Originally Posted by Dreamcat
We had the same problem and used self amalgamating mast tape ...
My DIY mast boot, made entirely of self-amalgamating electrical
splicing tape, lasted at least ten years in the sub-tropics, with narry a drop.
Excerpted from some earlier threads, these taping hints apply equally well to electrical
joints as to mast boot sealing applications:
Some TAPE TIPS:
- Use a quarter or half-lap wrapping technique, where each wrap overlaps the previous wrap by a quarter or half the width of the tape.
- Apply tape with enough stretch to conform to the object you are wrapping, usually reducing the width of the stretched tape to about 5/8 to 3/4 of it’s original width.
- On the last few turns reduce the stretch tension until it is zero at the last turn or two, to prevent flagging. Use a scissors to cut the tape end square, as a knife or tearing will add stretch to the last lap, and cause it to un-wrap.
- Any time you wrap tape on a threaded component, make sure you wrap it in the direction that tends to tighten the screw threads. This means if you are taping a splice, for example two PL-259's screwed into a double barrel female, you must tape each connector from the cable end to the barrel center, overlapping the first side tape with the second side tape.
- Always run the tape "uphill" - that is from a lower point to a higher point (vertical plane), or from a smaller diameter to a larger diameter.
- Rubber tapes should generally be over-wrapped with a vinyl tape for mechanical protection.
More TAPING TIPS:
When wrapping with any of the non-adhesive (self-fusing, amalgamating, vulcanizing) conformable rubber tapes, it may help to apply with the outside in. The inside (tacky) side of the tape is turned to lay on the outside of the wrap, keeping the roll closer to the work.
Electrical tapes are generally applied under in successive “half laps”, and under tension, so that the tape elongates (stretches) to the point where it’s width is about ½ to 3/4 of it’s initial dimension - then completed with a final lap which is not stretched at all. This prevents “flagging” (winding back on itself). Rubber tapes are often over-coated with a protective layer of regular vinyl tape.
This tensioning technique is not always suitable for co-axial cables
, especially foam cores, which have little compressive strength. The tension can cause dielectric breakdown of the cable.
When taping vertically, the final (top) layer should start at the bottom and tape uphill, creating a rain-shedding lapstrake (shingle lap) effect.
When taping screwed component co-ax connectors, tape in the direction (clockwise seen from cable end) of tightening the threaded joint.
There are several specifications to compare when selecting a particular electrical tape product, including:
Heat Resistance (operating temperature) & Thermal Dissipation
Linerless rubber tapes are slightly more expensive; but MUCH easier to use than lined rubber tapes.
There are any number of Self-Amalgamating Silicone Rubber Tapes, such as:
- 3-M Scotch 130C Linerless Rubber Splicing Tape (EPR)
- 3M Scotch 70 Self-Fusing Silicone (/w Liner)
- Scotch 23 Rubber Splicing Tape (EPR)
- “Tommy” Tape (Silicone)
- “Rescue” tape