Bertram 35 Convertible
Built 1970–1986 by Bertram Yacht
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About the Bertram 35 Convertible
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1970–1986
- Builder
- Bertram Yacht
- Length
- 35.33 ft
- Beam
- 13.25 ft
- Draft
- 3.17 ft
- Displacement
- 22,500 lb
- Hull / keel
- planing
- Propulsion
- inboard
- Water
- varies by year
- Holding
- 25 gal
- Bow thruster
- not fitted
- Stern thruster
- not fitted
Tank capacities — where the figures come from
-
Fuel unknown
“Fuel 285/273 gals.” — spec database, cdn.denisonyachtsales.com · “Fuel 285/273 gals.” — spec database, cdn.denisonyachtsales.com · “Fuel Capacity 260 gallons” — search excerpt (1971 (one listing)), s3.amazonaws.comThe PowerBoat Guide page gives two fuel figures (285 and 273 gal) without saying which years; a 1971 listing says 260. Our earlier 285 is the guide's first figure. Bertram's owner's-manual library for older models has no 35 manual.
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Water varies by year
“Water 50/75 gals.” — spec database, cdn.denisonyachtsales.com · “Water 50/75 gals.” — spec database, cdn.denisonyachtsales.com · “Water Capacity 50 gallons” — search excerpt (1971 (one listing)), s3.amazonaws.comThe guide lists two water capacities (50 and 75 gal); the 1971 listing's 50 suggests 50 on early boats and 75 later (perhaps the 1981 MK II), but no factory source confirms the years.
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Holding 25 gal
“Waste 25 gals.” — spec database, cdn.denisonyachtsales.comThe guide agrees with our earlier figure, but it isn't a builder source.
Tanks are often replaced or added on older boats — check the tank labels or a survey for yours.
Thrusters and steering — where this comes from
-
Bow thruster not fitted
Our earlier figure of none has no source, and nothing was found either way.
-
Stern thruster not fitted
Our earlier figure of none has no source, and nothing was found either way.
-
Steering unknown
Bertram's legacy manual library has no 35 Convertible manual, and nothing model-specific turned up on the owners' forums.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Sources disagree on hp (Cat diesel option), fuel tank — left blank rather than guessed.
Deep-V (19 deg). Most were diesel powered. MK II (1981) with updated bridge; teak interior from 1984. HMY lists fuel as 285/273 gal and water 50/75 gal (varies by year/power).
Engines fitted
-
Cummins 215 hp diesel — 215 hp, diesel, twin
factory option
HMY lists 215 hp Cummins (16-18 kn cruise) among the most popular diesel packages. Exact Cummins model not confirmed from a source read.Sources: hmy.com
-
Caterpillar 3208 — 300 hp, diesel, twin
factory option
HMY: 300 hp Cats (23-24 kn cruise) were among the most popular; its BoatUS note says optional 320 hp Cats (22 kn). Several Bass Barn members report 3208 Cats in their 35s, one listing at 320 hp.Sources: hmy.com · thebassbarn.com
-
Caterpillar 3116 / 3126 — 350 hp, diesel, twin
common repower
Bass Barn members report 35s repowered with Cat 3126s (350 hp and 420 hp) and a 1978 boat with Cat 3116TAs (350 hp).Sources: thebassbarn.com
-
Cummins QSB 5.9 — 380 hp, diesel, twin
common repower
A restored 35 Convertible repowered with Cummins QSB 5.9 (380 hp) is the subject of a Bass Barn thread.Sources: thebassbarn.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
An owners' forum comparison places the 35's generator far aft under the cockpit, and a 1987 Mk II listing shows an Onan 7.5; neither shows whether it was fitted at the factory.
