Fisher CZ-21 Dual Frequency Underwater Metal Detector with 10.5 Inch Concentric Waterproof Coil

The Fisher CZ-21 Quick Silver is a dual-frequency VLF metal detector that transmits 5 kHz and 15 kHz and is fully submersible to 250 feet (76 m). It has a 3-tone audio target ID, manual ground balance, a no-motion pinpoint and permanently attached waterproof headphones, runs 35 to 55 hours on four 9V alkaline batteries and carries a 2-year Fisher warranty. It suits divers and saltwater beach and surf hunters who want tone ID under water.

What is in the box with the Fisher CZ-21

Fisher's standard contents for the CZ-21 with 10.5 inch coil

• Fisher CZ-21 with 10.5 inch concentric waterproof searchcoil
• Waterproof headphones, permanently attached

Who the Fisher CZ-21 is for

The CZ-21 suits scuba divers who want a 3-tone target ID at depths to 250 feet, saltwater beach and surf hunters, and hunters who want to balance the ground by hand and pinpoint without moving the coil. Fisher’s owner’s manual explains that the saltwater signal is canceled using Fourier Domain analysis.

We recommend the CZ-21 for serious underwater hunters who put dependable operation in fresh and salt water ahead of modern display features: divers, experienced beach hunters and anyone regularly searching freshwater or saltwater swimming areas. It is purpose built for the water, with dual-frequency operation and a rugged design, and its audio target identification suits water hunters who do not need a display.

Modes and the 3-tone target ID

Auto-Tune is an all-metal search with a threshold tone, Target-ID is a silent search discrimination mode, and the no-motion VCO pinpoint raises the audio as the coil nears the target. In Target-ID mode the low tone is iron, the medium tone is foil and pull tabs and the high tone is coins, and an overload gives a bell tone. We would treat the low tone as iron and usually skip it, dig the high tones and check medium tones before deciding, because Fisher’s manual notes that gold rings can fall in any category except iron.

Ground balance and sensitivity

Ground balance is manual. We would balance with the Quick G.B. method in Fisher’s manual on the ground you will hunt, and rebalance when you move from dry sand to wet sand or into the water. Sensitivity has 10 levels; set sensitivity just below the point where the detector gets noisy. The control box slides off the handle and clips to a belt, but Fisher’s manual does not recommend hip mounting under water.

Where the CZ-21 works best and its limits

The CZ-21 fits saltwater and freshwater diving, the surf, swimming beaches and lakes, and it also works on land. There is no numeric target ID, so dig decisions come from the three tones. It weighs 6 lb 1 oz with the 10.5 inch coil, heavier than the 1280X, and the coil and headphones are part of the detector. For black sand and heavily mineralized beaches, the pulse induction Fisher Impulse AQ is the specialist.

A typical hunt is a popular Lake Huron swimming beach. We would work slowly through the areas where swimmers enter and leave the water, keeping the coil close to the bottom and overlapping each sweep. The 10.5 inch coil gives useful coverage in the more open areas.

The most common mistake we see is using too much discrimination and rejecting gold jewelry, especially lower-conductivity rings. Fisher's manual says gold rings may fall into any tone category except iron, so we keep discrimination low when rings are the goal.

For dry parks and farm fields, we would recommend the Fisher F75: it is lighter and better suited to general land detecting.

Fisher CZ-21 compared with the 1280X and Impulse AQ

The 1280X Aquanaut is the simpler dive-rated option, with one 2.4 kHz frequency and automatic ground balance. The Impulse AQ is a pulse induction detector waterproof to 3 feet (1 m), for wading the surf rather than diving.

Fisher CZ-21 specifications

The armrest and the free CZ-21 digital manual are in our Fisher CZ-21 collection. Fisher’s manual says to rinse the lower area under the two control knobs thoroughly after use in salt water.

Authorized Fisher dealer with a showroom in Ypsilanti, Michigan. Full manufacturer warranty and help from our staff by phone or email.