1987 Dehler 31 Manual

The 1987 Dehler 31 is a classic German-built sailing yacht known for its excellent performance, quality construction, and comfortable cruising capabilities. This 31-foot sloop features a balanced hull design, spacious cockpit, well-appointed interior, and reliable sailing systems. Below are key sections covering specifications, systems, operation, maintenance, and troubleshooting.

Specifications

Key dimensions and technical data for the Dehler 31.

Feature	Specification
Length Overall	9.45 meters (31 feet)
Length Waterline	8.20 meters
Beam	3.20 meters
Draft	1.65 meters (standard keel)
Displacement	4,200 kg
Ballast	1,700 kg
Sail Area	46.5 m²
Engine	Volvo Penta MD11C (18 hp)
Fuel Capacity	60 liters
Water Capacity	160 liters

Hull & Deck

Construction details and deck layout.

1. Hull Construction: Hand-laid GRP with balsa core for stiffness and insulation.
2. Deck Layout: Spacious cockpit with teak seating, wide side decks for safe movement.
3. Winches: Two self-tailing primary winches, one halyard winch on mast.
4. Hardware: Stainless steel stanchions, pulpits, and cleats.
5. Storage: Large cockpit lockers for fenders, lines, and safety gear.

WARNING! Always wear non-slip footwear when moving on deck. Check all deck fittings regularly for corrosion or wear.

Rigging & Sails

Mast, rigging, and sail handling procedures.

1. Mast: Deck-stepped aluminum mast with single spreaders.
2. Standing Rigging: 1x19 stainless steel wire with swage terminals.
3. Running Rigging: Main halyard, jib halyard, reefing lines, sheets.
4. Sails: Mainsail with two reef points, 110% genoa on furling system.
5. Furling System: ProFurl or similar roller furling for headsail.

CAUTION! Always release halyard tension when not sailing. Check for wear at sheaves and terminals regularly.

Interior Layout

Cabin arrangement and accommodation details.

• Saloon: U-shaped settee with folding table, seats 6-8 people comfortably.
• Galley: Two-burner stove, sink with manual pump, icebox storage.
• Navigation Station: Chart table with instrument panel and storage.
• Sleeping Accommodation: V-berth forward, two settee berths in saloon.
• Head: Marine toilet with holding tank, sink, and shower attachment.
• Storage: Multiple lockers and drawers throughout cabin.

Engine & Mechanical Systems

Power plant and mechanical components.

Volvo Penta MD11C: 18 hp diesel engine with fresh water cooling system.

Transmission: Hurth hydraulic gearbox with 2.5:1 reduction ratio.

Propeller: Two-blade fixed propeller (optional folding propeller available).

Steering: Wheel steering with emergency tiller provision. Engine Controls: Single-lever throttle/gear control at helm station. Fuel System: 60-liter aluminum tank with primary filter/water separator.

Electrical Systems

12V DC and optional 220V AC systems.

1. Batteries: Two 12V batteries (engine start and house bank).
2. Charging: Engine alternator with external regulator.
3. Distribution: Main DC panel with circuit breakers.
4. Navigation Lights: Port, starboard, stern, steaming, and anchor lights.
5. Instruments: Speed, depth, wind direction/speed (optional).

Tip: Turn off all electrical switches when leaving boat unattended.

Plumbing & Galley

Water systems and galley equipment operation.

1. Water Tanks: Two 80-liter polyethylene tanks under settees.
2. Water Pressure: Manual pumps at galley and head sinks.
3. Head System: Manual marine toilet with Y-valve for overboard/discharge.
4. Galley Stove: Two-burner alcohol or propane stove with safety solenoid.
5. Icebox: Insulated box under galley counter with drain pump.
6. Bilge Pumps: Manual pump in cockpit, electric pump with float switch.

WARNING! Always ensure proper ventilation when using stove. Never discharge waste in prohibited areas.

Safety Equipment

Required and recommended safety gear.

Lifejackets: Minimum 4 adult lifejackets with whistles and lights. Flares: Orange smoke and red parachute flares in waterproof container. Fire Extinguishers: Two dry chemical extinguishers (galley and cockpit). First Aid Kit: Comprehensive marine first aid kit. Throwable Device: Life ring or horseshoe buoy with light and drogue. EPIRB: Emergency Position Indicating Radio Beacon (recommended).

Maintenance Schedule

Regular maintenance tasks and intervals.

Weekly: Check engine oil and coolant levels, inspect bilges, test bilge pumps.

Monthly: Inspect standing rigging, check through-hull fittings, test navigation lights.

Annually: Haul out for antifouling, inspect hull for blisters, service seacocks.

Engine Service: Change oil and filters every 100 hours or annually.

Rigging Inspection: Professional rig inspection every 2-3 years.

CAUTION! Never ignore signs of corrosion or wear on critical components.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Flat battery/fuel issue	Check battery voltage; bleed fuel system; check fuel filters.
Poor sailing performance	Fouled hull/sails	Clean hull; inspect sails for wear; check rig tension.
Water in bilge	Leaking through-hulls	Inspect all fittings; check shaft seal; test seacocks.
Electrical failure	Corroded connections	Check battery terminals; inspect wiring; test circuit breakers.
Steering stiffness	Cable wear/misalignment	Lubricate steering system; check cable routing; inspect quadrant.

Emergency: Always carry VHF radio and know your position.

Service: Contact authorized Dehler dealer for technical support and parts.