Section 3 Additional Procedure for Hand Lay-up Method

301. Seams of Fibre Reinforcements

Fibre reinforcements are to be arranged so as to have seams of reinforcements as few as practicable. The overlapping breadths at butts and seams of mats which are composed of reinforce- ment layer are not to be less than 50 mm. The centre lines of overlaps of two adjacent plies are not be less than 100 mm apart from each other so far as no obstruction exist for the work.

302. Hand Lay-up

1. In laminating, after having the fibre reinforcements thoroughly impregnated with resin, air bubbles in the resin are to be removed by degassing rollers. However, excessive squeezing of resins is not desirable and care is to be taken to keep the glass content proper.

2. In case where heavy mats and fibers are used, special attention is to be taken to permeate com- pletely

3. When the dough materials with resin and glass fiber are used to increase the thickness of lami- nation, they are to be same with main lamination. And the content of fiberglass is not to be less than 25 % of resin and the length of fiberglass is not to be less than 25 mm.

4. Where the successive laminating is interrupted in such a case of laminating the thick shell plating, etc., non-paraffin resins are to be used for the first of any subsequent layers of reinforcement to be laid in that area and care is to be taken not to leave over the excessive resin layer.

5. As for laminating of the final ply, effective measures to cure the outer surface are to be provided.

6. The hull lamination and other hull structural members are to be tested in glass fiber content ratio, aperture content ratio, hardening degree and mechanical strength etc.

7. The laminations are to be free from defects such as blister, delamination, excessive resin etc.

303.

Glass Content

1. In the laminations for strucures, the ratio between fibreglass and resins is to be as same as mini- mum resins amounts which can impregnate that reinforcement completely.

2. In laminating, the standard glass content (ratio in weight) is approximately 30 % in case of chop- ped mats or approximately 50 % in case of roving cloths, and laminating is to be carried out uni- formly to avoid local excess or scarcity of resin.

3. The aggregated weight of roving cloths is

to be 25 % to 60 % of the total weight of glass. Where,

however, special fibre cretion of the Society.

reinforcements are

used,

the weight is to be in accordance with the dis-