Race Crew Backpacks: What We Look For

This is a research note, not a rated review. Where we cite performance figures they are the published or standard properties of a material or component; we have not yet run these bags through a season ourselves, and any bag-specific claim would need verifying against the maker's data.

A race crew bag is unglamorous but load-bearing kit: its job is to get a full day's gear to the boat dry, hold wet and dry apart, survive a hard life on non-skid, docks and gunwales, and carry comfortably when you are already spent. Get it wrong and you sail in a damp mid-layer, or find your phone swimming in the base. This note is about the engineering: how the two waterproofing philosophies actually work, the coating chemistry and hydrostatic-head numbers behind "water-resistant" versus "waterproof", how welded and stitched seams differ structurally, the mechanism inside a waterproof zip and its pressure ceiling, the fabric-durability metrics that matter, and how the choice plays out on a Grand Prix one-design campaign like a Melges 40.

Waterproof versus water-resistant: the physics behind the words

The two terms describe two different constructions, and the gap between them is measurable. Textile water resistance is quantified as hydrostatic head — the height of a water column, in millimetres, a fabric holds before it wets through, per the ISO 811 pressure test. The number is set almost entirely by the coating or laminate, not the base cloth.

A water-resistant bag is a woven fabric (typically Cordura nylon) with a polyurethane (PU) coating applied at roughly 50 to 200 g/m². That buys a hydrostatic head somewhere between about 1,000 and 5,000 mm — enough to defeat driven rain and spray, which impose only a few hundred millimetres of equivalent pressure. But the panels are sewn, and every stitch is a needle hole. Seam tape bridges the holes from the inside, yet a sewn bag under a standing puddle or a hosing — where local pressure and dwell time climb — will eventually weep at the seams and the zip. It sheds water; it does not exclude it.

A fully waterproof bag is a different object structurally. Its panels are joined by high-frequency (HF, also called RF or dielectric) welding: an electromagnetic field excites the polar molecules in a thermoplastic coating (PVC and TPU are dielectrically active; that is precisely why they weld and why plain PU-coated nylon does not) so the two layers melt and fuse into one continuous shell. A correctly tuned weld is as strong as, or stronger than, the parent fabric, because it is not an adhesive bond or a line of thread bearing point loads — it is the same material, homogenised, with no needle holes at all. Closure is either a roll-top or a genuine pressure-rated zip. Materials sit at the top of the head scale: PVC tarpaulin around 3,000 mm; TPU film laminates commonly 10,000 to 20,000 mm and higher with thicker film. These bags hold out submersion, not merely spray.

The trade-off is real. Welded, roll-top bags surrender internal organisation — fewer pockets, one large chamber, stiff cloth that will not pack down. Sewn water-resistant bags give you pockets, dividers, laptop sleeves and softer fabric, at the cost of absolute waterproofing. For most crew the honest answer is a system, not a single bag: a coated water-resistant holdall for the bulk of the kit, carrying a small HF-welded dry bag inside it for the handful of items that cannot get wet. You then match protection to each item instead of paying the waterproof penalty on everything.

Closures: roll-tops, welded zips, and their pressure limits

The closure, not the panel, is where a waterproof bag usually fails, so it is worth understanding how each type actually seals.

A roll-top is a friction and labyrinth seal. You purge most of the air, fold the stiffened opening back on itself three to four times, and clip it. Each fold forces water to negotiate another reversal against fabric held in compression by the buckle tension; three folds is the practical minimum for a reliable seal, four is better, and a deliberately retained cushion of air keeps the bag buoyant if it goes over the side. The failure mode is instructive: overfill the bag and the roll runs short, you get fewer folds, and the seal opens. This is the mechanical reason to buy volume you will not fully use.

