Andrew Holder wrote:

Arne, How does this look?

Cheers.

p.s. sorry, don't know how to make the picture big in the post.

Hi Andrew.  I had been thinking the aft, stbd side of the hatch might be a good compromise and I like the look of it, but cannot comment on the mathematical calculations.  It looks OK to my 'bush engineer's eye', though.  However, I can comment on mast specs.  I believe that for a 34 sq m sail, you need a similar-sized mast to that I had on ARION, 200mm dia at the partners, tapering to about 110mm at the truck, and with a wall thickness of 5mm.  150mm dia is too skinny if you have any likelihood of sailing in developed seas.  You can find pictures of ARION in my photo albums.

Hi Arne. Thank you for that update. I'm afraid to say that after going down yesterday and having a closer look at the area between mast and hatch, it doesn't look easy (please see photo).

I believe now the best position would be just into the rear of the hatch, so more like your first sketch but against the back edge of the hatch rather than the middle. That means the mast would be 57 cm further forwards, making the centre 2.09m from the bow.

I'm trying to draw it up myself but struggling to find whether it is easiest to do it in Fusion, Sketchup or Rhino, I have versions of all 3 but I'm not 100% competent in any of them!

I'm assuming I'll use something like a 150mm aluminium tube but delivery in one length will be difficult here. Do people join sections?

Cheers.

Andrew wrote:

Arne, thanks again. As you can see in the cabin photo, the doorway is offset to port slightly, as is the toilet pan. I don't think it's as much as 10cm but it certainly gives an advantage. It's quite a large area for the heads so I'm not too worried about making it a bit more cramped. I'm thinking I might even change the heads to a composting loo so potentially could move it even more.

Do you think it's possible, within reason, to decide the perfect position for the mast then adjust the sailplan accordingly? There's a nice space between the existing mast and the edge of the hatch that's just itching for a jigsaw! If necessary I can widen the companion way.

Can I ask where you got the drawings that you based your designs on? I have some but yours have a good amount of detail. I'm attempting a 3D drawing in Fusion 360.

Andrew,

about that mast position you want, do you mean through the foredeck right aft of the hatch (and a bit offset to sb.)?
That could be difficult, but I will have a closer look at it. The challenge is to achieve good helm balance (the position of the sail's CE must sit so and so far ahead of the CLR), and that without having to make the sail with too big mast balance (i.e. amount of sail forward of the mast). The question of good or bad tack has been debated before ( http://goo.gl/khii3l  ) .

As for the mast step; just remember that for an un-stayed junk mast, the forces in the mast step will mainly be horizontal, while the compression load is much lower than in a Bermudan rig.

The drawings were picked from those that Graeme came up with to begin within this thread. They were of reasonably high resolution, so I could just imported them into my QCAD program, aligned them, upscaled them, and finally traced them.

Cheers,
Arne

Hi Andrew, I rigged the sail on the port side of my mast in both my junk rig conversions, with the halyard and running parrels coming down in the starboard side of the mast.  If your mast was offset to starboard, as suggested, then your sail bundle could be on the centreline.  I doubt if any of this makes much difference one way or another, junk rig is inherently a flexible system with wide tolerances.  The philosophy of 'good enough', to quote JRA member Kurt jon Ulmer, prevails.  That's why I love junk rig so much, being something of a ramshackle sort of guy.

PS: I love your interior photos.

Is there any reason not to carry the sail on the port side?

You had better ask some of the long term junkies. It does seem to be a sort of tradition, but it is certainly not universal. I can't see that it matters. I heard somewhere about being hove-to and it being more convenient to heave to on the stbd tack and have right of way, maybe something like that. If you offset the mast I would be more concerned to  make sure of a well-designed mast step with a bit of structure, which spreads the load of the mast so that all the weight and momentum is not imposed on just a garboard plank.