Slieve wrote:

The Poppy rig was attractive, but remember that it was a 'proof of concept' prototype. The rig has evolved since then, and been simplified, and the Amiina Mk2 rig has now become the standard. It may not be as pretty as the Poppy rig, and even I call it a 'brutal' design, but when it is easier to build and use and performs as well then it is easy to overlook the harder angles.

In haste,

Cheers, Slieve.

"The first requirement of a yacht is that she should be beautiful"

- So said a yachting pundit whose name I've forgotten (or words to that effect, anyway). OK, I've designed brutalist-but-efficient rigs myself, but then I've generally tried to soften the brutalism a bit, to make them easier on the eye. Is there no way in which the Amiina mk II sailplan can be made easier on the eye without losing efficiency or ease of construction?

Two more questions - it undoubtedly has been shown to work in smaller sizes, but: 

• What is the largest Amiina mk II sail that has been made and successfully deployed, to date?
• Is there any hard evidence that it can be successfully scaled up to more than 50 sqm?

[to be clear, I look at Poppy's conservatively-designed sail, and see something that does not push too hard against the envelope, and will not be a risky enterprise to reproduce in similar sizes, ie above 50 sqm. I look at Amiina's sail, and while recognising its performance on small boats, I would hesitate to splash any of my cash on a very large version of it until medium-sized versions had been proven successful. To take just one practical point, Amiina's five sheeted battens are not really enough on a large offshore cruiser].

Thanks Slieve for the clarification on the egg and the hen, I was under the belief that the Poppy design preceded the Amiina. I really want to follow the KISS principle so I’ll probably go for the Amiina II design. My aim is to have a rig that is simple, effective and safe. 

About my current rig:

I have three forestays, the outer is a genoa, number two is the high cut foresail and the inner carries the staysail. The main has three reef points, and we quite often use the first or second point. Since the genoa is quite heavy and therefore difficult to trim, the setting I have used most often is two reefs in the main, staysail and the high cut. If needed to reef, the high cut is furled. Being  a bermudan, it’s a fantastic setup with a lot of alterations (I even have a drifter, for those days). But since the rigging and sails are old (needs to be replaced) and I love the philosophy of junking, a junk it will be. 

Thanks for your comments and insights. 
I’ve done the calculations to get the CE for the present bermudan sails, according to the PJR. The CE ended up pretty much fore of my expectations. I’ve redrawn the sail and also drawn a schooner alternative. 
If I go for the schooner alternative, can I lower the dimensions of the mast? I am thinking of joining two tubes (as suggested by Graeme) of aluminium AW6082-t6, 200x7.5mm for the lower section and 180x5mm for he upper. Both tubes are 6m long and with a bury of 80cm at the joint the masts wold be 11m-ish and about 9 m above deck. That would be sweet. 
I do understand that it is at least twice the work making two masts and sails, but if I have the space for them, aren’t the advantages in safe sailing greater?

/Marcus

If your current mast is 13-14 m above partners then a scaled up Amiina SJR might be a proposition after all – if you can manage a single sail of 55 sq m. I don’t have the experience in this size range but I am sure others can advise. A tapered aluminium spar, with no standing rigging, could well be lighter and with less windage than your current mast and rigging. (The sail, with its battens, will be heavier, of course – but then again, that weight is progressively lowered when you reef for heavy weather.)

The battens on Amiina’s sail are 2.17 metres. If the sail were scaled up to 55 sq m then the batten length would be 1.85 x 2.17 = 4.02 m. I keep referring to Amiiina’s Mkll sail because, brutally simple though it looks, it is extremely well designed and there is a lot more going on than at first meets the eye. Quite a few have now been successfully made. I am all for innovation and new ideas – but if I were planning a SJR for my first junk sail (as I was) I would think carefully and discuss with Slieve before departing too far from this proven sail.

(Comparing with a scaled up Amiina sail, if your mast is 13m and your battens are 6m then the area would be a lot more than 55 sq m - wouldn't it? Anyway, the Amiina design will give you a split junk sail of 55 sq m with 4.02m battens correction: 6m battens on a 13.5m above partners mast.)

[edit: batten length at scale factor 1.85 should be 6.01]

(In the above sketch mast position is an uninformed guess, also sheeting has not been considered, nor the distance below the boom which must accomodate the span of the spanned running parrel downhauls which are a feature of this rig. It still looks like a pretty big sail, to me. Comment added 12/12/2021)

You can make a mast from aluminium tubes, and achieve a crude form of taper by making the top tube or tubes of progressively smaller diameter(s). The transition between diameters can be built up from timber or epoxy/glass – or both – there have been a number of threads on this topic in the past. For example, here or here, here's another and here's another which goes a long way back, so there's some reading you can do. And for more, you can hunt through the threads on the technical forum, which are listed here 

I have made two masts this way, one of them 10m, was made of two aluminium tubes with the top tube smaller diameter than the main tube.The one I currently have on my little trailer boat was made with three tubes of different diameters. In these smaller sizes, it is not difficult. We do not have many choices here in New Zealand as tapered aluminium poles are not available and the longest parallel tubes available here are 6m. Another common method is to make a hybrid, with the bottom pole aluminium and the top section tapered timber. (Check Annie’s blog here for a beautifully done example).

[Edit: the ultimate would be an aluminium base tube, with a top section made from a tapered carbon fibre mast section. This has been done too.]

Currently I am planning a 13m mast using a large diameter (about 200 mm) spinnaker pole (off an obsolete maxi ocean racer) for the lower section, with a 6m x 125mm aluminium tube for the middle – and for the top, either a smaller diameter aluminium tube or a tapered wooden section. I don’t yet know if it is going to be difficult, but I am assuming it will be similar to the smaller ones, perhaps just take a little more time.

I checked my arithmetic and when you scale that sail up to 55 sq m the mast still comes to 13m+ above deck.

I made a mistake with the drawing and I have changed it.

It looks a little better now, but still a pretty tall rig.

What is the height of your current mast?