Reference may be made to Cellular plastics, rigid
— Determination of water absorption for assessing water
absorption properties (ISO 2896:1987).
The water absorption of low-density material should not
exceed 8% by volume after being fully submerged for 8 days according
to ISO 2896 and should be considered to be “impervious to water
absorption”. Material complying with the Revised Recommendation
on Testing of Life-Saving Appliances (resolution
MSC.81(70)) should also be deemed to satisfy this standard.
Refer to Small craft — Stability and buoyancy assessment
and categorization (ISO 12217).