A waterproof zip replaces the labyrinth with a moulded, pressure-tolerant chain. TIZIP MasterSeal is the recreational benchmark: extra-strong plastic teeth on a TPU-coated tape, certified to IPX8 after thousands of operating cycles, holding up to roughly 1.0 bar (14.5 PSI), equivalent to about 10 metres of head. TIZIP is candid that IP ratings describe a lab test, not open-ended field waterproofness, and that "water-resistant" and "waterproof" are not interchangeable. YKK Aquaseal takes a different route — Vislon-style moulded elements with an added elastomeric seal between them for a flexible, easy pull; YKK itself notes the Aquaseal is not intended for drysuit-grade constant submersion. For a gear bag, either is far beyond what rain demands; the point is that both are precision seals with wear surfaces, and both live or die by maintenance (below). An unbranded "waterproof zip" is typically a water-resistant coil with a storm flap — neither pressure-rated nor durable in salt.

Wet and dry separation: the feature that earns its keep

The single most useful feature in a regatta bag is a dedicated wet compartment. After racing you have a soaked spray top, dripping boots and salty gloves that must not touch your dry change or your electronics. A good holdall isolates the wet gear in its own chamber — usually a base or end compartment — so capillary migration of salt water cannot reach the dry side.

Look at how that chamber is built. The best have a wipe-clean or welded TPU/PVC lining and a drainage grommet so water runs out instead of pooling and breeding mildew. Cheaper bags merely zip off a fabric divider, which slows the damp but does not stop wicking through the seam and the divider itself. If a bag has no wet section, your inner dry bag does the job in reverse: seal the dry items and let the outer bag take the water.

Volume: sizing for the event, with margin

Buy for the trip, not the average day:

• 30 to 40 litres covers a single day: boots, gloves, spray top, a mid-layer, sunglasses, sunscreen, hat, water and food. Backpack or small-holdall territory, and the most useful all-round size for windward-leeward racing.
• 60 to 90 litres suits a multi-day regatta where you travel with wet gear and a full change. A soaked spray suit and boots are bulky and heavy; give them room.
• 100 litres and up is expedition and offshore luggage — more than a day-racing crew needs.

The recurring mistake is buying too small and packing to capacity. An overstuffed bag puts the zip chain and seams in tension precisely where water wants in, strains the slider, and — on a roll-top — leaves too little cloth to achieve the folds a friction seal requires. Slack is a design margin. Also weigh the empty bag: a heavy PVC duffel that starts at several kilograms before you pack it is a poor choice for anyone hand-carrying kit down a long jetty, where every kilo is felt over the walk.

Fabrics and abrasion: where durability lives or dies

Around boats, bags lead a brutal life — dragged across non-skid, dropped on concrete, soaked in salt, baked in the sun. Two properties decide whether a bag lasts a season or a decade.

Fabric. Coated Cordura is the water-resistant benchmark, quoted in denier (D) — the yarn's linear mass density in grams per 9,000 metres, so it indexes yarn thickness but says nothing about weave or coating. 500D packs softer and lighter; 1000D and 1680D carry thicker yarns and resist abrasion better where the bag is dragged. The fibre matters too: nylon 6,6 Cordura runs roughly 10 to 15 per cent tougher in abrasion than equivalent-denier polyester, though nylon absorbs more water and relies more on its coating and DWR face finish to stay dry. For fully waterproof bags the two workhorses are PVC tarpaulin (very tough, abrasion-proof, cheap, but stiff and awkward in cold) and TPU-coated cloth (lighter, more flexible at low temperature, and — being weldable — the basis of the best welded dry bags). Whatever the cloth, inspect the base and corners first: that is where wear starts, so a reinforced or double-layer bottom panel is a genuine tell of a serious bag.

How durability is measured. Fabric abrasion is graded by two standard rub tests, and it is worth knowing what the numbers mean. Wyzenbeek pulls a taut specimen and rubs it back and forth along warp and weft, counting double rubs to failure; roughly 30,000 double rubs is a heavy-duty threshold. Martindale rubs a flat sample in a figure-eight against worsted wool and counts cycles; around 40,000 cycles is the comparable heavy-duty mark. Critically, the two scales do not correlate — you cannot convert one to the other — and both measure flat abrasion, not the edge and corner abrasion that actually kills a bag on a gunwale. Treat a high rub rating as necessary but not sufficient, and let the reinforced base do the real work. Our carbon and material durability notes explain why abrasion and edge-wear resistance recur across race kit, not just bags.

