SEIKO Diving Watch 8L35/8L55 User Manual

Introduction

Thank you for choosing a SEIKO watch. To ensure correct and safe use of your SEIKO watch, please read the instructions in this booklet carefully before operation. Keep this manual handy for future reference.

Note on Bracelet Adjustment: The service for adjusting the length of metal bracelets is offered by the retail store where the watch was purchased. If you cannot return the watch to the store where it was purchased (e.g., due to receiving it as a gift or moving), please contact a SEIKO CUSTOMER SERVICE CENTER. This service may also be available at other retail stores for a fee, but not all stores offer it.

Note on Protective Film: 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, dirt, sweat, dust, or moisture can get under it, potentially leading to rust.

Important Safety Precautions

Please read the following instructions carefully before operation and strictly adhere to them.

⚠ WARNING: Diving Operations

During dives, never perform any operations other than those specified in this manual. Incorrect handling or misinterpretation of displayed information could lead to death or serious injury.

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

Never use this watch for saturation diving with helium gas.

Do not dive with this product unless you have received proper training in scuba diving, have acquired the necessary experience and skills for safe diving, and have thoroughly familiarized yourself with the operation and handling of this product. Verify all functions of this product before each dive.

⚠ WARNING: General Precautions

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

Immediately stop wearing the watch in the following cases:

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

Consult your retail store or contact a SEIKO CUSTOMER SERVICE CENTER immediately.

Keep watches and accessories out of reach of children. Be extremely careful to prevent children from accidentally swallowing any part of the watch. If a child swallows a battery or a watch part, seek medical attention immediately, as it can be harmful to their health.

❗ CAUTION: General Precautions

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

Avoid wearing or storing the watch in the following locations:

• Places where volatile substances evaporate (cosmetics such as nail polish remover, insect repellent, thinners, etc.).
• Places where the temperature is consistently below 5°C (41°F) or above 35°C (95°F).
• Places exposed to strong magnetism or static electricity.
• Places exposed to strong vibrations.
• Places with high humidity.
• Places with high dust content.

Allergic Reaction or Skin Irritation: If you experience an allergic reaction or skin irritation, 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. Please consult the retail store where the watch was purchased for such adjustments. Attempting to adjust the length 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. Take extreme care to prevent children from coming into direct contact with the watch to protect them from potential injuries, allergic reactions, or itching.
• If your watch is in the form of a keychain or pendant, the strap or chain attached to the watch may damage your clothing or injure your hand, neck, or other body parts.

Diving Precautions (Must be strictly observed)

Before Diving

Before diving, check the following:

• Correct Time Setting: Ensure the time is set correctly. [See "Setting the Time and Date" on page 19.]
• Winding: Turn the crown to wind the watch to prevent it from stopping in the water. [See "Screw-lock Crown" on page 16 and "How to Wind the Mainspring" on page 17.]
• Rotating Bezel: The rotating bezel should turn smoothly. (The bezel should not be too loose or too tight.) [See "How to Use the Rotating Bezel" on page 23.]

Diagram: Watch Parts Identification

Description of watch parts:

• 1. Minute hand
• 2. Hour hand
• 3. Second hand
• 4. Date
• 5. Rotating bezel
• 6. Crown
  • Normal position (locked): Wind the watch (for manual winding).
  • First click position: Adjust time/set date.
  • Second click position: Set time.

Diagram: Watch Case Construction

For models with the following types, please consider these operational features. The bezel or protective outer case is securely fastened to the watch with set screws. Never loosen these set screws.

Diagram: Bezel and Case Screws

Description: Illustration showing set screws securing the bezel or outer case.

⚠ WARNING: Never loosen the set screws that secure the bezel or protective outer case. Failure to do so 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, contact your retail store or a SEIKO CUSTOMER SERVICE CENTER.

During Diving

Observe the following precautions.

⚠ WARNING: Never use the helium gas diving system with this watch.

⚠ WARNING: During dives, never perform any operations with the watch other than those specified in this manual.

⚠ WARNING: Before using the diving watch, you must receive proper training in various types of diving, acquire the necessary experience and skills for safe diving, and strictly adhere to established rules during dives.

⚠ WARNING: Do not twist or pull out the crown when the watch is wet. Water may enter the watch. If the inner surface of the glass fogs up due to condensation, or if water droplets remain inside the watch for an extended period, the watch's water resistance may be compromised. Consult your retail store or a SEIKO CUSTOMER SERVICE CENTER immediately.

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

Remove the watch before taking a bath or visiting a sauna. Steam, soap, and certain compounds in hot springs can reduce the water resistance of the watch.

