The collar is what defines the boat. Material choice, chamber count, and the way the tube attaches to the rigid hull determine whether the asset is a 5-year throwaway or a 15-year working tender. The conversation usually starts with Hypalon vs PVC; the more revealing one is about chambers and bonding.
Material
Three families dominate:
Hypalon (and CSM modern equivalents)
A chlorosulfonated polyethylene rubber, originally a Dupont trademark; the original product is discontinued and modern fabrics are CSM-based equivalents from suppliers like Orca and Pennel & Flipo. Resists UV, ozone, fuel spillage, and chemical contact. Lifespan in Mediterranean exposure: 10 to 15 years before the fabric starts losing flex.
Cost: 30 to 60 percent more than PVC at build time. Repair is glue-based, requires patches of the same fabric, takes a skilled hand, and is messy. Realistic shop rate: 400 to 800 EUR per repair patch at a yard.
Best for: yachts that keep tenders on davits or in open-deck stowage where they see continuous UV.
PVC
A polyvinyl chloride coated fabric. Cheaper, lighter, can be welded rather than glued (faster repair). Vulnerable to UV; lifespan in Mediterranean exposure: 5 to 8 years before the fabric becomes brittle and cracks at flex points.
Best for: garage-stored tenders that only see use on guest days, or where the tender is genuinely a 5-year throwaway asset.
Polyurethane (PU)
Newer category. Better abrasion resistance than either Hypalon or PVC, similar UV performance to Hypalon, weldable like PVC. Used by Brig and a few smaller builders. Lifespan claims of 12 to 15 years; the segment is too young to verify in field service.
Chamber count
A RIB collar is divided into independent inflatable chambers separated by internal bulkheads. A puncture in one chamber leaves the others inflated, keeping the boat afloat and usable.
Three configurations:
- Three chambers (port, starboard, bow): the minimum, common on small crew RIBs and budget guest RIBs. A puncture takes 33 percent of buoyancy out.
- Five chambers (port front, port rear, starboard front, starboard rear, bow): standard on 6 to 9m guest RIBs. A puncture takes 20 percent out.
- Seven or nine chambers: high-end and SOLAS-coded RIBs. A puncture takes 11 to 14 percent out.
Five-chamber is the right answer for nearly all yacht-tender briefs. Three-chamber is acceptable on a sub-5m crew boat. Seven-plus is mandatory only when SOLAS coding requires it.
Bonding to the hull
How the tube attaches to the rigid hull is the single most important long-term reliability factor. Three methods:
- Mechanical fastening (track and bead). A bead extruded into the tube fabric clips into a stainless track bonded to the hull. Allows tube replacement without removing the hull. Adds a hard line where dirt collects. Found on Williams, AB Inflatables, many production RIBs.
- Glue bond. The tube fabric is glued directly to the hull along its full length. Cleaner aesthetic, no track. Tube replacement requires hull-level work and is essentially a refit job. Found on Ribco, SACS, Pirelli premium models.
- Hybrid bond plus track. Glue along the load-bearing portion plus a track for guidance and inspection access. Found on some Pascoe and Compass builds.
Glue-bonded tubes look better and last longer when undisturbed. Track-mounted tubes are easier to maintain and replace. Owners who plan to keep the boat 10 years should prefer glue; owners who treat the asset as a 5-year rotating purchase should prefer track.
Failure modes
In order of likelihood:
- Air loss at the inflation valve. Routine. Replace the valve, 30-minute job. Happens every 2 to 4 years on heavily-used boats.
- Seam delamination at high-stress points (bow tip, transom corners). Repairable with patch. Happens at the 5 to 8 year mark on PVC, 10 to 15 on Hypalon.
- Tube-to-hull bond failure (track-mounted: bead pulls free; glue-mounted: glue line lifts). The single most expensive failure. Avoid by inspecting annually and cleaning the bond line.
- UV-induced fabric brittleness. Terminal. The whole tube needs replacement. Cheaper to replace the tubes than the boat; budget 12,000 to 30,000 EUR depending on size.
Specification questions
- What fabric supplier and reference number are the tubes?
- What chamber count and what is the buoyancy retention with one chamber deflated?
- Glue or track bonding to the hull, and what is the manufacturer's documented lifespan?
- Where are the inflation valves located and is each chamber independently accessible from the deck?