attwood 9400 Marine Boat Hydro-Stabilizer Kit Installation Guide

: June 9, 2024
: attwood

Table of Contents

FEATURES:
TOOLS AND MATERIALS REQUIRED
INSTALLATION INSTRUCTIONS
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

Hydro-Stabilizer
9400 / 9401
INSTALLATION INSTRUCTIONS

SAVE THESE INSTRUCTIONS

FEATURES:

The 9400 Hydro-Stabilizer fits most outboard engines and strendrives 50 horsepower and above except Volvo-Penta 280 and 290 sterndrives. The 9401 Hydro-Stabilizer fits most outboards below 50 horsepower except Mariner 20 horsepower engines where the cavitation plate is too small for installation.
The Attwood Hydro-Stabilizer will provide performance benefits to most boats.

Puts your boat on plane faster and keeps the boat lower in the process.
Pulls skiers out of the hole quicker, especially if your boat is under powered.
Provides a smoother more stable ride and decreases porpoising.
Your boat will stay on plane even at lower speed. This is especially beneficial in rough seas.
Improve your boat’s fuel economy, since your boat will stay on plane at lower cruising speeds.

NOTE: The Hydro-Stabilizer will not correct serious problems in improperly matched boat and motor.

TOOLS AND MATERIALS REQUIRED

Drill and suitable drill bits
7/16″ wrench (2)
Pencil or scribe
Center punch
Hammer
4 C-clamps, 2″ or larger (optional)

INSTALLATION INSTRUCTIONS

Prior to installation, remove the boat from the water and pivot the outdrive or outboard motor lower unit to its upward-most position and remove ignition key.
**WARNING:** When working on the lower unit if any outboard or outdrive motor be sure to disconnect the positive (+) battery cable to prevent accidental starting. Remove the propeller to allow better clearance for drilling and installing nuts and bolts. Follow engine manufacturers’ instructions.
Place one of the two fins fully on the cavitation plate by placing the edge if the plate into the groove if the fin. Fin must angle upward with textured surface on top. (Figure 1)
Slide fin toward the rear of the cavitation plate until it is 3/8″ from the corner if your plate is square on the end (Figure 2), or 1/2″ past the corner if your plate is angled on the end (Figure 2A).
On older Mercruiser outdrives with a rounded cavitation plate, the angled cavitation plate instruction should be followed. On older OMC outdrives (pre- Cobra), the back of the Hydro Stabilizer should be about 3″ forward of the back of the cavitation plate.
WARNING: Installing any hydrofoil device to the cavitation plate may change the handling characteristics of some boats, which may cause loss of control and possible injury.
Hold fin in place, or use C-clamps (optional). If using C-clamps becareful not to overtighten.
While first fin is held in place, align the other fin and repeat steps 2-4. Check both fins to be sure they are fully on the cavitation plate. Mark the 4 installation hole locations on the underside of the caviation plate.
Remove both fins. Verify the marked hole locations are at least 1/4″ away from the edge of the cavitation plate. Center punch and drill 5/16″ holes in the marks you have made for the installation holes. Remove any burrs.
To allow for slight variations in the installation, we recommend drilling a 9/32″ hole for use with the 1/4″ holes provided. If drilled accurately and squarely in the location, however, a 1/4″ bit may be used.
**CAUTION:** The installed Hydro-Stabilizer must clear swim platform, trolling motor, etc. in all tilt and turn positions.
Place one of the fins on the cavitation plate in the correct position, place flat washer on bolt and insert through one of the two holes from the underside. Use a flat washer on both sides of the fin (see Figure 1). Start a nut on the upper side of the fin to keep the bolt in place while starting the second bolt. Repeat with the opposite fin and tighten all four bolts when in place. DO NOT OVERTIGHTEN. These are selflocking nuts which do not require additional lock washers.

NOTE: After first use, check for loose hardware and retighten if necessary. For best results, the outdrive or outboard motor should be trimmed all the way down when the boat is first underway until it reaches planing speed, then the motor should be trimmed upward until the best high-speed performance is reached.

WARNING: To prevent serious bodily injury:

Do not operate boat with only one fin in place. This may cause extreme steering difficulties and may result in tipping.
Do not sit or stand on fins. It is not designed to support additional weight and may bend or break which may result in direct exposure to the propeller and result in serious bodily injury.
Do not allow tow ropes (i.e. ski ropes, boat tow, etc.) to become tangled around the fins, which may result in damage to both rope and fin.
Allow for the extra width created by the Hydro-Stabilizer when attempting to navigate between water obstructions. Hitting an obstruction with the fins may cause loss of balance to people on board, endangering their safety and damaging the outdrive/outboard, transom or boat hull.
Do not operate the boat at planing speeds with the motor trimmed fully down (in). This can cause boat instability and tipping.

ONE-YEAR WARRANTY
This product carries the standard Attwood one-year warranty. See Product Catalog or attwoodmarine.com for details.

©2009 Attwood Corporation, 1016 N. Monroe Street, Lowell, MI 49331
www.attwoodmarine.com
09/01
69455 Rev. A