Sherwood LOGIC Owner's Manual
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Sherwood LOGIC Owner's Manual

Sherwood LOGIC Owner's Manual

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LOGIC DIVE COMPUTER
OWNER'S MANUAL
COPYRIGHT SHERWOOD SCUBA V.01.26.2024
1
SherwoodScuba.com
SherwoodScuba.com

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Summary of Contents for Sherwood LOGIC

  • Page 1 LOGIC DIVE COMPUTER OWNER’S MANUAL COPYRIGHT SHERWOOD SCUBA V.01.26.2024 SherwoodScuba.com SherwoodScuba.com...
  • Page 2 As you use the LOGIC, remember that the rules you learned in your SCUBA course(s) still apply to the diving you will do while using a dive computer - some will become even more important. Technology is no substitute for com- mon sense, and a dive computer only provides the person using it with data, not the knowledge to use it.

  • Page 3: Basic Considerations

    Authorized Sherwood Scuba Dealer before you utilize this product. • The LOGIC is intended for use by recreational divers who have successfully completed a nationally recognized course in scuba diving, and diving with enriched nitrogen-oxygen (nitrox) breathing gas mixtures.

  • Page 4: Responsible Computer Diving

    RESPONSIBLE COMPUTER DIVING • Always Plan Each Dive • Always Limit Your Dive to the Level of Your Training and Experience • Always Make Your Deepest Dive First • Always Make The Deepest Part Of Every Dive First • Check Your Computer Often During the Dive •...
  • Page 5 A NOTE is used to emphasize an important maintenance technique. Throughout this owner’s manual reference is made to the term ‘breathing gas’. The rationale being that the LOGIC can be used for Air dives or Nitrox dives. For clarity, these terms are defined as - Breathing Gas - the gaseous mixture breathed during a dive.
  • Page 6 Buttons Layout Advance Button Select Button Use the Advance Button to Use the Select Button to turn toggle through screen options backlight on & change values & access sub-menus within sub-menus SherwoodScuba.com...
  • Page 7 When you receive your new Logic dive computer, it is likely that it is going to be on a Deep Sleep Mode. To wake it up form that mode simultaneously depress both the A and the S buttons for 3 seconds.

  • Page 8: Features And Displays

    The LOGIC’s two Control Buttons allows you to activate the unit and access specific information when you choose to see it. While on the surface, you can use the buttons to maneuver through the LOGIC’s unique Menu System that allows - •...

  • Page 9: Bar Graphs

    4 represent No Decompression (NO DECO) status and the fifth at the top indicates a Decompression condition (DECO). When the LOGIC is set to operate in Nitrox mode, the Bar Graph will represent Oxygen accumulation when the O2 data screen (Alternate Display) is ac- cessed temporarily.
  • Page 10 Ascent Rate Bar Graph (ASC) The ASC provides a visual representation of Ascent speed (i.e., an ascent speedometer), ‘normal’ rate, a ‘cautionary’ rate, and ‘Too Fast’. The segments of the ASC represent 2 sets of speeds which change at a reference depth of 60 FT (18 M).

  • Page 11: Informational Displays

    INFORMATIONAL DISPLAYS Each numeric and graphic display represents a unique piece of information. It is imperative that you understand the formats, ranges, and values of the information represented to avoid any possible misunderstanding that could result in error. Underwater Display “DIVE” During dives, the Current Depth is displayed from 0 to 330 ft (99.9 m) in 1 ft (.1 m) increments (a).

  • Page 12: Audible Alarm

    Temperature can be viewed on an Alternate Display which can be accessed during dives as well by pressing the S (Right) button once while underwater. The MODE the LOGIC is on will be displayed at the bottom of the screen (Air, Nitrox or Gauge will be displayed here. (c)
  • Page 13 A single short beep is emitted after the Diagnostic check, upon automatic return to Surface Mode from Simulator Mode, upon com- pletion of a battery change with calculations/settings saved, or upon change from Delayed to Full Violation after that dive. If another Alarm situation occurs, any scrolling message will be displayed until it is acknowledged, at which time it will be replaced by a message that was previously scrolling.
  • Page 14 POWER SUPPLY The LOGIC utilizes one (1) 3 volt, CR2450 Lithium Battery that should provide from 300 dive hours of operation if you conduct one 1 - hour dive each time the unit is activated, to over 600 dive hours of operation if you conduct two or more dives each time the unit is activated.