Known problems for this model
-
Rotting plywood cockpit sole (pre-1982) deck
Boats before 1982 had a vinyl-covered plywood cockpit sole that tended to rot; later boats got a fiberglass sole.hmy.com
Engines & parts
Caterpillar 3208 (NA / T / TA) parts: good
Factory optional engine — you entered “Caterpillar 3208”
V8 introduced in the 1970s and discontinued in the late 1990s (Big Bear Engine gives 1999). Naturally aspirated versions run about 210 hp; turbo and turbo-aftercooled versions go up to 435 hp. Cat dealers still supply many genuine parts by serial number, and aftermarket in-frame/overhaul kits (pistons, rings, liners, bearings) are sold by Diesel Pro Power, Highway and Heavy Parts and others; complete remanufactured long blocks are also sold. The block is unsleeved from the factory but can be bored and sleeved during a rebuild.
Parts sources: Diesel Pro Power, Highway and Heavy Parts (Cat 3208), Big Bear Engine Company (3208 long blocks)
Common problems (3)
-
Aftercooler failure flooding the engine (TA models) cooling
The seawater-cooled aftercooler on turbo-aftercooled 3208s has aluminum parts that corrode; a failure can let seawater into the cylinders. Owners pull, clean, grease and pressure-test aftercoolers every 2–3 years and some replace them on a fixed schedule.trawlerforum.com · forums.ybw.com
-
Short life at high ratings / overloading engine
The higher-rated 3208TA engines last longer when run well below full power and propped so they can reach rated rpm; overheating or running at full load continuously shortens life.trawlerforum.com · trawlerforum.com
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Overheating at high throttle cooling
Common causes owners check are clogged heat exchangers, thermostats, fouled keel coolers or restricted raw water flow, and faulty temperature senders.justanswer.com · facebook.com
Maker’s service schedule (20)
| Engine oil & filter change | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Engine Oil and Filter - Change” — manufacturer, princessklubben.se |
| Fuel filters & water separator | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Fuel System Primary Filter/Water Separator Element” — manufacturer, princessklubben.se |
| Raw-water pump impeller | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Auxiliary Water Pump - Inspect” — manufacturer, princessklubben.se |
| Engine pencil zincs | 50 hrs | “Every 1900 L (500 US gal) of Fuel or 50 Service Hours ... Zinc Rods - Inspect/Replace” — manufacturer, princessklubben.se |
| Air filter / intake silencer | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Engine Air Cleaner Element - Clean/Replace” — manufacturer, princessklubben.se |
| Valve clearance check / adjust | 2,000 hrs | “Initial 9000 L (2400 US gal) of Fuel or 250 Service Hours or 1 Year ... Engine Valve Lash - Inspect/Adjust” — manufacturer, princessklubben.se |
| Coolant replacement & freeze-point test Cat DEAC / conventional coolant | 1,000 hrs or 2 yrs | “Every 36 000 L (9000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Cooling System Coolant (DEAC) - Change” — manufacturer, princessklubben.se |
| Coolant replacement & freeze-point test Cat ELC (extended life coolant) | 6,000 hrs or 4 yrs | “Every 216 000 L (57 000 US gal) of Fuel or 6000 Service Hours or 4 Years ... Cooling System Coolant (ELC) - Change” — manufacturer, princessklubben.se |
| Turbocharger inspection | 1,000 hrs or 2 yrs | “Every 36 000 L (9000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Aftercooler Core - Clean/Test” — manufacturer, princessklubben.se |
| Turbocharger inspect | 2,000 hrs | “Every 72 000 L (19 000 US gal) of Fuel or 2000 Service Hours ... Turbocharger - Inspect” — manufacturer, princessklubben.se |
