How to install the Humphree stabilizer system
A Hatteras motoryacht refit is always a good learning experience. Meeting with a new boat owner in a local boatyard doesn’t disappoint. This new owner has done his homework and has a list of to-do items to prepare his boat for long-range cruising. You may have heard of trim tabs and may also understand the concept of stabilizers to smooth the ride. He is combining the two with the installation of a Humphree All Speed Fin Stabilizer system and trim tab-like interceptors. Easy enough, right? But before you jump in with both feet, let’s take a peek at the prep and planning.
Preparing the Hull for Humphree System Installation: Step-by-Step Guide
Among the many updates, the hull has been glass bead blasted to remove all the years of built-up anti-fouling paint. The owner will apply a barrier coat of primer and new anti-fouling paint when the boat is ready to splash—after the Humphree stabilizer system installation.
The original trim tab planes have been removed from the curved transom. But removing the tabs isn’t enough. Hatteras originally built the boat with a recessed flat indentation at the bottom of the curved transom to attach the traditional straight trim tab hinges for the planes. This area is not large enough to add the new interceptors so the indentation must be filled in and flattened out.
Because the boat has been blasted down to bare fiberglass, the installer could seal the recessed areas and build it up to match the transom contour. Once that has been completed, the area then needs to be built up again to a flat surface to attach the Humphree Interceptor mounting plate. Note: This must be perfectly flat for the soon-to-be-attached interceptor unit to extend and retract the blades. Any curves or imperfect area could bind or warp the interceptor blades.
Interceptor Functionality: How the System Works
The interceptor function is powered by a servo motor mounted inside the lazarette and directly connected through the hull to the interceptor. It is powered by 12- or 24-volt DC current. Fortunately, it is waterproof to resist moisture caused by wet dock lines and fenders usually stored in the same area. Because of the large size of this 70-foot Hatteras and the two exhaust tubes venting at the transom, the design includes a total of four interceptors. Smaller boats may be fine with two.
The system is simple—all the electrical connections are plug and play. Wiring runs to the helm for the operator control panel. These interceptor devices offer trim ability and are expected to reduce vessel roll at speed. They are called interceptors because their blades or fins extend downward and intercept the water flow beneath the boat providing lift and trim control.
The interceptor includes a ride control device that is the brain of the system. When connected to the GPS and the rudder angle indicator for speed and steering input, you can enjoy automatic trim and roll control. The interceptors will also adjust for steering port or starboard at high speeds. You can intervene manually and correct a list caused by wind or wave action or a boat with too much weight on one side.
Comparing Humphree’s Fin Stabilizers with Traditional Trim Tabs: What to Know
Bonus! When guests swim behind the boat, there is no worry that they might kick the tabs as they may have on other systems that always protrude. And you will not have to be concerned about your big fish cutting the line like on a traditional trim tab.
Another factor to consider is these are made of a composite material and do not require anode (zinc) protection as the aluminum tabs do. Yes, you can prime the composite body and apply anti-fouling paint to keep the housing clean, but here is a really big feature: They can be programmed to fully extend and retract to self-clean any sea life like barnacles or tube coral trying to grow on the blades.
All Speed Fins: Adding Efficiency to Your Humphree Stabilizer System
The second part of this Humphree system is adding 24-volt fin stabilizers which rotate 360 degrees and must be custom-trimmed to clear the hull structures and keel. Why 360 degrees? When anchored in slight current or wave action, the fins rotate and swim the boat away from the anchor rode. This keeps the rode snug, anchor set, and the boat stable.
This model is powered electrically, not hydraulically. An electric system is self-cooled via the underwater flange plate. This design eliminates the need for a hydraulic reservoir, Power Take Off pump on the propulsion engine, and a remote heat exchanger to cool the hot hydraulic oil. No more hydraulic hoses to maintain.
This is the time to analyze your power sources. Consider how you will use the boat, the size of the fins, vessel speed, and if you plan to use the Zero Speed Stabilization for anchoring. All these factors consume power so more thought must go into the installation. Many boaters install additional 24-volt battery banks and recharge them from the alternator on the propulsion engine or via a standard 24-volt battery charger while plugged into shore power or operating the onboard generator.
The sensing device learns the movement of the boat with an inclinometer and accelerometer so the system will become proactive in reducing roll in the boat. This also has plug and play wiring to the helm station and connections to the GPS for speed input. Wi-Fi and Bluetooth technology is included so an authorized dealer can access your system remotely for any updates or troubleshooting.
Because the system knows the speed, it will power center the fins when idle for docking or anchoring. This prevents the fins from rotating freely when maneuvering the boat.
If at anchor, set the anchor feature. If you have a system failure, you can open the servo cover and use the special tool to center and then lock the fin in a forward-facing position. This keeps the fins stable and provides some help in reducing vessel roll.
Almost Ready to Splash
Before you paint the hull, remember that the fins are a composite material and can be trimmed to fit your hull shape. Be sure to use an epoxy resin to coat the open edge of the trimmed fin.
The fins can be primed and painted with anti-fouling paint, but beware. Do not use an anti-fouling paint on the hull fin flange. Remember, this flange is metal and is used to cool the servo motor. If an anti-fouling paint containing metal is used on this flange, there is concern of electrolysis. Consider using the same coating on this flange that you would use on your running gear.
Now you can cruise in comfort because of this innovative stabilization system. Anchor in crystal-clear waters overnight. The only rock and roll will be coming from your earbuds.
-by Chris Caldwell
