Spira international wooden boat plans. following are the stock plans available for the various types of boats, separated into the different categories.. The hells bay glade skiff is a similar design to the flats stalker 18. here’s a comparison table:. Osprey 18 flats skiff. the osprey 18 flats skiff was originally designed for a client (who stiffed me on half his bill!) in louisiana back in 2008..