Diagram: Watch Face with Bezel

Description: Illustration showing the watch face with the rotating bezel. Numbers indicate positions for setting time and date.

Diagram: Crown Positions

Description: Illustration showing the crown in its normal position, first click, and second click positions.

Diagram: Bezel Operation

Description: Illustration showing how to align the bezel marker with the minute hand.

Diagram: Watch Parts (numbered)

Description: Detailed illustration of watch parts including hands, date window, bezel, and crown.

Diagram: Screw-lock Crown Operation

Description: Illustration showing how to unscrew and screw back the crown.

⚠ WARNING: If any malfunction occurs with the watch, consult the retail store where the watch was purchased or a SEIKO CUSTOMER SERVICE CENTER.

After Diving

Follow the watch care instructions below after diving.

Rinse the watch in fresh water to remove any salt water residue and wipe it dry to prevent rust. Do not pour running tap water directly onto the watch. First, pour some water into a bowl, then immerse the watch and rinse it.

⚠ WARNING: Depending on the environment where the diving watch was used, the mobility of its components may be affected, or internal parts, the case, or the bracelet may be damaged. We recommend periodic servicing of the watch approximately every two to three years.

Watch Case Construction

When using models of the following types, 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.

Diagram: Case with Set Screws

Description: Illustration showing the watch case with set screws securing the bezel or outer case.

⚠ WARNING: Never loosen the set screws that secure the bezel or protective outer case. Failure to do so 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, contact your retail store or a SEIKO CUSTOMER SERVICE CENTER.

Characteristics of Mechanical Watches (Manual and Automatic Winding)

• This is a mechanical watch with a spring drive.
• To use it after it has stopped, wind the watch by turning the crown about 20 times to wind the mainspring before starting the watch.
• While the accuracy of quartz watches is measured by the difference over months or years, the accuracy of mechanical watches is measured by the difference per day (i.e., how much the watch gains or loses over a 24-hour period).
• Furthermore, mechanical watches are slightly affected by the conditions under which they are used (e.g., duration of wear, temperature, arm movement, winding status, etc.); therefore, the rate of gain or loss is not constant.
• Mechanical watches may temporarily gain or lose time when exposed to strong external magnetic fields. Depending on the degree of influence, the watch parts may become magnetized. In such cases, contact your retail store, as repair work, including demagnetization, will be required.

Parts Identification and Function

Diagram: Watch Parts Identification

Description: A detailed illustration of the watch face, labeling the following parts:

• 1. Minute hand
• 2. Hour hand
• 3. Second hand
• 4. Date
• 5. Rotating bezel
• 6. Crown
  • Normal position (not pulled out): Wind the watch (for manual winding).
  • First click position: Adjust time/set date.
  • Second click position: Set time.

How to Wind the Mainspring

This is an automatic self-winding mechanical watch with a manual winding mechanism.

• When the watch is worn on the wrist, the mainspring is wound automatically 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 the watch either by turning the crown or by swinging the watch from side to side until the second hand starts moving. Then, before wearing the watch, set the time and date. To wind the watch using the crown, unscrew it by turning it counter-clockwise, then slowly turn it clockwise. It is impossible 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 spring.
• When the watch is fully wound, it will run for approximately 50 hours (8L35) or 55 hours (8L55).

Note: If the watch is used without being fully wound, it may gain or lose time. To avoid this, wear the watch for more than 10 hours a day. If the watch is used without being worn on the wrist, be sure to wind it fully every day at the same time.

If you use a watch that 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 or force of the mainspring is low at the beginning of winding. The second hand will start moving after a certain torque is reached 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 the Time and Date

The watch is equipped with a date function and is designed so that the date changes approximately every 24 hours. The date changes around 12:00 AM (midnight). If the AM/PM time is set incorrectly, the date will change at 12:00 PM (noon).

⚠ WARNING: Do not change the date when the watch displays a time between 8:00 PM and 2:00 AM. Changing the date during this period may cause problems, such as the date not advancing to the next day.

1. Unscrew the crown. [See "Screw-lock Crown" on page 16.]
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 the date "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 AM. Move the hands forward to set the correct time.
5. Return the crown to its normal position according to the time signal. The second hand will immediately start moving. [Telephone time signals are useful for accurately setting the second hand.]
6. Screw the crown back in. [See "Screw-lock Crown" on page 16.]

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

Date Adjustment at Month-End: The date needs to be adjusted at the end of February and for 30-day months. Example: Setting the date on the first day of the month following a 30-day month. 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 watch displays a time between 8:00 PM and 2:00 AM. This may cause damage.

