible of choice in the early 1970s and the model was built up until 1988 when it was retired. The Bertram 46 was sold all over the world and are probably preferred by more fishing charter captains than any other. By our count there are about 100 currently on the market and most are powered with Detroit Diesel 8V92s or 8V71s. We found used Bertrams with anywhere from 435-hp to 750-hp, depending on how much bailing wire duct tape was on them. Most people would choose not to own a boat powered with these engines at any horsepower. That’s why used Bertram 46s with DDAs are so inexpensive.

Bertram 46 Repower
This 1974 Bertram 46 is for sale for $112,000. A few are even less, and many Bertram 46 are asking about $135,000.


The original Bertram 46 went through three versions from the early 1970s until 1988 when it was discontinued. Then, it was revived for three years from 1995 to ’97 and stopped again. In 2000, under the management and ownership of the Ferretti Group, the new 450 was introduced which had about the same displacement as this old Bertram 46 but carried a 14’11” beam, 13” less than the old Bertram.

Bertram 46/450 Pricing

The least expensive older Bertram 46 we found was selling for about $69,000 with 3800 hours on the engines, and obviously ready for a major overhaul. Major overhauls on the DDAs could easily run $65,000 and might be even higher, which would put this boat right up with the others Bertram 46s selling for $135,000.

yanmar6sy-stpdiesel
Yanmar 6SY-STP Diesel.

Interestingly, MarineMax appears to have cornered the market on non-current or very late model 450s and owns seven 2007 or 2008s which it is offering from anywhere from $789,000 for a 450 with 119 hours on it to $1,219,00 for a non-current one. Most of the boats are powered by 900-hp MAN diesels. So if you have the bucks and want a pristine new Bertram 450 you can find them for about $400k off of new MSRP pricing.

Our guess is pricing is even better than what is published as there is a scroll on most of these ads saying “Call us for Special Pricing.” The ad for the unit selling for $789,000 with 119 hours says it has never been titled (perhaps it was a demo) and is “loaded” and has a “huge price reduction.” If this sounds good to you, try Marine Max at 631-424-2710.

Performance Curves


Let’s Repower with Yanmar

Yanmar is the leading name in marine repowering so not surprisingly they have repowered a Bertram 46. The Yanmars in this example were installed by Coastal Carolina yacht Yard. Twin DDA 8V71TIs were replaced by twin Yanmar 6SY-STP diesels rated at 720-hp.

With the old engines, the Yanmar distributor reports that the boat had a WOT of 21 knots and a cruise of 20 knots. With the new Yanmars, the distributor reported the following performance table—

Performance Table

Based on this data, the WOT performance of the Bertram 46 increased 57% with the new Yanmar 720-hp engines, and best cruise improved 45%.

The big question is how much did it cost to repower the boat with the 6SY-STP diesels. According to the distributor, the total cost for the new engines, the engineering and the installation was $170,000.

Based on the prices above for used Bertrams it looks as if you can buy a used Bertram 46 and repower with the 720-hp Yanmar diesels for total cost of $250,000 to $300,000.

If you would like more information on repowering with Yanmar engines, find the name and phone number of your local Yanmar distributor…

Read other Yanmar repower articles --


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