You'll want to get his book, Pulse Power. I have it, bought it when I got my first Pi, Surfmaster Pro.
My Surfmaster belonged to the master water hunter who got Clive going. Its found a ton of gold for the master hunter and at one time found him a genuine Rolex watch. I got the Surf dirt cheap when he progressed to the Dual Field. It was kind of rough looking, worked just fine.

Hope your Surfmaster has the weighted diving coil and not the floating skimmer coil found on most.
The Surf is an excellent detector to start out with. Found my first gold with it being an 22kt ring.

The Surfmaster Pro does like iron. This lead me to building my own Pi that I also built for others who wanted better depth and better sensitivity to small gold and not towards iron.

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I dig it with a Nokta/Makro product-Legend,
DeepTech Vista X and Blisstool V5 The Beast