SEIKO 8L35/8L55 Diving Watch Instruction Manual

General Precautions

The service for adjusting the length of metal bracelets is offered by the retail store where the watch was purchased. If you cannot return your watch to the retail store where it was purchased, for example, if you received it as a gift or have moved, please contact the SEIKO CUSTOMER SERVICE CENTER. This service may also be available at other retail stores for a fee, but not all stores offer this service.

If a protective film is attached to the watch to prevent scratches, be sure to remove it before use. If the film is left on the watch, dirt, sweat, dust, or moisture may get under it, which can lead to rust.

CAUTION: Be sure to read the following instructions before use and strictly follow them.

CAUTION: During dives, never perform any operations other than those specified in this instruction. Improper handling of the product and misinterpretation of displayed information may lead to death or serious injury.

CAUTION: Diving watches are auxiliary instruments, primarily for time indication, not for user safety. Use these watches in conjunction with equipment (depth gauge, submersible pressure gauge, etc.) necessary for safe diving.

CAUTION: These watches are suitable for scuba diving. For scuba diving, you must have the necessary skills and experience; be sure to familiarize yourself with all rules for operating and handling the watch; check the watch before each dive. Until these conditions are met, do not perform scuba dives using these watches.

Usage Procedure

WARNING: Be sure to read the following instructions before use and strictly follow them.

WARNING: Before Diving, check the following:

• The watch is functioning normally.
• The battery has sufficient charge, and the mainspring is sufficiently wound.
• The rotating bezel turns smoothly. (The bezel should not be too loose or too tight.)
• The crown and other parts are securely tightened.
• There are no defects, such as gaps or cracks, on the bracelet or crystal.
• The bracelet is securely fastened (with spring bars, clasp, or other parts).

If any deviation is found in any of the above points, do not use these watches for diving.

WARNING: Do not operate the crown or buttons underwater.

WARNING: As diving conditions can affect not only the case and bracelet but also the internal mechanism of the watch, it is recommended to have the watch serviced for inspection and adjustment approximately every two to three years.

Table of Contents

CAUTION: The following safety rules must be strictly observed. Failure to do so may result in serious consequences, including the risk of severe injury.

Stop wearing these watches immediately in the following cases:

• If rust, etc., appears on the watch case or bracelet.
• If the pins holding the bracelet links protrude.

Consult your retail store where the watch was purchased or contact the SEIKO CUSTOMER SERVICE CENTER immediately.

Keep watches and accessories out of reach of children. Ensure that a child does not accidentally swallow any part of the watch. Seek medical attention immediately if a child swallows a battery or watch part, as it may be harmful to their health.

WARNING: The following safety rules must be strictly observed. Failure to do so may result in minor injuries or damage to the watch.

Avoid wearing and storing watches in the following locations:

• Places where volatile substances evaporate (cosmetics, such as nail polish remover, insect repellent, thinners, etc.)
• Places where the temperature is below 5°C or above 35°C for extended periods.
• Places exposed to strong magnetism or static electricity.
• Places exposed to strong vibrations.
• Places with high humidity.
• Places with high dust levels.

If allergic reactions or skin irritation occur, stop wearing the watch immediately and consult a specialist, such as a dermatologist or allergist.

Other Precautions

• Adjusting the length of a metal bracelet requires special knowledge and experience. Therefore, if necessary, consult the retail store where the watch was purchased. Attempting to adjust the length of a metal bracelet yourself may result in injury to your hand or fingers, or loss of bracelet parts.
• Do not disassemble or modify the watch.
• Keep watches out of reach of children. Exercise extreme caution to prevent direct contact with children, thereby protecting them from possible injuries, allergic reactions, or itching.
• If your watch is in the form of a pendant or charm, the strap or chain attached to the watch may damage your clothing or injure your hand, neck, or other body parts.

Precautions for Diving

CAUTION: Always observe the rated diving depth indicated on the dial or case back, and never use the watch at a depth exceeding the indicated limit.

CAUTION: During dives, never perform any operations on the watch other than those specified in this instruction.

CAUTION: Before using the watch for diving, you must undergo proper training in various types of diving and acquire the necessary experience and skills for safe diving. Strictly observe the established rules during diving.

WARNING: The following safety rules must be strictly observed. Failure to do so may result in minor injuries or damage to the watch.

Do not turn or pull out the crown when the watch is wet. Water may enter the watch.

