Northern Arizona University Lower Unit Team

(Grand Ganyon Project)

GCROA’s Challenge

Currently, river guides use boats propelled by gasoline-powered outboard motors. These motors are loud and environmentally toxic, which negatively impacts the passengers experience on the river. GCROA wishes to reduce the noise and utilize an environmentally friendly source for propulsion by redesigning the lower unit of the outboard motor. The engine of the outboard will be removed and replaced with an electric motor. The lower unit will be redesigned with the switch to the electric motor in mind.

Last Year’s Project

Last year’s capstone teams (2008-2009) researched alternative motors and recommended switching to electric. Further testing is needed for specific electric motor options to ensure performance requirements are met. Also, battery technology is insufficient for an entire river trip because of weight, cost, and short battery life.

GCROA has decided to investigate the effectiveness of an electric motor, which will be powered by batteries. A liquid fuel generator has been considered for recharging the batteries. This year’s capstone must redesign the mechanical components of the outboard lower unit to accommodate the switch to an electric motor. GCROA wishes to eventually switch all their motors to be sustainable, quiet, and environmentally friendly.

Specific Needs

The project will yield a prototype that:

• Implements a transition to an electric motor by translating the power output to the propeller shaft
• Has an increased durability against impacts
• Has less weight than current outboard
• Has a universal motor mount so that various electric motors can be easily switched

Additionally, the project should meet the following constraints:

• Interfaces with the existing engine saddle (component that connects the outboard motor to the existing steering/mounting jackass)
• Causes no significant increase in the overall drag of the lower unit
• Can be constructed from off-the-shelf components and standard machining techniques

Collaborating Universities

The NAU team will work with the University of Utah (UU) and Arizona State University (ASU). The ASU team will also develop a lower mount redesign. NAU will start by exploring the possibility of mounting the motor horizontally and utilizing a belt drive system; ASU will improve on or redesign a shaft drive similar to the current drive system. The ASU and NAU teams will work together with the UU teams to decide on a universal mounting interface that will allow for the option of attaching several different types of motors for testing. A basic bolt pattern, to be agreed upon by ASU and NAU, will allow UU to build a mating bracket with the same pattern to mount their chosen motor on. The UU teams will work on the mounting bracket as well as the electric motor and its system. The teams will communicate through use of telephone, email, in-person meetings, internet meetings and through Google docs.

 

Mid-Project Presentation

Project Poster