Mainship 34 Pilot
Built 1998–2008 by Mainship
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About the Mainship 34 Pilot
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1998–2008
- Builder
- Mainship
- Length
- 36.08 ft
- Beam
- 12.25 ft
- Draft
- 3.25 ft
- Displacement
- 16,000 lb
- Hull / keel
- semi-displacement
- Propulsion
- inboard
- Fuel
- 250 gal
- Water
- 70 gal
- Bow thruster
- standard
Tank capacities — where the figures come from
-
Fuel 250 gal
“Fuel: US Gallons 250 / 946 L” — review (2005), canadianboating.ca · “270-gallon fuel tank” — review (2005), canadianboating.ca · “a 2003 MP-34 with a single 250 gallon tank” — search excerpt (2003), trawlerforum.comCanadian Boating's spec box says 250 US gal, matching our earlier figure, and the owner of a 2003 boat reports a single 250 gal tank; the review's text says 270, likely a slip. No builder document was found.
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Water 70 gal
“Water: US Gallons 70 / 265 L” — review (2005), canadianboating.caThe magazine agrees with our earlier figure.
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Holding unknown
“Holding: US Gallons 14 531 L” — review (2005), canadianboating.ca · “But 10 gallons is really” — search excerpt, trawlerforum.comThe magazine's spec box reads 14 US gal (its litre figure of 531 looks like a typo for 53, which is 14 gal); an owners' forum post about a Pilot 34 with a VacuFlush toilet mentions 10 gal. Our earlier 20 came from a spec database. No builder figure was 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
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Bow thruster standard
“while her single engine occasionally might raise an eyebrow among less experienced boat handlers, her standard bow thrus” — search excerpt, trawlerforum.comA magazine review reprinted under a Mainship Corporation header calls the bow thruster standard on the single-engine Pilot 34. Later twin-engine Pilots weren't checked.
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Stern thruster unknown
No source mentions a stern thruster.
-
Steering unknown
No builder, review or association source states the steering system; our earlier note mentions a tilt helm.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Sources disagree on holding tank — left blank rather than guessed.
Downeast-style enlargement of the 30 Pilot; express models first, Sedan with semi-enclosed hardtop from 2001. Hull length 34 ft (36.08 with pulpit). Standard bow thruster, tilt helm, transom door; engine reached via a cockpit-sole hatch. Single 350 hp Yanmar cruises 14 knots; twin 240s cruise 18.
Engines fitted
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Yanmar 350 hp diesel (model not named by source) — 350 hp, diesel, single
standard
HMY lists a single 350 hp Yanmar first (14 kn cruise, 16-18 top); model code not given.Sources: hmy.com
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Yanmar 6LYA-STP — 370 hp, diesel, single
standard
A 2007 34 Pilot lists a single 6LYA-STP 370 hp (15 kn cruise, 19 top); an owner on Trawler Forum also reports the 370 Yanmar.Sources: bigwaterboats.com · trawlerforum.com
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Yanmar 4LHA-STP — 240 hp, diesel, twin
factory option
HMY: twin 240 hp Yanmars cruise about 18 kn; an owner of an '05 Pilot reports twin 4LHA-STPs.Sources: hmy.com · trawlerforum.com
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Cummins 6BTA 5.9 — diesel, single
factory option
A one-owner 2001 34 Pilot was described on Trawler Forum as having a Cummins 6BTA; rating not given. Single report only.Sources: trawlerforum.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
“Next Gen 5.5 kW generator” — search excerpt (2006), trawlersite.com · “Twin Engine with hardtop, NextGen generator, hard windows, cockpit air” — search excerpt (2001), trawlerforum.com
Two Pilot 34s (2001 and 2006) had Next Generation generators; only the 2006 boat gives a size (5.5 kW), so no unit is listed. Canadian Yachting's 2005 test does not mention a generator.
Known problems for this model
No well-sourced problem reports found yet.
Engines & parts
Yanmar 6LY (6LY2, 6LY3, 6LYA-STP) parts: good
Factory standard engine — you entered “Yanmar 6LYA-STP”
Current Yanmar dealer support; cooler service is costly (one owner was quoted about $8,000 for a full cooler service).
