RIB Collar Construction

Hypalon vs PVC, single vs multi-chamber, repair economics, and what fails first.

Published

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:

  1. 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.
  2. 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.
  3. 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:

  1. Air loss at the inflation valve. Routine. Replace the valve, 30-minute job. Happens every 2 to 4 years on heavily-used boats.
  2. 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.
  3. 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.
  4. 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

  1. What fabric supplier and reference number are the tubes?
  2. What chamber count and what is the buoyancy retention with one chamber deflated?
  3. Glue or track bonding to the hull, and what is the manufacturer's documented lifespan?
  4. Where are the inflation valves located and is each chamber independently accessible from the deck?

See also

Hypalon or PVC - which one should we specify?
Hypalon, or rather the modern CSM equivalents from suppliers like Orca and Pennel & Flipo, if the tender lives on davits or in open-deck stowage. It resists UV, ozone and fuel spillage and gives 10 to 15 years in Mediterranean exposure, against 5 to 8 years for PVC before the fabric turns brittle and cracks at flex points. The premium is 30 to 60 percent more than PVC at build time, and repairs are glue-based at a realistic 400 to 800 EUR per patch at a yard. PVC earns its place on garage-stored tenders used on guest days, or where the boat is genuinely a five-year throwaway asset.
How many chambers does a guest RIB actually need?
Five is the right answer for nearly all yacht-tender briefs: port front, port rear, starboard front, starboard rear and bow, so a puncture removes 20 percent of buoyancy. Three chambers, port, starboard and bow, loses 33 percent to a single puncture and is acceptable on a sub-5m crew boat. Seven or nine chambers cut the loss to 11 to 14 percent and belong on high-end and SOLAS-coded boats; specify them only where SOLAS coding requires it. Ask what the documented buoyancy retention is with one chamber deflated.
Is a glue-bonded tube better than a track-mounted one?
It depends on how long you intend to keep the boat. Glue-bonded tubes, as used by Ribco, SACS and Pirelli premium models, look cleaner and last longer when undisturbed, but replacement is hull-level work and effectively a refit job. Track and bead mounting, found on Williams, AB Inflatables and many production RIBs, lets you replace the tube without touching the hull, at the cost of a hard line where dirt collects. Keep the boat ten years, prefer glue; treat it as a five-year rotating purchase, prefer track. Hybrid glue plus track appears on some Pascoe and Compass builds.
What fails first on a RIB collar, and what does it cost to put right?
Valves go first. Air loss at the inflation valve is routine on heavily-used boats, recurring every two to four years, and a replacement is a 30-minute job. Next comes seam delamination at the bow tip and transom corners, patch-repairable, arriving at the 5 to 8 year mark on PVC and 10 to 15 on Hypalon. Tube-to-hull bond failure is the single most expensive one; inspect the bond line annually and keep it clean. UV-induced fabric brittleness is terminal, and a full tube replacement runs 12,000 to 30,000 EUR depending on size, still cheaper than replacing the boat.
Is polyurethane worth considering instead?
Only with your eyes open on the data. Polyurethane offers better abrasion resistance than either Hypalon or PVC, UV performance similar to Hypalon, and it welds like PVC, which makes repairs faster. Brig and a few smaller builders use it, with lifespan claims of 12 to 15 years. The segment is too young for those claims to be verified in field service, so we would treat the numbers as manufacturer projections rather than proven service life, and ask for the fabric supplier and reference number before signing.

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