Griswold's post on his speargun storage got me to thinking about protective caps on spear shafts.
We generally hunt with slip tips, and it is easy to remove them when the guns are stored. But even the adapter or bare threaded end of a shaft could easily be a danger if you fell onto it. One thing that I have found to work well on certain tips is a 2" piece of the bright orange hose on my air compressor. It is heavy walled, and the diameter is such that it will fit over the point, but not the double floppers on a JBL slip tip. It wouldn't work on a single flopper shaft, or the adapter end of a standard slip tip, though. The bright orange color is important to me, as I can get a little excited when the bottom machine lights up with fish, and often jump in the water with the protective cap still in place.
Probably the best protector would be something that is hollow inside to fit over a shaft, but closed at the end so that it can't be pushed down if someone falls on it. If you have ever seen the protective caps on re-bar at a construction site, then you have an idea what I am envisioning, but obviously smaller.
What do others use, if anything?