Hi, Tim. I am slightly familiar with your model of boat and have an idea of what it looks like; and I don't believe attaching the running backs to anywhere near the centerline is very helpful. They should each have two attachment points: one in the relaxed position and one when being tensioned. It's always valuable to be able to move one or both out of the way.
I cannot tell if your boat has swept-back spreaders; but in the absence of a standing mizzen backstay (which few ketches have) it should. The aftward angle of the spreaders leads the upper shrouds farther aft than the chord of the mast
(parallel to which they would lead if the spreaders were straight) and thus the upper shrouds act like minor backstays
. (This is the principle of the Bergstrom 'B&R' rig.)
I put in a pic of a Cherubini 44 which may show the swept-back spreaders and running backstays
. You'll see the mizzen runner attached to its tensioning position at the corner of the transom (this boat has cute wooden-shell blocks on it). We fit these with 4:1 purchase
and cam-cleat fiddle blocks. The mizzen has two shrouds, the upper and the aft, leading to a pair of attachment points about 24" aft of the chord (widest point) of the mast
section at the deck
. The forward lower goes to about 24" forward of the chord at the deck
(or on boats without a triatic stay, it's an intermediate going to about 36" forward). All C44s, as-designed, have swept-back mizzen spreaders. Aside from that the mizzen runners are the only backstays
for the mast. On the C44 they are led to the mizzentop; though I might prefer them attached a little lower, most properly where the intermediate attaches (to avoid inducing a moment there and to stiffen the rig). The reason they go to the top is to support mizzen staysails, mizzen spinnakers and mules; and for that reason, since so many C44 fly these, the mizzen runners are vital.
You are, of course, free to experiment
. Remember that these things are
stays-- they need attachment points, such as serviceable u-bolts, adequately fastened through the deck (or sides of the hull) on the order of chainplates. You can't just clip them to stanchion bases. Once you have established where the runners ought to attach (as far aft and as far outboard
as possible-- like to the corners of the transom) for sailing on the wind
, then see what you can do to provide rig stiffness on other points. For example, when on a quarter-run you might fully tension only the windward one; and as you bear off further, more downwind, the leeward one will either just drape loosely or be taken forward to allow the boom more space to wing out. Cinch up on the remaining one to windward; if you do not have enough purchase
to keep the masthead from sagging off, get better blocks. In no cases, however, do I see any reason to remove them completely. Doing so might end up as bad practice-- and if your boat has a triatic, as most ketches do, loss of the mizzen can entail damage to the main as well. At Cherubini we eliminated the triatic from all new-build and newly-restored boats, in the interests of safety
sanity; the forward intermediate takes its place and does very well too.
good thing about having a triatic stay is that the mizzen rigging
, especially the upper shrouds (presuming swept-back spreaders) and the mizzen running backs, will add support to the mainmast and therefore contribute to headstay tension-- too often slack in cruising boats with headsail-furler foils and rolled-up sails
. But it does come at the cost of complicating the rig and all degrees of tuning.
Many people insist on having a boomkin for a standing backstay on both ketches and schooners (including too many of our C48 buyers). I try to remind these people that, aside from being rather ugly and ungainly, this is entirely unnecessary so long as the boat is rigged and sailed responsibly. We never heard of any of John Alden's racing
schooners losing their spars in a jibe; and none of them were designed with boomkins.