If the inside of the glass fogs up due to condensation, or if water droplets remain inside the watch for a long time, the watch's water resistance will decrease. Consult your retail store where the watch was purchased or contact the SEIKO CUSTOMER SERVICE CENTER immediately.

Do not allow moisture, sweat, or dirt to remain on the watch for extended periods. Remember that the watch's water resistance may decrease due to deterioration of the adhesive on the glass or gasket.

Remove the watch before bathing or visiting a sauna. Steam, soap, and certain compounds in hot springs can reduce the watch's water resistance.

Before Diving

Check the following before diving:

1. Correct time setting.
2. Wind the watch by turning the crown to prevent it from stopping underwater. (Refer to "Screw-lock Crown" → P. 17, "Winding Procedure" → P. 18)
3. The rotating bezel turns smoothly (do not turn the bezel too quickly or too slowly). (Refer to "How to Use the Rotating Bezel" → P. 24)
4. The crown is fully screwed down. (Refer to "Screw-lock Crown" → P. 17)
5. There are no visible cracks or scratches on the crystal or strap.
6. The bracelet is securely attached to the watch (with spring bars, clasps, or other parts).

WARNING: If any malfunctions occur with the watch, consult your retail store where the watch was purchased or contact the SEIKO CUSTOMER SERVICE CENTER.

During Diving

Observe the following precautions.

The watch can be used for shallow (air) diving or scuba diving within the water resistance range indicated on the watch.

Do not operate the crown or buttons underwater.

Be careful not to strike the watch against hard objects, such as rocks.

In water, the bezel may be slightly stiff; this is not a malfunction.

After Diving

After diving, follow the watch care instructions below.

Rinse the watch in fresh water to remove all traces of seawater and wipe it dry to prevent rust.

Do not pour tap water directly onto the watch. First, pour some water into a bowl, then immerse the watch in the bowl and rinse it.

WARNING: Depending on the environment in which the diving watch was used, the movement of parts or internal components of the watch, as well as the case or bracelet, may be impaired. We recommend regular servicing of the watch every 2 to 3 years.

Case Construction

When using the following types of models, please consider the following operational features.

The bezel or protective outer case is securely fastened to the watch with set screws. Never loosen these set screws.

WARNING: Never loosen the set screws that secure the bezel or protective outer case. Failure to comply with this requirement may result in damage to the watch or further loosening of the screws.

If you find that the set screws have loosened or the watch is malfunctioning, consult your retail store where the watch was purchased or contact the SEIKO CUSTOMER SERVICE CENTER.

Water Resistance

Water Resistance for Scuba Diving

These watches are specifically designed for scuba diving requiring helium-mixed breathing gas.

Always observe the rated diving depth indicated on the watch dial or case back. Never use the watch at a depth exceeding the indicated limit.

Mechanical Watch Characteristics

Mechanical Watch Characteristics (Manual Winding, Automatic Winding)

• This is a spring-driven mechanical watch.
• To use the watch after it has stopped, wind the mainspring by turning the crown 20 times by hand before starting the watch.
• While quartz watch accuracy is measured in months or years, mechanical watch accuracy is measured in daily rate (i.e., how fast or slow the watch runs per day).
• Furthermore, mechanical watches are slightly affected by the conditions under which they are used (e.g., duration of wear, temperature, hand movement, winding frequency, etc.); therefore, the rate of accuracy is not constant.
• When exposed to strong external magnetic fields, mechanical watches may temporarily run fast/slow. Depending on the degree of influence, watch parts may become magnetized. In such cases, consult your retail store where the watch was purchased, as repair including demagnetization will be required.

Part Names and Functions

1. Minute hand

2. Hour hand

3. Second hand

4. Date

5. Rotating bezel

6. Crown

• Normal position (unlocked): wind the watch
• (with manual winding)
• 1st click position: time difference adjustment/date setting
• 2nd click position: time setting

Screw-lock Crown

The screw-lock crown is equipped with a mechanism that securely locks the crown when not in use, preventing operational errors and improving water resistance.

• To wind the watch using the screw-lock crown, first unscrew it, then pull it out.
• After using the crown, be sure to lock it again.

【Unlocking the Crown】

Turn the crown counter-clockwise to unlock it. The crown can then be used.

【Locking the Crown】

Turn the crown clockwise while gently pressing it towards the case until it stops turning. Do not force it.

When locking the crown, turn it carefully so that the screw properly engages the thread. Be careful not to force the crown, as this may damage the screw hole in the case.

