Most tools, like parallel rulers and dividers, are designed for warm, dry navigation stations. Fortunately, there are tools that work well with a spray-deck navigation station, but you won't find them mentioned in the average navigation book or at your local navigation course. Tools that work aboard a kayak have to be small, durable, and at least water resistant, if not waterproof. You may want to make some yourself, and even those available commercially may need or benefit from modification. These tools are the ones that we show students in courses on the Maine coast, where fog, big tides and rocks make navigation especially interesting.
Trips start with charts.
Waterproofing them goes a long way toward helping them survive immersion and mildew. The old waterproofing mixes were pretty volatile, and they needed ventilation or you lost brain cells, but the new waterproofing mixes are water-based and easy to use. All you need is sponge brushes and a piece of clean plywood to spread the charts out on. Charts need to be folded to be usable on deck. When you fold them, the section that you are using may lack important things like the compass rose and the scale.