Image icon  Hull-deck weld in a Topper boat

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Description: Filling the mould is a serious problem in injection moulding: the lower the melt flow index (MFI), the more difficult it is to push molten polymer down narrow tubes into a metal mould. Following injection of the hull and deck, the two parts are fused together near the waterline by incorporating a tape made from metal wire and polypropylene fibre at the joint. This is a schematic image showing a section through the hull-deck weld for a Topper boat. It demonstrates how the flange on the hull section fits into a recess in the deck section, and the joint fusion welded using sacrificial metal tape.
The Topper is a one-design boat sailed mostly in the British Isles. The Topper was originally designed with a glass reinforced plastic (GRP) hull, however, it was later decided that the Topper should be constructed with injection moulding, using polypropylene, which makes it a relatively light but durable boat. Following this change from the GRP to plastic hull sales of the Topper soared.
Keywords: Topper boat • glass reinforced plastic • GRP • injection moulding • polypropylene • hull • deck • fusion • weld • lightweight • dinghy • design • composite • image
Categories: Materials > Polymers & elastomers
Materials > Polymers & elastomers > Plastics
Materials > Polymers & elastomers > Plastics > Thermoplastics > Polypropylene (PP)
Processes > Shaping > Moulding
Applications > Sports & leisure
Other topics > Design
Created by: The Open University
Mike Levers, The Open University
Published by: The Open University
License: This resource is released under the Creative Commons Attribution Non-Commercial Share Alike license (2.0 UK: England & Wales).
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Date created: 09 March 1998
Date added: 15 December 2010
Resource ID: 3297