Boat towed PI Metal Detector coil - What are the issues and effectiveness?

[stevemc]

There are several large coil detectors being made now. As for the weight of the ferrous in both engines, maybe 300 lbs, maybe less, Maybe more, but there will be other ferrous objects, hydraulic valves, prop shafts,bolts used in the airplane, wheels and landing gear etc, so could be well over 500 lbs. Those engines were 1200 to over 2000 hp so they were heavy duty and used iron/steel components for the reciprocating components, and cylinder sleeves. Could be well into the 1000 lb range if more than reciprocating was steel-cylinders, heads, engine cases, which could be. I dont know the coil inductance. The coil is made with a 26 conductor cable, that is one turn, and soldered so that it mimics a 26 turn coil. The wire looks to be 18-22 ga wire. Most likely 22. They told me it was 100s of volts, but I dont know the amps/milliamps. The battery is wet cell lead acid 6 volt battery. Sled was similar to Salvor 6s, just longer/wider and rounded at front, not so high at the coil. PVC on top and bottom. It was made that if it flipped, it would be the same. Coil was protected.

 

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[Shipwrecked]

stevemc: Thanks for your estimate of the ferrous weight content in the C47. 500 to 1000 pounds would be a good target for the mag.
Is your PI coil shielded? How high off the bottom have you fixed the coil?
Happy Holidays.

 

[stevemc]

I dont think the coil itself is shielded. Like I said keep the coil off the bottom 10' and you wont get aluminum cans. But I had the coil about 4 or 5" up if sled was on bottom. But on bottom picked up cans. It was 1 1/2" PVC with 1 1/2" flexibel electrical conduit for the front curved section. About as tight as I could bend it. !/2" nylon rope for the tow. Make a bridal with a loop, then tie rope to that. Have to go real slow.

 

[Shipwrecked]

stevemc: Thank you. I may consider putting an underwater towed PI system together for the 2013 search season.

Does anyone have experience with the Powerscan 2Pro Pulse Induction units made in Bulgaria?

Thank you to everyone for your comments on use and experience with underwater towed PI systems. Please keep them coming as other Treasurenet member respond to these posts. I'll check back periodically.

Happy Holidays.

 

[old man]

MERRY CHRISTMAS, Steve, From the sounds of the detection depth of that PI detector, you might want to market it.
It sounds better then anything I've seen on the market. I think have a great detector.

 

[stevemc]

Unfortunatly they dont make it any more. I bought it 20 years ago from A & S metal detectors It was called the Pulse 2000.

 

[Darren in NC]

Does anyone have experience with the Powerscan 2Pro Pulse Induction units made in Bulgaria?

I do. It's based on the popular homemade Delta Pulse PI unit. Delta Pulse and the Sniffer XR71 are essentially the same schematic. I have sold PIs for years, but I don't advertise it as there's no money in it. If you want one already built, PM me. Mine comes with the small coil as well as the 1m x 1m at a lower cost than the Bulgarian model. I believe it's just as good as the pro models.

 

[Shipwrecked]

Hi Darren: Thanks for your post. Yes, interested, PM sent.

 

[mad4wrecks]

Aquapulse International made/makes a pulse towed sled:

Seven Seas Search & Salvage » METAL DETECTORS

Tom

 

[cornelis 816]

I built the DBP 2000 . The coil is 4ft by 4ft . Works like a sharm as long as you keep it away from metal objects . So mount it in front or behind your boat . Cornelius

 

[comfortably numb]

I built the DBP 2000 . The coil is 4ft by 4ft . Works like a sharm as long as you keep it away from metal objects . So mount it in front or behind your boat . Cornelius

Corny, Isn't it the object here to find metal objects? Just kidding So does yours work better pulling it on the surface or near the bottom?

 

[cornelis 816]

Jeff the best results you get is by towing it close to the bottom . The only way you detect objects is when they are in the field of the coil . So if you drag the coil on the surface you miss a lot of targets .

