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Overview
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.
Key Features
Key Features of 6LPA-STP2:
Compact profile
Easy access to maintenance points
24 valve overhead cam 6 cylinder in-line four stroke 4.1 liter
899 lbs per engine
Gear reduction starter
Two-stage fuel injectors
80 amp alternator
Cast stainless mixing elbow for longer life
Wet turbo
Multiple transmissions available
**Contact Bertram Yachts for complete model information**
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Test Power: 2 x 315-hp Yanmar 6LPA-STP2 Diesel
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Range |
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RPM
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MPH |
Knots |
Total GPH |
MPG |
NMPG |
Stat. Mile |
NM |
KM |
KPH |
LPH |
KPL |
dBA |
| 1250 |
8.5 |
7.3 |
2.7 |
3.13 |
272 |
620 |
539 |
998 |
13.68 |
10.2 |
1.33 |
83 |
| 1500 |
9.2 |
8.0 |
4.3 |
2.13 |
1.85 |
421 |
366 |
678 |
14.81 |
16.3 |
0.91 |
84 |
| 1750 |
10.1 |
8.8 |
6.2 |
1.63 |
1.42 |
323 |
280 |
520 |
16.25 |
23.5 |
0.69 |
85 |
| 2000 |
15.9 |
13.8 |
7.9 |
2.01 |
1.74 |
397 |
345 |
639 |
25.59 |
29.9 |
0.85 |
85 |
| 2250 |
20.1 |
17.4 |
10.0 |
2.01 |
1.74 |
397 |
345 |
639 |
32.35 |
37.8 |
0.85 |
86 |
| 2500 |
23.7 |
20.6 |
12.4 |
1.91 |
1.66 |
378 |
329 |
608 |
38.14 |
46.9 |
0.81 |
87 |
| 2750 |
26.4 |
23.0 |
14.4 |
1.83 |
1.59 |
363 |
316 |
584 |
42.49 |
54.5 |
0.78 |
88 |
| 3000 |
29.5 |
25.6 |
16.7 |
1.76 |
1.53 |
349 |
304 |
562 |
47.48 |
63.2 |
0.75 |
90 |
| 3250 |
31.3 |
27.2 |
19.1 |
1.64 |
1.42 |
324 |
282 |
521 |
50.37 |
72.3 |
0.7 |
89 |
| 3500 |
34.0 |
29.6 |
23.3 |
1.46 |
1.27 |
289 |
251 |
465 |
54.72 |
88.2 |
0.62 |
90 |
| 3750 |
35.9 |
31.2 |
26.8 |
1.34 |
1.16 |
265 |
231 |
426 |
57.78 |
101.4 |
0.57 |
90 |
| 3911 |
37.4 |
32.5 |
29.4 |
1.27 |
1.11 |
252 |
219 |
406 |
60.19 |
111.3 |
0.54 |
91 |
Speeds measured with Stalker ProSports radar gun. Fuel consumption (gallons per hour) measured with Floscan digital fuel-flow meter on gas inboards, sterndrives, and outboards, TechMate electronic scan tool on gas EFI inboards, Caterpillar digital fuel-flow meter on diesel engines, or permanently installed fuel-monitoring equipment. Range is based on 90% of published fuel capacity. Sound levels determined using Radio Shack digital decibel meter on A scale. 68 dBA is the level of normal conversation.
Performance Chart
Test Conditions
Test Power: 2 x 315-hp Yanmar 6LPA-STP2 Diesel
| Time To Plane |
5.3 sec. |
| 0 to 30 |
8.4 sec. |
| Test Power |
2 x 315-hp Yanmar 6LPA-STP2 Diesel
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| Transmission |
ZF63A |
| 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 |
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Engine Options
Bertram 31 (1981) - Yanmar Repower (Not Prod)
| Std. Power |
Not Available
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| Tested Power |
2 x 315-hp Yanmar 6LPA-STP2 Diesel
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| Opt. Power |
2 x 315-hp Yanmar 6LPA-STP2
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| Prices, features, designs, and equipment are subject to change. Please see your local dealer or visit the builder’s website for the latest information available on this boat model. |
Standard and Optional Equipment
Standard and Optional Equipment
 = Standard  = Optional
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**Contact Bertram Yachts for complete model information**
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Specifications
Bertram 31 (1981) - Yanmar Repower (Not Prod)
| Length Overall |
30' 7'' |
Dry Weight
| 9, 400 lbs. (with fuel) |
| Beam |
11' 2'' |
Fuel Cap
| 220 gal. |
| Draft |
2' 7'' |
Water Cap
| 18 gal. |
| Deadrise/Transom |
N/A |
Bridge Clearance
| 8' 0'' |
| Max Headroom |
6' 2'' |
| Prices, features, designs, and equipment are subject to change. Please see your local dealer or visit the builder’s website for the latest information available on this boat model. |
Line Drawing
Line drawing coming soon...
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A running shot of the repowered Bertram 31.
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