Anytime you need to span a distance longer than the lumber you have on hand, scarf joints are a good solution. This stop bladed scarf joint with cogs and wedges is a half-lap joint with stops, also called tongues or blades. The cogs in this joint are the t-shape projections in the cogs. Since they help lock the joint in place, they also increase the bending strength against horizontal loads.
All joints need to be further secured in some way. In this case, we use wedges inserted from either side to hold everything together. The two opposing wedges draw the joint tighter, adding more strength than you could get with just pegs.
Although it takes a bit more effort to cut this than a simple half-lap joint, it is extremely strong and the wedges really make the joint stand out. You will be happy to show off your joinery skills with this stop bladed scarf joint with cogs and wedges!