How to Use the Rotating Bezel

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

1. At the start of an event for which you need to measure elapsed time (e.g., when you start a dive), turn the bezel so that the marker on the bezel aligns with the minute hand.
• The rotating bezel is designed to rotate only counter-clockwise. Do not force it clockwise. [See "Rotating Bezel with Unidirectional Rotation Only" on page 24.]
2. Look at 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: If you start a dive at 10:10, after 20 minutes, the minute hand will point to the "20" mark on the bezel.

Diagram: Bezel Operation Example

Description: Illustration showing the bezel aligned with the minute hand at the start of an event, and then showing the elapsed time indicated by the minute hand after 20 minutes.

Diagram: Bezel Rotation Direction

Description: Illustration indicating that the bezel only rotates counter-clockwise.

⚠ WARNING: Before diving, always check the remaining air in your tank. During dives, use the elapsed time indication on the rotating bezel solely as a reference.

Daily Care

Your watch requires careful daily maintenance.

• Do not wash the watch while the crown is in the pulled-out position.
• Wipe off moisture, sweat, and dirt with a soft cloth.
• After the watch has been immersed in seawater, be sure to rinse it with clean fresh water and wipe it dry. Do not pour running tap water directly onto the watch. First, pour some water into a bowl, then immerse the watch and rinse it.
• If your watch is classified as "not water resistant" or "water resistant for daily use," do not wash such watches. [See "Watch Characteristics and Type" on page 26.]
• Periodically turn the crown. To prevent corrosion of the crown, turn it periodically. The same applies to the screw-lock crown. [See "Screw-lock Crown" on page 16.]

Watch Characteristics and Type

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

Diagram: Case Back Markings

Description: Illustration of a watch case back showing markings for water resistance, case number, caliber, and other information.

• Water Resistance: Indicates the level of water resistance.
• Case Number: The number for identifying the watch type.
• Caliber: The movement caliber (e.g., 6R35).
• Magnetic Field Resistance: See pages 28 and 29.

Lumibrite

If your watch has Lumibrite coating:

Lumibrite is a luminous paint that absorbs energy from sunlight and lighting fixtures in a short time and retains this energy to emit light in the dark. For example, if Lumibrite is exposed to light of over 500 lux for about 10 minutes, it can emit light for 3-5 hours. However, as Lumibrite emits the stored light energy, the brightness level of the emitted light gradually decreases over time. The duration of the luminous 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.

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

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

Brightness Levels:

Magnetic Field Resistance

When exposed to magnetism from nearby objects, watches may temporarily gain or lose time, or stop.

Diving watches possess magnetic field resistance that is equivalent to or exceeds the characteristics of Class 1 devices according to Japanese Industrial Standards (JIS).

❗ CAUTION:

• Keep watches more than 5 cm away from products that generate magnetic fields (JIS Class 1).
• Keep watches more than 1 cm away from products that generate magnetic fields (JIS Class 2).

If the watch becomes magnetized and its accuracy deteriorates to a degree exceeding the nominal specifications under normal operating conditions, demagnetization is required. If the watch loses accuracy due to magnetization, repair and demagnetization services 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.

Diagram: Examples of Magnetic Products

Description: Illustrations of common items that generate magnetic fields, such as smartphones, speakers, power adapters, magnetic clasps on bags, razors, walkie-talkies, magnetic necklaces, and magnetic pillows.

Bracelet

The bracelet is in direct contact with the skin and gradually becomes soiled by sweat and dust. Therefore, without proper care, the bracelet may deteriorate faster, cause skin irritation, or stain clothing sleeves.

For the watch to last longer, proper care is essential.

• 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 on the skin or cause yellowish or golden stains on shirt sleeves. Remove moisture, sweat, and dirt with a soft cloth as soon as possible. To remove dirt around the bracelet links, first rinse the bracelet with 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 forms, the pins may protrude or fall out of the bracelet, and the watch case may detach from the bracelet, or the clasp may stop opening. 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 from light and can deteriorate when exposed to solvents or high humidity. This is especially true for transparent, white, and light-colored straps, which easily absorb other colors, potentially leading to colored stains or discoloration. Wash off dirt with water and wipe dry with a dry 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. Continuing to use the strap in this condition may eventually cause cracks or make the strap brittle.
• Silicone Strap: Due to the material's characteristics, this strap can easily get dirty, stained, or discolored. Wipe the strap with a damp cloth or tissue to remove dirt. Unlike straps made of other materials, cracks in the strap may gradually turn into tears. Avoid contact with cutting tools.

