The CM2 product family
CM2 Cables and Winches
The new CM2 portable winch and 4.7mm cableSpecifications
The CM2's telemetry is so versatile that it can handle coaxial or twisted pair cables from 50m up to 6km long. For example up to 300m of 4.7mm (LOG5) cable can be used on a power winch that is light enough to be hand carried. This slim cable, like all other CM2 tow cables, carries both power and signal on a single pair of conductors.
Another alternative, for shallow water use, is so-called "soft" tow cable, with a coaxial core, a kevlar strain member and a polyurethane sheath. This cable can be handled manually without a winch or reel.
For the heavy (deep) end of the market the versatility of the telemetry means that virtually any 2-wire cable can be used, including most types that may have been inherited from older equipment. (A key point to note is that the CM2 is a true DIGITAL system, with the images being digitized in the towfish. Unlike sonars that rely on analogue towfish and analogue telemetry there is no loss of image quality in the tow cable.)
A newly designed portable winch with 300m cable capacity can be hand carried to the survey vessel and features:
- Only 47kg with 300m of cable
- All stainless steel construction
- Maintenance free, fully sealed mercury sliprings
- Built in overload clutch
- Soft-start feature gives smooth cable handling
- Fits into a Peli brand 1600 series transit and storage case
C-MAX can also provide larger winches, tailored to the job. Choices include electric or electro-hydraulic drive, multi-speed or soft-start, with or without leading-on (level wind) gear.
Important information about towcable selection
It can be assumed, as a "rule of thumb", that the length of tow cable required for a sidescan sonar towfish is about 3 times the depth of the towfish. This is because the drag on the tow cable causes it to lie at an angle astern. A normal towing altitude for the towfish is between 5 and 20m metres above the seabed.
For search depths down to approximately 40m the 'soft' kevlar/coax (CX) cable may be used, but, because the cable is light, it will drag out to a shallower angle astern than steel-armoured tow cables for the same speed. CX cables are available in 50m and 100m lengths, plus longer options to special order.
For search depths covering from very shallow down to 80-100m the 4.7mm (LOG5) cable on the SK172 winch is a convenient option.
To reach deeper tow depths this LOG5 cable can be used on a larger winch. If the required depths increase even further, a heavier armoured tow cable with a diameter of 8.2mm or 11.4mm is normally needed.