  • Page 15: Operating Temperature

    OPERATING TEMPERATURE The LOGIC will operate in water temperatures from 28° to 95° F (-2 to 35 °C) and out of the water from 20° to 140°F (-6 to 60 °C). At extremely low temperatures, the LCD may become sluggish, but this will not affect its accuracy. If stored or transported in extremely low temperature areas (below freezing), warm the unit and battery with body heat before diving.
  • Page 16 ACTIVATION SETUP SherwoodScuba.com...
  • Page 17 3 seconds and the computer will start the self-check mode and the TIME screen will appear right after. If the LOGIC screen is turned off but not on sleep mode it will auto- matically enter into DIVE mode once the computer reaches a depth of 1 m or 3.3 ft for 5 seconds.
  • Page 18 SURFACE SCREENS & BASIC SETTINGS To go to Settings, from the Time screen press the A button 6 times to go to the SET screen. To access SET screens press the S button to go to: SET 1 - MODE; chose from Air, Nitrox or Gauge. SET 2 - ALM - Alarms Options.
  • Page 19 SET 1 - MODE Toggles between Air, Nitrox or Gauge modes. The Air mode will simulate Nitrogen absortion/release in tissues using a 16-tissue model & considering a mix of 21% Oxygen/ 79% Nitrogen and will provide a NDL in minutes. The Nitrox mode will also conside Oxygen Toxicity within calculations.
  • Page 20 SET 2 - ALM Turn Dive Alarms ON/OFF and change the values for maximum depth and maximum dive time. Use the A button to view options, S button to select values, press the A button again to accept the selec- tion &...
  • Page 21 SET DEPTH ALARM VALUE Factory set for 100 FT, the DEPTH ALARM VALUE can be set from 30 to 330 FT (9 to 99 M) in increments of 10 FT (3 M). After saving ON as the setting for DEPTH ALARM ON/OFF, the SET DEPTH ALARM VALUE screen appears with the Set Point flashing.
  • Page 22 SET ELAPSED DIVE TIME ALARM VALUE Factory set for 3:00 (hr:min), the ELAPSED DIVE TIME (EDT) ALARM VALUE can be set from :10 to 3:00 (hr:min) in increments of :05 (:min). After saving ON as the setting for EDT ALARM ON/OFF, the SET EDT ALARM VALUE screen appears with the Set Point flashing. Information displayed includes: •Alpha graphics EDT and AL •EDT Alarm Set Point (hr:min) flashing, with DIVE and TIME icons...
  • Page 23 SET 3 - UNITS Change the computer units Metric/Imperial, Sampling Rate and Deep Stop alarm. Use the A button to view options, S button to select values, press the A button again to accept the selection & move to next option. SET 4 - TIME Change the computer’s Time Format, Time of Day and Date.
  • Page 24 SET 5 - DELETE Erases the computer’s logbook. Use the A button to view Y / N option, confirm deletion (Y) with A button, or exit without deletion (N) with S button & move to the previous screen. CAUTION: This feature is used only to clear the log memory when the unit has reached its maxi- mum which is about 999 dives.

  • Page 25: Plan Mode

    PLAN MODE The PLAN screens are accessible during a new activation period or greater than 10 minutes after surfacing from a dive. When set for Air or Nitrox operation, pressing and releasing the A (left) button 2 times (< 2 sec each time) while the TIME screen is being displayed (TIME >>...
  • Page 26 AIR MODE PLAN • Alpha graphic PLAN • Air graphic (indicating operating mode) • No Deco Limit (hr:min) with DIVE TIME icons, 3 dashes if no time available • Plan Depth with FEET (or METERS) icon • N2 Bar Graph (4 No Deco segments) NITROX MODE PLAN •...

