Seiko Prospex Diver's Watch 8L35/8L55 Instruction Manual

Introduction

Thank you for choosing a Seiko watch. For proper and safe use, please read these instructions carefully before using the watch. Keep this manual handy for easy reference.

Note on Length Adjustment: Service for metallic bands is available at the retailer where the watch was purchased. If you received the watch as a gift or moved, contact SEIKO CUSTOMER SERVICE CENTER. Service may be available at other retailers on a chargeable basis.

Note on Protective Film: If your watch has a protective film for scratch prevention, ensure it is removed before use. Using the watch with the film on can lead to dirt, sweat, or moisture accumulation, potentially causing rust.

Important Safety Information

WARNINGS

WARNING: Mishandling or misunderstanding displayed content may lead to fatal or serious accidents. Never carry out operations other than those specified in this manual while diving.

WARNING: This diver's watch is an auxiliary instrument for displaying time and does not ensure user safety. Use it alongside essential diving equipment like residual pressure gauges and water depth meters.

WARNING: Never use this watch for "saturation diving" using helium gas.

WARNING: Do not dive with this product unless you have proper scuba diving training, requisite experience, are thoroughly familiar with its operation and handling, and inspect all functions before each dive.

CAUTIONS

CAUTION: Please note the risk of minor injury or material damage if safety regulations are not strictly observed.

Before Diving: Inspect the following:

• Watch is operating normally.
• Sufficient battery level and mainspring winding.
• Rotating bezel turns smoothly (not too loose or too tight).
• Crown and other parts are securely tightened.
• No cracks or flaws on the band or glass.
• Band is reliably fixed (spring bars, buckle, etc.).

If any abnormality is found, do not use the watch for diving.

CAUTION: Do not operate the crown or buttons underwater. Water may get inside.

CAUTION: If the inner glass surface is clouded or water droplets appear for a prolonged period, the water-resistant performance is deteriorated. Contact SEIKO CUSTOMER SERVICE CENTER immediately.

CAUTION: Do not leave moisture, sweat, or dirt on the watch for extended periods. Water-resistant performance can decrease due to gasket deterioration or rust.

CAUTION: Do not wear the watch in a bath or sauna. Steam, soap, or hot springs can accelerate deterioration of water resistance.

CAUTION: Periodic overhauls (inspection and adjustment) are recommended every two to three years due to the impact of the diving environment on internal mechanisms.

Places to Avoid:

• Areas with volatile agents (polish remover, bug repellent, thinners).
• Temperatures below 5°C or above 35°C for extended periods.
• Areas with strong vibrations.
• Areas of high humidity.
• Areas with strong magnetism or static electricity.
• Dusty places.

Skin Irritation: If you experience allergic symptoms or skin irritation, stop wearing the watch and consult a specialist.

Other Cautions:

• Metallic band length adjustment requires expertise; contact a retailer. Attempting it yourself may cause injury or loss of parts.
• Do not disassemble or tamper with the watch.
• Keep out of reach of babies and children. Be cautious of injury or allergic reactions from contact.
• For fob or pendant types, be mindful of straps/chains damaging clothes or causing injury.

1. HOW TO USE

Precautions for diving (Please make sure to observe the following)

Before diving

Before diving, check the following:

• Time is correctly set.
• Wind the crown to ensure the watch does not stop in water. (Refer to "Screw down crown" P.16 and "How to wind the mainspring" P.17)
• The rotating bezel turns smoothly (not too loose or too tight). (Refer to "How to use the rotating bezel" P.23)
• The crown is completely screwed in. (Refer to "Screw down crown" P.16)
• No visible cracks or scratches on the crystal or watch band.
• The band is firmly attached (with spring bars, clamp, or other parts).

CAUTION: If any malfunctions occur, contact the retailer or SEIKO CUSTOMER SERVICE CENTER.

While diving

Please observe the following cautions for use:

• The watch can be used for air diving within the water-resistant range displayed on the dial.
• Do not operate the crown or buttons underwater.
• Take care not to bump the watch against hard objects like rocks.
• Bezel rotation may become slightly harder in water, but this is not a malfunction.

