This is from a doc I'm emailing to Festivus and Pete for the How-To page. Not a real procedure, but captures my lessons learned.
Supplement to Technical Service Bulletin 49
S22 Tracking Fin Installation
One of the first modifications I made to the boat was to add the tracking fin. This provided a noticeable improvement in towing manners, but at the same time made slow-speed maneuvering more difficult. The bow doesn?t slide like it used to when whipping it around to a dock.
The published procedure directs the technician to empty and remove the fuel tank. I presume this is to prevent the chance of driving a drill bit through the hull, liner and into the fuel tank. The results of that could be damage to your tank and EXPLOSION and fire, so it?s not to be taken lightly. However, be advised that removing the tank seriously adds to the amount of work (not a little, a lot). If you have a drill stop and are very confident in your patience, you might consider doing this procedure without removing the tank. I did remove the tank, but there were other reasons for me to do that.
There is an outstanding TSB that describes pulling the fuel tank and laying down some foam rubber tape in between the liner and fuel tank. EpicMarine doesn?t have a copy of that, but the dealers do (that was one I just didn?t copy and shouldn?t have). I believe that the foam is intended to prevent chafing between liner and nylon fuel tank. It could also be there to prevent the tank from riding squarely on the control cables running aft. After pulling the tank, I used adhesive-backed foam tape fairly closely spaced together to support the tank. I ensured there were channels for bilge water to run fore and aft without being impeded by the foam tape.
My S22 came without a drain installed in the ice chest under the observer seat. There was a recessed area in the mold (forward, inboard corner), but no hole. It?s impossible to get underneath that drain area without having the tank removed. So?once the tank was out, I trimmed back the aluminum floorboard underneath the ice chest drain and then installed a modified through-hull fitting into the ice chest. The modification was to move the stream of water outward so that it doesn?t drain directly onto the fuel tank; instead, it drains between the liner/stringer area and the fuel tank, directly down into the bilge.
The big problem I found with the procedure (besides getting the fuel tank empty) was that my hull has aluminum reinforcement in the hull area by the tracking fin. The procedure calls for ?? (#14) stainless steel sheet metal screws, and they can?t be driven into aluminum when predrilled. No, really. They will break off and die. Then you?ll be getting an easy out and trying to drill a hole into a broke off stainless screw. Really.
The big deal here is to pay attention to the tailings that come out of your first hole and onto your eye protecting devices. If there isn?t any aluminum in the tailings, you can proceed as directed. You may find that the #14 screws seem very small for the skeg mounting holes. Seem to remember thinking that we could definitely go for a larger size screw. PLEASE pay attention to the recommended pilot hole drill bit size before drilling ? would be very bad to drill too large a hole for the screw. Also, I believe I used a little more sealant than they show in the procedure. Pretty much covered the mating surfaces, squirted some into the screw holes and then covered the threads of the screws and spun them home.
If there?s aluminum mixed in with the fiberglass, I suggest switching immediately to a 5/16? stainless machine screw like I ended up with. The deal with these babies is that you?ll need to tap the imbedded aluminum plate, as they really have no purchase in fiberglass. The good news is that you?re getting metal to metal contact and you can use a nice beefy screw that fills the skeg mounting screw holes.
Get your skeg properly aligned and then mark one hole. Remove the skeg. From the tap and die set, punch the pilot hole NOT TO EXCEED 1 ?? depth. Carefully cut threads into the embedded aluminum reinforcement. A blunt tap will help prevent you get the threads cut without poking up into the liner.
Once the hole?s been drilled and tapped, temporarily mount the skeg using the single machine screw. Take your time in aligning it to centerline and then mark the remaining three holes. Remove the skeg and drill and tap the three. Test fit by mounting the skeg with all four screws prior to applying sealant.
I?m not sure how thick the aluminum sheet is in my boat, and I?m not sure how many boats have that reinforcement, so start with the approved procedure but pay attention for aluminum in the tailings. You might consider using a larger sheet metal screw (like take the skeg with you to the hardware store to find one that fills the countersunk area. Make sure you don?t exceed the depth limitation.
Any questions, please email derek.boyer@netzero.net or visit
www.epicmarine.com
