2.0 Mechanical Installation

2.1 Introduction

This document is intended to give details and guidance to a boat builder or equipment installer to install the Seakeeper 18.  The Seakeeper 18 can produce vertical loads up to 5,965 lbs (26.5 kN), longitudinal loads up to 3,509 lbs (15.61 kN), and transverse loads of 500 lbs (2.22 kN) at each of the four mounts. Careful consideration should be given to foundation design to ensure it is capable of transferring these loads into the hull. These loads do NOT include vessel motion accelerations, such as vertical slam loads which can be significant for high speed vessels and vary based upon the longitudinal location. The responsible party for designing the supporting structure (boat builder, installer, or hired sub-contractor) must accommodate the above forces plus a reasonable factor of safety. Seakeeper recommends a minimum safety factor of 3.0 (yielding a Safety Margin of 2.0).

There are two methods of installing the Seakeeper 18:

1. Bolt-In Installation: the Seakeeper 18 is bolted directly to a metal structure or embedded tapping plate.
2. Bond-In Installation: Seakeeper 18 is bolted to Seakeeper supplied saddles which are bonded to the vessels FRP Structure using a high strength structural adhesive.

It is assumed that the installer is familiar with installing mechanical fasteners in marine structures or using high strength adhesives on aluminum and fiberglass (FRP), and has performed structural analysis to assure the structure to which the Seakeeper mounts can properly transfer the loads the Seakeeper creates into the hull structure.  If the installer has any doubt about the ability of the structure to transfer the loads to the hull, then a licensed naval architect or marine engineer should be contacted to perform a structural analysis.

The installer should review the following list of reference drawings to ensure the mechanical installation procedure is fully understood.

Reference Drawings

• 90544  – Seakeeper 18 Bolt-In Installation Guide
• 90545  – Seakeeper 18 Bond-In Installation Guide
• 90282  – Seakeeper 16/12HD/18 Installation Template Kit
• 90679  – Seakeeper 18 Cable Block Diagram
• 90542  – Seakeeper 18 Bolt-In Clearances
• 90547 – Seakeeper 18 Bond-In Saddle Kit
• 90548 – Seakeeper 18 Bolt-In Kit
• 90648 – Seakeeper 18 Thru-Bolt Kit

2.2 Selection of Seakeeper Installation Location

The Seakeeper should be installed aft of amidships to minimize high acceleration loadings due to hull/wave impacts during operation at high speed or in large waves. If the only possible Seakeeper location is forward of amidships then the installer should have Seakeeper review the installation location prior to finalizing the design.

Seakeeper can only assess installation location regarding its impact on Seakeeper operation and serviceability. Seakeeper cannot determine how the installation location will affect the vessel static or directional stability other than cyclic roll reduction. The Installer is responsible for considering the Seakeeper’s effect on the Center of Gravity location, trim, overall stability, and performance of the vessel.

The Installer is solely responsible for ensuring that the Seakeeper is properly located and installed on the vessel foundation with an adequate margin of safety for the specified design loads and vessel operating characteristics.

Selection of mounting location of the Seakeeper should consider the following desirable features:

1. Adequate service access for scheduled maintenances and overhaul of the Seakeeper 18 is required. See Figure 3 and Drawing No. 90544 – Seakeeper 18 Bolt-In Installation Details for service clearance requirements.
2. The Seakeeper should be installed in a dry space to minimize effects of corrosion.

VIEWS SHOWING RECOMMENDED SERVICE CLEARANCES AROUND THE SEAKEEPER FOR USE OF HAND TOOLS, EASE OF MAINTENANCE, INSTALLATION AND PROPER OPERATION.

Refer to Figure 4 for required clearances to transverse beams.  If a transverse beam is located under the forward brace, it must be 1 in. (25 mm) from the edge of the Seakeeper to provide the necessary clearance for the swing of the motor power cable during the Seakeeper’s precession.  Clearances aft of the Seakeeper are shown to provide access for regular scheduled maintenance.

2.2.1 Noise/Soundproofing

Seakeeper 18 noise has been measured under steady state conditions (no wave load) in Seakeeper‘s lab and in our test boat. The steady state noise is typically <68 dBC at 1 meter. As the frequencies emitting the highest sound pressures are low (like other marine machinery), it is recommended that the Seakeeper be installed in an enclosed space such as a machinery space, lazarette, or bilge. If additional noise reduction is needed sound proofing insulation can be used in the space around the Seakeeper unit.

