APPLICATION NOTE NO. 59
A Load-Bearing Underwater Cable for Hand-Hauled, Real-Time Profiling
in real time, from small boats not equipped with a winch, calls for hand hauling
a CTD using a load-bearing data cable. Sea-Bird can supply cables up to 300
meters (985 feet) in length that provide a practical way to hand-haul SBE 19 /
SeaCAT Profilers or SBE 25 / 25plus Sealogger
CTDs, and acquire CTD profile data in real
time. In these cases the CTD is powered by its battery, and the cable allows
two-way* RS-232 communications (3 conductors - transmit, receive,
and common) and bears the weight of the CTD.
The cable is not intended
for static working loads above 45 kg (100 lbs); working loads above 18 kg (40
lbs) may be difficult to handle without a winch. The minimum
recommended cable bend radius is 10 cm (4 in.) (e.g., 20 cm sheave block nominal
diameter). Use with loads exceeding 45 kg (100 lbs) or cable bend radius less
than 10 cm (4 inches) will reduce the cable's useful life and void the
Drawings show the cable assembly and wiring details, and include tables of
Sea-Bird part numbers for cables of specific
- Drawing No. 32284 --
Standard connector to the CTD and 9-pin connector to the computer
- Drawing No. 32643 --
Wet-pluggable connector to the CTD and 9-pin connector to the computer
- Drawing No. 32821 --
Standard connector to the CTD and 4-pin connector to a SeaCAT/Sealogger
RS-232 & Navigation Interface Box (Interface Box PN 90488 or PN 90545)
length you need is not listed on the drawing, contact Sea-Bird with the
drawing number and desired length (300 meter [985 feet] maximum).
- Communications from the CTD to a computer -- An SBE 19, 19plus,
25, or 25plus reliably transmits data over 300 meters (985 feet) of cable to a
computer. See the applicable CTD manual for baud rate and real-time output rate
- Communications from a computer to the CTD
for instrument setup, data upload, etc. are dependent on the computer serial port hardware and software settings, but are
usually reliable over cables up to 300
meters (985 feet) long at low baud rates. Some laptop computers may have inferior serial port
hardware, limiting the cable length over which they can transmit. If a computer
cannot transmit over a long cable, disconnect the CTD from the long
cable and connect to the computer using the shorter I/O cable provided with the
Using Load-Bearing Underwater Cable for Real-Time Data
Acquisition with Seasave
- Communicate with the CTD via the terminal program* to set up
sampling parameters, initialize memory, etc. (see terminal program Help Files).
- Configure Seasave for real-time acquisition and display (see Seasave Help
- Start the CTD sampling via magnetic switch (or with computer command
in the terminal program* per
CTD manual instructions).
- Deploy the CTD to begin profile.
- Recover the CTD.
- Stop the CTD sampling via magnetic switch (or with computer command
in the terminal program*).
- Communicate with the CTD via the terminal
program* to upload data.
Sea-Bird has several terminal programs for communicating with instruments --
- SBE 19, 19plus, and 25: use
Seaterm terminal program
- SBE 19plus V2 and 25plus: use
SeatermV2 terminal program
O.D. 7 mm (0.270 in.)
- Twisted trio of 22 awg conductors
- Pressure-extruded polyurethane jacket, dull, non-slip finish
- Weight in air approximately 50 grams/meter (0.034 lbs/ft)
- Weight in water approximately 4 grams/meter (0.0027 lbs/ft)
- PMG-4FS connector with locking sleeve to CTD and DB-9 serial data
connector to computer -- Drawing No. 32284
- MCIL-4FS wet-pluggable connector with locking sleeve to CTD and DB-9
serial data connector to computer -- Drawing No.
- PMG-4FS connector with locking sleeve to CTD and MS3106A-14S-2P connector
to SeaCAT/Sealogger RS-232 & Navigation Interface Box -- Drawing No.
- Mechanical terminations are Chinese finger trap type, made from
hollow-core, polypropylene rope with stainless thimbles
- Internal Kevlar braid with 180 kg (400 lb) breaking strength
- Maximum recommended working load 45 kg (100 lbs)
- Minimum recommended cable bend radius 10 cm (4 inches) (e.g., a 20-cm
sheave block nominal diameter)
Application Note Revision History
||- Increase minimum cable bend radius
to 4 inches.
- Clarify that warranty voided if minimum cable bend radius is not
- Make cable limitations (maximum working load, minimum bend radius)
- Update drawing revisions.
- Add cable for connection to Seacat/Sealogger Interface Box.
- Provide wet-pluggable connector option for all instruments.
||- Update for 19plus V2.
- Reference SCPlusV2_RS232 terminal program as well as Seaterm.
- Update part number of DC Interface Box.
||- Update for SeatermV2.
- Update references to shorter cable that ships with CTD (PNs were
no longer correct).
- Update drawings that are part of application note (DN 32284,
- Update address.
||Update for SBE 25plus.
26 Dec 2012
Sea-Bird Home Phone: (+1) 425-643-9866
Fax: (+1) 425-643-9954 E-mail: