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Bayliner 3870 / 3888 Motor Yacht

Built 1983–1994 by Bayliner Marine

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About the Bayliner 3870 / 3888 Motor Yacht

Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.

Illustration of a Bayliner 3870 / 3888 Motor Yacht
Illustration, not a photo of this model. AI-generated illustration of a typical flybridge motor yacht.
Built
1983–1994
Builder
Bayliner Marine
Length
38.17 ft
Beam
13.42 ft
Draft
3.17 ft
Displacement
17,500 lb
Hull / keel
planing
Propulsion
inboard
Fuel
304 gal
Water
80 gal
Generator
fitted on some boats
Bow thruster
often added later
Stern thruster
often added later
Steering
hydraulic · Hynautic
Tank capacities — where the figures come from
  • Fuel 304 gal
    “304 gallons of fuel capacity” — search excerpt (1991), boattrader.com · “fuel cap. 304 gallons” — search excerpt (1989), boatexportusa.com · “150 gallons of fuel” — search excerpt (1994), boattrader.com
    Two listings agree with 304 gal; one 1994 listing says 150, possibly counting one tank only or describing an altered boat. No builder document could be checked.
  • Water 80 gal
    “80 gal water tank” — search excerpt (1989), boatexportusa.com · “80 gallons of water” — search excerpt (1994), boattrader.com · “303 liters (80 US gallons)” — search excerpt, yachtdatabase.com · “90 gallons of water capacity” — search excerpt (1991), boattrader.com
    Most non-builder sources agree with 80 gal; one listing says 90.
  • Holding unknown
    “40-gallon holding tank” — search excerpt (1991), boattrader.com · “holding tank 30 gallons” — search excerpt (1989), boatexportusa.com · “35-gallon holding tank” — search excerpt (1994), boattrader.com · “102 liters (26 US gallons) waste water capacity” — search excerpt, yachtdatabase.com
    Our earlier figure of 40 gal rested on the HMY powerboat guide. Listings give 30, 35 and 40 gal and a spec database 102 L; no builder document was checked. Some boats may carry separate tanks for two heads.
  • Water heater unknown
    No builder document, review or owners' source was found giving the heater size or whether it was standard.

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 often added later
    “Equipped with a New autopilot, Starlink, bow and stern thrusters, AIS, radar, and hydronic heat.” — search excerpt (1987), yachtworld.com · “Maneuvering is made easy with the powerful Side Power SP55S1-12-IP bow thruster and SE80/185T stern thruster.” — search excerpt (1985), breezewayyachts.com · “1987 Bayliner 3870 with Hino EH700 Diesels (175 hp x 2 @ 1750 hours.) Bow Thruster.” — search excerpt (1987), craigslist.org · “A standout feature of this vessel is the addition of both bow and stern thrusters” — search excerpt, curtisstokes.net
    No builder list of standard or optional equipment was found. Several separate 3870 listings show bow thrusters, one described as an addition and one a Side-Power SP55 of a model still made today, so they're treated as added later. The make appears on one listing only.
  • Stern thruster often added later
    “Equipped with a New autopilot, Starlink, bow and stern thrusters, AIS, radar, and hydronic heat.” — search excerpt (1987), yachtworld.com · “Side Power SP55S1-12-IP bow thruster and SE80/185T stern thruster.” — search excerpt (1985), breezewayyachts.com · “A standout feature of this vessel is the addition of both bow and stern thrusters” — search excerpt, curtisstokes.net
    Our earlier figure of none had no source. At least three separate 3870s for sale carry an added stern thruster, and nothing shows one as factory equipment.
  • Steering hydraulic · Hynautic
    “The 3888s have a Hynautic steering system with two helm pumps and a pressurized reservoir mounted to the transom.” — owners' association, tapatalk.com
    This comes from a Bayliner Owners' Club forum reply, not a builder document; it describes two helm pumps and a pressurized reservoir mounted on the transom. No builder brochure or manual was found for this model.

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.

Named 3870 through 1989, 3888 afterwards. Mid-cabin layout with berth under the salon sole, two heads, standard lower helm. About 1 nmpg at cruise per HMY/BoatUS. HMY's text calls the early name '3780', which appears to be a typo for 3870. A gas (Ford 351) version is discussed by owners but not documented in the specs read. Build count (approximate, not stored): HMY says about a thousand were built; BoatUS notes say over 1,000.

Engines fitted

Boats of the same model can differ — check which engines yours actually has before ordering parts.

Generator

“Does anyone know the model of the standard generator on a 1985 3870? Mine has a Westerbeke.” — owners' association (1985), tapatalk.com

Owners and listings report Westerbeke diesels: 8.0 kW (8BTD / WMD 8.0) on several 1986-1990 boats, a WMD 7.7 on one 3870, and a new replacement 5 kW on a 1990 listing. No Bayliner option list was found, so standard vs. factory option isn't confirmed; an Owners Club thread calls it standard, but that is one owner's assumption.

Generators are often replaced or added — check the unit's own plate before ordering parts.

Known problems for this model

Engines & parts

Hino (US Marine) W04D / W04C-T / W06 / EH700 parts: limited

Factory standard engine — you entered “Hino EH700 (sold as U.S. Marine)”

Sold under the US Marine name in many Bayliners. Marine Parts Supply (Canada) is the official North American distributor of Hino marine parts and imports directly from Hino Japan; North Harbor Diesel is a US source. Owners report parts are still available but some have become harder to find and pricier. W04D (about 110 hp) is considered underpowered for planing; W04C-T (135–150 hp) planes.