2.3 Selection of Installation Method

The Seakeeper 18 can be affixed to the hull structure using two methods:

1. Bolt-in installation or
2. Bond-in (Saddle) installation. See figures below.

OPTION 1 – DIRECT FASTENING OF SEAKEEPER FOUNDATION TO SHIP’S STRUCTURE

Option 1 would be applied when a metal structure or laminated tapping plates are available for attachment. The Seakeeper 18 frame would fasten directly to hull structure or plates using isolation gaskets for metal-to-metal contacts and (16) M14X2.0 fasteners. Depending on the structure to which the Seakeeper is fastened, blind threaded holes or thru-bolting can be utilized.

OPTION 2 – SADDLE INSTALLATION (4 PLACES)

Option 2 would most commonly be used on a FRP hull structure. For this option, four 12.9 in. (327 mm) long x 4.9 in. (125 mm) wide x 6.7 in. (170 mm) height saddles (P/N 90547) are bonded to properly spaced and prepared structural members that are an integral part of the hull structure. Seakeeper recommends using a structural adhesive with a lap shear strength of 2,000 psi (13.8 MPa) or greater. Careful consideration should be exercised by the installer while selecting the appropriate adhesive.  Compatibility with the Seakeeper’s cast aluminum A356-T6 saddles, hull structure and pot life are three important factors to consider. Proper surface preparation in accordance with adhesive manufacturer’s recommendations prior to installation is very important. Recommended adhesives can be found in Seakeeper Technical Bulletin 90382 – Structural Adhesive Recommendations.

2.4 Bolt-In Installation

2.4.1 Preparation of Hull Structure

Refer to Seakeeper Drawing No. 90544, Seakeeper 16/18 Installation Details – Bolt in Method. Important dimensional and load information is given in this drawing that will impact the design details of the structure that will receive the Seakeeper. It is assumed that a proper structural analysis has been performed for the hull structure to which the Seakeeper will be fastened to ensure proper strength margins for the loads the Seakeeper will create during operation. Seakeeper recommends a safety factor of 3.0.

The hull structure supporting the Seakeeper should be arranged so the Seakeeper is parallel to the waterline in the transverse direction and within 2 degrees longitudinally.

In addition, the four areas on top of the structure on which the Seakeeper 18 frame and isolation gaskets will rest need to be co-planar within .06 in. (1.5 mm) to minimize potential distortion of Seakeeper support frame when installed.  The isolation gaskets are only used when the Seakeeper 18 is mounted to a dissimilar metal structure.

Seakeeper provides an installation template kit, P/N 90282, which contains plates that match the mating surfaces of the four feet located on the Seakeeper’s frame. These plates have 4 holes located at the same centers as the mounting holes on the Seakeeper. The fixture locates the hole patterns at the proper spacing both in the fore-aft direction and the port-starboard direction, see Figures 7. Once assembled, the fixture can be used to check clearances and alignment of the hull structure.

Note:   Do NOT use the installation fixture to establish the Seakeeper envelope dimensions.  Refer to Drawing No. 90544 for envelope dimensions. A 3-D model of the Seakeeper is available on the Seakeeper Technical Library (www.seakeeper.com/technical-library/)  to aid in designing the Seakeeper foundation and the space around the Seakeeper.

NOTE: MAKE SURE NO OBSTRUCTIONS FROM THE HULL STRUCTURE CAN BE SEEN WITHIN THE INSIDE OF THE INSTALLATION TEMPLATE KIT (INSIDE THE MARKED RED LINES) AS SEEN IN FIGURE 7. REFERENCE SEAKEEPER DRAWING NO. 90544.

CAUTION: Tight clearances from cable guide bands to hull structure.
See above figure for dimensions and reference
Seakeeper Drawing No. 90554 for complete Seakeeper 18 envelope

2.4.2 Transfer of Holes to Boat Structure

1. Lower assembled fixture onto hull structure (See Figure 8).
2. The four areas where the feet of the Seakeeper will rest should be coplanar to within 0.06 in. (1.5 mm). See figure to the right.
3. Align fixture in desired location and transfer holes from fixture plate to the hull structure.  Note that holes in fixture plate are ø0.55 in. (14 mm).

