Features September 2017 Issue

Compact Scuba Kits for Sailors

Mini SCUBA Kits Can Save Your Skin

In general, many cruisers prefer the freedom of snorkeling to scuba diving, yet there are situations when extending the time you can spend underwater becomes a safety issue.

Scuba gear is useful for clearing a fouled prop, freeing stuck anchors, replacing zinc anodes, making underwater repairs, and of course, sightseeing, however, it is heavy and cumbersome, particularly if one is working in the vicinity of the prop or rudder in any kind of a seaway.

Hookah-type alternatives to scuba such as SNUBA, Brownie’s Third Lung are an option but you are then tethered by and at times limited by the length of the air hose.

Another alternative is using a small or ultra-small scuba tank which offers autonomy and freedom.

compressed air kit
Applying grease to the folding prop is made easier with a portable compressed air kit.

Several years ago I decided to eliminate my scuba tank which was stowed under the V-berth, in order to make room and save weight for the installation of a bow thruster. In a dive shop I found Spare Air, a very small scuba tank and regulator sold as an emergency back-up for scuba divers. Of the two sizes available, the larger (3.0 cu. ft., $320) is preferable. It comes with an adapter allowing it to be filled in 45-60 seconds from a scuba tank. As I no longer have a larger tank aboard to fill the Spare Air from, I have it filled in dive shops. About half the time, the shops have refused payment for such a small amount of air, and the other half have charged $10 or less.

The amount of floating lines plus cargo and fishing nets on the world’s oceans is alarming. During one Atlantic crossing we had to heave-to and get into the water four times to untangle nets and lines from our rudder and prop. Usually I can hold my breath long enough to clear the prop or rudder, but there have been several times when I’ve needed to use my Spare Air.

A few years ago in Fiji, changing wind and currents caused our anchor chain to shift from the sandy area where we’d dropped the anchor to instead become wrapped around a mushroom-shaped coral head. With excellent water clarity in the 70-foot depth, I snorkeled over the anchor and directed our helmsperson to let out a little more chain and slowly motor around to unwind the chain. This only caused the chain to become more tangled. Using the Spare Air, I pulled myself hand-over hand down the chain, physically lifted the chain free of the coral head and just made it back to the surface. This was only time I wished the Spare Air had a little more capacity.

At recent boat shows I’ve seen the very impressive package that Mantus (same company that makes the anchors) is selling containing a 13 cu. ft. aluminum tank, backpack, regulator, and spare regulator all in a compact, waterproof storage backpack for $600. The advantage of this package is four times the air capacity giving 15 – 20 minutes of working time at 30 feet, but the drawback is a little more bulk and weight; 15 pounds vs. 2 pounds for the Spare Air.

Ocean racers take note: Following the death of Andrew Simpson when the Swedish catamaran capsized in the last America’s Cup, crew members started carrying Spare Air as part of their safety gear. If dealing with escape from a capsized boat (monohull or multihull), Spare Air could prove useful.

It is essential that anyone using a compressed air cylinder underwater first completes a dive course. Holding one’s breath while ascending after having breathed compressed air can be fatal, even when coming up from relatively shallow depths. Any scuba tank (including Spare Air) needs annual visual inspections and a hydrostatic test every five years.

Comments (9)

Hi Surazo,

First, before getting any kind of air system I strongly recommend getting dive training. Even diving 2-3 meters under a boat can have risks when breathing air from a tank or even a Hookah system.

A small system that is very portable would be to buy a small tank and a regular SCUBA regulator for it. If cutting rope or net around the prop the little Spare Air system would probably not give you enough air.

The most common, standard tank is an aluminum 80, rated for 80 cubit ft in US standards. These are a little large if you have a small boat so a 20 or 40 cubic foot tank would be better and should have enough air for all but the most difficult jobs. As someone mentioned, to get a SCUBA tank filled at a dive shop you will probably have to show your dive training certification card.

Posted by: skipmac | August 20, 2017 10:29 AM    Report this comment

I rode all the opinion and all of that gave an additional point of view ,but I'm only a sailor that need cut a rope or net under the boat equal as the most of the sailor .Which type of bottle is recommended or this minikit is enough?

Posted by: surazo | August 16, 2017 4:26 PM    Report this comment

This article needs to differentiation between checking props and bottom condition on one hand and emergency substitution for SCUBA gear. If;, as some suggest , the small tanks can't be filled without SCUBA certification, that should be stated up front.