Winding Procedure

• This is an automatic self-winding mechanical watch with a manual winding mechanism.
• When worn on the wrist, the mainspring is automatically wound by the normal movement of the wrist. The watch can also be wound by turning the crown.
• To start the watch after it has completely stopped, wind it by turning the crown or by shaking the watch from side to side until the second hand starts moving. Then, set the time and date before wearing the watch. To wind the watch using the crown, unscrew it by turning it counter-clockwise, then turn it clockwise slowly. It is not possible to wind the watch by turning the crown counter-clockwise. Turning the crown clockwise will fully wind the watch. Furthermore, continued turning of the crown will not damage the mainspring.
• When fully wound, the watch will run for approximately 50 hours (8L35) or 55 hours (8L55).

If the watch is not fully wound, it may run fast or slow. To avoid this, wear the watch for more than 10 hours a day. If the watch is not worn, fully wind it every day at the same time.

If you use the watch after it has stopped because the mainspring has run down, the watch will not start immediately when you wind the mainspring using the crown. This is due to the characteristics of mechanical watches, where the torque of the mainspring is low at the beginning of winding. The second hand will start moving after a certain torque is generated from the start of winding the mainspring. It is possible to start the watch faster by swinging it from side to side to forcibly move the balance wheel.

Setting Time and Date

The watch is equipped with a date function and is designed to change the date every 24 hours.

The date changes around midnight. If the AM/PM setting is incorrect, the date will change at noon.

WARNING: Do not change the date when the time displayed is between 08:00 PM and 02:00 AM. Changing the date during this period may cause problems, such as the date not advancing to the next day.

1. Unlock the crown. (Refer to "Screw-lock Crown" → P. 17)
2. Pull the crown out to the first click.
3. The date can be set by turning the crown clockwise. Turn it until the date of the previous day is displayed. For example: to display "6", first set it to "5". Turn the crown clockwise to set the date.
4. Pull the crown out to the second click and set the time. Pull the crown out to the second click when the second hand is at the 12 o'clock position; the second hand will stop. Turn the crown to move the hands forward until the date changes to the next day. The time is now set for the AM period. Move the hands forward to set the correct time.
5. Push the crown back to its normal position in accordance with the time signal. The second hand will immediately start moving. A time signal service is useful for precise setting of the second hand.
6. Lock the crown again. (Refer to "Screw-lock Crown" → P. 17)

WARNING: The mechanism of a mechanical watch differs from that of a quartz watch. When setting the time, be sure to move the minute hand slightly past the desired time, then move it forward to set the exact time.

Date Adjustment for Month-End

The date needs to be adjusted at the end of February and for 30-day months.

Example: Setting the date for the day after a 30-day month, before noon.

The watch shows "31" instead of "1". Pull the crown out to the first click. Turn the crown clockwise to set the date to "1", then push the crown back to its normal position.

WARNING: Return the screw-lock crown to its normal position. Do not change the date when the time displayed is between 08:00 PM and 02:00 AM. This may cause damage.

How to Use the Rotating Bezel

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

1. At the start of an event (e.g., when you begin a dive), turn the bezel so that the mark on the bezel aligns with the minute hand. The rotating bezel is designed to rotate only counter-clockwise. Do not force it clockwise. (Refer to "Unidirectional Rotating Bezel" → P. 25)
2. Observe the graduation on the rotating bezel that the minute hand points to. The graduation on the rotating bezel indicated by the minute hand corresponds to the elapsed time.

Example: You begin a dive at 10:10. After 20 minutes, the elapsed time is 10:30.

WARNING: Always check the remaining air in your tank before diving. During a dive, use the elapsed time indication on the rotating bezel solely as a reference.

Handling and Care

Daily Care

Your watch requires careful daily maintenance.

• Do not operate the crown when it is pulled out.
• Wipe off moisture, sweat, and dirt with a soft cloth.
• After diving in seawater, rinse the watch with clean fresh water and wipe it dry. Do not pour tap water directly onto the watch. First, pour some water into a bowl, then immerse the watch in the bowl and rinse it.
• If your watch is classified as "not water-resistant" or "water-resistant for daily use," do not rinse it. (Refer to "Water Resistance" → P. 14, "Performance and Type" → P. 27)

Periodically turn the crown

• To prevent corrosion of the crown, turn it periodically.
• The same applies to the screw-lock crown. (Refer to "Screw-lock Crown" → P. 17)

Performance and Type

The caliber and performance specifications of the watch are indicated on the case back.

