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Teaching with SDI. What are the differences?

When you switch to SDI from another agency there will be some things that are very similar and some things that are different. This article is intended to lay out the differences and similarities in order to make it easier for an instructor who is used to teaching with one agency to feel comfortable teaching with SDI.

Let’s start with the things that are similar. Diving physics is the same no matter what agency you are teaching for, equally there are only so many ways to clear a mask so the principles of what you will be teaching remain the same.


The SDI course structure is broadly similar to other agencies with a few significant differences.























Many of the SDI courses map directly onto similar courses with other agencies. Our Open Water course is broadly comparable with other agencies OW course, as is Scuba Discovery, Rescue Diver and Dive Master. The main difference is that we do not have an Advanced Open Water course. SDI has an Advanced Diver course but this requires significantly more experience than a traditional AOW course. Specifically, an SDI Advanced Diver must have 25 logged dives and 4 specialities. Once they have gained this experience they can apply for the Advanced Diver card as a recognition of their experience. The equivalent to other agencies AOW course is SDI Advanced Adventure. The reason for this change is that in other agencies the jump from AOW to Rescue is a big jump and many people are put off making that jump. With SDI once you have OW then Advanced Adventure is a manageable next step. Once you have completed this, Advanced Diver is achievable and once you are an Advanced Diver, Rescue Diver is an achievable step. This means that by having a progression of courses the student always has an achievable goal to aim for. This keeps them engaged in diving, keeps them improving their skills and, of course, keeps them as a customer.

The SDI Open Water course has a similar structure to most other agencies in that the training is split into 4 sections;

  • Self-study theory (either online or with a paper manual)

  • Face to face theory with an instructor

  • Confined water training

  • Open water training

The student can choose between doing the theory online or using a traditional paper manual. Once the student has completed the self-study the instructor will carry out the face to face training and give the student a chance to review the material, ask any questions, discuss local examples or practices and ensure that they have fully understood the materials. One difference with SDI is that we believe that e-learning (or a paper manual) does not replace face to face instruction. It doesn’t matter if the student has reviewed the paper manual or completed the e-learning we still expect the instructor to spend time going through the materials face to face to ensure that they have fully understood the concepts and can apply them in a real-world setting.

During the face to face theory the instructor is not forced to sell additional training, equipment and travel. The primary focus of the academic sessions is education not sales. Of course, there are times when it is entirely appropriate to mention additional training, equipment or travel but this should only be done when it makes sense in order to satisfy the students diving goals rather than being mandatory in every session.

When the student progresses to confined water, the basic skills remain the same. SDI, PADI, SSI and a number of other agencies are all members of the Recreational Scuba Training Council (RSTC) as well as being accredited by the European Underwater Federation (EUF) as meeting the EN standards for diver training. This means that the basic skills in each course are agreed and must be covered.


The difference with SDI is that we do not mandate which skills must be done in each confined water session. For example, if a student is struggling with mask clearing some agencies insist on persevering with that skill as a you cannot go on to the next confined water session without completing all the requirements for the current CW session. This can lead to instructors forcing their students to continually try mask clearing until they either get it or alternatively give up or develop a lifelong aversion to mask clearing. With SDI you are able, even encouraged, to move skills around to reflect the number and abilities of the students. If they are struggling with mask clearing then switch to another exercise and build up their confidence then come back to mask clearing in another session.  Of course, all students must complete all skills by the end of the confined water sessions but they can do them in any order.

This is just good teaching practice and most good instructors do this anyway. The difference is that SDI standards allow and support the instructor in using this flexibility to provide better instruction for their students.


Another difference with SDI is we encourage students to become neutrally buoyant as soon as possible. It is common for SDI instructors to focus the first confined water session purely on buoyancy, trim and finning. Once they are comfortable with buoyancy they can then move on to the other skills such as mask clearing and regulator recovery. After all, we want students to be able to maintain buoyancy in the open water rather than having them do all of the skills on their knees. This is summed up in a key phrase “Teach divers, not skills”. We always want to think about the end goal of creating a confident diver rather than just completing a tick box list of skills. 

Of course, if the student is struggling with buoyancy control, the flexibility of teaching methods allows the instructor to switch things around and teach some skills while the students are on their knees and then return to buoyancy control in a later session.


This flexibility means that instructors have the ability to structure the course with a varying number of confined water sessions. There must be at least 4 confined water sessions but the instructor is free to add additional sessions in order to ensure the diver is comfortable in the water before going on to open water.

SDI also mandates that all students learn how to use a computer from their first confined water session. Most students will go out and buy a computer as soon as they qualify so why not teach them how to use it safely right from the beginning. SDI standards state that all students must use a computer on all confined and open water dives. Instructors can teach tables if they think it will help a student to understand the principles behind a computer but it is not mandatory.

In open water we also focus on buoyancy and creating divers. By the time the student has completed confined water training we would expect them to have a good grasp of buoyancy control and be able to do most of the open water skills while maintaining neutral buoyancy.

Just like in the confined water session the instructor is free to structure each open water session in a way that makes sense for the environment and the students.  It is common for SDI instructors to say that on the first dive the students are not going to do any skills, just have a fun dive. However, in “just having a fun dive” the student will still need to assemble their equipment, perform a buddy check, enter the water, descend, demonstrate finning techniques and buddy awareness, show a controlled ascent including a safety stop, exit and disassemble their kit. In reality they have done plenty of skills but they have had a great time and learnt in a real situation. This is what we mean by “teaching divers, not skills”.

All of this means that an experienced instructor should be able to start teaching SDI courses very quickly. There will always be a temptation to fall back on what you know but most good instructors will find it easy to incorporate the advantages of SDI training. In fact, it may quickly feel very comfortable as the SDI system allows the instructor to use flexible teaching techniques and so they can use all the creative teaching techniques that they have built up over time without having to worry about whether it is consistent with a rigid way of teaching the skills.

(Courtesy Mark Powell)

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