Thermoformed ABS Kayak Hull with Rotomolded Pedal Drive Mount
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Propulsion systems cannot be satisfactorily installed in thermoformed ABS kayaks due to the high stresses imposed on the hull and deck, which can lead to cracking.
Innovation Solution
A rotomolded polyethylene or polypropylene insert is placed within the kayak hull, housing a propulsion device, which absorbs the stresses and is secured to the thermoformed ABS hull using fasteners and a foam PVC block, allowing for the installation of propulsion systems like pedal drives in ABS kayaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a propulsion system is installed directly in a thermoformed ABS kayak, then the kayak can be propelled, but the stresses imposed on the hull and deck are too great and can lead to cracking
Solution Approach 1:
A rotomolded polyethylene or polypropylene insert is introduced as an intermediary component between the propulsion system and the ABS kayak hull. This insert absorbs and distributes the stresses imposed by the propulsion system, preventing direct stress concentration on the ABS hull and deck, thereby avoiding cracking while enabling propulsion functionality.
Solution Approach 2:
The solution combines two different plastic materials: thermoformed ABS for the kayak hull (providing lightness, stiffness, and scratch resistance) and rotomolded polyethylene or polypropylene for the insert (providing impact strength and stress absorption). This composite material approach allows the kayak to maintain its lightweight and stiff characteristics while gaining the ability to withstand propulsion system stresses.
2Weight of moving object
If ABS plastic is used for the kayak hull, then the kayak is lighter and stiffer, but it does not have the same impact strength as polyethylene kayaks
Solution Approach 1:
Different regions of the kayak structure are assigned different material properties: the ABS hull provides lightness, stiffness, and scratch resistance for the overall structure, while the rotomolded polyethylene or polypropylene insert provides localized impact strength and stress absorption at the propulsion system mounting location. This local quality differentiation allows the kayak to achieve both lightweight performance and impact resistance where needed.
Data Source
AI summary
An improved kayak has a hull of thermoformed ABS plastic having a bow and a seat having a void between the bow and the seat, a top of the hull being a deck with a foam PVC block glued to a bottom face of the deck. A rotomolded polyethylene plastic insert is located in the void and joined to the hull by fasteners that pass through the insert and the deck of the hull and engage the foam PVC block within the hull, with caulking between the hull and the insert. A propulsion device is removably mounted in the rotomolded plastic insert that allows a user of the kayak to propel the kayak.