  • Page 27: Last Dive Screens

    LAST DIVE SCREENS The LAST Main screen is accessible by pressing the A (Left) button 3 times while the TIME/WET screen is being displayed (TIME >> DATA >> PLAN >> LAST). It displays data for the most recent dive conducted. Pressing the S (Right) button will access the ALT screen, if set for Nitrox, which returns to the Main after 5 seconds or if S is pressed again.

  • Page 28: Log Mode

    LOG MODE Log Mode stores information for each dive as 3 screens referred to as the Date Screen, Screen #1, and Screen #2. Upon gaining access to the screens, information displayed is frozen until either button is pressed again. If neither button is pressed, operation reverts to the TIME screen in 2 min- utes.
  • Page 29 LOG Screen #1 (SCR1) • Alpha graphic SCR1 • Temperature (minimum recorded that dive) with degrees icon and graphic F (or C) • Surface Interval if a repetitive dive, 3 dashes ( - : - - ) if no previous dive that Activation Period, with TIME and SURFACE icons •...

  • Page 30: History Mode

    HISTORY MODE HISTORY records information for up to 999 Total Dives and 2999 Dive Hours, and retains the infor- mation indefinitely, even if the Battery is removed. •10 minutes after a Non-Violation Dive, pressing the A button 5 times will access the HISTORY 1 screen (TIME >> DATA >>...
  • Page 31 DIVE MODES SherwoodScuba.com...

  • Page 32: Safety Stop

    TYPICAL DISPLAY INFORMATION Max Depth Dive Time Nitrogen Buildup Ascent Speed NO FLY Required Time Time of Day Current Depth NDL minutes SAFETY STOP Required Depth Countdown 3:00 min Current Depth NDL minutes SherwoodScuba.com...
  • Page 33 DIVE MODES During Dive Modes, a Main (Default) screen of information relevant to that Dive Mode is displayed. During No Deco dives deeper than 80 FT (24 M), if enabled a Deep Stop (a Set 3 selection) to be taken at 1/2 Max Depth for 2 minutes (2:00 min:sec) is triggered and displayed as a Preview screen when accessed while 10 FT (3 M) deeper than the calculated Stop Depth and as a Stop screen upon ascent to 10 FT (3 M) below the Stop Depth.
  • Page 34 NO DECO ALT 1 Information displayed includes: • Temperature with ° icon and graphic F (or C) • Time of Day (hr:min) with TIME icon • Current Depth with feet (or meters) icon > Pressing and releasing the A (Left) button accesses the ALT 2 screen, if Nitrox. >...

  • Page 35: No Deco Deep Stop

    NO DECO DEEP STOP During No Deco dives in which Depth exceeds 80 ft (24 m), a Deep Stop Preview screen can be accessed that will revert to the No Deco Main after 5 seconds. •The intent of this screen is to suggest that a Stop should be made as indicated (at 1/2 Max Depth) to help reduce the probability of DCS (decompression sickness).
  • Page 36 Upon ascending to within 10 ft (3 m) below the calculated Deep Stop, a Deep Stop (DS) Main screen will automatically appear with the alpha graphics DEEP and STOP scrolling at the top of the screen (each On for 2 seconds). Information displayed also includes: The recommended Stop Depth (1/2 the calculated Max Depth) with the 2 minute Countdown Timer that counts down from 2:00 to 0:00 (min:sec), Current Depth, NDC Time Remaining, and the N2BG.

  • Page 37: No Deco Safety Stop

    NO DECO SAFETY STOP Upon ascending to 15 ft (5 m) on any No Decompression dive in which Depth exceeded 30 ft (9 m), a Safety Stop screen appears with a countdown timer beginning at 3:00 (min:sec) and counting down to 0:00. NOTE: The Safety Stop is not required and although recommended, it does not have to be taken.