 

[Salvor6]

Aquapulse also makes a towable coil with a 60' kevlar tow cable. I made this sled for it and it works great. It doesn't cover a wide area so you have to know where the wreck is first. Good for pinpointing metal concentrations.

 

[Shipwrecked]

Are there issues with the towed sled when making a turn and having the possibility of it turning over?
What experience has anyone had with the coil mounted on a towfish such as that offered by JW Fisher?
What issues would there be if a separate weight was put down on the bottom and the towfish mounted coil is attached on the line a few feet above bottom?

Salvor6: nice set up with the towed sled with coil

 

[User]

I have a large coil PI a Pulse 2000, with a 1 meter coil, I have it fiberglassed into a rounded rectangle 5' wide and 3 1/2' long. Made in the US but not anymore. I lengthened the cable with a type of shielded coaxial cable like they use for cable TV . On land in air it will pick up an automobile at about 25'. I have several PIs with 10" and 9 1/2" coils and they will all pick up the auto at about 5 1/2' to 6' in air max. The large coil will pick up an aluminum beer can at 6' in air and in salt water about 8' unfortunatly. They will pick up hi power lines 100s of feet away, and wont work under bridges or anywhere with rebar and metal reinforcing, as way to much metal. They work good away from powerlines and buildings etc. PIs work better in water and ground than in air. Especially salt water.

Yeah, PI is a very good deal when to use it on mineralized soil/in salt water. The detecting range increasing in 1.3- 1.6 times against pure air.

One of the disadvantages of PIs while searching - is absolutely weak discrimination of Ferros and NonFerros metals.
PI works on the delay of reply. The most long delay have Ferros metals. The shortest - Au (gold)

Another one (disadvantage) of PIs - is on detecting Au (i.e. gold). The delay of impulse from gold is extremely short, so most of PIs have absolutely weak ability to detect some gold. The other one bad news - is that that big coils have a very long delay, so they're unable to detect gold AT ALL!. However Minelab GPX has beated that limit and now it producing coils of 1meter in diameter for gold prospecting... Minelab GPX really works on those extremely high depths (my friends has a work with it - they said - "Incredible" by depth, but it only works fine on soils free of ferrous or ferrous artifacts - when any ferrous matials no exist in soil - wire, nail, Fe scail )...

BTW - Aluminium has just like the same with Ferros depth detection range. Аluminium has a littlebit less range (10-20%) аgainst Fe (I have tested several saucepans Fe and Al with my PI - FYI).

SO - PI- detector IS EXTREMELY FINE FOR the PostCreator's ALUMINUM TARGET Search...

 

[diverjon123]

Going to build a tow sled unit with the 1m could from pulse star, but I have a questions. Can I use any top side unit to hook up to that coil or does it have to be pulse stars unit that they sell? Thanks

 

[old man]

Going to build a tow sled unit with the 1m could from pulse star, but I have a questions. Can I use any top side unit to hook up to that coil or does it have to be pulse stars unit that they sell? Thanks

diverjon, I think you would have to use the pulse star top side unit with the 1 meter coil. I do know that the unit is not cheap.
I believe that Darren on TNET makes his own unit for a reasonalble price and it is very good. You might want to PM him and see if his unit meets your needs.

 

[diverjon123]

diverjon, I think you would have to use the pulse star top side unit with the 1 meter coil. I do know that the unit is not cheap.
I believe that Darren on TNET makes his own unit for a reasonalble price and it is very good. You might want to PM him and see if his unit meets your needs.

Thank you for that information old man. Ill be pm him very soon, thanks

 

[Darren in NC]

Unless your unit has identical specs as another unit, coils are not interchangeable. You have to use a coil specific to your unit. Diverjon, check your PM.

 

[aimee123]

aimee123

HI my name is mark boudreaux . I from south louisiana. wanting to see if you could E-mail me my E-mail address is [email protected]. I'm wanting to talk to you about the towing metal detector you showing on this site . please let me know if you got my message. Thank you for your time.