Mainship 400 / 414 Trawler
Built 2003–2012 by Mainship
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Looking at one? Sea-trial scorecard
About the Mainship 400 / 414 Trawler
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 2003–2012
- Builder
- Mainship
- Length
- 41.33 ft
- Beam
- 14.17 ft
- Draft
- 3.67 ft
- Displacement
- 24,000 lb
- Hull / keel
- semi-displacement
- Propulsion
- inboard
- Fuel
- 300 gal
- Water
- 130 gal
- Holding
- 47 gal
- Generator
- factory option
- Steering
- hydraulic
Tank capacities — where the figures come from
-
Fuel 300 gal
“Fuel capacity 300 gal twin alu[minum tanks]” — search excerpt (2003), yachtworld.com · “300 gallons of fuel capacity” — search excerpt (2003), boattrader.comListings agree with our earlier figure; no builder document was found.
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Water 130 gal
“130 gallons of water” — search excerpt (2003), boattrader.comOne listing agrees; there's no builder source.
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Holding 47 gal
“a 47-gallon holding tank” — search excerpt (2003), boattrader.comOne listing agrees; there's no builder source.
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Water heater unknown (Atwood)
“Water Heater Attwood (6 Gallon)” — search excerpt (2004), yachtr.com · “Atwood 6 gallon water heater” — search excerpt, curtisstokes.netTwo separate 400s for sale list a 6 gal Atwood heater; no builder or review figure was found, so the size rests on those listings.
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
“the 400's bow thruster — a standard feature with single-engine packages (optional with twin engines)” — review (2003), boats.comOne 2003 sea-trial review (reprinted by Denison Yacht Sales) says the bow thruster was standard with a single engine and optional with the twin 240 hp Yanmars; no builder list or second review was found. One owner report mentions a Side-Power bow thruster on a single boat.
-
Stern thruster unknown
“I am looking to install a stern thruster to my Mainship 400.” — search excerpt, trawlerforum.com · “A friend had a 2005 Mainship 400 with Sidepower bow and stern thrusters ... he installed the stern thruster well off to” — search excerpt (2005), trawlerforum.comOwners describe adding stern thrusters (one a Side-Power, set off the centreline for space). None appears in the builder's standard or option list as reported by the 2003 review.
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Steering hydraulic
“We found the 400 Trawler's Teleflex Sea Star steering to be quite responsive.” — review (2003), boats.comThe 2003 review's test boat had Teleflex SeaStar hydraulic steering; that review is the only source.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Stretched version of the 350/390 on the same hull (hull length 38.33 ft; 41.33 ft with pulpit). Called the 41 Expedition in 2009 and 414 Trawler 2010-12. Single Cat or Cummins cruises about 12 knots. Shares the 390's hull, so the 390 bustle and deck-core checks are worth doing (not confirmed for this model in the sources read).
Engines fitted
-
Caterpillar 3126 — 385 hp, diesel, single
standard
One of five factory single-diesel choices (Cat, Cummins or Yanmar, 315-385 hp); the review test boat had a 385 hp 3126.Sources: denisonyachtsales.com · hmy.com
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Yanmar 6LYA-STP — 370 hp, diesel, single
standard
Factory single-engine choice; several 400 owners report the single 370 hp Yanmar.Sources: trawlerforum.com · trawlerforum.com
-
Cummins single diesel (model not confirmed) — diesel, single
standard
HMY names a single Cummins as one of the choices; hp for the 400 specifically not confirmed (Mainship's single Cummins of the period was the 6BTA 370 per owners, but not tied to the 400 in the sources read).Sources: hmy.com · denisonyachtsales.com
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Yanmar 6LY2A-STP — 440 hp, diesel, single
factory option
One owner reports a single 440 hp Yanmar; owners note this model had valve problems.Sources: trawlerforum.com
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Yanmar 240 hp — 240 hp, diesel, twin
factory option
Twin-engine package offered for buyers who wanted two engines.Sources: denisonyachtsales.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
factory option
“Options Two-zone air conditioning; 8 kw Kohler auxiliary generator” — review (2003), boats.com · “The 8kW Kohler generator has a sound shield and is accessible from a hatch in the afterdeck” — review, yachtingmagazine.com
The 2003 boats.com sea trial lists the 8 kW Kohler under options; Yachting's test boat (with nearly every option) had it.
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Kohler — 8 kW
factory option
One owner on TrawlerForum calls the Kohler 8EOZ on a 2004 boat original; fuel isn't stated in the reviews.“8 kw Kohler auxiliary generator” — review (2003), boats.com · “The 8kW Kohler generator has a sound shield” — review, yachtingmagazine.com · “my original Kohler 8EOZ Generator has crapped out” — search excerpt (2004), trawlerforum.com
Generators are often replaced or added — check the unit's own plate before ordering parts.
Known problems for this model
No well-sourced problem reports found yet.
Engines & parts
Caterpillar 3126 / 3126B parts: good
Factory standard engine — you entered “Caterpillar 3126”
Electronically controlled HEUI engine that evolved into the C7 (around 2003); Cat dealers support it and released upgraded aftercoolers/cores. Aftercooler replacement is costly (owners cite thousands per engine).
Parts sources: Diesel Pro Power
Common problems (3)
-
Aftercooler leaking seawater into the engine cooling
Early 3126s had seawater-cooled aftercoolers that corroded from dissimilar metals and could leak salt water into the engine; Cat later offered upgraded aftercoolers, and surveyors check for this specifically.trawlerforum.com · samsmarine.com · clubsearay.com
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HEUI pump, hose and spool valve problems fuel
The high-pressure oil (HEUI) pump can fail, early 3126B high-pressure hoses were prone to failure (a steel-tube conversion exists), and sticky injector spool valves cause hard starting or rough running.trawlerforum.com
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Power loss and sooting engine
Owners troubleshoot engines that will not reach rated rpm and soot heavily at cruise, checking air filters, aftercooler condition, turbo and injectors.facebook.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 3126 / 3126B” — dealer, marisolmarine.com |
| Zinc / anode heat-exchanger anode |
Caterpillar 6L-2283 × 2 | “Replaces Caterpillar 6L2283, / 6L2282 (With the plug) Used on Caterpillar 3126, 3208 diesel marine engines. Qty 2 on Hea” — 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.
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)
-
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.
Model sources (6)
hmy.com · denisonyachtsales.com · trawlerforum.com · trawlerforum.com · boats.com · yachtingmagazine.com
Other Mainship models
- Mainship 34 Diesel Cruiser (34 Trawler, 1978) 1978–1982
- Mainship 34 Pilot 1998–2008
- Mainship 34 Trawler (2005) 2005–2009
- Mainship 350 / 390 Trawler ?–2005
- Mainship 430 Trawler 1999–2006
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.