We find our boat travels 0.5-0.6 of the TWS with a spinnaker downwind so that almost halves the apparent wind when running pretty square. We look at taking down the spinnaker when the TWS gets to 25 knots as any slow downs due to waves or whatever can mean rapid increase in AWS (our reefing plan says remove when over 15kts AWS).
Reefing a spinnaker with a sock isn’t possible as the sock and pull down line is not strong enough for that purpose. A way of reducing the power
in a symmetrical spinnaker is to allow the foot to rise up (easing both guys/braces). This creates a larger belly up high and reduces the frontal area. If you have your mainsail
up, easing the windward guy/brace and using the leeward sheet to pull the spinnaker around behind the mainsail
will also work
Regarding mainsail boom angle, 45* is just fine, as the top will twist further open anyway (if you ease the mainsheet and/or let the boom out beyond the traveller). A single
or double reef won’t slow you down much if at all in decent breeze and will allow more air into the spinnaker.
For taking down the spinnaker with a sock we’ve always eased the leeward sheet until it luffs and collapses, then pulled the sock down. This always keeps the spinnaker nice and straight in the sock. After reading some of the posts in this thread we tried lowering it by easing the guy/brace to hide the spinnaker behind the main. What a schmozzle! The waves tossed the collapsed spinnaker around and back and forth such that it threatened to wrap around the forestay, got caught up in the rig, and went into the sock a twisted mess. Never again! (Though that is the preferred method to take down a spinnaker without a sock.)