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Torpedo Bulb Installation Guide

Please note that this is a general outline and can not examine every possibility encountered in the project. Therefore it is always advisable to have a professional install the bulbs or rely on a combination of ours and their advice in the case of questions.
  1. Open the crate of the Split Torpedo Bulbs, checking that the bulbs, hex nuts, flat washers and threaded rod is there.
  2. If it is a draft reduction and if the keel is not cut, mark the keel at the level of draft reduction desired. The marking should be parallel to the water line of the boat.
  1. If the bulbs are used for a Stability bulb the installation process starts right away.
  2. The bulbs should be dry fitted on the keel.
a. The forward end of the bulb halves are generally made to be fitted approx. 1” aft of the leading edge of the keel.
b. The bulb should be parallel to the water line, fore and aft.
  1. The marking of the holes for the mounting bolts can be done once the position of the bulbs is set and finalized.
a. You will notice the holes in the bulbs are larger then the diameter of the provided threaded rods. This is done to allow fine tuning of the fitting.
b. Mark the holes from both sides of the keel. This will minimize the chance of major misalignment.
c.  Mark the outline of the bulbs on the fin.
  1. The holes can be drilled out with bulbs still on or against the keel, it is not necessary. This will require a longer drill bit but removes the need to remove and then replace the bulbs for the last step in the dry fitting process, tightening.
a. Take your time with the drilling process, it is a long process. If you push it too hard you will probably end up with broken bits jammed in the lead causing more problems.
b. Drill the lead with a twist bit, drilling slowly, lubricating the bit with water, and drilling only a ½” at a time. Withdraw the bit and clean the tip every time.
  1. It is recommended that the bulbs be tightened into place at this point
  2. Remove all the paint, fairing material on the keel inside the marked bulb area. This area should be clean lead, left with a rough surface, scratched. (Tooth for the epoxy to adhere to.)
  3. Place the bulbs against the keel. Install the bolts loosely, until they are all ready to be tightened and the bulbs are sitting where you want them.
  4. Tighten the bulbs to the keel. Tightening the bolts in sequence a little at a time.
a. This will bring the bulbs into their final shape. The bulbs will bend under the clamping force; this is both normal and desired. Any area, right at the nose of the keel, that is not forming can be complete with a mal and a block of wood.
b. Once you are happy with the fit the bulbs can be removed.
  1. Check to ensure the inside surface of the bulbs and the mounting surface of the keel are clean of debris and oil, water etc. the surfaces should not be smooth, they should be roughened to offer the thickened epoxy a tooth to hold to.
  2. Apply thicken epoxy to both mounting surfaces. Ensure that you have good contact with the metal.
a. The application process and the tightening have to be done rather quickly, the thickened epoxy will cure faster then normal, so please be prepared, have all the required people and tools at hand that you think you will need. It is not a race, once the epoxy has been spread out on the surfaces the curing will slow down giving you some time.
b. Epoxy should be applied in the bolt holes as well.
  1. Once the bulbs are tightened into place, the position is checked and correct, the excess epoxy can be cleaned off. Some of it can be used to fill the bolt holes, the trailing edge and any gaps between the bulb and the fin.
  2. At this point the completion of the job is fairing and painting.
a. Once the bulbs are faired to your liking the entire area should be coated with the required number of coats of a barrier coat, Interprotect 2000E or similar, before the final coats of anti fouling paint is applied.