Uniflite 42 Double Cabin
Built 1971–1984 by Uniflite Inc. (Bellingham, WA)
Own one? Keep her maintenance, manuals and checklists here — free for a week
Shopping? Find the right used boat
Looking at one? Sea-trial scorecard
About the Uniflite 42 Double Cabin
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1971–1984
- Builder
- Uniflite Inc. (Bellingham, WA)
- Length
- 42 ft
- Beam
- 14.75 ft
- Draft
- 3.75 ft
- Displacement
- 35,000 lb
- Hull / keel
- planing
- Propulsion
- inboard
- Fuel
- varies by year
- Water
- 160 gal
- Bow thruster
- not fitted
- Stern thruster
- not fitted
- Steering
- hydraulic
Tank capacities — where the figures come from
-
Fuel varies by year
“the fuel capacity was increased in 1977 to 500 gallons” — search excerpt (1977-1984), hmy.com · “1,514 litres” — search excerpt (1974), dailyboats.comThe HMY powerboat guide (source of our earlier figure) says fuel went up to 500 gal in 1977, so 1971-76 boats carry less; a listing site gives 1,514 L (about 400 gal) for a 1974 boat. A forum post cites a Uniflite factory manual giving 350 gal in three tanks, without naming the model. No builder document could be checked.
-
Water 160 gal
No source found.
-
Water heater unknown (Raritan)
“Raritan 12 Gallon Water Heater” — broker listing (1973), denisonyachtsales.com · “Water heater” — broker listing (1984), boatsdata.comOnly listings: a 1973 boat (much upgraded) with a Raritan 12 gal heater and a 1984 boat with a heater of unstated size. No builder document found.
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
“42 Double Cabin Sedan specification brochure: Standard Equipment and Optional Equipment price lists - no thruster” — brochure (c1981), boatbrochure.comFrom the builder's specification brochure for the 42 Double Cabin Sedan (the lower-helm version of the same hull); standard and option lists carry no thruster. The 1977 42 Double Cabin brochure's spec page has no equipment list.
-
Stern thruster not fitted
“Standard and optional equipment lists - no thruster” — brochure (c1981), boatbrochure.com
-
Steering hydraulic
“STANDARD EQUIPMENT ... Steering, hydraulic” — brochure (c1981), boatbrochure.comHydraulic steering is standard in the builder's 42 Double Cabin Sedan specification brochure (twin Detroit Diesel 6-71 engines standard) and is assumed to apply to the 42 Double Cabin as well. Earlier 1970s boats weren't checked, and no maker is named.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Early raised full-width aft-deck motor yacht. Fuel 400 gal until 1977, 500 after. Post-1978 boats have a stall shower forward. Molds later built as the Chris-Craft 425/426/427 Catalina. Sturdy build and comfortable ride per HMY.
Engines fitted
-
Detroit Diesel 6-71N (J&T marinized) — 310 hp, diesel, twin
standard
HMY's reference power (about 18 knots cruise, 20-21 top). Owners of a 1977 boat report twin naturally aspirated J&T 6-71Ns; 6-71TI versions also appear.Sources: hmy.com · trawlerforum.com · groups.google.com
- Detroit Diesel 6-71 — 310 hp, diesel standard
-
Cummins V903 — diesel, twin
factory option
An owner reports Cummins 903 V8s in his 1974 42; hp not stated.Sources: groups.google.com
-
Caterpillar 3208 — diesel, twin
factory option
Named by an owner as one of the diesels found in these boats; hp not stated.Sources: groups.google.com
-
Chrysler 440 gas V8 — gas, twin
factory option
Some boats were built with gas engines; owners call them overstressed in a boat this heavy.Sources: groups.google.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
Listings show different sets: a Westerbeke 5.5 kW in a sound shield (1973 double cabin) and a generator of unstated make on a 1984 aft cabin; a 1977 42 Convertible (a different model) has an Onan 5 kW. No builder or review source found.