After diving

Please follow the care instructions below after diving:

• Rinse the watch in fresh water to remove seawater and wipe it thoroughly dry to prevent rust. Avoid direct faucet water; use a bowl of water to wash the watch.

CAUTION: Diver's watches can be affected by their usage environment. Periodic overhauls (inspection and adjustment) are recommended every 2 to 3 years.

Structure of the case

For certain models, the bezel or protective outer case is secured with setscrews. Never loosen these setscrews. Doing so may cause damage or further loosening.

(Diagram description: Illustration shows a watch case with setscrews securing the bezel or outer case.)

CAUTION: If setscrews appear loose or abnormal, consult the retailer or SEIKO CUSTOMER SERVICE CENTER.

Mechanical watch characteristics (Hand-wound, auto-wound)

• This is a mechanical watch powered by a spring.
• To start a stopped watch, wind the crown 20 turns by hand.
• Mechanical watch accuracy is measured daily, unlike quartz watches measured over months/years.
• Accuracy is affected by usage conditions: duration worn, temperature, arm movement, mainspring winding status. Error amounts are not constant.
• Strong magnetism can cause the watch to gain or lose time, and magnetize parts. Consult a retailer for demagnetization and repair.

Names of the parts and their functions

(Diagram description: A watch face is shown with numbered indicators pointing to different parts.)

1. Minute hand
2. Hour hand
3. Seconds hand
4. Date
5. Rotating bezel
6. Crown

Crown Positions:

• Normal position (not locked): For winding the watch (hand-wound).
• First click position: For date setting.
• Second click position: For time setting.

Screw down crown

The screw down crown locks securely to prevent operational errors and improve water resistance. Always unlock before operating and relock afterwards.

To unlock the crown: Turn the crown counterclockwise to unscrew it. The crown can now be operated.

To lock the crown: Turn the crown clockwise while gently pressing it towards the watch body until it stops.

(Diagram description: Shows unlocking the crown by unscrewing it, and locking it by turning clockwise while pressing.)

CAUTION: When locking, turn slowly and carefully to ensure proper engagement. Do not force it, as this may damage the screw hole.

How to wind the mainspring

• This is an automatic mechanical watch with manual winding.
• The mainspring is wound automatically by wrist movement when worn. It can also be wound by turning the crown.
• To start a stopped watch, wind the crown or swing it until the seconds hand moves. Set time/date before wearing. Turn the crown clockwise slowly to wind. Counterclockwise rotation does not wind. Full winding will not damage the spring.
• For watches with a screw down crown, unlock it before operating and relock afterwards.
• A fully wound watch operates for approximately 50 hours (8L35) or 55 hours (8L55).

Note: Insufficient winding may cause time gain/loss. Wear the watch for over 10 hours daily. If not worn, wind it fully every day at a fixed time.

Starting a stopped watch by winding may not be immediate due to initial low mainspring torque. Swinging the watch can help start the balance sooner.

How to set the time and date

The watch has a date function that changes every 24 hours, typically around midnight. Incorrect AM/PM setting can cause the date to change at noon.

CAUTION: Do not change the date when the watch displays between 8 PM and 2 AM, as this may cause problems with the date change.

1. Unlock the crown. (Refer to "Screw down crown" P.16)
2. Pull out the crown to the first click.
3. Set the date by turning the crown clockwise. Turn until the previous day's date appears (e.g., to set date "6", show "5").

(Diagram description: Shows pulling the crown to the first click.)

4. Pull out the crown to the second click and set the time. Stop the seconds hand at the 12 o'clock position by pulling the crown to the second click.
5. Turn the crown to advance the hands. Advance them past 12 o'clock until the date changes to the next day to set the AM period correctly. Then, set the exact time.
6. Push the crown back to the normal position according to a time signal. The seconds hand will start moving. (A telephone time signal service is useful for precise setting.)
7. Relock the crown. (Refer to "Screw down crown" P.16)

CAUTION: Mechanical watch mechanisms differ from quartz. When setting time, turn the minute hand slightly behind the desired time and then advance it to the exact time.

Date adjustment at the end of the month

Adjust the date at the end of February and 30-day months.

