Dry Bags

What dry bags are and what they do aboard a sailing boat

Dry bags are soft, flexible sacks made from waterproof fabric and closures intended to exclude water from their contents. Sailors use them to protect clothing, electronics, paper charts, food, spare sails and other buoyant or vulnerable gear from spray, rain and accidental immersion. On a boat they are an everyday piece of kit: used on deck during day sails, carried in a dinghy, stored in lockers, or taken ashore for a beach landing.

Where and how dry bags are normally used

Typical uses include keeping foul-weather gear and personal items dry on deck, stowing sleeping gear below where bilge water or condensation is a risk, carrying provisions ashore, and assembling an emergency grab-bag. They are also used as simple flotation or to keep items together in an anchor locker. Dry bags are portable and usually fast to open and close, so they suit variable conditions and short trips ashore.

Main product types and configurations

• Roll-top dry bags — the most common type. The mouth is rolled several times and clipped to form a seal. Simple, highly reliable for splash and temporary immersion when done correctly.
• Zip-top waterproof bags — use a specialised waterproof zipper. Faster to access but zips can be more vulnerable to grit, salt and pinch damage; maintenance and cleaning matter.
• Compression dry sacks — include straps or buckles to reduce volume once closed. Useful for sleeping bags and compressible clothing; they can also change buoyancy characteristics.
• Backpack or duffel-style dry bags — include shoulder straps or carry handles for shore use and crew transfer. They combine dry-bag sealing with carry comfort.
• Lite ‘packable’ dry bags — low-weight, thin fabrics for occasional use and minimal stowage space; better for day use where long-term submersion is unlikely.

What is included and excluded from this category

This category covers soft, flexible waterproof bags and sacks intended to keep dry contents dry. It excludes rigid waterproof containers and specialised dry boxes, watertight electronics housings, and heavy-duty immersion cases designed for long-term submersion or pressure resistance. It also excludes bags specifically marketed as survival flotation devices — although some dry bags will float when packed with buoyant contents.

Why dry bags matter on a sailing boat

Water is the constant nuisance aboard a yacht. Even modest spray or a few litres of bilge water can ruin electronics, clothing and important documents. Dry bags provide a lightweight, portable, and often buoyant layer of protection that reduces downtime and damage after unexpected wetting. Their portability means dry items can be moved quickly in changing conditions, which is valuable for safety and comfort.

Key decisions sailors should make before buying

Choosing the right dry bag requires matching the product to the boat and the intended use. Key factors include:

• Intended contents: Clothing and bedding need different sizes and compression than small electronics. A phone in a lunch-bag-sized pouch has different closure and visibility needs than a sleeping bag in a large sack.
• Frequency of access: If you’ll open the bag several times a day, a zip-top or a smaller, easily accessible roll-top may be preferable to a bulky roll-and-clip sack.
• Exposure risk: Day sailing with occasional spray needs lighter, more packable bags. Offshore or dinghy work exposed to waves requires tougher fabric, reinforced seams and reliable closures.
• Size and stowage space: Consider locker dimensions and whether the bag must fit standing upright, flat or in a curved space. Compression sacks help shape bulky items.
• Weight and packability: Lightweight fabrics save weight and space but sacrifice abrasion resistance; heavier fabrics resist chafe in anchor lockers and on decks.
• Closure type: Roll-top closures are robust and simple; waterproof zips are convenient but need care. Decide which failure mode you prefer to mitigate.
• Buoyancy needs: If you want floating capability for an overboard bag, choose a design and packing method that traps air or use a specifically buoyant bag. Do not assume all dry bags float when loaded.

Material and construction considerations

Fabric choices influence durability and feel. Common materials include PVC-coated nylon or polyester, PU- or TPU-laminates. Factors to evaluate:

• Denier and fabric weight: Heavier denier fabrics resist abrasion but add weight—useful for deck or locker work. Lightweight fabrics are fine for occasional or shore use.
• Seam construction: Welded seams are common and minimise leak paths. Stitched seams with tape can be strong but require correct tape quality and application.
• UV resistance: UV degrades fabrics over years; look for UV-stable coatings or treat bags with protective care if left exposed.
• Hardware quality: Buckles, D-rings and zips should be corrosion-resistant. Plastic hardware can fail under heavy loads, while metal may corrode without the right alloys.

