Section 4 Additional Procedure for Spray Lay-up Method

401. Resin Spray

The gel or laminating resin can be applied by using spray system when the attending Surveyor is satisfaction.

402. Spray Lay-up Apparatus

1. The spray lay-up apparatus is to be approved by the Society.

2. The spray lay-up apparatus is to be those which can mould FRP so that the glass content, mechan- ical properties, etc., are uniform.

3. Moulding by means of the spray lay-up apparatus is to be carried out by skilled moulding operators.

403. Spray moulding

1. For the spray lay-up apparatus used by filling with resin and glass fiber at the same time, it is necessary to consider specially and the Surveyor may require proper test to confirm the performance.

2. The spray moulding should be used only for the approved structures. Attention is to be paid to maintain strength continuity in the spots that reinforcement by spray lay-up and by hand lay-up are adjacent.

3. Spray lay-up of resin and/or reinforcement fibers should be limited to applications where, in gen- eral, a specified even thickness of the sprayed laminate can be achieved and consideration should be given to;

(1) Exothermic heat by excessive wet laminate thickness

(2) Sagging or drainage of the laminate

(3) De-aereation

4. The weight of glass reinforcement to be deposited between resin/glass consolidation depends upon the complexity of the mould. In general, this should not be more than 1150 gÕmĪ of fiberglass, un- less it can be demonstrated that a satisfactory laminate can be achieved with a greater glass re- inforcement weight.

5. The uniformity of the laminate and glass content should be checked at regular intervals. Where the back-up layer behind the gelcoat is sprayed-up, the type and length of the fibers should ensure that no wicking effect can occur. The spray equipment should be calibrated and should be checked for the desired setting for the resin/catalyst and resin/reinforcement fiber ratios at the beginning of each working day.

6. Where the chopped mat parts of the primary structural members of hull are moulded by means of the spray lay-up method, the method is to be pre-approved by the Society.