Anonymous wrote:

I have assumed that boats of this size around 35ft and fairly voluminous would require a two mast rig. So one up in the bow which could encroach on the V-berth hence why I would like a walkthrough aft cabin.
Not necessarily. There are boats such as the 36' Pearson called Blossom that were given a sloop rig and Arne Kverneland has drawn up some great sloop sail plans for boats up to 38'. (My Jasmine, a 32ft Samson C-Mist, is getting a sloop rig.)
David's comment on sail size is, I suspect, mostly based on the ease of hoisting it without having to resort to powering the halyard winch.

I will be finding out in the next few weeks as Jasmine's sail is 64.2 m².
(A Winchrite™ or similar may be in my future.)

That leaves the location of the aft mast/centre cockpit arrangement being a possible snagging point.  I think your advice on trying to get plans of the boats and even doing a rough plan of the rig rather than a full design could help to alleviate my concerns.
Indeed it does and a true center cockpit will make that harder.
Center cockpits are great for safety and do allow for aft cabins with greater headroom but there are also designs with "aft of center cockpits" that allow less intrusive aft mast placement just forward of them.

I plan to get a boat fairly soon, sell my house and liveaboard then before I retire in the next 10-15 years do the junk conversion and other works required for casting off the lines for good. That way I can spread the costs, save the required money, set up the boat how I want it and know the boat intimately before voyaging.

Certainly get a boat sooner rather than later but once you have become enthralled with the idea of owning and sailing a junk I suspect you may not last 10--15 years before doing so. :-)

The best advice I can give is that you make your selection of boat design based not so much on the JR conversion aspect, but more on the usual considerations of seaworthiness for the ocean sailing you hope to do.
eg. Full keel or not, heavy or light displacement, headroom (living aboard always stooped over could be a pain.) whether you want a JR sloop or a two master and aesthetics that are pleasing to you.

Having done so, put a short list of two or three together within your purchase budget, allowing for the conversion costs which can at least double that (Especially if you end up unable to sell on the Marconi meccano set you will be removing.) and bounce them off the talented folk here at the JRA to see how they would best be junked.

David Thatcher has given some great advice and this is my attempt at adding 2c.

Blossom can be found here and I have other images I could mail you if you wish to see more of her.

Hello Jacob, they say that any boat can be converted to junk rig, but there are many considerations within that statement. In most cases the mast of a junk rig yacht will need to be a lot further forward than the current bermudan rig mast, So that brings considerations of how the new mast location will impact on the interior of the yacht, whether there will be sufficient 'bury' for the new mast, and what strengthening of the cabin top or foredeck is going to be required for the mast partners.

Another consideration is size of boat and whether it will be a one sail, or two sail junk rig. If the sail area is to be over 55 sqm then there is a good chance it may need to be two sail junk rig, so that is also a consideration for mast placement.

Because the three yachts you have mentioned are known production designs a good place to start would be to obtain whatever plan details you can get hold of for these boats, but especially current sail plans and also underwater profiles. Then using the information found in the book Practical Junk Rig, you could start drawing up some preliminary sail plans just to see what might work.

Some people have found a split junk rig to be a good option for converting a bermudan rig to junk. That type of rig is not covered in Practical Junk Rig but you will find some information through this the JRA.

There are other practical considerations such as who is going to do the work, where can you get a suitable mast, who is going to make the sail, and what is going to be the cost above the purchase cost of the boat and is it affordable.

But for a lot of older yachts which might have tired rigs conversion to a junk rig is a sensible direction to go. Plus you will get a simple rig which can make sailing more enjoyable. Good luck with your project.