2.4.3 Blind Hole Installation

1. Remove Template Fixture and drill four (4) x 9/16 in. ø (14.29 mm ø) holes perpendicular to the vessel structure to a minimum depth of 0. 84 in. (21 mm). Take special care to drill perpendicular to mounting surface.
2. Tap drilled holes for M14-2.0 threaded inserts.
3. Install four (4) M14-2.0 X 1.5D (21 mm length) locking threaded inserts into holes in hull structure at drilled and tapped locations using threaded insert manufacturer provided installation tool.

4. Remove threaded insert prong / tang after threaded inserts are installed

2.4.4 Through-Hole Installation

1. Remove Template Fixture and drill sixteen (16) (15mm ø) holes perpendicular to the vessel structure. Take special care to drill perpendicular to mounting surface. A drill guide is recommended.

2.4.5 Installation of Seakeeper

1. Lower Seakeeper into position onto the hull foundation beams and align over drilled holes. Apply a small bead of marine sealant (e.g., SILI-THANE 803 or equivalent) between mating surfaces of Seakeeper frame and hull structure to prevent moisture wicking into bolt holes.
   
   1. For dissimilar metal foundations locate and position 4 isolation gaskets onto foundation beams and apply a small bead of marine sealant (e.g., SILI-THANE 803 or equivalent) between both mating surfaces of each isolation gasket where it contacts the beam and the Seakeeper.

2. Install mounting bolts:
   
   1. For Blind-Hole installations (Seakeeper Kit #90548), install the Seakeeper supplied Grade 10.9, M14-2.0 x 100 mm fasteners or alternative Grade 10.9, M14-2.0 bolts to maintain a minimum thread engagement of .82 in. (21 mm). Apply a moderate coat of nickel-based anti-seize (e.g., SAF-T-EZE nickel grade anti-seize, SBT-4N or equivalent) to the threads of each bolt and include a small bead of marine grade sealant (e.g., SILI-THANE 803 or equivalent) under each bolt head and washer before installation.
   2. For Through-Bolt installations (Seakeeper Kit #90648), install the Seakeeper supplied Grade 10.9, M14-2.0 x 120 mm fasteners or alternative Grade 10.9, M14-2.0 bolts to maintain a minimum of 2 threads protruding past nut. Apply a moderate coat of nickel-based anti-seize (e.g., SAF-T-EZE nickel grade anti-seize, SBT-4N or equivalent) to the threads of each bolt and include a small bead of marine grade sealant (e.g., SILI-THANE 803 or equivalent) under each bolt head and washer before installation.

3. Torque all fasteners to 100 ft-lbs (136 Nm).
   
   1. New bolts, matching the Seakeeper specification, must be used for each installation and reinstallation that meet the requirements listed above.
4. Proceed to electrical and cooling portion of the installation.

2.5 Saddle Installation

Seakeeper provided mounting hardware is intended to apply to typical installation arrangements. However, each installation, especially custom aftermarket foundations, should be thoroughly reviewed to ensure the provided hardware meets the required thread engagement for the Seakeeper unit being installed. The mounting bolt thread engagement requirements are outlined in the Installation Manuals and Installation Details Drawings for each Seakeeper model. This also applies to Seakeeper model adapter kits and OEM built frames where the bolt hole depth should be checked to ensure the bolts will not bottom, preventing the bolts from achieving the intended preload.

When the Seakeeper provided hardware is not appropriate, the bolt specification (diameter and thread pitch) and grade should be matched in the required length and used with the Seakeeper provided washers. Mounting bolts should always be torqued to the Seakeeper specification. All Seakeeper provided bolts are metric course thread. Hardware specifications are also listed in the Installation Manuals and Installation Details Drawings.

See Sheet 6 of Seakeeper drawing No. 90545 for loads information and recommended adhesive properties.

2.5.1 Preparation of Hull Structure

Refer to Seakeeper Drawing No. 90545, Seakeeper 18 Installation Details – Bond-In Method. Important dimensional and load information is given in this drawing that will impact the design details of the structure that will receive the Seakeeper as well as selection of the adhesive to bond the Seakeeper into the hull.