How to understand common specifications

Specifications are simple but subtle in meaning:

• Capacity (litres): Useful for comparing sizes, but the internal shape matters. A 20 L dry bag’s usable volume depends on how soft or structured its contents are.
• Dimensions: Check length and diameter; a tall, narrow bag fits differently in lockers than a short, wide one.
• Weight: Heavier bags indicate more robust construction, but also more crew load when carrying multiple bags.
• Closure type: Roll-top numbers (eg three-roll closure) are a performance guide. Zippers should be identified as waterproof-rated by the manufacturer and understood to need maintenance.

Beware of marketing language claiming absolute waterproofing. Most soft dry bags are intended to exclude spray and brief immersion; continuous submersion or deep immersion can find weak points at closures or seams.

Compatibility and installation

Dry bags are portable, so installation is rarely structural. Still check:

• Locker and shelf dimensions to ensure the chosen size fits.
• Attachment points if you plan to lash bags to rails, lifelines or stanchions — use purpose-made clips or lashings and avoid overloading small fastenings.
• Carry and access routes: can you reach the bag in foul weather without removing other gear?

Day sailing, coastal cruising and offshore considerations

Day sailing

Prioritise simplicity and low weight. Smaller roll-top pouches and a medium duffel for foulies will usually suffice. Quick access and packability matter more than extreme abrasion resistance.

Coastal cruising

Expect wet lockers and occasional heavy weather. Use heavier fabrics, consider compression sacks for bedding, and keep at least one bag for electronics in a zip-sealed pouch inside a larger roll-top bag.

Offshore and remote cruising

Redundancy and longevity matter. Carry multiple bags sized for grab-bags, survival kits and electronics. Choose robust materials, keep replacement buckles and a spare zip-sleeve if possible, and test whether packed bags float or how they behave under immersion.

Trade-offs to weigh

• Weight vs durability: Lighter bags save carry weight but wear faster.
• Speed of access vs security of seal: Zips are quick; roll-tops arguably more secure against prolonged soaking.
• Packability vs structure: Structured or pannier-style dry bags keep shape but take more space when empty.
• Floatation vs storage volume: Trapping air to make a bag float reduces usable storage or changes how items are packed.

Maintenance and service life

Dry bags need modest care to last:

• Rinse with fresh water after salt exposure and dry fully before long storage to prevent mould and coating degradation.
• Inspect seams and closures regularly for wear, pinholes or damaged welds.
• Lubricate and clean zips with fresh water and suitable zipper lubricant; avoid grit inside the mechanism.
• Replace worn buckles or carry spare attachment points for long cruises.

Common mistakes sailors make

• Buying solely on labelled litres without checking shape and locker fit — consequence: bag won’t stow where needed.
• Assuming all dry bags float — consequence: a sunk bag can mean lost gear unless flotation was planned.
• Over-reliance on a single bag for all needs — consequence: no redundancy if that bag fails or is lost overboard.
• Using zips without maintenance in salt environments — consequence: zipper failure or leakage at the closure.
• Choosing a bag too heavy or bulky for day crew to carry comfortably — consequence: crew use declines and items get left on deck.

Before buying: practical checklist

• Define the main uses (electronics, clothing, sleeping gear, grab-bag) and list typical contents.
• Measure the locker or storage space where the bag must fit; note any height or width limits.
• Decide how often you need access and whether quick-opening zips are worth extra care.
• Choose materials and denier appropriate to abrasion risk and weight constraints.
• Check closure type, seam construction and where hardware attaches; ask about replacements for buckles and straps.
• Consider buoyancy requirements and test a filled bag to verify whether it floats as you expect.
• Ask a supplier about care and cleaning recommendations specific to the material and any warranty scope for seam failures.

Prioritise choices that match how you sail: choose lighter, more portable bags for frequent shore trips and rugged, well-built bags for coastal or offshore cruising where reliability and redundancy matter most. A practical mix of sizes and types usually suits most boats rather than a single ‘do-it-all’ bag.