Diving With The Fisher Impulse
By Kevin Reilly
From Page 18
October, 1994 issue of Lost Treasure
The new Fisher Research Impulse Metal Detector arrived at my shop a little while ago. As I opened the box I was very impressed with it. It comes packed in the same hardbound carrying case as the Fisher 1280-X Aquanaut. The Impulse even looks like the Aquanaut, being in the same housing.
I took the Impulse out of the case and assembled it right away. On the front panel of the Impulse are two control knobs, a LED indicator light and a digital intensity meter. The switch on the left is the tuner and battery check and the switch on the right is the on, off and volume control. The digital intensity meter is pretty impressive and very functional. The LED lights up when checking the batteries and when a target is run in front of the coil.
There is an 8 spider coil on the unit that I am using. You can also purchase this detector with a 10-1/2 spider coil. Both coils are very sensitive.
The Impulse operates on 8 AA size batteries. Regular carbon zinc batteries will last about 40 to 50 running hours. Alkaline batteries have a great operating life span and can last over 100 operating hours. One will not have to worry about the detector running out of battery life on a two-tank dive.
The battery compartment is separated from the control housing. This is a nice treat just in case the battery compartment ever took water in due to lack of 0-ring maintenance.
Turning the Impulse on at the shop for a quick bench test helped me to figure the unit out a little better before! took it underwater on my dives. This pulse detector has a very quick response to all metals. I took a gold ring and ran it in front of the coil and it receives a good loud response at afar distance away from the coil. I also ran some coins in front of the coil and it also responded very quickly. Turning the threshold up to hear a slight tone helps on the depth of the target.
Now the real test for the Impulse, diving with it underwater, I opened the battery compartment and put some silicone 0-ring grease on the 0-ring to keep the battery door from leaking.
The first time out with the Impulse, I asked my friend Gary to take his boat and go diving on one of the local wrecks a ship which sunk in 1900. We were going to test the Fisher there because of the massive amounts of metal objects lying all around this wreck site. Gary, the captain of the boat, Brian my nephew and myself were all set to dive in over the side of the boat onto the wreck site. Gary had a little problem with his diving gear so in the last minute, could not make the dive with us.
We hit the sand bottom at about 30 feet. I turned the Impulse on and before I could swing it, eye balled a rope chain in front of us. I picked it up and looked at it. It seemed to be gold! That was the only real treasure we found on our dive. The rest of the objects I found were 50 caliber bullets and oddball hunks of wreckage that we left down on the bottom of the ocean.
Even though I didnt find the rope chain with the Impulse, it had to be luck for us to anchor up right there and see this chain while out testing the Fisher. The rope chain turned out to be 14K gold plate over .925 sterling silver.
Going out the Boynton Beach Inlet with a couple of my friends, we decided to try metal detecting around another old shipwreck. I asked my friend Steve Singer to bring his camera and take some underwater pictures with me using the Impulse. The only items I found searching around this wreck are lead sinkers, the famous pull-tabs everyone normally digs up and a ships sheathing nail. It wasnt a great day for finds, but the diving and visibility was great.
Other types of diving I do are search and recovery salvage work in canals, the Intercostals Waterway and in the ocean where people lose things off their docks or boats.
Since I have the Impulse to use and test out I decided to bring the Impulse with me on these types about diving. Diving with the detector here is where I found out a great deal of pinpointing with the Impulse. Watching the bar graph as you run the coil over the target and seeing the highest peak on the graph is where to dig for your item. I wound up getting all my targets right under the center ring of the coil. The bar graph has helped me from wasting my time trying to pinpoint the targets.
Diving in these conditions under docks and boats sometimes makes the visibility poor. Hearing the target underwater and then seeing a glimpse of the red LED light also helped to pinpoint my targets. Out of one canal I pulled a pair of pliers an arms length in the muck. I was laying down on the bottom of the canal and kept digging with my hand in the muck until I reached the pliers. I am really impressed with how deep the Fisher Impulse picked up the pliers.
Now for some fun diving with the Impulse. I dive offshore in about eight to ten feet of water. This area is just past the shallow water hunters. Diving in the ocean with great visibility allows you to see the bar graph and pinpoint your targets quite easily. Productivity is a little slower, but coins and jewelry do come out of the sand here too. The day 1 went out 1 only found some common clad coins, pennies and of course pull tabs. I really didnt dig up any iron junk in that area. You normally find quite a bit of iron junk on shipwrecks.
All total of using the Impulse, I am very satisfied with the unit. I am still on the same batteries I received with the detector and logged in about 25 hours bottom time in diving.
I will be looking forward to diving with the Fisher Impulse up on the 1715 shipwrecks this summer with some friends of mine. The Fisher Impulse is very easy to use and operate.