Parts sources: Mack Boring & Parts (Yanmar distributor)
Common problems (2)
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Aftercooler, heat exchanger and oil cooler service cooling
Owners service the aftercooler, coolant heat exchanger and oil cooler about every three years in salt water; neglect shows as green corrosion at seams, corroded O-ring grooves and seized bolts, and can require a new cooler.trawlerforum.com
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Turbo oil leaks and lag exhaust
Turbos leaking oil into the intake and aftercooler, and slow turbo response with smoke, are recurring 6LYA complaints.downeastboatforum.com · justanswer.com
Maker’s service schedule (21)
| Engine oil & filter change 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Change the engine oil after the first 50 hours of operation and then at every 250 hours thereafter.” — manufacturer, nhmr.nl |
| Fuel filters & water separator 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “When the engine is operated on light diesel oil, replace the fuel filter element every 250 hours or one year of operatio” — manufacturer, nhmr.nl |
| Drain fuel filter and fuel/water separator 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 50 hrs or 1 mo | “Perform the following maintenance every 50 hours or one month of operation, whichever comes first. Drain Fuel Filter and” — manufacturer, nhmr.nl |
| Raw-water pump impeller 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 500 hrs or 2 yrs | “Perform the following maintenance every 500 hours or two years of operation, whichever comes first. Replace Seawater Pum” — manufacturer, nhmr.nl |
| Engine pencil zincs 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. ... Replace the Anode” — manufacturer, nhmr.nl |
| Coolant replacement & freeze-point test 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. ... Replace Engine Co” — manufacturer, nhmr.nl |
| Air filter / intake silencer 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. ... Clean the Air Int” — manufacturer, nhmr.nl |
| Exhaust mixing elbow inspection 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. ... Clean the Exhaust” — manufacturer, nhmr.nl |
| Turbocharger inspection 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. ... Clean the Turboch” — manufacturer, nhmr.nl |
| Valve clearance check / adjust 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 1,000 hrs or 4 yrs | “Perform the following maintenance every 1000 hours or four years of operation, whichever comes first. ... Adjust Intake” — manufacturer, nhmr.nl |
| Injector test / service 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 250 hrs or 1 yr | “Perform the following maintenance every 250 hours or one year of operation, whichever comes first. Check Fuel Injector S” — manufacturer, nhmr.nl |
| Drive belts inspect / replace 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 50 hrs or 1 mo | “Perform the following maintenance every 50 hours or one month of operation, whichever comes first. ... Adjust Alternator” — manufacturer, nhmr.nl |
| Replace flexible engine mounts 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 1,000 hrs or 4 yrs | “Be sure to replace the Yanmar flexible engine mounts every 1000 hours or 4 years, whichever comes first.” — manufacturer, nhmr.nl |
| Heat exchanger & oil cooler cleaning 6LY3-ETP / 6LY3-STP / 6LY3-UTP (6LY3 manual) | 2,000 hrs or 8 yrs | “Perform the following maintenance every 2000 hours or eight years of operation, whichever comes first. Overhaul and Chec” — manufacturer, nhmr.nl |
| Engine oil & filter change 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 250 hrs or 1 yr | “4.3.4 Inspection Every 250 Hrs.(or 1 yr.) ... Replace the engine lube oil every 250 hours. Replace the lube oil filter,” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Fuel filters & water separator 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 250 hrs or 1 yr | “4.3.4 Inspection Every 250 Hrs.(or 1 yr.)” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Engine pencil zincs 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 250 hrs or 1 yr | “4.3.4 Inspection Every 250 Hrs.(or 1 yr.)” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Turbocharger inspection 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 250 hrs or 1 yr | “4.3.4 Inspection Every 250 Hrs.(or 1 yr.)” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Drive belts inspect / replace 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 500 hrs or 2 yrs | “4.3.5 Inspection Every 500 Hrs. (or 2 yrs.) 1 Inspection of AIternator V-Belt Tension” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Raw-water pump impeller 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 2,000 hrs | “(Note) The impeller must be replaced periodically (every 2000 hours).” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
