30+ A-sails
Those who have read my posts already know where I am going-but for a cruiser (and a racer as well) a cruising spinnaker/flasher/APC/Gennaker/thingamajig is a must have-In light air, as long as you don't actually HAVE to sail as close to the breeze as possible, they will drive the boat a knot faster that a full size furling genoa-You should be able to get well into the low 40's apparent wind angle with ease-and you can use it like this until the breeze is high enough that comfort and control issues call for a different sail (your genoa). Of course, you can leave it up in higher winds at deeper angles-
You are correct that a broad reach is about as low as you can go without a pole, but if you are willing to use the pole, you can run quite well with most of them-square back just like a symetrical!
They are by definition more effcient aerodynamically than a symetrical-at any angle, and if you are willing to use the pole for deeper angles, the limitation at these angles is not that they are assymetrical, but that they are often flatter and smaller (to maximize the close and beam reaching portion of their job).
I have advised many folks to order their a-sails with more of an "AP" shape than a reaching shape-this will make them faster at deeper angles with or without a pole, yet sacrifice VERY little at the closer angles-they will sail almost as close, but may not be able to carry it at those close angles into quite as much breeze as the reaching shaped A-sails..a fair trade. It should not affect the purchase price (unless you ask for a slightly bigger than "standard" size). Note that each sailmaker has their own cruising sail product-with a specific size. Most are quite close to each other-but not exactly-The UK Flasher, for example, has historically been a bit smaller than the Doyle or Quantum flavors of this idea. This means you have to be careful when shopping-look at the sail area or dimensions. All are good, just slightly differing design philosophies..You can always request a slightly larger one (and pay the difference). Typically they will have SMW's (Mid-width girths) of 1.6-1.75 X J-which can also be equated to LP size (e.g. A 150% Genoa has an Luff Perpendicular, or "girth" of 1.5 X J). The max size of any standard spinnaker, symetrical or not, is 1.8 X J.
Be careful with the masthead sheave..Are you sure you are not seeing the back of the topping lift sheave? The top of this rig is not supported, and in any case, the intended spinnaker for this boat was to be flown from the spinn halyard at the hounds-not the masthead! If you do have this halyard, and order a sail that big-I would use it VERY carefully, and only in the lightest of winds-but boy will you fly in the light stuff!! But seriously, use the proper sheaves (at the hounds)!
Fair winds,
S