[quote=erice]yeah, like aluminium extrusion masts, once you have the machinery, [i]100's of thousand$?[/i], the materials are only probably less than a $100 dollars a hull
[i]The introduction of roto-molded plastics has also enabled kayak designers to create many specific and specialist designs of kayaks for all forms of kayaking such as ocean kayaks made with a longer and sleeker hull to enable better straight ling tracking through open water. Roto-molded plastic White-water kayaks which are designed with a shorter overall length for greater manoeuvrability through ruff water. Plastic River kayaks which are designed for general use and therefore have a balance of specialist kayak characteristics. The process of rot molding involves a mold which is heated to the required temperature.
Once the required temperature is reached polypropylene plastic beads are added and the mold is enclosed and spun in order to distribute the polypropylene beads evenly around the mold. The kayak mold is then left to cool and the resultant kayak is removed from the mold for finishing buy the kayak maker. Polypropylene is an extremely durable and resilient material offering the kayaker both strong construction and light weight transport. Roto molded plastic kayaks have now largely taken over from fibreglass models as the number one kayak material. The first modern plastics kayaks were manufactured in the early 1970s when the technique was perfected for rotation molding of polypropylene kayaks.
The biggest cost by far for the manufacturer is the design and construction of a mold which must be made of a heat conductive material such as aluminium for this reason the price of plastic kayaks remains reasonably high although with a greater market share and more manufacturers the cost of plastic kayaks continues to drop. Polypropylene is an extremely durable and lasting material for this reason , plastic kayaks are very popular in the used kayaks market where very good deals can be found. Modern composite materials such as carbon and Kevlar are starting to grow in popularity however the relative cost of manufacture of these newer material kayaks still makes plastic kayaks a very popular choice amongst the kayaking
fraternity.[/i]
http://www.strikehook.com/forum/31-kayak-fishing/122775-how-plastic-kayaks-are-made<!-- editby --><em>Edited by erice on Dec 23, 2010 - 04:26 AM.</em><!-- end editby --> [/quote]
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