• Water Resistance
• Magnetic Field Resistance
• Case Number
• Case Number: For identifying the model.
• Magnetic Field Resistance: See P. 29 and P. 30.

Lumibrite

If your watch has Lumibrite coating

Lumibrite is a luminous paint that absorbs light energy from sunlight or artificial light sources in a short time and emits light in the dark. For example, if Lumibrite is exposed to light exceeding 500 lux for about 10 minutes, it can emit light for 3 to 5 hours. However, as Lumibrite emits previously stored light energy, the duration of illumination gradually decreases over time. The length of the illumination period may also vary slightly depending on factors such as the brightness of the place where the watch was exposed to light, and the distance from the light source to the watch.

In general, when moving from a bright place to a dark place, it takes some time for human eyes to adapt to the darkness, making it difficult to distinguish objects at first. (Dark adaptation)

Lumibrite is a luminous paint that stores and emits light. This paint is safe for people and the environment, and does not contain toxic materials such as radioactive substances.

Magnetic Field Resistance

When exposed to nearby magnetic fields, watches may temporarily run fast, slow, or stop.

Diving watches have magnetic field resistance equivalent to or exceeding Class 1 standards of the Japanese Industrial Standards (JIS).

CAUTION:

If the watch becomes magnetized and its accuracy deteriorates beyond the normal operating specifications, it will require demagnetization. If the watch loses accuracy due to magnetization, repair and demagnetization will be charged, even if it occurs within the warranty period.

Reason why magnetic fields affect watches

Strong external magnetic fields can affect the balance spring.

Examples of common items with magnetic fields that can affect watches

• Smartphone, mobile phone, tablet computer (speaker)
• AC adapter
• Shaver, electric razor, hair dryer (speaker)
• Radio (speaker)
• Bag with magnetic clasp
• Magnetic necklace
• Magnetic pillow

Bracelet

The bracelet is in direct contact with the skin and gradually becomes soiled by sweat and dirt. Therefore, without proper care, the bracelet may deteriorate faster, cause skin irritation, or stain clothing sleeves. For long-term use of the watch, careful maintenance is required.

Metal Bracelet

If moisture, sweat, or dirt is not removed from the watch for a long time, it can cause rust even on stainless steel bracelets.

• Lack of care can lead to rashes or yellowish/golden stains on long-sleeved shirts.
• Wipe off moisture, sweat, and dirt with a soft cloth as soon as possible.
• To remove dirt from the gaps in the bracelet, first rinse the bracelet in water, then clean it with a soft toothbrush. (Protect the watch case from water by wrapping it in a plastic bag, etc.) Clean it with a soft cloth.
• Some titanium bracelets use stainless steel pins for structural strength, which may rust.
• As rust develops, the pins may protrude or fall out of the bracelet, and the watch case may detach from the bracelet, or the clasp may become difficult to open.
• Protruding pins can cause injury. In such cases, stop wearing the watch and take it for repair.

Polyurethane Strap

• Polyurethane straps are prone to fading in sunlight and can deteriorate if exposed to solvents or high humidity.
• This is especially true for transparent, white, and light-colored straps, which easily absorb other colors, leading to colored stains or discoloration.
• Wash off dirt in water and wipe dry with a cloth. (Protect the watch case from water by wrapping it in a plastic bag, etc.)
• If the strap loses flexibility, replace it with a new one. If the strap is used in this condition, cracks may appear over time, or the strap may become brittle.

Silicone Strap

• Due to the material's characteristics, this type of strap can easily get dirty, stained, or discolored.
• Wipe the strap with a damp cloth or wipes to remove dirt.
• Unlike straps made of other materials, cracks in the strap may gradually turn into tears. Avoid contact with sharp objects.

Notes on Skin Irritation and Allergies

Skin irritation from the strap may occur due to various factors, such as allergies to metals or leather, friction, dirt, or the strap itself.

Notes on Bracelet Length

Adjust the strap so that there is a small gap between it and your wrist to ensure proper air circulation. When wearing the watch, leave enough space so that a finger can be inserted between the bracelet and your wrist.

How to Adjust the Bracelet for Diving

If your watch's metal bracelet has a diving adjustment function, its length can be easily changed. This is very convenient when wearing the watch over a diving suit or winter clothing.

1. Lift the clasp so it is at approximately a 90° angle, then press it down further by about 20° and hold it lightly.
2. Gently pull the bracelet from the 6 o'clock side of the watch along the curved line of the bracelet to extend the slider.
3. Press the button to lift the clasp, releasing the buckle, and put the watch on your wrist.
4. First, close the clasp (4-1), then the buckle (4-2).
5. Holding the bracelet on both sides, adjust the slider length so that the bracelet fits comfortably around your wrist.

