Fishing Craft Technology

Unit 4 - Boat building materials and construction of boat

4.10.Construction of Ferro-cement boat
As various methods of construction are available to the builders, no detailed construction method should be taken mandatory standards to be followed. Methods which have given satisfactory result is the use of construction of a reinforce armature of rods and mesh over mesh covered span frames (By making reinforcement using the pipes and wire mesh over this cement is applied).

• As per the loft measurement the station moulds are prepared by suitably bending the iron or GI water pipe of half to one-inch diameter.
• In the outside of the mould frames, the mild steel rods (¼” to 3/8”) will be attached at 2” –3” center space with help of either welding or by using 19-20 Steel Wire Gauge (SWG) iron wire.
• Attach four layer of machine woven half inch mesh size of GI chicken wire mesh (20 SWG) with a both side of frame work of reinforcement. For fastening purpose use 19 – 20 SWG GI wire.
• Plastering is done on both sides with special pozzolena cement in combination with good quality fine and sharp river sand and uncontaminated fresh water at the ratio of 1:1.5:0.4-0.5. If the pozzolena cement is not available then with the combination of ordinary Portland cement with fly ash at the ratio of 85:15 to get the required pozzolena effect at cheaper rate.
• The finished hull thickness should be in between ¾ inch to 11/2 inch.
• Once a plastering is complete it should be allowed to set hard, 15-20 days are required for curing under shade condition with frequent sprinkle of coldwater. Hull must be kept fully wet condition.
• The hull must be thoroughly dry and clean before painting. Use epoxy cold tar or heavy-duty bituminous paint to fill if there is any depressed holes.
• Apply one or two coat of antifouling paints above the load water line before launching the vessel.