Known problems for this model
-
Fire-retardant-resin blisters hull
Post-1975 Uniflite hulls are associated with blistering from the replacement fire-retardant resin; a moisture survey is advised.nautipedia.it
Engines & parts
Detroit Diesel 6-71 (inline, N / T / TI) parts: good
Factory standard engine — you entered “Detroit Diesel 6-71N (J&T marinized)”
Two-stroke 71-series engine with a huge commercial, bus and marine population; basic engine parts and complete overhaul kits (liners, pistons, injectors, blowers, bearings, gaskets) are cheap and widely available from Diesel Pro Power, Highway and Heavy Parts and others. Some marine-specific parts (coolers, manifolds) are harder to find. Designed to be rebuilt in-frame repeatedly; naturally aspirated engines with good care have been reported past 15,000 hours, turbo versions more like 3,000–5,000.
Parts sources: Diesel Pro Power (Detroit Diesel parts), Highway and Heavy Parts (Series 71)
Common problems (2)
-
Oil leaks engine
Owners describe 71-series Detroits as habitual oil leakers; chasing leaks with the right gaskets and sealants is a routine topic even on freshly rebuilt engines.trawlerforum.com · cruisersforum.com
-
Noise and smoke exhaust
Injector and exhaust noise is loud unless mufflers are well designed, and some smoke is typical of the two-stroke design.trawlerforum.com
Maker’s service schedule (18)
| Engine oil & filter change | 150 hrs | “Industrial & Marine 150 Hours (max. engine oil change interval, fuel sulfur 0 to .50%)” — manufacturer, archive.org |
| Fuel filters & water separator | 300 hrs | “Install new elements every 300 hours or when plugging is indicated (Item 13 fuel strainer and filter)” — manufacturer, archive.org |
| Coolant replacement & freeze-point test | 1,000 hrs | “Clean the cooling system every 1,000 hours using a good radiator cleaning compound” — manufacturer, archive.org |
| Engine pencil zincs | 500 hrs | “Every 500 hours ... remove the zinc electrodes from the inlet side of the raw water pump and the heat exchanger” — manufacturer, archive.org |
| Heat exchanger & oil cooler cleaning | 1,000 hrs | “remove the retaining cover every 1,000 hours and inspect the heat exchanger core” — manufacturer, archive.org |
| Drive belts inspect / replace | 200 hrs | “check the tension of the drive belts every 200 hours” — manufacturer, archive.org |
| Air filter / intake silencer dry-type air cleaner | 1 yr | “Dry type elements should be discarded and replaced with new elements after one year of service or when the maximum allow” — manufacturer, archive.org |
| Transmission fluid change Allison Torqmatic M / MH marine gear | 200 hrs | “Drain the oil every 200 hours and flush the gear with light engine oil (Item 41 Torqmatic marine gear)” — manufacturer, archive.org |
| Clean crankcase breather | 1,000 hrs | “Remove the externally mounted crankcase breather assembly every 1,000 hours and wash the steel mesh pad” — manufacturer, archive.org |
| Inspect blower screen | 1,000 hrs | “Inspect the blower screen and gasket assembly every 1,000 hours” — manufacturer, archive.org |
| Check / clean air box drain tubes | 1,000 hrs | “check for flow of air from the air box drain tubes every 1,000 hours” — manufacturer, archive.org |
| Check thermostats and seals | 5,000 hrs or 1 yr | “Check the thermostats and seals at 5,000 hours or once a year” — manufacturer, archive.org |
| Inspect all hoses | 500 hrs or 1 yr | “all hoses should be thoroughly inspected at least every 500 operating hours ... and/or annually” — manufacturer, archive.org |
