Masthead fractional?

[Draughty]

Hi,
I'm seeing commonly on sports boats but also appearing on larger racing monohulls fractional headstays with masthead caps led through an extra set of spreaders at about the headstay attachment level.
I'm not talking here about 9/10th fractionals but more like 3/4. Similarly I'm not talking about jumper struts.

There seems to be a dearth of info out there about this set up; anyone know the pros and cons?

Thanks all.

[Snowpetrel]

Sounds like a cathedral rig. The topmast shrouds support masthead code zeros and kites, but don't effect mast bend adversely like jumpers can.

The way they are angled aft means the masthead can flex off to leeward as well as aft, and running the shrouds out to the next spreader below instead of back to the mast also reduces compression in the top panel of the mast and in the spreader compared to jumpers.

[Snowpetrel]

I guess it also means you can get away with no backstay or runners in many cases so you can run a big squaretop main.

[Draughty]

Thanks for all that Snowpetrel. Sounds logical; and a Win-Win development for fractionals.

Rgds

[Snowpetrel]

I haven't actually sailed with this rig, so its all theory from me, but it seems about right. If you have a backstay a set of jumpers is probably cheaper to add and can be adjusted to stiffen the top of the mast if needed by altering the angle forward, and tightening the jumper stays. But when you start from scratch and want no backstay and MH running sails the Cathedral rig makes a lot of sense. Hence it's use on many sportsboats.

It's facinating how the design spiral for rigs keeps tweaking things. Fron the outside it can look quite circular, ie the change from fractional to masthead and back, then back again, but each time the reasons and details are subtly different.

Chris Mitchell at AES is one of the Guru's of rig design, worth reading his thoughts here.
https://www.aes.net.nz/info.html

This is another interesting article.
https://www.google.com.au/url?sa=t&s...=1536730380533

[Draughty]

Thanks again Snowpetrel; terrific links!
Now that I know it's called a Cathedral rig I'm finding plenty on-line; trying to search by description was getting me nothing.
My single swept spreader fractional rig (Farr 11.6) has some limitations but it was sure cheap to replace the standing rigging a few years ago: not much of it!

Rgds

[Snowpetrel]

Farr certainly nailed the fractional rig very early. If you find any interesting links it would be great to post them here. I know in NZ they regularly 'Turbo' those kind of rigs. It would be facinating to see how they go about it from a design point of view.

[Suijin]

Originally Posted by Snowpetrel

Farr certainly nailed the fractional rig very early. If you find any interesting links it would be great to post them here. I know in NZ they regularly 'Turbo' those kind of rigs. It would be facinating to see how they go about it from a design point of view.

Fractional rigs have been around a long time. I grew up racing on Atlantic class boats, designed by Starling Burgess in 1928. And the Shield did not come long after. Fractional rigs tack faster and more easily so are preferred in any one design effort, which Farr has always been involved in.

I’m trying to remember what the rig on the Farr 400 I recently raced on was. But it does have a square top and runners, which you put a few tons of tension on when beating hard into a stiff breeze.