Mk 1 standing rigging

[ianc]

Hi, I'm Ian and have spent some time over the last few years renovating sail no. 28 (though her bronze rudder-tiller link piece is clearly stamped 26). She's made it to the water this year, in Portsoy harbour, Aberdeenshire, home of the annual Scottish Traditional Boats Festival.
My query is about the standing rigging, which consists of one set upper shrouds channeled through the spreaders, and one set of lowers directly from the point at which the spreaders are attached to ther mast down to the chainplates on the hull. I have the upper shrouds going to the forward chainplates, making them at 90 degrees to the mast, and the lowers to the chainplates aft of them, ie giving some aft pull to the centre of the mast. I've seen pictures of other Mk 1s rigged this way, KUDU for example. However, I see that the drawings for the original boats on the publicity leaflets have them the other way round - uppers to the aft chainplates, lowers to the forward chainplates. I've also seen other Mk 1s rigged that way eg BETSIE. Anyone got ideas about which set is most likely to support the mast correctly? I don't fancy a crumpling mast..

[Declan McKinney]

Hi Ian. I'm probably the worst to advise, since my junkie has no shrouds! I had a look in the Corribee Manual, and no clues there. However, I did turn up an old post from the 'retired' Yahoo! forum that may be helpful:

Question: “Our rig (I'm guessing standard for a mk 1?) is fractional, with two pairs of shrouds and chain plates - upper shrouds and lowers. We've guessed (based largely on pictures of other mk 1's) that the upper shrouds go onto the forward chainplates (result: spreaders pretty much perpendicular to mast) and the lowers go onto the aft plates - but is this right? We also thought that because the rig is fractional, some aftwards pull from the uppers, which attach at the same height as the forestay, might be desirable in tensioning the forestay (we weren't sure how much effect the backstay has on forestay tension on a mk1 rig)- so we wondered whether they should come to the aft plate (result: spreaders very much swept back from mast)”.

Answer #1: I asked *exactly* this question of this group about two months ago ... and got no response at all. I also trawled the web for photos, but as you have no doubt discovered most are not of MkI's and those that are often have the mast lowered!
Anyway, I did yet more trawling and this is my answer (for what its worth).
Normally the cap (outer) shrouds go to the outer, most forward chain plates, and the lowers (which go part way up mast), go to the further aft chain plates. Reason for that is lowers are used to control the forward bend in the mast when it is under load on a beat. When you sheet in the main and pull on the kicker, the middle of the mast will want to normally flex forward. This is normally ok, except the effect of that is to flatten the main sail...which in light to medium airs is not what you want. So the lowers stop the middle bending forward and to leeward. The cap shrouds should be tight all the time, and the lowers slightly less tight. When on a beat, you should feel the leeward shrouds just go soft/slack, but not so much they wave about!
Answer #2: “You are right as the cap shrouds (uppers) to the forward chainplates and the lowers to the aft chainplates”.

[ianc]

Declan, many thanks, I'll stick with caps to the forward chainplates and lowers to the aft chainplates.