Example: If the watch shows "31" on the first day of a month following a 30-day month:

1. Pull out the crown to the first click.
2. Turn the crown clockwise to set the date to "1".
3. Push the crown back to the normal position.

(Diagram description: Shows pulling the crown to the first click for date adjustment.)

CAUTION:

• Return the screw down crown fully to its original position.
• Avoid amending the date between 8 PM and 2 AM to prevent damage.

How to use the rotating bezel

The rotating bezel can be used to measure elapsed time since the start of an event.

1. At the start of the event (e.g., starting a dive), rotate the bezel so that the mark on the bezel aligns with the minute hand.
2. Read the graduation on the rotating bezel that the minute hand is pointing to. This indicates the elapsed time.

(Diagram description: Shows aligning the bezel mark with the minute hand and reading the elapsed time on the bezel.)

Example: If the minute hand points to the "20" mark on the bezel after 20 minutes, 20 minutes have elapsed.

Note: The rotating bezel is designed for one-way rotation (counterclockwise only) to prevent accidental shortening of the displayed elapsed time.

CAUTION: Always check the correct remaining air in your cylinder before diving. Use the elapsed time display from the rotating bezel only as a guide.

2. TO PRESERVE THE QUALITY OF YOUR WATCH

Daily care

• Do not wash the watch with the crown extended.
• Wipe away moisture, sweat, or dirt with a soft cloth.
• After exposure to seawater, wash the watch in clean fresh water and dry it thoroughly to prevent rust. Avoid direct faucet water; use a bowl of water.
• Do not wash watches rated "Non-water resistant" or "water resistant for everyday life." (Refer to "Performance and type" P.26)

Turn the crown from time to time: Periodically turn the crown to prevent corrosion, including for screw-down crowns. (Refer to "Screw down crown" P.16)

Performance and type

The case back displays the watch's caliber and performance specifications.

(Diagram description: Shows a watch case back with labels for Water resistant performance, Magnetic resistant performance, and Case Number. The Case Number identifies the watch type.)

• Water resistant performance: Indicates the watch's water resistance rating.
• Case Number: Identifies the specific watch model.
• Magnetic resistant performance: Refer to P.28 and P.29 for details.

Lumibrite

Lumibrite is a luminous paint that absorbs light energy and emits it in the dark. It can glow for 3-5 hours after about 10 minutes of exposure to light above 500 lux. The luminance gradually decreases over time. The duration of emitted light may vary based on light source brightness and distance.

Human eyes take time to adapt to darkness after moving from a bright place (dark adaptation).

Lumibrite is harmless, containing no toxic materials.

Brightness Levels:

Magnetic resistant performance

Watches can temporarily gain/lose time or stop operating when affected by nearby magnetism. Diver's watches meet or exceed JIS Class 1 magnetic resistance standards.

DANGER:

• Keep the watch more than 5 cm away from magnetic products (JIS level-1 standard).
• Keep the watch more than 1 cm away from magnetic products (JIS level-2 standard).

If magnetism affects accuracy beyond specified rates, demagnetization (repair) is required. Charges apply even within the guarantee period.

Reason for Magnetism Effect: The balance spring can be influenced by strong external magnetic fields.

(Diagram description: Lists common magnetic products like smartphones, AC adapters, magnetic necklaces, etc., that can affect watches.)

Band

The band contacts skin and can accumulate sweat and dust, leading to deterioration or skin irritation. Regular care is needed for long-term use.

Metallic band

• Moisture, sweat, or soil can cause rust on stainless steel bands if left untreated.
• Lack of care can cause rashes or stains on shirt sleeves.
• Wipe off moisture, sweat, and soil promptly with a soft cloth.
• Clean soil from band joints with water and a soft toothbrush (protect the watch body with plastic wrap).
• Titanium bands with stainless steel pins may rust. Rust can cause pins to poke out, the case to detach, or the clasp to fail. If a pin protrudes, seek repair immediately.

Polyurethane band

• Susceptible to discoloration from light, solvents, or humidity.
• Translucent or light-colored bands can absorb colors, leading to smears or discoloration.
• Wash dirt with water and dry with a cloth (protect watch body from splashes).
• If the band becomes less flexible, replace it. Continued use can lead to cracks or brittleness.

