The keel rollers form the basis of your boat’s support These keel rollers ensure that your boat runs smoothly after centring the bow guide rolls onto (or off) your trailer. The bilge rollers also provide stability and support during loading and unloading, as well as during travel. In short, the combination of the keel and bilge rollers offer a complete, functional and reliable package for carefree cruising. Depending on the type of boat trailer, we have put together a configuration that basically guarantees optimum operation. The price list shows the numbers.