  • Page 38: Digital Gauge Mode

    DIGITAL GAUGE MODE When set for Digital Gauge Mode, the unit operates without any decompression or oxygen monitoring functions, ba- sically as a Depth Gauge/Timer, NOT providing NDL minutes. A contiguous 24 hour post dive surface interval is then required for the unit to operate as a full function diving computer. GAUGE DIVE MAIN (Default) Information displayed includes: •...
  • Page 39 HIGH PO2 Upon reaching .20 ATA less than the PO2 Alarm Set Point, a cautionary mode is entered. The graphic UP, Up Arrow icon, and PO2 value (x.xx ATA) with graphic PO2 are displayed solid on the Main Dive screen with Current Depth, NDT, and the N2 Bar Graph.
  • Page 40 HIGH O₂ A cautionary mode is entered when O₂ increases to 80% (240 OTU) of the Maximum allowed for a single dive or 24 hour period (100% or 300 OTU). The Audible Alarm sounds, the graphics HIGH >> O2 flash (each on 1/2 second), and the UP Arrow icon flashes.

  • Page 41: Decompression Dive Mode

    DECOMPRESSION DIVE MODE Decompression Dive Mode (DECO) is entered when nitrogen calculations determine that you cannot safely surface without stopping at a predetermined depth to allow off gassing of absorbed nitrogen. The Audible Alarm sounds, and the message DECO >> STOP >> xxFT (or xxM) scrolls at the top of the screen (each on 2 seconds). The UP Arrow icon will be displayed flashing, if 10 ft (3 m) deeper than the required Stop Depth, then is removed once within 10 ft (3 m) below the required Stop Depth.

  • Page 42: Conditional Violation (Cv)

    CONDITIONAL VIOLATION (CV) If you disregard a Decompression obligation (i.e., ascend above the Required Stop Depth), operation enters Condi- tional Violation Mode. The Audible Alarm sounds and the message DOWN >> TO >> STOP scrolls at the top of the screen (each on 2 seconds).
  • Page 43 DELAYED VIOLATION # 1 (DV1) DV1 is a continuation of CV which occurs if you remain above the Stop Depth for longer than 5 minutes. At 5 minutes, the Audible Alarm will sound (even if set Off), the Down Arrow icon, Total Ascent Time, and full N2BG will flash, and the message DOWN >>...

  • Page 44: Violation Gauge Mode (Vgm)

    VIOLATION GAUGE MODE (VGM) When a Decompression Stop Depth greater than 70 ft (21 meters) is required, operation enters VGM for the remainder of that dive and subsequent dives made within a 24 hour period. Once in VGM, the unit operates with limited functions without any nitrogen or oxygen monitoring or calculating func- tions.
  • Page 45 This rule applies to the use of all dive computers, but is especially important when using the LOGIC, due to the personal information it provides.

  • Page 46: Maintenance

    Indication of tampering with the module will void the unit’s warranty. WARNING: If you are unsure how to properly replace the LOGIC’s battery and ensure the O-ring is well lubricated and the batery hatch secured after replacing the battery do not hessitate on contacting any authorized Sherwood Dealer for assistance.

  • Page 47: Care And Cleaning

    CARE AND CLEANING The LOGIC is a sensitive electronic instrument. Although it has been built to endure the rigors of diving, it still must be handled carefully to protect it from shock, excessive heat, chemical attack, and tampering. The housing is made of an impact resistant resin that is shock resistant but susceptible to scratches and attack by strong chemicals.

  • Page 48: Annual Inspections And Service

    It is possible to damage the LOGIC Depth Sensor if it is not pressure tested properly. The LOGIC must be placed com- pletely underwater when being pressure tested to protect the Depth Sensor.

  • Page 49: Battery Life

    LOGIC. If the LOGIC did not display the Low Battery symbol prior to entering the Dive mode, and a Low Battery condition occurs during a dive, there will be sufficient battery power to maintain unit operation for the remainder of that dive, however the Backlight will be disabled.

