He's right you need a way bigger machine than a 20U which is made for sewing clothes.Look for a big Singer 7 class ,you need to use a large size #346 thread to be sure your stitching will hold on these straps.On real light duty rachet straps rated for 3-600 lbs 69 "might" work in a pinch as long as you had alot of lines 4-5" long ,close together the width of the strap probably like a 2" wide one,but the wider HD type of strap needs thicker thread.