| Heat exchanger & oil cooler cleaning | 2,000 hrs | “Every 72 000 L (19 000 US gal) of Fuel or 2000 Service Hours ... Heat Exchanger - Inspect” — manufacturer, princessklubben.se |
| Injector test / service | 2,000 hrs | “Every 72 000 L (19 000 US gal) of Fuel or 2000 Service Hours ... Fuel Injection Nozzles - Test/Exchange” — manufacturer, princessklubben.se |
| Sea water strainer clean/inspect | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Sea Water Strainer - Clean/Inspect” — manufacturer, princessklubben.se |
| Coolant SCA test/add | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Cooling System Supplemental Coolant Additive (SCA)” — manufacturer, princessklubben.se |
| Hoses and clamps inspect/replace | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Hoses and Clamps - Inspect/Replace” — manufacturer, princessklubben.se |
| Crankcase breather clean | 250 hrs or 1 yr | “Every 9000 L (2400 US gal) of Fuel or 250 Service Hours or Yearly ... Engine Crankcase Breather - Clean” — manufacturer, princessklubben.se |
| Thermostat (water temperature regulator) replace | 1,000 hrs or 2 yrs | “Every 36 000 L (9000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Cooling System Water Temperature Regulator - R” — manufacturer, princessklubben.se |
| Marine transmission oil cooler clean/inspect | 1,000 hrs or 2 yrs | “Every 36 000 L (9000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Marine Transmission Oil Cooler - Clean/Inspect” — manufacturer, princessklubben.se |
| Crankshaft vibration damper inspect | 2,000 hrs | “Every 72 000 L (19 000 US gal) of Fuel or 2000 Service Hours ... Crankshaft Vibration Damper - Inspect” — manufacturer, princessklubben.se |
| Jacket water pump inspect | 3,000 hrs or 2 yrs | “Every 108 000 L (28 500 US gal) of Fuel or 3000 Service Hours or 2 Years ... Water Pump - Inspect” — manufacturer, princessklubben.se |
Service part numbers (4)
| Fuel filter | Caterpillar 1R-0750 | “| Fuel Filter | 1R0750 |” — dealer, marineenergy.com.au · “Fuel Filter for Caterpillar 3208 Natural and Turbo engines 1R0750 Advanced Efficiency” — dealer, dieselpro.com |
| Zinc / anode heat-exchanger anode (10 mm); 2 on the 4W-9164 heat exchanger, 3 on the 7C-3114 heat exchanger |
Caterpillar 6L-2283 | “| Anodes on 7C-3114 Heat Exchanger | 6L-2283 | [CM6L2283] x 3.” — dealer, marineenergy.com.au · “Zinc Anode for Caterpillar Marine Engines 6L2283 NPT: 1/4”” — dealer, dieselpro.com |
| Zinc / anode 16 mm anode, starboard bottom of bonnet, 4W-9164 heat exchanger only |
Caterpillar 6L-2289 | “Anodes on 4W-9164 Heat Exchanger | 6L-2283 6L-2289 ... [TEC 02023] x 1. Starboard Side, bottom of the bonnet. 16mm” — dealer, marineenergy.com.au · “Zinc Anode for Caterpillar Marine Engines 6L2289 NPT: 1/2”” — dealer, dieselpro.com |
| Zinc / anode transmission oil cooler anode (if the cooler has one) |
Caterpillar 6L-2288 | “| Anode - Transmission Oil Cooler (If present on cooler) | 6L-2288 |” — dealer, marineenergy.com.au · “Zinc Anode for Caterpillar Marine Engines 6L2288 NPT: 1/2”” — dealer, dieselpro.com |
From the engine maker’s parts lists, or two independent parts dealers. Numbers change with serial number and get superseded — check yours before ordering.
Sources disagree on horsepower — left blank rather than guessed.
Caterpillar 3116 parts: limited
Factory common repower engine — you entered “Caterpillar 3116 / 3126”
Supported by Cat dealers by serial number; aftermarket rebuilders (e.g., Big Bear Engine) sell parts and address known problems. Some 3116s built in France ('soft block') were problematic and owners are told to check serial numbers with Cat.
