2.5.2 Bonding Saddles to Hull

Seakeeper Saddle Preparation

1. Ensure that screws fastening saddles to the installation fixture are tight.
2. Check that each saddle contains 4 plastic screws which will ensure an adhesive gap of 0.080 in. (2 mm) on top surface of hull as shown in Figure 15. Do not remove these screws.
3. Thoroughly clean with alcohol or acetone the inside surfaces of Seakeeper foundation saddles to remove any contaminates as shown in Figure 15. Use new paper towels for cleaning, not shop rags.

4. Thoroughly sand all saddle inside surfaces with 80 grit sandpaper. (IMPORTANT – BOND STRENGTH MAY BE REDUCED IF THIS STEP IS SKIPPED.)
5. Wipe surfaces clean from dust with alcohol or acetone using new paper towels, not shop rags.
6. If using Plexus MA590 adhesive, apply Plexus PC-120 surface conditioner to inside surfaces of Seakeeper foundation saddles in accordance with manufacturer instructions. These instructions are located at the end of this section. If using an alternate adhesive, check with manufacturer if any surface conditioner/etch is required for the aluminum saddles.

Bonding Saddles to the 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 adhesive 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 below.

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 12 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 adhesive to the hull structure as shown in the figure below. Apply approximately 1½ cartridges at each of the four locations. Work deliberate and fast as it takes some time to apply the adhesive to the structure. These working times can be reduced at elevated temperatures. Two workers should apply the adhesive at the same time to finish the installation before the adhesive starts to cure.
   See TB-90382 – Structural Adhesive Recommendation for more details.
   
   • MA590 has a working time of 90 minutes.
   • SciGrip SG300-40 has a working time of 35 to 45 minutes.
   • Pro-Set ADV-176/ADV-276 has a working time of 90 minutes

6. Lower fixture and saddles over the hull structure and apply light downward pressure to each of the four saddles until the four nylon screws rest on the hull structure. 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 six 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 foam tape, 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.