The foundation “saddles” of the Seakeeper are designed to be bonded directly to the composite hull structure of the vessel to effectively distribute Seakeeper loads.  A complete bond is required between the inside surface of the saddles and the hull structure. An estimate of adhesive volume required should be calculated for each installation based on gaps between saddles and structural members. There is some adhesive waste as a part of the process, so a good rule of thumb is to purchase up to 50% more adhesive than estimated volume to ensure a complete bond. Depending on conditions and adhesive used, two workers may be required to apply the adhesive at the same time to finish the installation before the adhesive starts to cure. To aid in determining the quantity of adhesive required, the interior surface area (bonding surfaces) of each saddle is 164 in.² (1,058 cm²) for a total bonded surface area for all four saddles of 656 in.² (4,232 cm²). 

The hull structure supporting the Seakeeper should be arranged so the Seakeeper is parallel to the waterline in the transverse direction and within 2 degrees longitudinally.  The four areas on top of the beams that the saddles will bond to need to be co-planar within .13 in. (3 mm) for consistent adhesive bond gap.  In addition, the four areas on top of the saddles on which the feet of the Seakeeper foundation will rest need to be co-planar within .06 in. (1.5 mm) to minimize potential distortion of Seakeeper support frame when installed.

Note that any paint or gelcoat present in bond area should be removed so that adhesive will bond directly to laminate fibers and resin.  

Seakeeper provides an installation fixture template, P/N 90282 that locates the saddles at the proper spacing both in the fore-aft direction and the port-starboard direction. See Figures 10, 11, & 12. Once assembled with the provided saddle fittings, the fixture can be used to check clearances and alignment of the hull structure. The fixture will allow the builder / installer to lay-up and adjust the foundation dimensions to create a low-clearance fit between the Seakeeper foundation saddles and the hull structure. Shear strength of the adhesive will be maximized if the cured thickness between the vessel structure and Seakeeper saddles is at the thinner end of the adhesive manufacturer’s recommended range. Therefore, the fixture should be used to confirm that the overall dimensions of the foundations are square and level and that the adhesive gap is within Seakeeper’s recommended range of .04 to .13 in. (1 to 3 mm).Note:   Do NOT use the installation fixture to establish Seakeeper envelope dimensions.  Refer to Drawing No. 90545 for envelope dimensions.   A 3-D model of the Seakeeper is available on the Seakeeper Technical Library (www.seakeeper.com/technical-library/) to aid in designing the Seakeeper foundation and the space around the Seakeeper.

NOTE: MAKE SURE NO OBSTRUCTIONS FROM THE HULL STRUCTURE CAN BE SEEN WITHIN THE INSIDE OF THE INSTALLATION TEMPLATE KIT (INSIDE THE MARKED RED LINES). REFERENCE SEAKEEPER DRAWING NO. 90545.

2.5.2 Fiberglass Hull Preparation

1. Position installation fixture (Figure 12) on hull girders noting recommended clearances for maintenance from Figure 3.  Check that the screws fastening the saddles to the installation fixture are tight (Figure 14).

2. Mask hull area (Figure 13) around foundation saddles for easy clean-up and to create outline of surface area to receive adhesive as (Figure 12).  Ensure that the bond gap is within Seakeeper’s recommended thickness, or 3 mm if using Plexus MA590.

3. Raise fixture clear of foundation.  Check all four mounting areas are co-planar to within 0.13 in. (3 mm) to each other, as well as parallel to the water line plane, as shown in Figure 14.

4. Thoroughly clean with alcohol or acetone all areas of girders to be bonded to remove any contaminates. Use new paper towels for cleaning, not shop rags.
5. Remove any paint or gelcoat from bond surfaces so that adhesive will bond directly to laminate fibers and resin as shown in Figure 13.
6. Thoroughly sand hull girder bond surfaces with 80 grit sandpaper.  (IMPORTANT – BOND STRENGTH MAY BE REDUCED IF THIS STEP IS SKIPPED.)
7. Wipe surfaces clean from dust with alcohol or acetone using new paper towels, not shop rags.
8. Re-position installation fixture on girders and double-check that the adhesive gap is within the adhesive manufacturer’s maximum recommended thickness. Seakeeper recommends a maximum gap of 3 mm if using Plexus MA590.

Note if bonding saddles to a metal structure, contact Seakeeper for hull preparation instructions.

2.5.3 Seakeeper Saddle Preparation

1. Ensure that screws fastening saddles to the installation fixture are tight (Figure 11).
2. Check that each saddle contains 2 plastic screws which will ensure an adhesive gap of .080 in. (2 mm) on top surface of hull as shown in Figure 15. Do not remove these screws.
3. Thoroughly sand all saddle inside surfaces with 80 grit sandpaper in cross-hatch pattern. (IMPORTANT – BOND STRENGTH MAY BE REDUCED IF THIS STEP IS SKIPPED.)
4. Thoroughly clean with alcohol or acetone the inside surfaces of Seakeeper foundation saddles to remove any contaminates as shown in Figure 11. Use new paper towels for cleaning, not shop rags.

