5. Identify Installation Location

Installation Location Introduction

The performance of the Seakeeper Ride system is a direct result of the proper mounting location of the Controllers. It is vital to abide by the criteria in the Seakeeper Ride Installation Location Guide to choose the optimal mounting point for the Controllers.

For new production installations, please consult with the Seakeeper Applications Engineering Team or a naval architect for the proper location of the Seakeeper Ride Controllers according to the hull shape, hull type, engine configuration, and other relevant application details.

For refit installations, please review the following sections to determine the ideal location for the Seakeeper Ride Installation.

5.1. Longitudinal Location

The Seakeeper Ride Controllers will be mounted to the transom, the approximately vertical surface at the aft end of the running surface, as shown in Figure 3 and Figure 4.

Figure 3 – Longitudinal Location for Seakeeper Ride Controller Installation with Bracket
Figure 4 – Longitudinal Location for Seakeeper Ride Controller Installation without Bracket

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.

Figure 5 – Seakeeper Ride Controller Constituent Parts

1) Blade

2) Seal Plate

3) Rotary Actuator

4) Actuator Plate

5) 5 Degree Wedge Plate

6) 4 Degree Wedge Plate

7) 3 Degree Wedge Plate

8) Transom Plate

The Ride Reference Line (RRL) provides a guideline for the vertical location and orientation of the Seakeeper Ride system while considering many possible hull features. This section of the guide demonstrates how to find the RRL with different hull features.

The RRL is the intersection of the hull bottom and the transom planes, ignoring filleting or radiuses at the intersection. The hull bottom plane can be approximated by holding a long straight edge (3 ft [0.9 m]) flush with the hull bottom, parallel to the centerline. The transom plane can be approximated similarly by holding a short straight edge (6” [0.15 m]) flush with the transom.

Figure 6 – Straight Edges on Hull Bottom and Transom

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.

For optimal performance, the Seal Plate must be in line with the RRL and the bottom of the hull. The Seal Plate can be above the RRL up to 1/8 in. with negligible effects on system performance. If the Seal plate is more than 1/8 in. above the RRL or below the RRL at all, a significant negative impact on the performance of the system will result.

Figure 8 – Acceptable Vertical Variance

Figure 10 to Figure 13 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.

Figure 9 – Demonstration of View


For hulls with lifting strakes or spray strakes, the strake can be ignored during installation. The RRL, in this case, is defined as the intersection of the hull bottom and transom plane on either side of the strake, as shown below.

Figure 10 – Strakes on Hull Bottom with RRL and Transom Plate Trace

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. For vessels with concave curvature, the RRL is defined as the tangent to the hull bottom, shown by the blue line.

Figure 11 – Concave Hull Bottom RRL and Transom Plate Trace

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. 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.

Figure 12 – Convex Hull Bottom RRL and Transom Plate Trace

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 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. In hulls with a variable deadrise, the RRL is the highest portion of the deadrise that the Seakeeper Ride system will cover. See Figure 12 for this position. Because performance may degrade at vertical changes between hull sections greater than 0.75 in. (19 mm) (Dimension A), please reach out to Seakeeper for guidance in this instance.

Figure 13 – Variable Deadrise Hull RRL and Transom Plate Trace

5.3. Beam-Wise Location

There are several hull features that should be considered when determining the location of the Controllers in a beam-wise orientation. Generally, the Controllers should be mounted as far outboard as possible, up to the chines (if the hull has chines).

Engine Spacing

Because the Controllers have the potential to change water flow into the boat’s propellers, the Controllers should be mounted as far from the propellers as possible.

The distance discussed in this section is measured along the deadrise of the hull when viewing it from the stern, as illustrated in Figure 13.

Figure 14 – Distance Between Controller and Propeller

The Controllers can be mounted as close as 3 in. (76 mm) between the inboard edge of the Controller and the outboard diameter of the propeller tip. In the figure above, D represents the measurement between the Controller and the outboard diameter of the propeller tip, and Label 4 indicates the diameter of the propeller tip.


Based on the considerations of engine spacing and transom appendages, some installations will require the Controllers to extend outboard of the inboard edge of the chine, as shown below.

An overlap of the outboard chine of 1.5 in. (38 mm) is acceptable.

For overlaps greater than 1.5 in. (38 mm), performance may degrade rapidly. Please consult with Seakeeper for specific installations where chine overlap may be greater than 1.5 in. (38 mm).

Figure 16 – Chine Overlap

Hull Side Spacing

It is possible to have an installation where the Controller is mounted too far outboard causing water flowing around the hull side to interfere with the Controller and substantially reduce performance.

To avoid this issue, the Controller should be mounted at least 1.5 in. (38 mm) inboard of the hull side, as shown below.

Figure 16 – Hull Side Clearance

5.4. Overhead Clearance

Because the Controllers are mounted externally on the hull, there may be some installations where space must be cleared to create room for the Controllers. There must be at least 5 in. (127 mm) of clearance between the aft most running surface and any surface above where the Controller will be placed (this includes any bracket or similar hardware that hangs over the Controller). This clearance height is represented by H in the figure below. The Controller will extend aft of the hull by 8 in. (203 mm).

Figure 17 – Overhead Clearance of Controller

5.5. Loading and Storage Details

The Controllers should not be installed where they will carry any load of the boat while on bunks (i.e. a trailer, storage rack, or fork truck). If this is a concern, the Controllers may be mounted up to 1/8 in. up from the bottom of the hull to increase the longevity of the system. See Figure 8.

5.6. Asymmetrical Details

Many boats are not perfectly symmetrical about the centerline, resulting in subtly different mounting locations and angles for each Controller. This is acceptable and may require different Wedge angles used for port and starboard Controllers. Following this guideline for the correct installation location will result in a proper installation even if there are asymmetries in the hull.

5.7. Cable Entry

In the final details of the installation, the cable that powers and drives the Controllers must pass through the transom of the hull. The location for cable penetration will be based on available access to the transom on the interior.

Concealed Cable Entry

The preferred cable location is through either of the oval holes of the Transom Plate (highlighted in blue in Figure 18). To utilize either location, you must be able to reach the hole from the inside to tighten the supplied cable gland and prevent water ingress into the hull.

Figure 18 – Transom Plate Internal Routing Oval Holes

As an example for internal routing, the figure below depicts a stringer shown with dotted lines that is preventing use of the inboard cable penetration. In this example, the outboard cable pass-through is available as indicated by the blue arrow. This can only be used if there is access on the interior side of the penetration.

Figure 19 – Cable Penetration Through Transom Plate

Exposed Cable Entry

Locations outside the Transom Plate can be used as well. If the cable penetration location is below the waterline, the supplied cable gland must be used to ensure a watertight hull after the penetration.

This cable penetration method can be used in locations above the waterline as well.

Cable Lengths

In all cases, the supplied cable for the Controllers is limited to 10 ft (3 m). Carefully consider the cable routing and location of the Distribution Module to ensure both cables can connect to the Distribution Module.