You can install an inexpensive durable ramp for small boats without pouring concrete. Ramp is for light duty, foot traffic, not for motorized vehicles, and minimizes impact on waterline.To see my related Instructables, click on "unclesam" just below the title above or in the INFO box to the right. On the new page that appears, repeatedly click "NEXT" to see all of them.
Step 1: Precast Pavers Cover the Ramp Surface
This ramp design uses precast unreinforced pavers over a crushed stone bed that gradually slopes to the waterline and pavers on a pressure-treated wooden tray that runs into the water. I bought wet-cast pavers 2' by 3', 2" thick that have a nonslip surface cast into them, rather than dry-cast pavers that are not durable. Each weighs 75 pounds, so it will remain in place, and I used two 2' by 2' pavers to transition between the overland section of the ramp and the section in the water.
My tray is made from 12' lenths of 2" wood treated to 1.5 pounds per cubic foot retention level, some boards 8" wide and some 6" wide to make up the width I needed. It was so heavy I assembled in on skids near the water line at low tide and slid it into the water once the tide rose. A rim of pressure-treated wood strips contains the pavers on the tray, and cross-cleats underneath hold the boards together and keep the tray from sliding away from the shoreline.
Step 2: Overland Gravel Path
End view of the overland portion of the ramp shows that no excavation was done. Landscaping fabric was placed on the ground and covered with enough crushed stone to level the gravel bed side-to-side. Heavy lawn edging was run alongside to contain the gravel. 3' long sections of gravel were screeded and made flat lenthwise, two pavers put in place side by side, then another section of gravel screeded and made flat. This produced a ramp that was level side-to-side but that progressed up the gradual slope away from the water to a line that would rarely become covered by the tides. Cinder-block caps were added to keep wave action from scattering the gravel.
For a more detailed discussion, link to album that contains article I had published in 01 April 1995 MESSING ABOUT IN BOATS magazine, "No-Pour Concrete Boat Ramp." Click link, then click "READ FIRST" instructions for reading and printing fine text. http://www.flickr.com/photos/sm_vermn/tags/boatramp
Step 3: Photo of Ramp
This photo shows the ramp in place as it disappears down into the water. The nearest part of the path leading down to the ramp, the part that rarely is covered by tidal water, is not made of concrete. It is made of pressure-treated wood planks laid directly on the ground and crosswise to the path and strung together with two 1/8" nylon ropes running through two holes drilled through the edges of each plank. Half-inch lengths of gray 1/2-inch diameter plastic electrical conduit serve as spacers between the planks. Large staples bent from 1/4" metal rod and driven into the ground to pin the ropes fasten the walkway to the ground. If I were to rebuild this walkway, I would use planks made of composite decking material instead of wood.
See my Instructables "Kayak Dolly" and "Plug for Hobie Mirage Propulsor Slot."