This:
Its a foam boat collar for aluminum boats.
Pros: safer in rough conditions
Less money and more floor space compared to a RIB.
More durable than air filled tubes.
Cons: not as safe as a RIB ( having less floatation than a RIB. Hard to install and not widely available, locally.
Here is mine ( attached) which I made from raw eva foam. Its a little 12 footer with a 10hp 4 stroke. Super light for beach launching with 2-3 people and gear, without wheels.
It was kind of a bitch to do though and not cheap, but it was well worth it knowing that you can fill the boat with water and still get out of a dangerous situation.