Many people in the high tech industry have heard the expression down a rathole, but which rathole? Many groups use this phrase, but with very different meanings.

A Bachelor's Apartment

Rathole – like a bachelor’s apartment?

The literal description of a rathole is a place where rats dig a hole through ground, wood, plaster, or even concrete to get into their nests, which are often dirty, small, and cluttered. This leads to the use of the phrase to describe a person’s living quarters which are dirty, small, and cluttered: like a bachelor’s apartment.


In the oil drilling industry, a rathole is a vertical shaft drilled near the main well hole, or a hold in the floor of the drilling platform used for temporary storage of the Kelly (the hardware that connects the hoisting cables and the rotating drill turntable which rotates the drill shaft).

Rathole and mousehole in Oil Industry

A rathole and mousehole – oil industry

In this case, the rathole is often accompanied by a mousehole: another vertical storage shaft for holding the drill rods. Rathole is also used to describe an extension of the well hole drilled below the target elevation at the bottom of the well hole for storing machinery attachments and waste.

Down the rathole at Gaping Gill Cave System

Down the Rathole – Entrance at Gaping Gill Cave system. Photo by John Gardner

Surprisingly, but for good reason, Rathole is also the name of an entrance cave to Gaping Gill cave system in North Yorkshire, England. Finally, there are Rat’s Hole annual custom motorcycle shows in Daytona and Myrtle Beach, Fla.

In the high tech world, going down a rathole usually refers to a syndrome of a discussion which consumes a lot of time and goes into minute details of some aspect of the design that promises little return in terms of actual progress on the project. It can also refer to a detailed technical investigation or mathematical calculation that goes into a lot of detail when the outcome is non-critical, or not appropriate for the project’s goals. This mathematical over-analysis has been termed “mathematical diarrhea” by a prominent Cal Tech Engineering Professor. His advice is to use rounding and estimation to quickly get a ballpark answer before committing time and resources to find a mathematically perfect but practically useless answer. The mathematically perfect answer might describe a part that doesn’t exist, so it isn’t very useful information to an Engineer. If you find your initial guestimate is in the ballpark then you can do the detailed calculation, knowing it is time worth spending.

Avoiding this syndrome is a challenge for project managers, and outcome depends on their experience, a well defined set of requirements and goals, as well as the experience, skills, and judgment of the designers. This combination is what separates teams whose projects are completed successfully and those whose projects never seem to end, or see the light of day.

rathole or black hole?

A rathole or a black hole?


Sometimes people refer to a rathole as the place where government money and taxes go, but that may be more accurately described as a black hole.