Scuba dive or snorkel?

Yachting Monthly - - EXPERT ON BOARD -

Snorkelling and scuba div­ing are both means of breath­ing un­der wa­ter so you don’t have to sur­face for each breath. Snorkelling lim­its you to re­main­ing on or very close to the sur­face but re­quires very lit­tle equip­ment, while scuba div­ing uses pres­surised air to let you go deeper and stay down far longer.

It’s of­ten been sug­gested to sim­ply ex­tend your snorkel with a hosepipe or sim­i­lar. While this sounds like a great idea, the laws of physics and bi­ol­ogy mean your lungs can­not suck in air when your head is deeper than 18in un­der wa­ter. The air pres­sure at the sur­face is much less than the weight of wa­ter squeez­ing your lungs, and your lungs are not strong enough to in­hale against it. Us­ing a pipe longer than 18in also means a swim­mer would be reusing the same air with an in­creas­ing CO2 con­tent, which can lead to a dan­ger­ous lack of oxy­gen. Sys­tems that send com­pressed air down from the sur­face to a breath­ing reg­u­la­tor are achiev­ing the same thing as a scuba set and this risks of breath­ing com­pressed air at depth re­main ex­actly the same.

Scuba div­ing is not a solo ac­tiv­ity and should al­ways be done in pairs. When work­ing un­der the boat, it is pos­si­ble for your buddy to be on board rather than in the wa­ter along­side you as long as you have a safety line. If you know what you are do­ing and how to mitigate the in­her­ent risks, scuba div­ing is in­cred­i­bly safe. A lack of knowl­edge or ex­pe­ri­ence is the most dan­ger­ous thing.

There are a num­ber of ‘spare air’ prod­ucts on the mar­ket, as used by Amer­ica’s Cup teams. These are re­ally only for emer­gen­cies and an in­ex­pe­ri­enced diver will use up the air sup­ply within just a few breaths, so they aren’t a prac­ti­cal so­lu­tion on board.

Scuba div­ing

Scuba div­ing will let you spend a much longer time un­der wa­ter, which means you can do more ma­jor jobs like clearing a badly fouled pro­pel­ler or check­ing the an­odes and skin fit­tings. Scuba div­ing is not that com­pli­cated and learn­ing is not hard, but if you don’t know what you’re do­ing and don’t un­der­stand the risks, there is the po­ten­tial to hurt your­self, as with any sport. It is also a re­ally en­joy­able ac­tiv­ity to add on to your sail­ing. Some of the world’s best div­ing is to be had in wa­ter shal­lower than 9m, where there is very lit­tle risk of bends. If you have a dive buddy and some­one on the sur­face keep­ing a look­out, you will have the free­dom to ex­plore the amaz­ing ma­rine life that is found be­neath the sur­face around the UK coast­line as well as more ex­otic lo­ca­tions. It is huge fun.


You will need a cer­tain amount of equip­ment to scuba dive. The basics in­clude an air tank with back­straps, a reg­u­la­tor and a gauge, but most sets will also have a buoy­ancy com­pen­sator de­vice and a spare reg­u­la­tor. A ‘sailor’s set’ or mini-scuba setup is the most pared-down ver­sion, fol­lowed by a Mini-b and then the full scuba set (see over for de­tails). Al­ter­na­tively, in many of the places you might want to dive, it is quite easy to hire kit and to go out with lo­cal dive boats, par­tic­u­larly if you’re al­ready trained. If you are go­ing off on a se­ri­ous cruise, it is worth con­sid­er­ing tak­ing ba­sic scuba div­ing kit with you whether you can dive or not. In re­mote places, you won’t be able to haul out and the chances are that some­one on a boat nearby knows how to dive but doesn’t have their kit with them.


A bit of train­ing goes a very long way in keep­ing you safe. While you can do a one-day mi­cro-dive course to see if you like it, it only qual­i­fies you to dive to depths of 5m with an ex­pe­ri­enced diver. The first rung on the lad­der is the PADI Open Wa­ter Course. It in­cludes the­ory and prac­ti­cal both in­doors and in open wa­ter. You will be qual­i­fied to dive to depths of 18m or deeper with an ex­pe­ri­enced diver. It gives you enough knowl­edge to safely go un­der your boat with scuba gear and to make in­formed judg­ments about safety.

Over four days, you’ll learn how to wear the kit, get in and out of the wa­ter, breathe nor­mally un­der wa­ter, con­trol your buoy­ancy, work and com­mu­ni­cate with your dive buddy and deal with prob­lems like clearing your mask or giv­ing your buddy air. These skills are suf­fi­cient to be able to scuba dive, wher­ever you find your­self sail­ing.

You should never use scuba kit with­out proper train­ing. Even at 3m, you have the po­ten­tial to re­ally hurt your­self if you don’t know what you are do­ing.

There are other cour­ses and be­spoke train­ing avail­able too, as well as train­ing for fam­i­lies.

Scuba div­ing hugely in­creases the time you can spend un­de­wa­ter, if you’re trained

When snorkelling, hands be­hind your back will help you re­lax. Slow finning is enough to pro­pel you for­ward

Once you’re used to the equip­ment, be­ing un­der wa­ter can be a lot of fun

Work­ing to­gether with a buddy is a large part of scuba train­ing

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