  • Page 50: Battery Replacement

    MODULE REMOVAL FROM BOOT If the LOGIC is in a Wrist Boot, it will be necessary to peel the lips of the Boot downward off the Module while apply- ing pressure from underneath, working it out slowly. Submerging the boot or console in warm water for 5 minutes may facilitate the operation.
  • Page 51 •Inspect the Buttons, Lens, and Housing to ensure they are not cracked or damaged. •If there is any sign of moisture in the module, DO NOT use the LOGIC until it receives proper service by an Authorized Sherwood Scuba Dealer.
  • Page 52 •Lift the Hatch up and away from the Housing using a small plastic prying tool. •Remove the Battery Hatch. •Remove the O-ring from the Hatch by hand or using a small plastic tool. •Using care not to damage the Battery Con- Battery Removal tacts, slide the Battery up and out of the Battery Compartment.
  • Page 53 WARNING: If damage or corrosion is found in the Battery Compartment, return your LOGIC to an Authorized Sherwood Scuba Dealer, and DO NOT attempt to use it until it has received factory pre scribed service. Battery Installation • Slide a new 3 volt type CR2450 Lithium Battery, negative (-) side down into the Battery Compartment. Press the battery inwards and ensure good engagement with the contacts.
  • Page 54 WARNING: If there are any portions of the display missing or appearing dim, or if a Low Battery condition is indicated, install another new battery, if the condition persist then return your LOGIC to an Authorized Sherwood Scuba Dealer for a complete evaluation before attempting to use it.
  • Page 55 •The oxygen features of the LOGIC are intended for use only by recreational divers trained for nitrox diving by an instructor certified by a recognized training agency to teach diving with nitrox.
  • Page 56 REFERENCE SherwoodScuba.com...

  • Page 57: Decompression Model

    NO DECOMPRESSION LIMITS (NDL) Note how the No Decompression Limits for the LOGIC are contrasted with the U.S. Navy limits. The LOGIC’s Dive Planner does not scroll past 190 ft (57 m), or to depths at which projected dive time is less than one minute .
  • Page 58 WARNINGS: Using the LOGIC, just as using any other dive computer or the U.S. Navy (or other) No Decompression Tables, is no guarantee of avoiding decompression sickness (i.e., the bends). Sherwood Scuba advocates responsible diving practices. Decompression diving is inherently hazardous and greatly increases your risk of decompression sickness, even when performed according to the computer’s calculations.
  • Page 59 WARNING: The nitrox features of the LOGIC are intended for use only by recreational divers trained for nitrox diving by an instructor certified by a recognized training agency to teach diving with nitrox.
  • Page 60 OXYGEN LOGIC Depth NDL-mins. Maximum Exposure Time Eng (Metric) mins. 260 (283) - - - Per Dive Per 24hr - - - (ATA)(Min) (Min) (12) 137 (144) 0.60 (15) 81 (85) 0.70 (18) 57 (59) 0.80 (21) 40 (41) 0.90...

  • Page 61: Altitude Diving

    The LOGIC senses ambient pressure when it is activated, every 15 minutes while it is activated, or every 30 minutes when it is not activated. At an Altitude of 3,001 feet (916 meters), it will automati- cally recalibrate itself to measure depth in feet of fresh water rather than feet of sea water.

  • Page 62: Flying After Diving

    WARNING: The LOGIC will not sense ambient pressures or provide Altitude compensation when it is wet. DO NOT dive at any different Altitude until the unit shuts off and is reactivated at the new Altitude. If the unit is activated at elevations higher than 14,000 feet (4,270 meters), it will perform a diagnostic check followed by immediate shutdown.

  • Page 63: Dive Time Remaining (Dtr)

    DIVE TIME REMAINING (DTR) One of the most important pieces of information on the LOGIC is the patented DTR numeric display. To numerically display Dive Time Remaining, the LOGIC constantly monitors two critical pieces of information; no decompression status and oxygen accumulation status.
  • Page 64 This is a feature of the decompression model that is the basis for multilevel div- ing, one of the most important advantages the LOGIC offers. Sherwood Scuba Decompression Algorithm uses a 16-tissue organizational interval model called Bühlmann ZH-L16C.

