He was astonished that another 8 year old had picked up on his problem when no adult had.
"I just thought I was a weakling, but I was quite strong mentally," he said.
Mr Gemmell, who is still very active, decided to create aid devices after the only aid he was given was a chair with four extendable legs.
He wanted to make devices so he could carry out everyday activities.
"It's very easy to say bugger off and give up," he said. "I don't intend to do that."
The aids he has created to make his daily life easier enable him to do simple tasks such as pick up a salt-shaker or pour a glass of water.
"I wouldn't be where I am today without them," he said.
He made an arm sling to help him pick up items while sitting at the table.
"It comes from my sailing days, with the bungee cords," he said.
"It's about thinking outside the square."
The arm sling, which he designed six years ago, cost Mr Gemmell about $500 to produce and took a year to create.
"It's just bits and pieces from hardware shops," he said.
He also created the "dancing pole" which enables easier use of his arm while in the kitchen but it can only be used for lifting light objects.
"It took a year to design. The first steel pole crashed through the ranch slider," he said.
Mr Gemmell is now looking to take his devices to the next level.
"I'm going to need to find an engineering company in Tauranga and look at how we can improve the aids," he said.
"I do believe there is a big market as our population ages."
He would like to see others with upper-body issues, such as people who had suffered strokes, also be able to use the devices.
Muscular dystrophy
For more information on muscular dystrophy, go to: www.mda.org.nz.
For more information on Mr Gemmell's aids, email rossagem@hotmail.com.