Reels vs. Spools: What’s the Difference?

Rees vs SpoolsWhich is the better choice, a reel or a spool? As with so many things in cave diving, the answer depends entirely on circumstances. Neither is right for every situation and smart divers make use of both. To better understand which is right for a specific application, you first need to understand the relative strengths and weaknesses of reels and spools, compared to one another.

Spools: The Good, the Bad, the Ugly

At first glance, spools have a lot going for them, including:

  • Spools generally cost less.
  • Spools are more compact, meaning that you can carry them in pockets, reducing the risk of entanglement or loss.
  • What is, perhaps, the greatest benefit is the fact it is nearly impossible to jam a spool. This can be critical in an emergency.


Everything about spools, however, is not all hearts and flowers. They do have some drawbacks:

  • No matter how carefully you clip a spool to a harness D-ring, they can still come off and get lost. Or, worse, the snap can remain clipped off while the spool itself bounces merrily along the cave floor behind you, paying out line as it goes. (We’re going to cover the better way to clip off spools in a separate article.)
  • Perhaps the biggest single drawback is the fact spools are a pain in the butt to wind up. Additionally, there is a tendency for the guideline to become twisted each time you retrieve the spool. This means you have to periodically unwind the spool, straighten out the line and rewind it. (We’ll describe a workaround for this in yet another article.)

Let’s take a look at how reels fare in comparison.


Reels: They Do One Thing Well

At first glance, it seems reels do not have a lot going for them.

  • To start, they are more expensive than spools.
  • As they are bigger and bulkier, you cannot stow them in pockets and can only clip them off to your harness (possible entanglement hazard and risk of loss).
  • And, most damning of all, reels are prone to jamming.

While newer reel designs have minimized the risk of getting the guideline caught between the spool and frame, all reels are still subject to “bird nesting.” This occurs when the guideline piled up on one side of the spool collapses on itself. This type of jam is almost impossible to fix under water.


Because of the risk of jamming, effective reel use requires regular practice. Even with this, do you really want a situation in which your only means of finding your way to safety could jam at the worst possible moment? Which begs the question, why even bother with reels? And the answer is:

  • Because reels make it vastly easier to manage large quantities of guideline.

Imagine running a spool to the start of the permanent line in Orange Grove Sink or Little River. Do you really want to wind that much guideline back on a spool?

Reel and Spool

Making the Choice

As we said going in, smart cave divers use both reels and spools and make the choice of which to use based on circumstances.

  • Reels are generally better suited for connecting cave entrances to the start of permanent guidelines, cave surveys and any other situation where significant line is in play.
  • Spools are great for small jumps and gaps — especially when the distance involved is less than 3 m/10 ft.

Cookie Spool

Whether to carry reels or spools for jumps and gaps can also be situational. For example:

  • If your dive will only involve a single jump or gap, it may be easier to carry just a single, small reel.
  • If your dive will involve multiple jumps and gaps, you may want to use spools for the smaller ones, as these may be able to fit easily in your pocket.

This still leaves the question of what is best in lost-diver or lost-line emergencies.

  • To start, wise divers never carry just a single safety reel or spool. A diver we know once spent nine miserable hours trapped in an air pocket because her only safety reel jammed. A spool would most likely not have jammed under these circumstances; however, it can be dropped and lost. Having a backup reel or spool would have prevented this diver from having to wait until someone came and found her. (The outcome could have been much worse.)

Lost Diver

  • You can make a strong argument for making sure that at least one of your safety devices is a spool. This will give you something you know can’t jam.
  • Bear in mind, though, that in a lost-diver or lost-line situation, you may have to quickly search in multiple directions, over long distances. Under these circumstances, you may want to take advantage of the fact you can wind a reel faster than you can a spool.

So, as you can see, a wise diver may carry both a safety reel and a safety spool. That will best prepare him or her for any eventuality.


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