Posted by: gdecon | August 14, 2017 3:19 PM    Report this comment

This article needs to differentiation between checking props and bottom condition on one hand and emergency substitution for SCUBA gear. If;, as some suggest , the small tanks can't be filled without SCUBA certification, that should be stated up front.

Posted by: gdecon | August 14, 2017 3:19 PM    Report this comment

I don't usually comment, but having worked search and rescue (most often recovery) this needs emphasis. As another poster already commented, using 3 cubic feet of air to descend to 70 feet is not a good idea. Doing it to do work is an even worse idea. The Spare Air website states three cubic feet is enough for up to 57 breaths. That is presumably at shallow depths or assumes an emergency descent from depth. At 70 feet, those 57 breaths are more like 17 breaths and are intended for a diver making an emergency ascent from that depth. A safe ascent rate is between 30 - 60 feet per minute, so at best 70 feet calls for a minimum of 70 seconds to reach the surface.

Assuming a diver got down to 70 feet without weights in one minute, once there they would be lucky to have ten breaths of air left at that depth and essentially be counting on the expansion of the air in the tank to cover them for the 70 seconds to surface. Divers are trained to be heading for the surface when they have 500 PSI of an 80 cubic foot tank left. A diver with a three cubic foot tank is basically starting with well under that 500 PSI limit.

In reviewing dive accidents the common take-away was that most divers can survive one thing going wrong, but often not two. A dive buddy obviously enhances safety. Descending past one atmosphere on limited compressed air is already doing one thing wrong. Doing it solo eliminates whatever safety net may have been there.

I appreciate the write-up on Spare Air as I have been debating whether to deal with SCUBA tanks aboard or to go with the Mantus system. I like the idea of Spare Air for clearing the prop, for emergencies, etc. I'm sure the author knows his capabilities and made a considered decision for himself that he may have already re-considered after running out of air (it's happened to me, too). In this instance, it just seemed best to underscore for less experienced divers the risks involved in using such a small quantity of air as if it were at least a Mantus system - which incidentally is a 19 cubic foot cylinder recommended by the manufacturer for dives no deeper than 45 feet.

Posted by: Elzaar | August 14, 2017 5:23 AM    Report this comment

Whoa!! Did you say you dove a 70 foot chain drop by yourself with a puny spare air tank?? And ended up out of air at end of dive?? I think you need to correct a disservice you did to all those non diver sailors who may now think what you did was somehow "ok". Not according to any dive organization anywhere. You're lucky you didn't pop some alveoli!!

Posted by: skipjack 61 | August 13, 2017 5:00 PM    Report this comment

I saw one advertised recently that could be refilled with a foot pump or small compressor. 10 mins of air and refill on your own boat. handy.

Posted by: Cpt Dick | August 13, 2017 1:09 PM    Report this comment

As a diver with 45+ years diving experience in all conditions I read with interest Mr. Neal's article on Spare Air (and the Mantus package). My only concern with his article is that he mentions the dangers of using Spare Air (or any compressed air) at the very end of the article and not at the beginning.

"It is essential that anyone using a compressed air cylinder underwater first completes a dive course. Holding one's breath while ascending after having breathed compressed air can be fatal, even when coming up from relatively shallow depths. Any scuba tank (including Spare Air) needs annual visual inspections and a hydrostatic test every five years."

I would have preferred if this caution had been at the very beginning of the article in bold letters. As stated by Mr. Neal, the improper use of compressed air can cause, among other medical issues, arterial gas embolisms (AGE) which can be fatal if not medically/hyperbarically treated immediately. These days it is easy to take a SCUBA class and get certified. Among the many safety issues one will learn is a cardinal rule of divers - NEVER HOLD YOU BREATH ON SCUBA. NEVER!!!

Posted by: Sea Hunt Video | August 13, 2017 11:26 AM    Report this comment

A Spare Air can be handy but as you noted, the time it gives you is extremely limited. If doing anything strenuous like cutting lines or nets away from a prop or deeper like freeing the anchor rode a small tank and regulator is a much better option. I have several smaller tanks including 10, 20 and 40 cu ft sizes. Would store in a much smaller space than a standard Al80 but will be I think, much more useful than the Spare Air for boat jobs.

On the other hand, for emergency use or self rescue, a Spare Air could be a lifesaver and you can probably fit one in a large foul weather jacket pocket.

Posted by: skipmac | August 13, 2017 9:21 AM    Report this comment

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