Butt Plate vs No Butt Plate
Overview
One of the most debated configuration choices in sidemount diving is whether or not to use a butt plate. While both approaches are widely used and effective, the decision is not arbitrary. It is driven by the style of sidemount harness and wing a diver chooses to dive with and the cylinder characteristics and how those cylinders interact with the diver’s trim, buoyancy, and attachment geometry.
This isn’t a question of preference alone, but of matching equipment configuration to cylinder behavior in the water.
Cylinder Buoyancy and Its Impact
Diving Without a Butt Plate
Diving With a Butt Plate
The Role of Wing and Harness Design
Choosing the Right Configuration
Practical Considerations in the Water
Final Thoughts
Cylinder Buoyancy and Its Impact
The primary factor influencing this decision is the difference between aluminum and steel cylinders.
Aluminum cylinders are relatively light and approach neutral buoyancy during the dive. As gas is consumed, they become increasingly positive, requiring active management to maintain proper trim. This is why many divers choose to have multiple D-rings along the waist strap or to use sliding D-rings on the waist strap. This means that aluminum cylinders can be clipped closer to the diver’s centerline.
Steel cylinders behave very differently. They remain negatively buoyant throughout the dive and are heavier overall. This creates a downward pull that must be managed carefully to prevent the cylinders from dropping below the diver’s profile.
This difference in buoyancy characteristics is what drives the need for different attachment strategies.
Diving Without a Butt Plate
Configuration
In a setup without a butt plate, cylinders are typically clipped to:
- Standard waist D-rings
- Sliding D-rings
- Offset waist D-rings
- Crotch strap D-rings (rear-mounted)
This configuration keeps the system streamlined and minimal.
Advantages
- Simplicity and reduced hardware
- Cleaner profile with fewer entanglement points
- More flexibility in cylinder positioning
- Ideal for aluminum cylinders
Because aluminum cylinders are not as negatively buoyant, even at the beginning of the dive when full, they can be secured closer to the diver’s sides without compromising trim and leave rear D-rings available for other items.
Limitations
The main limitation arises when diving with steel cylinders. This is partly because of the negative buoyancy characteristics of most steel cylinders, as well as the design characteristics of some sidemount rigs.
Manufacturers of many sidemount systems position the wing lower along the back to compensate for heavier feet when diving steel cylinders (this is another topic covered in detail in the Sidemount Diving Guide). This results in the waist harness being covered by the wing and blocking access to traditional rear D-ring positions. Without a butt plate, this leaves limited options for attaching heavier cylinders in a way that maintains proper alignment.
Diving With a Butt Plate
Configuration
A butt plate introduces dedicated rear attachment points positioned behind the diver’s hips. These are typically fixed rails attached to a semi-rigid plate that is positioned below the waist strap and held in place by the crotch strap. Butt plates allow attachment of the body of the cylinders at a location that is not available on many sidemount rigs because of the wing placement.
Advantages
- Optimized positioning for steel cylinders
- Improved trim with negatively buoyant tanks
- Reduced interference from wing placement
Limitations
- Additional hardware
- Less flexibility compared to minimalist setups
The Role of Wing and Harness Design
A key factor often overlooked is how the wing interacts with the harness. Many sidemount systems position the wing so that it overlaps the waist strap on the diver’s back. This design improves buoyancy distribution as long as the wing is fully functional, but it blocks access to traditional rear D-rings.
This is where configuration choices become critical:
- If the wing allows access → standard or offset D-rings may be sufficient
- If the wing blocks access → rearward attachment becomes limited
Choosing the Right Configuration
The decision comes down to a few key considerations:
Use a Butt Plate When:
- Diving primarily with steel cylinders
- Additional rearward attachment is required
- Wing design restricts access to optimal D-ring positions
- Maintaining trim with negative cylinders is a challenge
Skip the Butt Plate When:
- Diving primarily with aluminum cylinders
- A minimalist, streamlined setup is preferred
- Offset or crotch strap D-rings provide sufficient positioning
- Flexibility and simplicity are priorities
Practical Considerations in the Water
Regardless of configuration, proper trim is the ultimate objective when diving sidemount.
A well-configured sidemount system should allow cylinders to:
- Remain positioned parallel to the diver’s body
- Remain stable throughout the dive
- Be easily adjusted as cylinder buoyancy changes
- Not interfere with other aspects of the sidemount rig
If cylinders are able to be secured in a streamlined manner along the sides of the diver, the issue is not preference, it is configuration mismatch.
Final Thoughts
The choice between diving with or without a butt plate is not about which system is better, but about which system is appropriate for the equipment being used. There are many factors involved in this decision.
Aluminum cylinders favor simplicity and flexibility, making butt plates largely unnecessary. Steel cylinders, with their weight and negative buoyancy, often require more deliberate rearward attachment. This is something a butt plate is specifically designed to provide.
In sidemount diving, configuration is not static. It evolves with environment, equipment, and experience. The most effective setups are those that align these elements into a system that works with the diver, not against them.
Readers of this article can receive $10 off the book Sidemount Diving or $5 off the book Recreational Sidemount Diving when purchasing directly from the website.
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Frequently Asked Questions
Do you need a butt plate for sidemount diving?
No. It depends on cylinder type. Aluminum cylinders typically do not require a butt plate, while steel cylinders often benefit from rearward attachment points.
Why use a butt plate in sidemount?
A butt plate allows cylinders to be clipped farther back, improving streamlining when using negatively buoyant steel tanks.
Related Articles
How to Set Up a Sidemount Harness
How to Choose the Right Sidemount Cylinders
Proper Sidemount Cylinder Rigging: What Matters Most
How Sidemount Bungees Work (And Why they Matter)
Why Your Sidemount Cylinders Are Floating (And What It Means)
Common Modifications of the Dive Rite Nomad
For a complete overview of how these elements work together, see The Complete Guide to Sidemount Diving Configuration.