5. If using Plexus MA590 adhesive, apply one coat of Plexus PC-120 surface conditioner to inside surfaces of Seakeeper foundation saddles in accordance with manufacturer instructions.  These instructions are located in the following section.  If using an alternate adhesive, check with manufacturer if any surface conditioner/etch is required for the aluminum saddles.

2.5.4 Bonding Saddles to Hull

Note: This is a sample if using Plexus, if using another adhesive follow manufacturer’s

recommendations. If using Plexus MA590 adhesive, the Seakeeper saddles should be installed when PC-120 is confirmed dry.

1. Assemble Plexus cartridge into either the manual or pneumatic gun as shown.  Remove cap on cartridge and attach mixing tip.  For pneumatic gun, start with low air pressure and increase until desired flow rate is achieved.

2. Cut tip of mixing wand as shown in photo.

3. Prepare a second mixing wand as shown in photo below by attaching the simple flexible nozzle to the end of the mixing tip. Set aside for now as this will be used to inject adhesive into the sides of each saddle after the fixture / saddles are in position.

4. Install provided rubber plugs in six holes of each saddle. The plugs will limit the adhesive being forced out of the injection holes in step 6 below.
   
   
   
5. Apply large bead of Plexus adhesive to the hull structure as shown in the figure to the right. Apply approximately ²/_3rds to 1 cartridge at each of the four locations.  Work deliberate and fast as it takes some time to apply the adhesive to the structure. MA590 has a 90-minute working time at room temperature (73°F / 23°C).  This working time can reduce to 40-50 minutes at elevated temperatures. Two workers should apply the adhesive at the same time to finish the installation before the adhesive starts to cure.
6. Lower fixture and saddles over the hull structure and apply light downward pressure to each of the four saddles until the two nylon screws rest on the hull structure (SEE FIG. 7). The adhesive will be forced towards the forward and aft ends of each saddle and partially down the sides of the foundation beams.
7. Insert full adhesive cartridge along with mixing wand / nozzle assembled in Step 3 above into gun.
8. Begin to inject adhesive into the three holes provided on each side of each of the four saddles. Follow the numbered sequence shown until the adhesive pushes out the edges of the saddle perimeter. The intent is to pump in the adhesive working from the top down and from the middle to the ends to fill the gaps and displace any air.

A complete bond is required – excess adhesive will be needed to make sure all bond gaps are filled.

9. Repeat above step for remaining 7 sides of the saddles.
10. When gaps have been completely filled, clean off excess adhesive, remove plugs, and remove masking tape.
11. Allow adhesive to cure per manufacturer’s recommendations.  Follow adhesive guidelines for curing time versus temperature prior to removing the fixture.
12. Bonding of Seakeeper saddles onto the hull is now complete.  Remove installation fixture.

2.5.5 Installation of Seakeeper

1. The four areas where the feet of the Seakeeper will rest should be coplanar to within .06 in. (1.5 mm). See Figure 14.
2. Rig the Seakeeper for lifting and lower it into position onto top surface of four saddles.
3. Apply a small bead (approximately 4 mm wide) of sealant or caulk to the mating surfaces between the saddles and the Seakeeper foundation.  Adjust position of the Seakeeper until alignment is achieved for the 16 fasteners that will attach Seakeeper foundation frame to saddles.

4. Install the Seakeeper supplied Grade 10.9, M14-2.0 x 90 mm fasteners or alternative Grade 10.9, M14-2.0 bolts to maintain a minimum thread engagement of .83 in (21 mm). Apply a moderate coat of nickel-based anti-seize (e.g., SAF-T-EZE nickel grade anti-seize, SBT-4N or equivalent) to the threads of each bolt and include a small bead of marine grade sealant (e.g., SILI-THANE 803 or equivalent) under each bolt head and washer before installation.
5. Torque all fasteners to 100 ft-lbs (136 N-m).
   
   1. New bolts, matching the Seakeeper specification, must be used for each installation and reinstallation that meet the requirements listed above.
6. Proceed to electrical and cooling portion of the installation.