The wetted part should be paved with portland cement-concrete, as asphaltic or 

 bituminous paving does not hold up well from traffic in submerged areas. Unpaved ramps 

 will soon deteriorate under even moderate use. A single-lane ramp should not normally be 

 narrower than 15 feet, and a multiple-lane ramp should not have raised divider strips. 

 Lane-marking is not necessary and may lead to less than optimum use during peak hours. 



Ample maneuver room should be provided beyond the top of the ramp, usually 40 to 60 

 feet, on a gentle rampward slope (about 1 on 50) for proper surface drainage. About 50 

 puUthrough parking spaces should be provided for each ramp lane, with a clearly marked 

 traffic-circulation pattern between the parking area and ramp. 



Boarding docks should be provided, preferably on each side of the ramp and extending 

 out into or along the sides of the basin, with a total boarding length of at least 50 feet for 

 each ramp. The ramp should adjoin fairly quiet water, although not necessarily as quiet as 

 that needed for a berthing site. Ample protected holding area in the water just off the ramp 

 and boarding dock location should also be available for boats awaiting their retrieval turn 

 during peak hours. 



Ramps leading into saltwater or polluted waters should have a conveniently located 

 washdown faciUty, just outside the maneuver area if possible. This area should be large 

 enough to accommodate one car and trailered-boat per ramp. A waiting area of about the 

 same size for boats just retrieved should also be provided. Freshwater piped from the local 

 supply main and washdown hoses of ample length should be available at this site, together 

 with an adequate drainage system. Boaters will desire to wash saltwater and pollutants from 

 the boat huU and from the wheels and hubs of the trailer and car. In washing, some oil, 

 grease, mud, or other debris will be hosed off the undercarriages of the vehicles. For this 

 reason most controlling agencies require that the washdown area drain into a debris-trap 

 sump and then into the sanitary sewer system of the area rather than back into the basin. 

 The sewer intake must then be provided with a rain valve to avoid flooding the sewer system 

 with rainwater. Whether or not the use of detergents is permitted with this operation is 

 largely a decision to be made by the controlling agency. Ramp users often beach their craft 

 temporarily before retrieving them. Accordingly, users will appreciate having a small sandy 

 beach reserved for this purpose near the launching area. A typical launching-ramp facility is 

 shown in Figure 135. 



Where the ramp area can be unwatered down to the lowest elevation, a poured concrete 

 pavement is normally the easiest and least costly to construct. The surface should be 

 finished with deep, square-shouldered grooves molded into the surface parallel to the 

 contours (Fig. 136). Raked, rough -broomed, or other coarse -grain finishes without the deep 

 grooves will soon lose traction. Although the grooves may fill with mud, pneumatic tires will 

 force enough mud out to bring full bearing on the squared concrete shoulders and thus 

 prevent skidding. The grooves are usually made with 1- by 1-inch oiled sticks located about 

 3 inches apart on a frame that is pressed into the freshly poured surface and then carefully 



192 



