Twinset or Sidemount? Making the Right Choice for Your Next Adventure

When progressing in your scuba diving journey—especially into the realm of technical or advanced recreational diving—you’ll likely encounter a key equipment choice: Should you dive with a twinset (backmount doubles) or sidemount configuration? Both systems offer unique advantages and have passionate supporters. Here are a few things to consider when trying to decide which configuration is best for you.

Twinset (Backmount Doubles): In a twinset setup, two cylinders are mounted on your back, connected by a manifold. This traditional configuration is the standard for many technical diving courses and is commonly used in deep, wreck, and decompression dives.

Advantages:

• Familiarity: Many divers progress from single tank to twinset, making the transition easier.
• Streamlined profile: Keeps hoses, regulators, and tanks close to the body—especially useful in tight spaces.
• Balanced Buoyancy: The symmetrical position of tanks helps maintain balance and trim in the water, especially when properly weighted.
• Standardization: Twinsets are standard in most technical diving centers worldwide, making it easier to find training, rental equipment, and team familiarity.
• Redundancy: With two separate regulators and valves, you have reliable backup in the event of equipment failure.
• Gas Management: The manifold system allows easy isolation and management of the gas supply between the tanks.
• Simplicity: Stage cylinders are easy to remove and replace and can be carried in either ‘lean left’ or ‘rich right’ positions, depending on the diver’s preference.

Considerations:

• Out-of-water weight: Twinsets are bulky and heavy, potentially making them difficult to lift, don, and walk long distances in, especially on moving boats, for shore diving, or for those with physical limitations.
• Access to valves: Accessing the valves can be difficult for some divers.
• Limited availability: Finding twinset cylinders and suitable manifolds may be challenging in remote or less technologically advanced dive destinations.

 Sidemount: Sidemount involves mounting cylinders along your sides rather than on your back. Originally popularized by cave divers, it’s now mainstream for caves, wrecks, open water, and technical diving.

 Advantages:

• Customizable Setup: The sidemount harness and cylinders can be configured and tailored to meet your specific needs. This can aid in advanced comfort and result in achieving proper trim.
• Comfort: Sidemount places the cylinders on the side of the body, reducing strain on the lower back.
• Easier Equipment Transportation: Tanks can be donned before entry or once the diver is in the water. They can also be carried separately to the water, reducing the impact on the back and knees, while making shore and boat entries more manageable.
• Flexibility: Sidemount allows you to carry as few as 1 cylinder or multiple cylinders, depending on your gas needs and dive profile.
• Improved Accessibility: All valves and regulators are in front of you, making it easier to identify and resolve issues underwater.
• Streamlined Profile: When properly configured, sidemount offers a narrow profile ideal for navigating through restrictions or tight spaces.
• Enhanced Safety: In case of entanglement or emergency, tanks can be quickly removed or repositioned.

Considerations:

• Skill Development: Sidemount requires adapting to new equipment and procedures, especially to maintain optimal trim and manage hoses effectively.
• Configuration: Not all dive boats or destinations are sidemount-friendly (e.g., cylinder availability, space on boats).
• Team compatibility: If your dive buddies use backmount, sidemount protocols may differ.

How to Decide:

1. Assess Your Diving Environment: If you’ll be diving caves, wrecks, or places with tight restrictions, both configurations work, but sidemount shines for tight penetrations. For open water technical dives, twinset is often the default.
2. Consider Your Physical Needs: If you struggle with heavy lifting or have back issues, sidemount may be more comfortable.
3. Think About Logistics: Are rental sidemount cylinders available at your destination? Are your dive buddies and instructors familiar with your chosen setup?
4. Training and Support: Both systems require proper training. Choose a configuration that your local dive community and instructors can support.
5. Personal Preference: Ultimately, try both if possible! Comfort, confidence, and enjoyment are the most important factors.

Conclusion:  Both twinset and sidemount have proven their value for technical and advanced recreational diving. Your best choice depends on your diving goals, physical needs, and the environments you wish to explore. With proper training, you’ll find that either configuration opens new possibilities underwater.

Once you have decided on the configuration you prefer, you will need to begin acquiring the equipment needed for your next adventure.  Here is a list of the minimum equipment you will need to get started on your SSI Extended Range journey:

Minimum Twinset Total Diving System

◦  A backplate or soft pack with a harness

◦  A buoyancy wing with appropriate lifting capacity for the planned dive

◦  A backup buoyancy device: dry suit, double-bladder wing, or lift bag

◦  One delivery system that has a regulator with a

1.8-to 2.1-meter hose

◦  One delivery system that has a regulator with a 50-to 75-centimeter hose, neck retainer, and an attached SPG

◦  One set of double cylinders with an isolation manifold

◦  Two integrated depth and timing devices

◦  Stage cylinder(s) with delivery systems that each have a 15-to 25-centimeter hose and attached SPG

Minimum Extended Range Sidemount Total Diving System

◦  Buoyancy compensator with sufficient lift capacity for the planned dive

◦  A backup buoyancy device: dry suit, double-bladder wing, or lift bag

◦  An industry-approved sidemount harness

◦  One delivery system that has a regulator with a

1.8- to 2.1-meter hose

◦  One delivery system that has a regulator with a 50-to 75-centimeter hose and neck retainer

◦  Two cylinders with independent valves

◦  Submersible pressure gauge with a 15- to 25-centimeter high-pressure hose (all cylinders must have an SPG attached)

◦  Two integrated depth and timing devices

◦  Stage cylinder(s) with delivery systems that each have a 15- to 25-centimeter hose and attached SPG

For either configuration: 

◦  Two masks

◦  Fins

◦  Exposure suit appropriate for the environment

◦  Two cutting devices

◦  A compass

◦  Two signaling devices for deploying from depth (red and yellow delayed surface marker buoys are recommended, but follow local guidelines)

◦  A reel or spool (appropriate for the maximum planned depth)

◦  One surface signaling device (whistle or similar)

◦  Extended Range Dive Planning Sheets

◦  Wet notes or slate for dive plans

Need additional help deciding which configuration or equipment to choose?  Our trained professionals at Tank'd Pro Dive Center are here to help you.