If you have a tabernacle mast this is the procedure. We do it every time we go out because we happen to park on the wrong side of the bridge.
1. First you need a very long mainsheet
line coming off the end of the boom. A six to one tackle is recommended.
2. A good backstay cable is recommended because the weight of the mast will be on this cable.
Next you must release any
lines, vang, rope clutches etc. which may hang up during the lowering process.
Now loosen your shrouds (on the sides of the mast. They do not have to be disconnected unless they are too far behind the mast to lower it.
Disconnect your back stay and attach it to the end of the boom with the mainsheet
line taught.
Have someone go forward and pull on the forestay as
line is let out from the mainsheet tackle. Pulling on the forestay starts the weight to move forward. Continue to let out
line until the mast is low enough for your needs. Pay special attention to the boom so that it does not move to the side. Another person could hold it for this part of the process. If you intend to leave the mast down for some time, two
lines can be attached to the end of the boom and tied off to the stern corners. To raise the mast just reverse the process. If you have dropped it all of the way down it may be necessary to get someone to lift up on the end of the mast as you pull in the mainsheet tackle.
This process takes my wife and I about fifteen minutes on our 30 ft Cal. I hope it is helpful to someone.