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Bertram 31 (1981) - Yanmar Repower (Not Prod)

2 x 315-hp Yanmar 6LPA-STP2 Diesel

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Brief Summary

Just sprucing up the interior, updating the electronics and maybe adding a new paint job isn’t enough when you are trying to take a classic like the 31 Bertram and breathe new life into her. Richard Mastry of Mastry Engine Center in St. Petersburg, Florida recently took us on a ride down memory lane with one of his passions-- repowering beautiful old Bertrams. He has repowered over 30 of them, so we would call him a pro and since he helped bring Yanmar marine engines into the US, he could also be considered a professional resource for repowering a boat with Yanmar engines. This particular model has been repowered with twin Yanmar 6LPA-STP2s.

Test Results

RPM MPH Knots GPH MPG NMPG SM NM dBa
1250 8.5 7.3 2.7 3.13 272 620 539 83
1500 9.2 8 4.3 2.13 1.85 421 366 84
1750 10.1 8.8 6.2 1.63 1.42 323 280 85
2000 15.9 13.8 7.9 2.01 1.74 397 345 85
2250 20.1 17.4 10 2.01 1.74 397 345 86
2500 23.7 20.6 12.4 1.91 1.66 378 329 87
2750 26.4 23 14.4 1.83 1.59 363 316 88
3000 29.5 25.6 16.7 1.76 1.53 349 304 90
3250 31.3 27.2 19.1 1.64 1.42 324 282 89
3500 34 29.6 23.3 1.46 1.27 289 251 90
3750 35.9 31.2 26.8 1.34 1.16 265 231 90
3911 37.4 32.5 29.4 1.27 1.11 252 219 91
View the test results in metric units
bertram31-chart.jpg

Specifications

Length Overall 30' 7''
Beam 11' 2''
Dry Weight 9, 400 lbs. (with fuel)
Draft 2' 7''
Deadrise/Transom N/A
Max Headroom 6' 2''
Bridge Clearance 8' 0''
Fuel Capacity 220 gal.
Water Capacity 18 gal.

Acceleration Times & Conditions

Time to Plane 5.3 sec.
0 to 30 8.4 sec.
Ratio 2:1
Props Michigan 18 x 25 4 blade broze
Load 3 pers., Fuel 107 gal., Water 12 gal , min. gear
Climate Temp: 90 deg., humid: 47%, wind: 5 mph, 10 mph: min chop

Engine Options

Tested Engine 2 x 315-hp Yanmar 6LPA-STP2 Diesel
Std. Power Not Available
Opt. Power 2 x 315-hp Yanmar 6LPA-STP2

**Contact Bertram Yachts for complete model information**