Parts sources: Big Bear Engine Company, Diesel Pro Power
Common problems (4)
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Failures in high-load use engine
3116s generally do fine in trawlers but problems show up in fast boats run near full power for long periods; poor propping that overloads the engine ages it quickly.trawlerforum.com
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'Soft block' engines engine
A batch of French-built blocks had a reputation for early failure, sometimes within a few hundred hours.trawlerforum.com
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Injectors, fuel rack and heads fuel
Owners and rebuilders report injector/injector-cup, fuel rack and cylinder head problems; good maintenance history matters when buying.4btengines.com · facebook.com
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Low turbo/exhaust mixer height exhaust
The low-mounted turbo and exhaust mixer make it harder to get adequate exhaust riser height, so the exhaust installation needs care to avoid water backflow.trawlerforum.com
Maker’s service schedule (18)
| Engine oil & filter change | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Engine Oil and Filter - Change” — manufacturer, oxfordyachtagency.com |
| Fuel filters & water separator | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Fuel System Primary Filter/Water Separator Element” — manufacturer, oxfordyachtagency.com |
| Raw-water pump impeller | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Auxiliary Water Pump - Inspect” — manufacturer, oxfordyachtagency.com |
| Engine pencil zincs | 50 hrs | “Every 1500 L (400 US gal) of Fuel or 50 Service Hours ... Zinc Rods - Inspect/Replace” — manufacturer, oxfordyachtagency.com |
| Valve clearance check / adjust | 2,000 hrs | “First 7500 L (2000 US gal) of Fuel or 250 Service Hours ... Engine Valve Lash - Inspect/Adjust” — manufacturer, oxfordyachtagency.com |
| Coolant replacement & freeze-point test Cat DEAC / conventional coolant | 1,000 hrs or 2 yrs | “Every 30 000 L (8000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Cooling System Coolant (DEAC) - Change” — manufacturer, oxfordyachtagency.com |
| Coolant replacement & freeze-point test Cat ELC (extended life coolant) | 6,000 hrs or 4 yrs | “Every 182 000 L (48 000 US gal) of Fuel or 6000 Service Hours or 4 Years ... Cooling System Coolant (ELC) - Change” — manufacturer, oxfordyachtagency.com |
| Turbocharger inspection | 1,000 hrs or 2 yrs | “Every 30 000 L (8000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Aftercooler Core - Clean/Test” — manufacturer, oxfordyachtagency.com |
| Turbocharger inspect | 1,000 hrs or 2 yrs | “Every 30 000 L (8000 US gal) of Fuel or 1000 Service Hours or 2 Years ... Turbocharger - Inspect” — manufacturer, oxfordyachtagency.com |
| Heat exchanger & oil cooler cleaning | 2,000 hrs | “Every 60 000 L (16 000 US gal) of Fuel or 2000 Service Hours ... Heat Exchanger - Inspect” — manufacturer, oxfordyachtagency.com |
| Drive belts inspect / replace | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Belt - Inspect” — manufacturer, oxfordyachtagency.com |
| Fuel injection timing check | 2,000 hrs | “First 7500 L (2000 US gal) of Fuel or 250 Service Hours ... Fuel Injection Timing - Check” — manufacturer, oxfordyachtagency.com |
| Thermostat (coolant temperature regulator) replace | 3,000 hrs or 2 yrs | “Every 91 000 L (24 000 US gal) of Fuel or 3000 Service Hours or 2 Years ... Cooling System Water Temperature Regulator -” — manufacturer, oxfordyachtagency.com |
| Sea water strainer clean/inspect | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Sea Water Strainer - Clean/Inspect” — manufacturer, oxfordyachtagency.com |
| Jacket water pump inspect | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Water Pump - Inspect” — manufacturer, oxfordyachtagency.com |
| Coolant SCA test/add | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Cooling System Supplemental Coolant Additive (SCA)” — manufacturer, oxfordyachtagency.com |
| Hoses and clamps inspect/replace | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Hoses and Clamps - Inspect/Replace” — manufacturer, oxfordyachtagency.com |