Silicone band

• Easily dirtied, stained, and discolored. Wipe with a damp cloth or cleaning tissue.
• Unlike other materials, cracks can cause the band to break. Avoid damaging with sharp tools.

Notes on skin irritation and allergy: Skin irritation can result from metal/leather allergies or friction from dust/band.

Notes on band length: Adjust the band for proper airflow, allowing enough space to insert a finger between the band and your wrist.

How to use the diver adjuster

The diver adjuster on metallic bands allows easy length adjustment, useful for wearing over wetsuits or winter clothing.

1. Lift the flap approximately 90° until upright, then press it down further about 20° and hold lightly. (Do not force the flap; it requires light pressure.)
2. Lightly pull the band on the 6 o'clock side to pull out the slider. (The slider extends about 30 mm; do not pull beyond this limit.)
3. While pressing the push button, lift the clasp to release the buckle and place the watch on your wrist.
4. Close the clasp first (4-1), then the flap (4-2).
5. Hold both sides of the band to adjust the slider length for a snug fit.

(Diagram description: Illustrates lifting the flap, pressing it down, pulling the band to extend the slider, and securing the clasp.)

How to use the diver extender

The diver extender on metallic bands allows easy length adjustment, useful for wearing over wetsuits or winter clothing.

1. Lift the flap.
2. While pressing the push button, open the clasp. Push the flap back to its normal position for safety.
3. Open the two-piece foldover portion of the Diver Extender in the direction of the arrow. It clicks when opened.
4. Slide the upper cover of the Diver Extender in the direction of the arrow and pull up to extend the two-piece foldover portion fully.
5. Place the watch on your wrist, close the clasp (5-1) first, then the flap (5-2).

To fold the Diver Extender, reverse the steps. The two-piece foldover portion clicks when fully folded.

After sales service

Notes on guarantee and repair

• Contact the retailer or SEIKO CUSTOMER SERVICE CENTER for repair or overhaul.
• Present the guarantee certificate for services within the guarantee period.
• Guarantee coverage is detailed in the guarantee certificate; read and retain it.
• For repairs after the guarantee period, services are available upon request and payment if functions can be restored.

Replacement with functional parts

Original parts may be replaced with substitutes whose appearance might differ if original parts are unavailable.

Inspection and adjustment by disassembly and cleaning (Overhaul)

Periodic inspection and adjustment (overhaul) every 2-3 years is recommended for optimal performance.

The watch's movement requires regular maintenance: washing parts, changing oil, adjusting accuracy, checking functions, and replacing parts. The first overhaul is crucial for long-term use.

Usage conditions can affect oil retention, cause wear, or lead to time inaccuracies or stoppage.

Deterioration of parts like gaskets can impair water resistance due to perspiration and moisture intrusion.

Overhaul should be performed by a retailer specifying "SEIKO GENUINE PARTS." Request gasket and spring bar replacement at this time.

The watch movement itself may be replaced during an overhaul.

CAUTION: The environment where a diver's watch is used can affect its internal parts. Periodic overhauls every 2-3 years are recommended.

Accuracy of mechanical watches

Accuracy is indicated by the "daily rate."

Mechanical watch accuracy can vary due to usage conditions: duration worn, arm movement, mainspring winding status, and watch position. These factors influence loss/gain, which is measured over about a week, not just daily.

Accuracy variation according to temperature: Metal parts expand/contract with temperature, affecting accuracy. Watches tend to lose time at high temperatures and gain time at low temperatures.

Mainspring wound condition and accuracy

Regularly supplying energy to the balance wheel is key for accuracy. The mainspring's driving force varies. Steady accuracy is achieved by frequent wear (self-winding) or daily winding (manual).

Effect of magnetism

Strong magnetism can cause time gain/loss or magnetization of parts. Consult a retailer for demagnetization and repair.

Troubleshooting

For other issues, contact the retailer.

Specifications

Note: Accuracy is factory-adjusted. Actual daily rates may vary based on usage conditions (wear duration, temperature, arm movement, winding status).