How to Use the Bracelet Extension for Diving

If your watch's metal bracelet has a bracelet extension function for diving, the bracelet length can be easily adjusted. This is very convenient when wearing the watch over a diving suit or winter clothing.

1. Lift the clasp.
2. Press the button to open the clasp.
3. Turn the two-section extension part of the bracelet in the direction indicated by the arrow.
4. Pull the upper cover of the extension part in the direction indicated by the arrow, then pull upwards to fully extend the two-section extension.
5. Put the watch on your wrist, then close the clasp (5-1) first, and then the buckle (5-2).

To fold the bracelet extension, perform the above procedure in reverse. When the two-section extension is fully folded, you will hear a click, similar to when it is extended.

After-Sales Service

Notes on Warranty and Repair

• For repair or maintenance inquiries, please contact the retail store where the watch was purchased or the SEIKO CUSTOMER SERVICE CENTER.
• For repair services within the warranty period, you must present the warranty certificate.
• Warranty conditions are stated in the warranty certificate. Please read and keep it carefully.
• After the warranty period expires, repair services will be provided on a charge basis, only if the malfunction can be corrected.
• Please note that non-original parts may be used for repairs, and their appearance may differ.

Inspection and Adjustment, Including Disassembly and Cleaning (Servicing)

• To ensure optimal performance of the watch for a long period, it is recommended to have the watch inspected and adjusted, including disassembly and cleaning of the movement (servicing), approximately every 2 to 3 years.
• The power transmission mechanism, which is responsible for the watch's operation, is constantly subjected to stress. To ensure this mechanism functions properly at all times, it is important to regularly clean parts, replace oil, adjust accuracy, check operation, and replace consumable parts. For long-term use of the watch, the first servicing after purchase is particularly important. Depending on the usage conditions, the ability of the mechanical parts to retain lubrication may decrease, leading to wear due to oil contamination or the watch running significantly slow or stopping altogether.
• As parts such as gaskets deteriorate over time, water resistance may decrease, allowing sweat and moisture to enter the mechanism.
• Inspection and adjustment, including disassembly and cleaning (servicing), should be performed by the retail store where the watch was purchased, using "GENUINE SEIKO PARTS." When requesting service, also ask to replace the gasket and spring bar.
• Based on the results of inspection and adjustment, including disassembly and cleaning (servicing), the movement of your watch may be completely replaced.

WARNING: Depending on the environment in which the diving watch was used, the movement of parts or internal components of the watch, as well as the case or bracelet, may be impaired. We recommend regular servicing of the watch every 2 to 3 years.

Mechanical Watch Accuracy

The accuracy of mechanical watches is indicated as a "daily rate."

The accuracy of mechanical watches may not match the period specified in the technical specifications due to factors such as the watch's position, duration of wear, hand movement, mainspring winding status, etc.; therefore, the rate of accuracy is not constant.

The daily rate of mechanical watches is measured not over a single day, but as an average daily rate over approximately one week.

Variation in Accuracy Due to Temperature

The parts that determine the accuracy of mechanical watches are made of metal. It is well known that metals expand and contract with temperature. This affects the watch's accuracy. Mechanical watches generally run slow at high temperatures and fast at low temperatures.

Winding State and Accuracy

To improve accuracy, it is important to regularly supply energy to the balance wheel, which regulates the rate. The driving force of the mainspring, which powers mechanical watches, varies significantly when it is fully wound and just before it runs down. As the mainspring unwinds, its force decreases.

Consistent accuracy can be achieved by wearing the watch frequently for self-winding watches, and by fully winding the mainspring at the same time every day for manually wound watches.

Effect of Magnetism

When exposed to strong external magnetic fields, mechanical watches may temporarily run fast/slow. Depending on the degree of influence, watch parts may become magnetized. In such cases, consult your retail store where the watch was purchased, as repair including demagnetization will be required.

Troubleshooting

If a problem occurs that is not listed above, consult your retail store where the watch was purchased.

Technical Specifications

* The accuracy indicated above is adjusted at the factory.

* Due to the characteristics of mechanical watches, the actual daily accuracy may not match the accuracy for the period specified in the technical specifications, depending on usage conditions, such as duration of wear, temperature, hand movement, and whether the mainspring was fully wound or not, etc.