According to the manual the Safety line on the topping lift should be 4’5" long.
At that length the boom will be dangerously low, almost on the binnacle.
How long are people making their topping lift safety lines?
Randy Gadikian
Phoenix
NS 26C #37
Buffalo, NY
Sounds like something is out of whack, Randy. Maybe the topping lift is too long?? Here’s a shot of part of mine -
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
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[/details]Hi Randy,
The length of the safety assumes the static topping lift is the correct length. This was an incorrect assumption on Soave.
I suspect a new static topping lift was installed a few years ago that is longer than the original spec. As a result, the old safety was too long.
I determined Soave’s, safety was too long by slowly lowering the topping lift. Before the safety was loaded, her wishbone was touching our bimini and would have engaged the head of someone standing at the helm. Not good.
For this season, I spliced a length of Dyneema to use as a safety that loads up about a couple inches before the wishbone engages our bimini. My new safety is about 14" shorter than the old one.
The static portion of Nonsuch topping lifts needs to be short enough to permit raising the wishbone during reefing. It’s a common practice to use the topping lift to raise the wishbone to make it easier to secure the aft reef lines. I’m going to experiment a bit with reefing to determine if I like the length of Soave’s static topping lift.
It is not clear if the topping lift length stated in our manuals reflects that the topping lift would be used during reefing. The old marketing videos do not mention using the topping lift during reefing.
Rob
s/v SOAVE
NS33 #009
Cedar Point YC
Westport, CT
The point of a safety strap is safety. It is there to keep the boom from injuring someone or damaging your bimini or other equipment should the running topping lift line fail or come loose. I think considerations such as how the topping lift hangs when sailing or what the manual specs out are irrelevant. If the boom is hanging at the right (safe) height when the running topping lift line is slack, then the length of your standing topping plus safety strap is correct. If you cannot slack the topping lift without the boom hitting something important (your bimini, your binnacle, your head…) then it is too long and the easiest way to correct that is with a shorter safety strap.
If the safety strap is the wrong length you can measure how much to add or remove by first supporting the boom with the topping lift line, disconnecting the safety strap, setting the correct (safe) boom height with the topping lift line, then hold use a tape to measure how much too long or short the safety strap is. Adjust it (or make a new one) accordingly, then re-check it.
I recently had some mast work done and while it was down I had the wire topping lift standing part and the safety strap replaced. I asked the rigger to make the topping lift 6" shorter to give me a little more adjustment range. I also asked him to make the safety strap longer so that the overall length was the same, but he missed that part. So my safety strap is 6" too short. This is what happens when you hire a professional. They are always in too big a hurry to pay attention to anything unusual. I partially fixed the problem by adding in a soft shackle, but the sailing store only had one in stock, so I’m still a tad high. I’ll get it dialed in soon. Or maybe I will attempt to make my own safety strap from some leftover Dyneema cored line. But Rob’s skills must be better than mine because I am not sure I can splice an eye with sufficient accuracy to get the length I want. 
BTW, with my topping lift safety set a couple of inches too high, the topping lift is still very slack when the sail is set and the boom is fully supported by the sail. This was actually just pointed out to me the other day when out sailing with some friends. (“Is that line supposed to be so loose?” “Yup.”) That may not be true for every boat, but on mine the safety role of the safety strap does not interfere with anything.