WRECK, CAVE AND ICE DIVERS rely on line-reels for deployment and retrieval of guidelines. Recreational divers use them to deploy lift-bags and, more frequently, SMBs while drift-diving and delayed SMBs on ascents.
For divers who rely on such devices for safe returns or ascents, there is little worse than one that becomes jammed, tangled or knotted up in their gear. Divers must possess the skill and knowledge to use reels properly if they are to enjoy their benefits.
However, the evidence suggests that divers are suffering problems more frequently than we might expect.
Concern about rapid and unplanned ascents in recreational diving has been growing, primarily because of the potential for injuries that can occur in such a situation. The 2005 British Sub Aqua Club Diving Incidents Report suggested that a large number of abnormal ascents involved deployment of a delayed SMB.
The root cause of nearly a third of these incidents was undetermined, but 20% of the 98 abnormal ascents (see Table 1) involved deployment of an SMB that went awry.
This frequency was more than double that involving any other item
of equipment.

THERE WERE FAR FEWER SMB-RELATED abnormal ascents in the 2006 BSAC data (roughly 8% of 91 incidents), but the 2007 data showed a similar trend as 2005. SMB deployment was again causal, or a causal factor, in 20% of ascent incidents. At the same time, total incidents declined by 8%.
The 2007 report notes that ascents have become the biggest category of incident following a dramatic rise over the past 10 years, and that the great majority of these incidents relate to poor buoyancy control and rapid ascents, often resulting in missed decompression stops.
So whats going wrong, and what can we do to avoid it
Scuba STAR Network, which is an independent organisation dedicated to improving safety in recreational diving, carried out an informal online survey in co-operation with Divers Alert Network (DAN). More than 70 divers (about half of them DIVER readers) took part.
The results were thought-provoking and, more importantly, provided some practical advice for divers who use these devices.

Divers who responded to the survey represented a broad cross-section of the diving community, including wreck, cave and other technical divers (38%) and 51% recreational divers.
The majority reported receiving their training in reels and associated equipment as part of speciality programs in deep, decompression, advanced nitrox, cave/cavern, wreck and search & recovery diving.
Nearly a third received formal instruction in use of line-handling devices during their advanced open-water training. Despite any other qualifications and experience, about one in five respondents had received no formal training in the use of dive-reels, SMBs or lift bags. Very few divers were trained in reel use during their initial scuba certification courses.

There are common threads in the fabric of the incident and survey data.
One common mistake is to attempt to deploy an SMB while the reel is still attached to the diver.
When the reel jams or the line becomes tangled, the hapless diver is usually unable to detach the device, and has little hope of avoiding an express service to the surface.
A certified Divemaster deployed a lift-bag 8m down in the Philippines. According to his incident report, filed with Scuba STAR Network, his line-reel was clipped to his BC. It birds-nested, resulting in an uncontrolled ascent to the surface.
This was a diver who had done more than 600 dives, a quarter of them in the preceding year. Fortunately he did not report any injury.
A similar situation occurred with two divers on a wreck at 38m. According to a BSAC report, one suffered a regulator free-flow and was assisted to the surface by two other divers.
The remaining diver looked round for his buddy, proceeded up the wreck and then deployed a delayed SMB at 17m. The reel jammed and he made a rapid ascent to the surface, missing a planned safety stop on the way.
At the surface he saw the boat crew recovering his buddy and the two other divers. Back on the boat he felt ill, and was airlifted to a recompression facility for precautionary treatment.
Another problem appears to be simply holding onto the reel too tightly during deployment. If it jams or birds- nests, the diver is yanked, often with considerable force, causing injury or at least upsetting his or her buoyancy.
In some cases divers re-establish control and complete a normal ascent. More often, this is not the case.
Entanglements can also be a hazard. One respondent reported that while completing the last part of his open-water certification dive, his instructor asked him to deploy an SMB.
As the device ascended, it caught on the divers octopus, resulting in a rapid ascent to the surface. No injury was reported, but the diver noted that more training was needed.

