By: Stokes Marine
If you are in the market for a new lift, or just curious about how they work, we have compiled some basic information to educate you on boat lifts.
Top Beam- Most boat lifts that you see will have a top beam. This will either be made of galvanized steel or aluminum. There are several different designs of a top beam depending on manufacturer and model. The top beam spans between two or three pilings depending on the lifting capacity. The purpose of the top beam is to span the weight of the boat between the pilings. It also has the drive units and cable winders attached to it.
Drive units- There are several different types of drive units made depending on manufacturer and model. The drive unit acts as the transmission of the boat lift. As the motor turns, it rotates the gears inside the drive unit which rotates the drive shaft. As the drive shaft turns it wraps cable onto the cable winder, moving the cradle and bunks.
Cables- The cables leave the winder and run to the cradles. As the cable winder is turned by the drive unit, cable is wrapped onto the cable winder. This in turn lifts the cradle and bunks.
Sheaves- Sheaves are used as part of the pulley system that lifts the boat. Sheaves are added to increase the capacity of the boat lift. for every sheave you add, you reduce the load on the motor and drive unit in half. The sheave needs to be routinely greased and should always be turning when the boat lift in being raised or lowered.
Cradles- Cradles are the bottommost piece of the lift and span the width of a boatlift. They are made of galvanized steel or aluminum. There is one cradle in the front and one in the rear. The cradles are what the cables pull on to lift the boat.
Bunks- Bunks are mounted on the cradles. Bunks span between the front and rear cradle. This is the part of the lift that is in contact with the boat while being lifted. Bunks are either made of wood wrapped with carpet, or extruded aluminum and a rubber top insert. Bunks can be adjusted to each boat to try and maximize the hull capture. Hull capture is the amount of surface area of the hull touching the bunks.
Guide Poles- The guide poles are set to each boat specifically. They are used to align the bottom of the boat with the bunks. They are white PVC pipes attached to the cradle, and when properly set will gently touch the side of the boat.