Towing a coil behind a boat

[Surfline]

I have an XL500 and a Minelab Excalibur 800. I would like to add a long extension to the main unit and tow the coil behind a boat. I would like to keep the unit itself topside so that it does not get lost underwater. Does anyone know how I can modify the XL500 or Excalbur to do this (for example tested cable length)?

Thanks,

Surfline

 

[gear box]

Are you serious? If you are, you would be going way to fast and probably never be able to pinpoint the target unless it's the size of a 56 Buick. What would you be looking for? I give you credit for ingenuity though.
Good luck with your project. Gary

 

[homefires]

I think you will find the added coaxial would add too much capacitance and knock your sensitivity down in the dirt. You would be better off with a Manometer.

 

[grumpyolman]

Been there done that! However, we didn't use a metal detector. We rented a proton magnetometer and towed it. We were looking for a Martin PBM a WWII amphib plane with 80' or more of wing, that hunted subs. We did lots of towing and lots of bounce dives at potential targets. The targets were usually a sunken log bundle with the steel cables wrapped around them. If you're looking for something the size of a buick you might find something with the magnetometer but it better be a large target. Oh! We were searching in water from 30-100' deep. You know the bottom is not flat and smooth? Think what you have to do with a coil anywhere. It skims across the surface as close to the target as you can get it. Then air test what you're looking for. If it was 18" that's be good depth. The speed of the boat, current, wind, and changing depth, will add more variables hard to control. It's be like blindfolding you,putting you in a football field, covering your ears, and telling you to walk across a bumpy hill, with people pushing on you every now and then, at a walking speed, find a shovel. If it's a good treasure research other ways to find it. Side scanning sonar, Underwater TV, etc.///Jim

 

[Surfline]

Thanks Jim. I agree with your perspective. I have been on the boat towing cameras and it is not easy when everything is happening: current, wind, waves, etc. It is hard to imagine how a coil will work, but thought that I would see what opinions were out there.

Thanks,

Surfline

 

[Surfline]

Gary,

I would be looking for coins, metal objects, etc. from shipwrecks. I have used underwater cameras. I am familiar with Fisher's Pulse 10, which can be towed behind a boat. I would like to use the current technology that I have with out spending mega bucks on another instrument.

Thanks,

Surfline

 

[Surfline]

Yes, that was my concern as well. However, I recently learned of a 6 meter cable with 13 inch searchcoil for the XL500.

Thanks,

Surfline

 

[gear box]

Hey Surfline,my guess would be that you need to keep the coil under control first and not surfing all over the place,then figure out how to slow down and pinpoint. You could try to rig a skeg of some kind under it to keep it going in a straght line. if you look at the planer boards that fisherman use you might get an idea of what would work.If you only used a trolling motor you could slow way down and still cover a fair amount of water. Maybe keep some marker buoy's handy when you do get a hit toss one out,just like fishing. Then you could turn around and dig it out with a long scoop. let us know how this turn's out for you.
Good hunting, Gary

 

[Carl-NC]

Forget about the XL and Excal. Also forget about detecting small items, you won't get the coil to track the bottom.

The best you can do is detect very large items. For this you need a high-current pulse detector, and build a large-coil tow sled for it.

- Carl