| Drain water/sediment from fuel tank | 500 hrs | “Open the drain at the bottom of the fuel tank every 500 hours to drain off any water and/or sediment” — manufacturer, archive.org |
| Coolant filter/conditioner element (if fitted) | 500 hrs | “the filter element should be changed every 500” — manufacturer, archive.org |
| Check emergency (air) shutdown | 700 hrs | “check the operation of the emergency shutdown every 700 hours” — manufacturer, archive.org |
| Check engine and transmission mounts | 2,000 hrs | “Check the engine and transmission mounting bolts and the condition of the mounting pads every 2,000 hours” — manufacturer, archive.org |
| Replace fresh-water pump seal | 6,000 hrs | “Replace the water pump seal after it has been in service for 6,000 hours” — manufacturer, archive.org |
Service part numbers (7)
| Raw-water impeller Detroit raw-water pump with 2 1/2 in. impeller (pumps 5115396 / 23507971) |
Detroit Diesel 5193602 | “Impeller for Detroit Diesel and Volvo Penta Marine Water Pumps 5193602 Impeller with 10 Blades and 12 Spline Drive” — dealer, dieselpro.com · “Detroit Diesel Series 71 Raw Water Pump Impeller, New (5193602)” — dealer, highwayandheavyparts.com |
| Raw-water pump kit pumps 5115396 / 23507971 (2 1/2 in. impeller) |
Detroit Diesel 5197224 | “Detroit Diesel Marine Water Pump repair kit 6V53, 6V71, 6-71, 6V92 5197224P For 2 1/2" impeller height” — dealer, dieselpro.com · “A-5197224 1 1 1 Reconditioning Kit ... Pumps #5115396,#23507971” — dealer, interstate-mcbee.com |
| Raw-water pump kit pumps 5122599 / 23507972 (3 1/2 in. impeller) |
Detroit Diesel 5197222 | “Detroit Diesel Marine Water Pump repair kit for 6-71, 8V71, 8V53, 12V71, 6V92, 8V92 5197222” — dealer, dieselpro.com · “A-5197222 1 1 1 Reconditioning Kit Pumps #5122599,#23507972” — dealer, interstate-mcbee.com |
| Zinc / anode electrode assembly, 2 1/8 in., at raw-water pump inlet |
Detroit Diesel 8517479 | “A-8517479 1 1 1 Electrode Assembly - 2 1/8" L At pump inlet” — dealer, interstate-mcbee.com · “Detroit Diesel Electrode, 2.125" Long (8517479) - In-Line 71 Series Heat Exchangers” — dealer, powerlinecomponents.com |
| Zinc / anode electrode assembly, 3 3/8 in., in heat exchanger |
Detroit Diesel 8515850 | “A-8515850 1 1 1 Electrode Assembly - 3 3/8" L In exchanger” — dealer, interstate-mcbee.com · “Detroit Diesel Zinc Electrode, 3.375" Long (8515850) - In-Line 71 Series Heat Exchangers” — dealer, powerlinecomponents.com |
| Thermostat 173 F non-blocking type |
Detroit Diesel 5172141 | “57 5.2050 5172141 Thermostat Assy.” — manufacturer, tractorparts.com · “Detroit Diesel Thermostat for 371, 471, 671 5172141” — dealer, dieselpro.com |
| Thermostat 170 F full-blocking type (needs seal 5132155) |
Detroit Diesel 23503826 | “A-23503826 1 1 Thermostat 170° F Full blocking use seal” — dealer, interstate-mcbee.com · “Detroit Diesel Thermostat, 170 Deg. (23503826)” — dealer, powerlinecomponents.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.
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
-
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.
Model sources (7)
hmy.com · nautipedia.it · trawlerforum.com · groups.google.com · denisonyachtsales.com · boatsdata.com · boatbrochure.com
Own a Uniflite 42 Double Cabin? Add her to your boats, then share a photo — names, numbers and faces are blurred before it appears.
Other Uniflite models
- Uniflite 28 Mega 1977–1984
- Uniflite 34 Sport Sedan / Tournament Fisherman 1974–1984
- Uniflite 36 Double Cabin 1972–1984
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.