Small Vessel Buoyancy | Floatation

This is a much-discussed topic with varying degrees of understanding and knowledge of the regulations. This is a valid document and audit by SAMSA Mosselbay.

WHAT Vessels Require Buoyancy:

On all categories of vessels, other than category A & R, built-in buoyancy only replaces the liferaft when it is sufficient to provide a stable level platform upon which the crew can be secured in an emergency (fully flooded, swamped or capsized). Category R vessels are not required to carry liferafts however they still require sufficient buoyancy so as to keep the vessel afloat in an emergency.

Buoyancy must consist of either foam or approved plastic bottles, or a combination of both. Buoyant material may not be affected by oil or oil products. The foam should be of a suitable closed cell type (usually a polyurethane type) and until such time as ?approved? bottles are identified the only plastic bottles used should be H.D.P.E.(High-Density Polyethylene) Grade 2? plastic bottles with secure watertight caps, or sealed six-sided ?boat floats? manufactured of H.D.P.E, designed specifically for the purpose of providing buoyancy in small vessels. Sufficient hatches are to be provided for inspection of the bottles.

The quantity of Floatation Required: Inland 30% and Offshore 60%

The 30% / 60% means the following: The volume displaced by the buoyancy (i.e. the foam or bottles) provided inside the vessel must represent a figure of 30% / 60% of the gross weight of the vessel. Gross weight means; the weight of the vessel, engines, stores, fuel, persons, fish etc.

A different buoyancy requirement applies to inflatable vessels and the regulations require these vessels to have at least 3 compartments, the smallest of which must be able to keep the vessel afloat.

“Note, a rigid hull is not included in this calculation, and also that extreme uses of inflatable vessels for commercial use such as cargo carrying or the like may require additional buoyancy to the satisfaction of SAMSA, by way of foam filled hulls or additional compartments, as this was never the intention of this exception.”


  • All vessels above 15hp and under 9m in length carrying a suitable “Liferaft” – No passenger vessels excluded
  • Any vessel under 15hp and 9m in length do not need to have a certificate to prove buoyancy BUT must have sufficient buoyancy to keep the vessel afloat if SWAMPED

Types of Floatation acceptable and renewal of certificates times



Where SAMSA officers or Authorised Agency safety officers and inspectors are faced with alternative documentation produced by other parties, the following principles must be applied to all forms of buoyancy certificate.

  1. It must be clear who the issuer is, for instance, the boat builder, private surveyor, safety officer, owner etc.

The vessel itself must be clearly identified by photograph, serial number or similar.

The basic dimensions and build details of the vessel must be included to aid the reader with not only identifying the vessel but also making it possible to detect any major alterations which may affect the validity of the certificate.

The quantity, type and distribution of buoyancy must be described in detail.

The net weight (lightweight) of the vessel must be noted, as this is the best method of monitoring absorbency or water retention of either foam or bottles.

The certificate must attest to compliance with the requirements of regulation 6 and Annex 1 or conversely state exactly what is, in fact, being certified.

Any limitations, conclusions or comments must be clearly noted, especially when bottles are used as they have a limited lifespan.

Buoyancy Fitment:

There are only regulations for the standards of buoyancy, SAMSA does NOT authorise any business, boat builder or such to be an approved installer. There is also NO legislation that says a specific person or body must issue a floatation certificate.

If you are having the floatation/buoyancy fitted you should request photographic evidence of all the steps of the process. It is not a legal requirement but it will give you peace of mind that it is being done correctly. Getting it fitted by and getting a certificate from a registered boat builder is also a good idea.

Link: MIASA (Marine Industry Association of South Africa)