| Crankcase breather clean | 250 hrs or 1 yr | “Every 7500 L (2000 US gal) of Fuel or 250 Service Hours or 1 Year ... Engine Crankcase Breather - Clean” — manufacturer, oxfordyachtagency.com |
Service part numbers (3)
| Oil filter | Sources disagree: 1R-0658 / 324-2598 | “**Oil Filter** **CAT 1R-0658** | 3126B C7 3306 3304 3116 C4.2 3046 3066” — dealer, marineenergy.com.au · “Caterpillar 324-2598 Advanced Efficiency 3116 and 3126 Diesel Engine Oil Filter” — dealer, marineengineparts.com |
| Fuel filter | Caterpillar 1R-0751 Also: Baldwin BF7632, Fleetguard FF5324, WIX 33626 |
“Caterpillar 1R-0751 Advanced Efficiency 3116 and 3126 Diesel Engine Fuel Filter” — dealer, marineengineparts.com · “the secondary fuel filter Cat specifies for the 3114, 3116, 3126/B/E, C7, and C9 family” — dealer, allprodiesel.net |
| Raw-water impeller keyway-shaft Sherwood seawater pump |
Sherwood 17000K | “| **Impeller** | 17000K KEY WAY |” — dealer, marineenergy.com.au · “Caterpillar Marine Engines ... Common applications include: ... CAT 3116” — dealer, marisolmarine.com |
| Zinc / anode | Caterpillar 6L-2283 × 3 | “**Anode kit CAT3116** | 3 x 6L2283 2 x 6L2281 1 x 6L3104” — dealer, marineenergy.com.au · “Zinc Anode for Caterpillar Marine Engines 6L2283 NPT: 1/4”” — dealer, dieselpro.com |
From the engine maker’s parts lists, or two independent parts dealers. Numbers change with serial number and get superseded — check yours before ordering.
Cummins QSB 5.9 parts: good
Factory common repower engine — you entered “Cummins QSB 5.9”
Electronically controlled (common-rail) successor to the mechanical 6BTA; current Cummins dealer network plus marine specialists such as Seaboard Marine supply parts. Electronic diagnostics require dealer tools more often than on the 6BTA.
Parts sources: Seaboard Marine, Diesel Pro Power
Common problems (3)
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Raw water pump leaks cooling
Owners most often report the seawater pump leaking or being replaced around 1000 hours; an improved pump version is available. Some also updated fuel coolers as a precaution.forums.ybw.com
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Aftercooler service and cracking cooling
As with the 6BTA, the aftercooler needs periodic removal and resealing; a cracked aftercooler is generally replaced rather than repaired.trawlerforum.com · facebook.com
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Burnt intake valves / loss of power engine
Seaboard Marine forum threads describe burnt valves and high-rpm power loss on some QSB 5.9s.sbmar.com
Service part numbers (5)
| Oil filter | Fleetguard (Cummins-specified) LF3959 Also: Cummins 3937743 |
“MMK001SK59 QSB5.9 Marine Service Kit ... LF3959 Oil Filter 1” — manufacturer, cummins.com |
| Fuel filter | Fleetguard (Cummins-specified) FF5488 | “MMK001SK59 QSB5.9 Marine Service Kit ... FF5488 Fuel Filter 1” — manufacturer, cummins.com |
| Fuel pre-filter / separator | Fleetguard (Cummins-specified) FS20402 | “MMK001SK59 QSB5.9 Marine Service Kit ... FS20402 FS Filter 1” — manufacturer, cummins.com |
| Drive belt serpentine belt, post-Jan 2008 QSB 5.9 with 21/22SI or 24SI alternator (brown belt) |
Cummins 4981117 | “Cummins Serpentine Belt for QSB 5.9 (post January 2008) 21/22 SI Alternator CPN 4981117 (BROWN)” — dealer, sbmar.com · “4981117 Alternator Belt for Cummins® QSB 5.9 Engine” — dealer, seapowermarine.com |
| Cummins QSB5.9 marine service kit (zincs, oil, fuel and FS filters, minor water-pump kit) | Cummins MMK001SK59 | “MMK001SK59 QSB5.9 Marine Service Kit” — manufacturer, cummins.com |
From the engine maker’s parts lists, or two independent parts dealers. Numbers change with serial number and get superseded — check yours before ordering.
Model sources (3)
Own a Bertram 35 Convertible? Add her to your boats, then share a photo — names, numbers and faces are blurred before it appears.
Other Bertram models
- Bertram 28 Flybridge Cruiser 1971–1994
- Bertram 31 Flybridge Cruiser 1961–1983
- Bertram 33 Flybridge Cruiser 1977–1992
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.