5.2. Vertical Location

Seakeeper Ride’s Controllers must be mounted so that the bottom surface of the Seal Plate (Item Number 2 in Figure 5) aligns with the hull bottom. The goal is to have the Seal Plate acting like an extension of the hull bottom. The Seal Plate’s location is determined by the Transom Plate (Item Number 8 in Figure 5), which is affixed to the transom and adjusted up and down during installation to allow for fine-tuning the location.

The Ride Reference Line (RRL) is a guide for where the bottom of the Controller should be when mounted. The RRL is a representation of the bottom edge of the transom where it meets the running surface of the hull. Because of the unique shapes of different hulls, the RRL may not follow the bottom edge of the hull exactly. The following examples give guidance on where the RRL should lie on hull bottoms that are not perfectly straight.

An example transom with an exaggerated radius is shown below. The RRL is shown in blue and is the intersection of the two straight edges.

Figure 6 – Finding Reference Line with Straight Edges

Figure 8 to Figure 11 in the following section show a view from the stern of the vessel looking toward the bow. Label 1 indicates the bottom of the hull, Label 2 indicates the RRL, and Label 3 indicates the outline of the Transom Plate.

Strakes

For hulls with lifting strakes or spray strakes, they can be ignored for the placement of the equipment and determination of the RRL. Please note, strakes which extend all the way to the transom can reduce the authority of the Seakeeper Ride equipment.

Concave and Convex Deadrise

The Seal Plates (Item Number 2 in Figure 5) have a straight design. Some hulls may have curvature along the deadrise which will cause the Seal Plate to show gaps between the deadrise at either the ends or center of the plate. The following sections describe how to find the RRL in concave and convex deadrise hulls.

Concave Deadrise

For vessels with concave curvature, the Seal Plate should be mounted such that the center of the Seal Plate is flush to the hull bottom and the ends of the Seal Plate are equidistant from the hull bottom (measurement A in the figure below). Measurement A must be 0.5 in. or less. More curvature decreases Seakeeper Ride Authority. For vessels with concave curvature, the RRL is defined as the tangent to the hull bottom, shown by the blue line.

Convex Deadrise

For vessels with convex curvature, the ends of the Seal Plate should be mounted flush with the hull bottom with a gap between the center of the Seal Plate and the hull bottom (measurement B in the figure below). Measurement B must be 0.5 in. or less. More curvature decreases Seakeeper Ride Authority. For vessels with convex curvature, the RRL is defined as the straight line along the transom between inboard and outboard ends of the seal plate’s destination.

Variable Deadrise

Variable deadrise hulls are those where the running surface has breaks that run longitudinally. Generally, these hulls have decreasing deadrise angle in each successive panel moving outboard from centerline. Seakeeper Ride Controllers are capable of being mounted on variable deadrise hulls, so long as the following mounting conditions can be met:

• Distance from inboard edge of the Controller to the hull (Dimension A in the figure below) is 0.75 in. (19 mm) or less. This requirement only applies to vertical changes beneath the Controller.
• The portion of the Controller extending inboard of the deadrise break (Dimension B in the figure below) is 3 in. (76 mm) or less.

In hulls with a variable deadrise, the RRL is the highest portion of the deadrise that the Seakeeper Ride system will cover. See the figure below for this position. Because performance may degrade rapidly if these conditions are not met, please reach out to Seakeeper for guidance in this instance if a boat falls outside these parameters.