| Heat exchanger & oil cooler cleaning 6LYA-STP / 6LY2A-STP (older Yanmar Diesel Engine Co. manual) | 2,000 hrs | “4.3.7 Inspection Every 2000 Hrs. (1) Cleaning the Cooling Water System and Inspecting & Adjusting Parts” — manufacturer, s2b4aa72b8b1c7323.jimcontent.com |
Service part numbers (6)
| Oil filter | Yanmar 119593-35100-12 Replaces 119593-35100, 119593-35110 |
“119593-35100-12 Oil Filter” — dealer, oldportmarine.com · “It fits Yanmar 6LY-UTE, 6LY3-ETP, 6LYA-STE, 6LY2A engines. Cross Reference: 11959335110 119593-35110 119593-35100” — dealer, deltadieselparts.com |
| Fuel filter | Yanmar 41650-502330-12 Replaces 41650-502330 |
“41650-502330-12 Fuel Filter” — dealer, oldportmarine.com · “It fits Yanmar 6LY-UTE, 6LY2-STE, 6LY2A-STP, 6LY3-ETP, 6LY3-UTP, 6LYA-STP, 6LYA-STE, 6LY2A engines.” — dealer, deltadieselparts.com |
| Raw-water impeller | Yanmar 119574-42530 | “119574-42530 Impeller Box Kit” — dealer, oldportmarine.com · “compatible with engine models 6LY2-ST, 6LY2-WDT, 6LYA-STE, and 6LY2A-STP” — dealer, shop.marinedieselinc.com |
| Drive belt 6LY, 6LYA, 6LY2(A) |
Yanmar 119593-42280 | “119593-42280 Belt” — dealer, oldportmarine.com · “It fits Yanmar 6LY2A-STP, 6LY2A engines.” — dealer, deltadieselparts.com |
| Air filter | Yanmar 119593-18880 | “119593-18880 Air Element” — dealer, oldportmarine.com · “119593-18880 Air Filter Foam Element for Yanmar 6CX 4CX 6LY 6LP 6HY 6KY 6HYM” — dealer, jlmmarine.com |
| Zinc / anode all 6LY except 6LY3 |
Yanmar 119574-44150 × 4 | “119574-18790 (1) & 119574-44150 (4) Zincs” — dealer, oldportmarine.com · “Oil cooler and heat exchanger zinc anode for Yanmar 4LHA's, 6LP's and all 6LY's (except 6LY3)” — dealer, boatzincs.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 6BT / 6BTA 5.9 parts: good
Factory optional engine — you entered “Cummins 6BTA 5.9”
Mechanically injected 5.9 L inline six from the Cummins B-series truck/industrial family, so base-engine parts are everywhere. Cummins still sells factory ReCon (remanufactured) marine 6BT/6BTA engines (152–210 hp ratings) with a 2-year/2000-hour warranty. Seaboard Marine is the best-known marine specialist, selling aftercooler/heat-exchanger service kits, upgraded raw water pumps and technical guidance; TAD also sells Cummins packages.
Parts sources: Seaboard Marine, Cummins (ReCon 6BT/6BTA), Diesel Pro Power
Common problems (2)
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Aftercooler corrosion letting seawater into the intake cooling
On the turbo-aftercooled 6BTA the seawater-cooled aftercooler core has vertical tubes and an aluminum housing that corrodes from condensate; a leak can put salt water into the cylinders and wreck the engine. Owners pull, clean, grease and pressure-test the core every few years and fit new O-rings.trawlerforum.com · sbmar.com
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Heat exchanger and aftercooler service cooling
Routine seawater-side service (O-rings, gaskets, zincs) is a recurring owner job; kits are sold for it and refilling coolant without trapping air is a common question.sbmar.com · sbmar.com
Service part numbers (5)
| Oil filter | Cummins 3937743 | “| Oil Filter | 3937743 |” — dealer, marineenergy.com.au · “Cummins Oil Filter 3937743 Spin-on type, 3.66" outside diameter, 6.95" height” — dealer, dieselpro.com |
| Fuel filter 6BT 5.9 210 hp (CPL 742) |
Fleetguard FF5052 Replaces FF42000, FS1251 |
“on-engine fuel filter with drain for all 6BT 210 B’s (CPL 742). Replaces the FF42000, FS1251.” — dealer, sbmar.com · “Cummins 6BT Fuel Filter 3931063 FF5052” — dealer, marineenergy.com.au |
| Fuel filter late 6BTA (also late 4BTA and 6CTA) |
Fleetguard FF5285 | “Fleetguard FF5285 Fuel Filter – late 4BTA 6BTA and 6CTA’s” — dealer, sbmar.com · “Cummins 6BTA Fuel Filter 3890017 FF5285 ... suits late model Cummins 6BTA's, 6CTA8.3-M” — dealer, marineenergy.com.au |
| Raw-water impeller seawater pump with 1-1/4 in hose ports (Sherwood M70/M71 type, early 4BT/6BT) |
Sherwood 10615K | “Seawater Pump Impeller | **1-1/4" PORTS** 3908220 10615K” — dealer, marineenergy.com.au · “Cummins Marine Water Pump Impeller 10615K 2 9/16" diameter, 1 5/8" length” — dealer, dieselpro.com |
| Raw-water impeller keyway-shaft pump, 2 in inlet / 1-3/4 in outlet, 11° offset flange (e.g. P1716/P1730 on 6BTA) |
Sherwood 17000K | “**2" inlet & 1-3/4" outlet ports with 11° OFFSET flange** 17000K” — dealer, marineenergy.com.au · “Cummins Impeller for Key Shaft 17000K” — 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.
Model sources (4)
hmy.com · bigwaterboats.com · trawlerforum.com · canadianboating.ca
Other Mainship models
- Mainship 34 Diesel Cruiser (34 Trawler, 1978) 1978–1982
- Mainship 34 Trawler (2005) 2005–2009
- Mainship 350 / 390 Trawler ?–2005
- Mainship 400 / 414 Trawler 2003–2012
- Mainship 430 Trawler 1999–2006
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.