Parts sources: Marine Parts Supply (Hino/US Marine), Fab Heavy Parts (Hino EH700)

Common problems (2)
  • Parts availability and cost other
    The most common Hino question is whether parts are still obtainable and affordable; the distributor says most EH700 parts are stocked, while some owners report rising cost and harder-to-find items.
    marineengine.com · baylinerownersclub.org · trawlerforum.com
  • Fuel supply problems fuel
    Owners of older twin-Hino Bayliners list fuel supply issues as a top problem and recommend surveys with oil analysis.
    facebook.com
Service part numbers (12)
Oil filter
W04C-T / W04CTI / W06DTI (spin-on, oil filter base 156003490)
Mercury (US Marine) 803899T
Replaces 836071630
“19 Mercury Marine 836071630 FILTER803899T Required: 1 ... FILTER, OIL - SPIN-ON ... Replaces 836071630” — manufacturer, crowleymarine.com
Fuel filter
W04CTA (150 hp)
Mercury (US Marine) 834011133
Replaces 834011132
“5 Mercury Marine Fuel Filter834011133 Required: 1 ... FILTER, FUEL ... Replaces 834011132” — manufacturer, crowleymarine.com
Fuel filter
W06DTI (250 hp), spin-on
Mercury (US Marine) 834011341
“4 Mercury Marine Spin On Fuel Filter834011341 Required: 1 ... FILTER, FUEL - SPIN-ON” — manufacturer, crowleymarine.com
Raw-water impeller
W04CTI (210 hp) and W06DTI (250 hp) raw-water pump 831003011
Mercury (US Marine) 807184
Replaces 831311510
“NS Mercury Marine Water Pump Impeller807184 Required: 1 ... IMPELLER, PUMP ... Replaces 831311510” — manufacturer, crowleymarine.com
Raw-water impeller
W04CTA (150 hp) raw-water pump 807121T; cam and impeller kit
Mercury (US Marine) 807189A1
Replaces FI8090176
“NS Mercury Marine CAM/IMPELLER KIT807189A1 Required: 1 ... IMPELLER ... Replaces FI8090176” — manufacturer, crowleymarine.com
Raw-water impeller
EH700N / EH700TI raw-water pump 831002481
Mercury (US Marine) 809866T
Replaces 831311350
“14 Mercury Marine Water Pump Impeller809866T Required: 1 ... IMPELLER ... Replaces 831311350” — manufacturer, crowleymarine.com
Drive belt
EH700N / EH700TI raw-water pump drive (set of 2 V-belts)
Mercury (US Marine) 830149104
“33 Mercury Marine V BELT SET (2 Belts)830149104 Required: 1 ... V-BELT, RAW WATER PUMP DRIVE” — manufacturer, crowleymarine.com
Thermostat
W04CTA, W04CTI, W06DTI
Mercury (US Marine) 830146177
“12 Mercury Marine Thermostat830146177 Required: 1 ... THERMOSTAT” — manufacturer, crowleymarine.com
Thermostat
EH700N / EH700TI
Mercury (US Marine) 830146187
“53 Mercury Marine Thermostat830146187 Required: 1 ... THERMOSTAT” — manufacturer, crowleymarine.com
Air filter
W04CTI (210 hp) air cleaner 177203360
Mercury (US Marine) 838013340
Replaces 838012450
“2 Mercury Marine 178013340 ELEMENT838013340 Required: 1 ... ELEMENT ... Replaces 838012450” — manufacturer, crowleymarine.com
Air filter
W06DTI (250 hp) air cleaner 177204320
Mercury (US Marine) 838012660 × 2
“2 Mercury Marine Air cleaner element838012660 Required: 2 ... ELEMENT, AIR CLEANER” — manufacturer, crowleymarine.com
Air filter
EH700N / EH700TI air cleaner-silencer (sock element)
Mercury (US Marine) 838013290
Replaces 838012130
“5 Mercury Marine 178013290 ELEMENT838013290 Required: 1 ... SOCK, CLEANER ... Replaces 838012130” — manufacturer, crowleymarine.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.

Steering

Hynautic — K-series pressurized hydraulic steering (H-series helms, K-series cylinders) parts: obsolete

SeaStar bought Hynautic and kept making components and rebuild kits for years; after Dometic bought SeaStar, Hynautic pages and parts were removed from Dometic's site. Helms H-21 through H-52 and cylinders K-6 through K-31 are discontinued. Seatech Marine Products publishes SeaStar direct-replacement equivalents (e.g., H-50/H-52 replacement kits usable in the pressurized system with a non-vented fill plug) and offers rebuild services; independent hydraulic shops rebuild helms and cylinders for roughly $250–350 each. Kobelt/Accu-Steer also supply steering and power-assist equipment used on larger boats.

Parts sources: Seatech Marine Products (Hynautic alternatives & rebuilds), Kobelt (marine steering systems)

Common problems (3)
  • Helm pump shaft seal leaks steering
    The upper helm shaft seal deteriorates from sun, salt and dirt and weeps oil; raising system pressure is only a stopgap, and the helm must be removed and resealed.
    samsmarine.com · trawlerforum.com · youtube.com
  • Cylinder rod seal leaks steering
    Damaged wiper/rod seals let fluid out the end of K-6 type cylinders.
    facebook.com
  • Olive-type tubing fittings leak steering
    Some owners dislike Hynautic's olive compression fittings on plastic tubing because they are prone to leaks.
    trawlerforum.com
Model sources (7)

hmy.com · trawlerforum.com · baylinerownersclub.org · baylinerownersclub.org · baylinerownersclub.org · tapatalk.com · tapatalk.com

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Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.