Notes on Skin Irritation and Allergies: Skin irritation from a strap can occur due to various factors, such as metal or leather allergies, friction, dust, or the strap itself. Adjust the strap so that there is a small gap between it and your wrist, allowing for proper air circulation. When wearing the watch, leave enough space to insert a finger between the bracelet and your wrist.

How to Adjust the Bracelet for Diving

If your watch's metal bracelet has a dive adjustment function, its length can be easily changed. This is very convenient when wearing the watch over a wetsuit 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.
• Be careful not to press the clasp with excessive force. You may feel slight resistance, but only light force is needed.
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.
• Only light force is required for this operation. Be careful not to pull the bracelet out forcefully.
• The slider can be extended by approximately 30 mm. Be careful not to extend the slider beyond this limit.

Diagram: Bracelet Adjustment Mechanism

Description: Illustration showing how to lift and press the clasp to release the slider, and how to pull the slider to extend the bracelet.

3. Press the button to lift the clasp, freeing the buckle, and put the watch on your wrist.
4. First close the clasp (4-1), then close the slider (4-2).
5. Holding the bracelet on both sides, adjust the slider length so that the bracelet fits comfortably around your wrist.

Diagram: Bracelet Adjustment Steps

Description: Illustrations showing the steps for putting on the watch with the adjusted bracelet.

How to Use the Dive Extension

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

1. Lift the clasp.
2. Press the button to open the clasp.
• After opening the clasp, press the clasp again to return it to its normal position.

Diagram: Dive Extension Clasp

Description: Illustration of the dive extension clasp mechanism.

3. Open the two-section folding part of the dive extension in the direction indicated by the arrow.
• Some force is required to open the folding part, and you will hear a click when it opens.
4. Slide the upper cover of the dive extension in the direction indicated by the arrow, then pull upwards to fully extend the two-section folding part.
5. Put the watch on your wrist, then first close the clasp (5-1) and then the slider (4-2).

Diagram: Dive Extension Operation

Description: Illustrations showing the steps for extending and using the dive extension.

To fold the dive extension, perform the above procedure in reverse. When the two-section folding part of the dive extension is fully folded, you will hear the same click as when it was unfolded.

Checking and Servicing (Maintenance)

To ensure optimal performance of your watch over a long period, it is recommended to have it checked and serviced, including disassembly and cleaning of the movement, approximately every 2-3 years.

The power transmission mechanism, which is responsible for the watch's timekeeping, is constantly subjected to force. To ensure this mechanism operates properly at all times, it is important to regularly lubricate the parts, replace the oil, adjust accuracy, check operation, and replace consumable parts. The first maintenance service after purchase is particularly important for ensuring the long life of the watch. Depending on the usage conditions, the ability of the mechanical parts of the watch to retain lubrication may decrease, leading to wear of parts due to oil contamination or causing the watch to gain or lose significant time, or even stop.

As parts such as gaskets deteriorate over time, water resistance characteristics may decrease, allowing sweat and moisture to enter the movement. Checking and servicing, including disassembly and cleaning, should be performed by the retail store where the watch was purchased, using "GENUINE SEIKO PARTS." When you bring it in, also request replacement of the gasket and spring bar.

As a result of checking and servicing, including disassembly and cleaning, the movement of your watch may be completely replaced.

⚠ WARNING: Depending on the environment where the diving watch was used, the mobility of its components may be affected, or internal parts, the case, or the bracelet may be damaged. We recommend periodic servicing of the watch approximately every two to three years.

Accuracy of Mechanical Watches

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

The accuracy of mechanical watches may not correspond to the accuracy for the period specified in the technical specifications due to gaining/losing time depending on the watch's position, which in turn depends on factors such as the duration the watch is worn on the wrist, arm movement intensity, whether the mainspring was fully wound or not, etc.

The gain/loss amount of mechanical watches is measured not per 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 depending on temperature. This affects the accuracy of the watch. Mechanical watches generally lose time at high temperatures and gain time at low temperatures.

Troubleshooting

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

Malfunction: Date changes at 12:00 PM.

Possible Causes: Incorrect AM/PM time setting.

Solutions: Manually advance the time by 12 hours.

Malfunction: Condensation under the glass.

Possible Causes: A small amount of water entered the watch due to gasket wear, etc.

Solutions: Consult your retail store.

If a problem occurs that is not listed above, contact your retail store.

Technical Specifications

The accuracy indicated above is adjusted at the factory. Due to the characteristics of mechanical watches, the actual daily accuracy may not correspond to the accuracy specified in the technical specifications depending on usage conditions, such as the duration the watch is worn on the wrist, temperature, arm movement intensity, and whether the mainspring was fully wound or not, etc.

If a problem occurs that is not listed above, contact your retail store.