Ocean Alexander 50 Pilothouse MK I
Built 1978–1983
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About the Ocean Alexander 50 Pilothouse MK I
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1978–1983
- Length
- 50.25 ft
- Waterline
- 45.67 ft
- Beam
- 15.5 ft
- Draft
- 4.5 ft
- Displacement
- 46,500 lb
- Hull
- fiberglass
- Hull / keel
- semi-displacement
- Propulsion
- inboard
- Number built
- 92
Tank capacities — where the figures come from
-
Fuel unknown
“Fuel capacity 1,000 Gallons” — spec database (1978-1983), yachtbuyer.com · “Fuel tank (litre) steel 1250; Fuel tank 2 (litre) steel 1250” — broker listing (one boat), devalk.nlYachtBuyer and the HMY powerboat guide give 1,000 gal, likely from one shared source; a Dutch broker's listing of a Mark I gives two 1,250 L steel tanks (2,500 L, or 660 gal). That boat may have been re-tanked, and no factory figure was found to settle it.
-
Water unknown
“Fresh Water capacity 420 Gallons” — spec database (1978-1983), yachtbuyer.com · “Freshwater tank (litre) steel 1000” — broker listing (one boat), devalk.nlSpec databases say 420 gal; one boat for sale lists 1,000 L (264 gal). No factory figure was found.
-
Holding unknown
The listing names a polyethylene toilet-waste (black water) tank without a capacity.
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 unknown
“She has a bow and stern thruster for hassle free docking” — search excerpt (1981), fairhavenyachts.comOnly a single 1981 listing mentions bow and stern thrusters; no builder or review source was found.
-
Stern thruster unknown
“She has a bow and stern thruster for hassle free docking” — search excerpt (1981), fairhavenyachts.comSingle listing only.
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Steering unknown
No builder, review or owners' source found.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Sources disagree on model (Cummins 270 hp), fuel tank, water tank — left blank rather than guessed.
The first Ocean Alexander model sold in the U.S.; 92 sold. Solid fiberglass construction with Portuguese bridge around the pilothouse; two staterooms with amidships owner's cabin. Among several engine choices, 320 hp Cats or 270 hp Cummins cruise 11-12 knots.
Engines fitted
-
Cummins VT-555 — 270 hp, diesel, twin
standard
Soundings: standard power was twin 270 hp Cummins or 320 hp Cats (about 11-12 kn cruise per HMY). Owners describe the Cummins as the V8 'triple nickel' (VT-555).Sources: soundingsonline.com · hmy.com · yachtforums.com
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Caterpillar 3208T — 320 hp, diesel, twin
standard
The other standard choice per Soundings; YachtBuyer names it the 3208T at 320 hp.Sources: soundingsonline.com · yachtbuyer.com · hmy.com
-
Ford Lehman 120 — 120 hp, diesel, twin
factory option
An owner reports his MK I had twin Lehman 120s (slow boat); HMY says there were 'several engine choices'. Factory vs repower not stated.Sources: yachtforums.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
One 1983 listing shows an Onan 6.0 kW diesel; no builder, review or second-boat confirmation.
Known problems for this model
No well-sourced problem reports found yet.
Engines & parts
Caterpillar 3208 (NA / T / TA) parts: good
Factory standard engine — you entered “Caterpillar 3208T”
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
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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.
Ford Lehman 120 (6D380 / 2715E) parts: good
Factory optional engine — you entered “Ford Lehman 120”
Marinized by Lehman from the Ford of England 'Dorset' 2715E six-cylinder (380 cu in) industrial/truck diesel; Ford built the Dorset base engines 1964–1984. Base-engine internals interchange with the Ford 2715E, and marine-specific parts (raw water pumps, heat exchangers, injection elbows, gaskets, lift pumps, air filters) are widely stocked. American Diesel Corp (founded by former Lehman people) still sells parts, publishes spare-parts lists and gives technical advice. Rebuilt and used 120s are also sold by salvage yards.
