The plastic part of the buoy is usually self coloured and should not require painting for the first 5 years of the buoy's life. If there is a steel core structure this will probably require major maintenance by the end of this 5 year period. The first cost is similar to an all steel buoy although the comparison will vary from country to country and may also depend on the number ordered. The predicted life plastic buoys may be up to 10 years while there are many examples of steel buoys lasting 30 to 50 years, however the maintenance of steel buoys is becoming increasingly expensive.
The cost of grit blasting and paint spraying facilities necessary for effective long term maintenance of steel buoys may be prohibitive to many authorities while the health and safety and environmental restrictions that apply to many high performance paint coatings are becoming increasingly severe. Restrictions applying to the application of high performance paints will apply to both steel and plastic buoys.
For moulded plastic buoys maintenance will be limited to cleaning usually with H.P. water jets.
For urethane coated foam buoys maintenance will entail cleaning and repainting but it should be noted that urethane paint presents health and safety problems.
Painting of moulded thermoplastic buoys is not usually successful due to surface adhesion problems however specialised hot spraying processes are available.
GRP buoys will require cleaning and repainting and any necessary repair to the gell coat.
The steel component of all types of plastic buoys will require painting or regalvanising and in the case of mooring eyes, re-surfacing.
The integrity of any internal load bearing structure must be regularly monitored to ensure handling safety as components may suffer corrosion or abrasion damage.
The light weight of the plastic buoy is probably the major advantage for many authorities. If a buoy of a certain size is required the limited lifting capacity of the available servicing vessel may force the authority to use a lightweight plastic buoy.
If a steel buoy can be handled by servicing vessels, either by lifting or by towing to station, then the local availability of long term maintenance facilities must be considered before the whole life costs of equivalent plastic and steel buoys can be investigated.
CONCLUSION
1. For large buoys the first cost of plastic buoys may, in some areas of the world, be equal or less than the cost of a steel buoy however any cost advantage needs to be considered as part of the whole life cost of the buoy. The shorter potential life of the plastic buoy must be compared with the much longer(typically over 40 years) life of a regularly maintained steel buoy.
2. Small plastic buoys have the advantages when compared with steel of light weight, minimum servicing requirements within their planned life span and ease of handling by the smaller type of service craft with which they are associated.
