Widen Narrow Gaps Between Deck Boards To Improve Deck Drainage To Extend It's Life. The Saw Guide gives you professional looking results without the cost of hiring a journeyman carpenter. With the Saw Guide you can make smooth cuts along the side of the plank to widen the spaces between your deck boards. If the gaps between boards are full of pine needles or debris nothing cleans it out better than the Saw Guide. The patented Saw Guide has Guide Fins that fit in the gap between the decking making it simple to avoid gouging or wandrering cuts.