Parts sources: American Diesel Corp, Go2marine (Ford Lehman parts collection), Fred Warner Marine & Outdoors
Common problems (2)
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Chronic oil leaks engine
Most 120s weep oil somewhere; owners often trace it to the rear of the engine near the heat exchanger (head/head gasket area) or to the drive seals of the gear-driven injection pump. Moderate oil use is treated as normal on these engines.trawlerforum.com · marineengine.com
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Fuel leaks at injection pump, lift pump and return lines fuel
Slow diesel drips usually come from loose bleed screws or banjo washers, perished rubber injector return hoses, a failing lift-pump diaphragm, or worn internal seals in the Simms or CAV injection pump, which needs a pump shop to overhaul.yescenters.com
Maker’s service schedule (16)
| Engine oil & filter change | 200 hrs | “After first 15 hours running .... 1. Change Engine Oil ... Every 200 hours running ..... 17. Change engine and transmiss” — manufacturer (1986), marinedieselbasics.com |
| Fuel filters & water separator | 200 hrs | “Every 200 hours running ..... 18. Change all engine and fuel oil filters.” — manufacturer (1986), marinedieselbasics.com |
| Change oil in fuel injection pump | 50 hrs | “Every 50 hours running ...... 13. Check cleanliness of intake air filter. 14. Check (exchanger) zinc pencil. 15. Change” — manufacturer (1986), marinedieselbasics.com |
| Transmission fluid change | 200 hrs or 1 yr | “Change oil every 200 hours of operation or at least once each season under normal conditions” — manufacturer (1986), marinedieselbasics.com |
| Valve clearance check / adjust | 400 hrs | “After first 15 hours running .... 3. Adjust valve clearances. ... Every 400 hours running ..... 22. Adjust valve clearan” — manufacturer (1986), marinedieselbasics.com |
| Injector test / service | 400 hrs | “Every 400 hours running ..... 21. Remove and service injectors.” — manufacturer (1986), marinedieselbasics.com |
| Engine pencil zincs | 50 hrs | “After first 15 hours running .... 4. Check (exchanger) zinc pencil. ... Every 50 hours running ...... 14. Check (exchang” — manufacturer (1986), marinedieselbasics.com |
| Drive belts inspect / replace | 200 hrs | “After first 15 hours running .... 5. Adjust belt tension. ... Every 200 hours running ..... 16. Adjust belt tension.” — manufacturer (1986), marinedieselbasics.com |
| Air filter / intake silencer | 50 hrs | “After first 15 hours running .... 8. Check cleanliness of intake air filter. ... Every 50 hours running ...... 13. Check” — manufacturer (1986), marinedieselbasics.com |
| Clean fuel lift pump | 200 hrs | “Every 200 hours running ..... 19. Clean fuel lift pump.” — manufacturer (1986), marinedieselbasics.com |
| Clean injection pump cover filter | 200 hrs | “Every 200 hours running ..... 20. Clean injection pump cover filter.” — manufacturer (1986), marinedieselbasics.com |
| Remove raw water pump and check drive coupling | 400 hrs | “Every 400 hours running ..... 23. Remove raw water pump and check drive coupling. Place dab of grease on coupling halves” — manufacturer (1986), marinedieselbasics.com |
| Adjust idling speed (if required) | 400 hrs | “After first 15 hours running .... 10. Adjust idling speed (if required). ... Every 400 hours running ..... 24. Adjust id” — manufacturer (1986), marinedieselbasics.com |
| Check engine/propeller shaft alignment | 6 mo | “After first 15 hours running .... 9. Check engine/propeller shaft alignment. (twice annually, minimum).” — manufacturer (1986), marinedieselbasics.com |
| Replace Borg Warner transmission oil cooler | 1,200 hrs | “Suggested replacement is at 1200 hours.” — manufacturer, img1.wsimg.com |
| Inspect drive damper | 2,500 hrs | “Inspect your drive damper if you have more than 2500 hours on the engine.” — manufacturer, img1.wsimg.com |
Service part numbers (3)
| Raw-water impeller | Jabsco 1210-0001 | “6D380 5850-0001 040 3/4" NPT Flange SK33 3298 1210-0001” — manufacturer, marineengine.com · “Breakdown of 2C48 Pump ... 9 1 1210-0001 IMPELLER” — manufacturer, marinesurveyorontario.com |
| Raw-water pump kit original 2C45 pump (Jabsco 5850-0001) |
Jabsco SK33 | “6D380 5850-0001 040 3/4" NPT Flange SK33 3298 1210-0001” — manufacturer, marineengine.com |
| Raw-water pump kit Lehman 2C48 replacement pump (Jabsco 10950-2401 type) |
Jabsco SK239 | “Service Kit SK239 - Comprising Key 7/8/9/17” — manufacturer, marinesurveyorontario.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 (7)
hmy.com · pacificyachting.com · soundingsonline.com · yachtforums.com · yachtbuyer.com · yachtbuyer.com · devalk.nl
Other Ocean Alexander models
- Ocean Alexander 40 Double Cabin 1980–1989
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.