  • Page 65: Specifications

    SPECIFICATIONS SURFACE MODES / SCREENS (continued) •Activation/Diagnostic •Set 3 (Utilities): •Time •Units of Measure (Imperial/Metric) •Fly/Dsat •Sampling Rate (15, 30, 60 min) •Data (Air, Nitrox, Gauge) •Deep Stop (On/Off) •Plan (Air, Nitrox) •Last (most recent dive data) •Set 4 (Date/Time): •Log •Hour Format (12/24) •History...
  • Page 66 DIVE MODES DISPLAY RANGES / RESOLUTION BAR GRAPHS •No Decompression Dive: Range: Resolution: N2BG: segments •Main display •Dive Number 0 - 50 •No Deco up to 4 displayed •Alternate #1 •Depth 0 - 399 FT (0 - 120 M) 1 FT (.1/1 M) •Deco all 5 displayed •Maximum Depth...

  • Page 67: Operational Performance

    OPERATIONAL PERFORMANCE Function: Accuracy: •Depth ±1% of full scale •Timers 1 second per day Dive Counter: •Displays Dives #1 to 50, 0 if no dive made yet •Resets to Dive #1, upon reactivation after shutdown Dive Log Mode: •Stores 999 most recent dives in memory for viewing •After 999 dives, the memory is saturated and it will be required to clear the log (SET 5 - Page 24) Altitude: •Operational from sea level to 14,000 feet (4,270 meters) elevation...
  • Page 68 Operating Temperature: •In Water >> between 28 and 95 °F (-2 and 35 °C) •In Air >> between 20 and 140 °F (-6 and 60 °C) ACCESSORIES (optional items available from your Authorized Sherwood Dealer) •Lens Guard •Battery Hatch •Battery Kit - includes 1 battery, 1 battery hatch O-ring, silicone grease...
  • Page 69 NO DECOMPRESSION MODEL DEFAULT SETTINGS AS SHIPPED FROM THE FACTORY Basis: •Operating Mode •Modified Bühlmann Algorithm •PO2 Alarm •16-tissue compartments •PO2 Alarm Value 1.60 ATA •FO2 Data Base: •All Alarms •ZHL16-C - Albert A Bühlmann •Ascent Alarm •Depth Alarm Performance: •Depth Alarm Value 100 FT •Tissue compartment halftimes (mins.) Bühlmann “M”...
  • Page 70 Air Dive - A dive conducted using air (approximately 21% oxygen & 79% nitrogen) as the breathing gas. Algorithm - A step-by-step mathematical formula designed to accomplish a particular result (i.e. Dive Time Remaining in the LOGIC). Alternate Display - Additional information accessible by pressing a control button.
  • Page 71 Multi-level Dive - A type of dive profile where the diver spends various times at different depths (opposite of a “Square Wave” dive profile). Nitrogen Bar Graph - A graphic display of simulated nitrogen absorption on Sherwood dive computers. Nitrox - A nitrogen-oxygen breathing gas mixture that contains a higher fraction of oxygen than air.
  • Page 72 DSAT NDLS (HR:MIN) AT ALTITUDE (IMPERIAL) Altitude 3001 4001 5001 6001 7001 8001 9001 10001 11001 12001 13001 (feet) 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 Depth (FT) 4:20 3:21 3:07 2:55 2:45 2:36 2:28 2:21 2:15 2:10...
  • Page 73 DSAT NDLS (HR:MIN) AT ALTITUDE (METRIC) Altitude 0 1221 1526 1831 2136 2441 2746 3051 3356 3661 3966 (meters) to 1220 1525 1830 2135 2440 2745 3050 3355 3660 3965 4270 Depth 4:43 3:37 3:24 3:10 2:58 2:48 2:39 2:31 2:24 2:18 2:12...

  • Page 74: Inspection / Service Record

    INSPECTION / SERVICE RECORD SERIAL NUMBER DATE OF PURCHASE PURCHASED FROM (DEALER) BELOW TO BE FILLED IN BY AN AUTHORIZED SHERWOOD SCUBA DEALER: DATE INSPECTION/ SERVICE PERFORMED DEALER/ TECHNICIAN SherwoodScuba.com...
  • Page 75 LOGIC DIVE COMPUTER OWNER’S MANUAL COPYRIGHT SHERWOOD SCUBA V.01.26.2024 SherwoodScuba.com SherwoodScuba.com...

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