Failure modes and maintenance

Bags fail in predictable ways, and nearly all of it is preventable once you understand the mechanism:

• Seized zips. The killer is recrystallised salt plus grit abrading the slider and packing the element gaps. Rinse the whole bag, and especially the zip chain, in fresh water after every salt exposure, and work the slider several times while still wet to flush grit before the salt dries. On waterproof zips, apply the maker's paraffin wax (Aquaseal) or a drop of silicone grease at the slider dock (TIZIP) every few uses to keep the sealing lips supple, and store the zip closed so the tape and lips are not held bent, which is how they start to admit water.
• Delaminated coatings. PU and TPU degrade under UV and heat — the polymer chains scission and the coating crazes and lifts. Do not store a bag baking on a car parcel shelf or leave it sealed wet in a hot locker; dry it open, out of direct sun.
• Worn bases. Once the base fabric abrades through the coating and then the weave, water wicks straight in and no seam tape helps. Catch it early; a reinforced base buys years. See our salt corrosion prevention guide for the wider rinse-and-dry routine that protects bags, hardware and electronics together.
• Mildew and stink. The commonest death of a good bag is being packed away damp: trapped moisture plus organic salt residue feeds mould that stains the lining and rots the coating. Empty it, turn out the wet compartment, and let it dry fully before storage.

What good versus bad looks like

A good race bag has HF-welded or heavily taped seams, a corrosion-resistant Vislon or genuine pressure-rated zip under a storm flap, a dedicated wet compartment with a drainage grommet and a wipe-clean lining, a reinforced double-layer base, comfortable padded straps that stay put under load, and a size matched to the event with a little slack. It carries dry through a downpour and a wet dock, and it survives being thrown around a container.

A bad bag announces itself on inspection: unbranded coil zips, thin single-layer bases, taped seams already lifting at the corners, no wet and dry separation, and a "waterproof" claim resting on a coating and a storm flap with no welded construction and no zip pressure rating. It looks fine in the shop and lets you down in the boat park.

On a Melges 40 Grand Prix campaign

One-design Grand Prix racing is logistics-heavy. A Melges 40 sails with a crew of eight to nine on an all-carbon, canting-keel, twin-rudder, retractable-bowsprit hull of just under 12 metres — figures worth confirming against the current class rules and the boat's own documentation before you rely on them. That crew travels to regattas, often internationally, then lives out of gear bags on a tight dock or in a shared container for a week. Two things matter more here than for club sailing.

First, standardisation and identification: matching, clearly labelled crew bags stow predictably, move fast between airport, hotel, container and RIB, and do not get mixed up in a crowded tender. Second, wet and dry discipline: with racing back-to-back over multiple days, kit rarely fully dries, so a proper drained wet compartment and a disciplined rinse-and-dry routine keep the boat and the accommodation liveable and stop kit rot mid-series — the same salt-management logic that protects the boat's hardware.

For the individual sailor, the practical setup is a robust water-resistant holdall in the 60 to 90 litre range for travel and dock life, plus a small HF-welded dry bag for the on-the-water essentials that ride in the boat. Keep the phone, keys and a spare warm layer in the dry bag; everything else can take the weather. Bags are boring until the day yours is the one that stayed dry.

For what goes inside these bags, see our race sailing jackets comparison, sailing footwear compared and sailing gloves guide. Unfamiliar terms are defined in the sailing terms glossary.

How we'd evaluate

When we test, we will assess measured water resistance under a timed hosing and a soaked-dock soak, seam and zip integrity after a season of salt (including slider drag and any weeping at the tape), base and corner abrasion against a real gunwale, wet and dry separation in practice, carry comfort under a loaded strap, and whether a bag still seals cleanly — roll-top folds and zip lips alike — after months of use. Ratings only once we have used them.