How often do such incidents occur According to the survey, often enough to cause concern. The majority of the reporting divers (57%) encountered problems with these devices only rarely, but another 29% reported occasional problems, which means one or two out of every 10 dives.
The survey data gives an indication of the relative frequency of the various problems. As shown in Table 2, most common are tangled lines (birds-nesting), reported by nearly two-thirds of the divers.
About half the divers had tangled their lines in equipment. Such situations can be particularly troublesome towards the end of a dive, as the divers air supply runs low, or as he or she approaches a no-stop limit.
Loss of buoyancy control, unplanned ascents and rapid ascents round out the list of the most common problems.

Divers responding to the survey provided valuable insights into procedures that can help prevent problems with reels and surface-seeking devices. Their strategies cover equipment selection, diligent maintenance and adherence to time-proven operating techniques.
A number suggested that when it comes to selecting the tool for the job, low cost should not be the deciding factor. A high-quality reel incorporates design features and materials that enhance its operation and reliability.
That said, a fancy reel isnt always the best option. Several divers recommend using a simple finger spool to deploy a delayed SMB, because it doesnt clip to the diver and is unlikely to drag you to the surface should it jam. Often a simple line-holder may be all thats needed.
A reel may be mechanically simple, but maintenance is critical to its reliable operation.
Experienced divers recommend the following procedures to minimise the potential for malfunctions and failures:

  • KEEP IT NEAT After using a reel, soak it in fresh water, then unwind the line and let if dry thoroughly. Then rewind it with slight tension, neatly and tidily.
    As the line is wound onto the reel, inspect it visually. Run it through your fingers to detect nicks or cuts, and remove any section that is not in good condition.
  • SERVICE REGULARLY Disassemble the reel for inspection regularly. Clean it thoroughly and lubricate all bushings, axles and moving parts before reassembly.
  • NEVER OVERLOAD A reel loaded with more than 75% of its maximum line capacity is more likely to jam as the line is rewound.

    Try these deployment techniques:
  • UNCLIP FIRST Never deploy a buoy with the reel still attached to you or your gear.
    Leave time so that you dont have to deploy an SMB in a hurry. Do it right, paying attention to detail.
    As you begin deployment, hold the reel away from your body, your equipment and your buddy. Failure to do so could result in the line being entangled in someones gear.
    When deploying an SMB in mid-water, some divers recommend first releasing some air from the BC to make it slightly negative. Even when deploying from the bottom, some suggest that, if possible, divers should anchor themselves to reduce the chance of being accidentally pulled upwards.
    Deploy the device slowly to avoid birds-nests. If the reel overspeeds and exceeds the rate of line-deployment, slack will form and can cause a sorry mess. Set the brake to control deployment rate, or apply friction to the reel with your finger.
    Anticipate problems such as entanglements and jammed reels, and leave time and air supply to cope with them. Having a second reel and/or SMB can also save the day if a problem does develop.
Instruction in using reels, DSMBs and lift-bags is not included in many basic training programmes, and this is unlikely to change soon, but even experienced divers are encouraged to seek training in their use.
Accident data suggests that some incidents occur not so much because
of reel malfunction as through task-loading of the diver, and inability to control buoyancy properly during deployment. Controlling buoyancy is complicated by the fact that using
a reel is a two-handed procedure.
By redoubling our efforts in the selection, maintenance and safe operation of reels and associated equipment, we can enjoy the added safety these devices bring to diving.

For full results from the SMB Safety Survey, visit

Table 1: Causes of Reported Abnormal Ascents Incidents
(Source: BSAC Diving Incident Report 2005)
Cause of IncidentsIncidents%
Equipment-Related Incidents (49)
- SMB1920
- Regulator Freeflow77
- Drysuit system66
- Other regulator-related55
- Weight system55
- BC44
- Mask/Fin33
Lost control (poor buoyancy control)1212
Air management44

Table 2: Reported Incidence of Problems
(Source: Scuba STAR Network, 2008)
Problem% Divers Affected
Tangled line65
Equipment entangled in line46
Loss of buoyancy control28
Unplanned ascent17
Rapid ascent17
Stuck valve when inflating lift bag5
Line cut or failure3