Mermaid J-444NA55 Naturally Aspirated Workboat Diesel Engine

Description

High-grade monobloc cast iron construction anchors the Mermaid J-444NA55 Workboat Diesel Engine for severe continuous duty in canal punts and mooring tenders. This atmospheric 4.4L Inline-4 produces 55BHP continuous output at a low-stress 1,800 RPM. Tubular heat exchanger cooling requires regular inspection of raw water neoprene pump impellers to maintain uncompromised heat transfer in dirty waterways.

Premium monobloc cast iron forms the parent-bore cylinder block and 16-Valve cylinder head for structural endurance. The 12V electrical setup mounts a 3.0 kW electric starter and 95A marine alternator, with optional 24V isolated ground configurations. Unrigged dry weight totals 1,014 lbs. The chassis envelope spans 35.8in long by 26.4in wide and 32.3in high. The heavy-duty oil sump holds 3.70 US gal and internal coolant jackets contain 4.23 US gal.

Key Features of Mermaid J-444NA55 Workboat

Canal maintenance authorities buy Mermaid J-444NA55 Workboat engines to run municipal maintenance punts and push-tugs at low operational cost. The low 1,800 RPM continuous rating minimizes fuel burn and mechanical wear across non-stop harbor work shifts.

• A mechanical rotary injection pump supplies metered fuel without sensitive engine computers.
• The 16-Valve cast iron cylinder head provides superior thermal dissipation across continuous duty cycles.
• Tubular heat exchanger cooling circulates closed coolant through a copper-nickel tube bundle.
• An SAE 3 flywheel housing integrates with PRM 260, PRM 280, and ZF 25M transmissions.
• The deep-sump oil pan holds 3.70 US gal to permit 500-hour commercial service intervals.
• Low 1,800 RPM governor calibration reduces engine noise and extends internal bearing longevity.
• A 95A alternator maintains strong electrical reserves for hydraulic pump solenoids and searchlights.

Dynamometer Bench Testing Operating Tolerances

Continuous dynamometer testing certifies 55BHP continuous P1 output at 1,800 RPM and 74BHP intermittent power at 2,200 RPM. Shaft torque registers at 215 ft-lbs at 1,300 RPM to rotate large diameter displacement propellers. Closed cooling circuits stabilize coolant temperature between 175°F and 185°F under continuous 100 percent load. Engine lube oil pressure reads between 40 PSI and 60 PSI at operating speed. Crankshaft journal runout remains under 0.0004in TIR to protect babbit bearings during non-stop commercial service cycles.

Field Servicing Operating Hull Constraints

Heavy mechanical throttle levers require 6 lbs of actuation effort, providing positive tactile speed control. Naval architects must not specify this low-RPM 55BHP displacement diesel engine for planing sport craft, high-speed passenger launches, or vessels demanding high power-to-weight ratios above 20 knots.

• Drain and renew crankcase lube oil and spin-on filter every 500 operating hours or 12 months.
• Inspect raw water pump neoprene impellers and clean strainers every 250 operating hours.
• Check and adjust mechanical valve lash clearances every 1,000 operating hours across all valves.

Factory Warranty Manifest Breakdown

Mermaid Marine protects each workboat engine with a 1-Year or 2,000-Hour commercial warranty. The factory wooden shipping crate contains the J-444NA55 diesel engine core, SAE 3 flywheel housing, heat exchanger cooling package, 95A alternator, 3.0 kW starter, engine mounts, control panel harness, and complete workshop maintenance documentation manuals.