Magnet Fishing Magnets
What is a magnet?
Wikipedia defines a magnet as a “material or object that produces a magnetic field: …a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.” There are many kinds of magnets each with many configurations that determine the size, shape, strength, and pattern of the magnetic field.
What is the best type of magnet for magnet fishing?
Magnet fishing is the search and retrieval of magnetically-attracted objects from a body of water. In this hobby or activity, the magnet is the primary piece of equipment. The best magnet for magnet fishing is a rare-earth magnet in a mounting enclosure. To understand what makes one type of magnet better than another type, we must first identify the three limiting factors bounding a successful retrieval:
- The muscular strength of the user
- The pulling strength of the magnet
- The tensile strength of the rope
The magnet is only one factor in this equation. Ideally, the tensile strength of the rope matches or exceeds the pulling strength of the magnet. Rare-earth magnets produce stronger magnetic fields than compound magnets of equivalent size. There are rare-earth magnets with tremendous pulling power, but these super strong magnets come with increased size, weight, cost, and risk. Ultimately the muscular strength of the user is the most limiting factor. If the strength of the magnet exceeds the strength of the user, there is an increased risk of losing the magnet to permanent or very heavy objects. The magnet must be small enough to handle, yet large enough to be useful.
The magnet configuration is another variable that determines why some magnets are better than others. The typical factors to consider for magnet configuration are:
- Magnetization direction
Magnets have two poles that are either axially or diametrically magnetized. If you ever played with magnets, you know that the magnetic field is strongest near the poles. An axially magnetized disc has the poles on the large flat faces on opposite sides of the magnet while a diametically magnetized copy has the poles on the exterior radius. Axially magnetized magnets optimize the surface area of the magnet and allow for more pulling area.
The enclosure is an overlooked factor. A simple enclosure provides protection but does not improve the magnetic performance. An ideal enclosure for an axially magnetized disc is a thin, steel cup slightly larger than the magnet itself. When placed inside this enclosure, the pole in contact with the steel cup is curved toward the other pole. This induces a lot of magnetic flux in the steel enclosure and places the poles in closer proximity. A proper enclosure makes magnets even stronger. Check out the magnetic flux in this Quora post:
Whether you are new to the hobby or looking to upgrade your equipment, remember your own physical limitations and what to look for in a new magnet. Have fun magnet fishing!