SIB vs RIB: What Soft Inflatable Boats Really Are (And Which One Suits You)

Ask three boaties what a SIB is and you will get three answers. The acronyms are the single biggest barrier for people buying their first inflatable, so let us kill the confusion in one page.

The definitions, without the jargon

SIB — Soft Inflatable Boat. Every part of the hull is fabric. Inflatable tubes, plus a floor that is either an inflatable air deck, slatted timber, or removable aluminium panels. Deflate it, roll it, put it in a bag.

RIB — Rigid Inflatable Boat. Inflatable tubes bonded to a solid moulded hull, usually fibreglass or aluminium. The tubes are soft; the bottom is not. It does not pack down and it lives on a trailer.

RHIB is the same thing as a RIB, just with "hulled" spelled out. There is no difference.

Inflatable catamaran. A soft inflatable, but with two full-length hulls instead of one hull with side tubes. That single change is what makes it behave differently from both a conventional SIB and a RIB.

Side by side

Why the floor matters more than the badge

The single most useful question when comparing soft inflatables is not "SIB or RIB" — it is what is the floor and what is the fabric.

A cheap SIB with a slat floor and thin fabric flexes underfoot, feels nervous when you stand up, and wears out. A soft inflatable with a high-pressure air deck or aluminium floor and heavy fabric feels like a boat.

Our numbers, so you can compare like for like:

• AeroCat series: 1100 GSM / 0.9mm German VALMEX® — 5-year hull warranty
• Viper series: 1500 GSM / 1.2mm VALMEX® Heavy Plus — 7-year hull warranty
• Working life of premium VALMEX fabric in Australian sun and salt: 10–12 years
• Transom height: 380mm, which keeps more propeller in the water and kills the ventilation that plagues shallow transoms

Fabric is always quoted as GSM and millimetres. If a listing only gives you one of the two, you are being told half the story.

Which one should you buy?

Buy a RIB if you want a permanently rigged boat, you tow to a ramp anyway, you have somewhere to keep it, and you are running serious horsepower over long offshore distances.

Buy a conventional SIB if you need the smallest, lightest possible tender to hang off a yacht and you rarely have more than two people aboard.

Buy an inflatable catamaran if you want the packability of a soft inflatable without the compromise: a boat that stores in the boot, launches off a beach with no ramp and no trailer, and still sits flat enough to stand up and fish from.

The stability difference explained

On a single-hull inflatable, buoyancy comes from tubes running down each side of a hull that tapers to a keel. Step to one side and it leans.

On a catamaran, the two hulls are the widest part of the boat and run the full length. Weight moving to one side has almost nowhere to tip to. That is not marketing — it is where the buoyancy physically sits. It is the reason people cast standing up from a 3.3m cat and would not attempt it in a 3.3m single-hull inflatable.

What "packs into a bag" actually means

Deflated, a 3.6m catamaran plus its air deck fits in the boot of a mid-size SUV. No trailer registration, no bearings, no tyres, no driveway. You drive a normal car to a spot with no ramp, carry the bag down, and you are on the water in about fifteen minutes with a hand pump.

The short version

SIB means the whole hull is fabric. RIB means the bottom is solid. An inflatable catamaran is a SIB that borrowed the stability a RIB is bought for, and kept the ability to go in the boot.

Built to last. Made to explore.