Re: tacking a junk-rigged yacht.  My boat, Arion is a heavy, long keeled vessel with a fairly large transom-hung rudder.  First I had a bermudian rig, then a cambered junk sail and now a flattish junk sail.  It always tacked like a dinghy in flat water with all three rigs, but was a bit slow at times in a choppy sea, occasionally missing stays if I did not time it carefully, putting the boat around in a smooth patch.  I did not notice too much difference in tacking between the cambered sail and the flat sail, though in the open sea I always fall off onto a close reach for a few minutes before tacking, to build up speed.  What is very noticeable is that the flat sail is a lot slower to accelerate out onto the new tack, to build hull speed back up after the manouvre.  But there has been an interesting development lately.  Last October, while on the slips, I increased the size of my self-steering gear's trim tab, or servo rudder, which is attached to the trailing edge of my rudder, by 60%.  I wanted more power in the system when running in a fresh breeze, as Arion loves being driven hard downwind.  I was amazed to discover afterwards that the boat tacks much more quickly now in the open sea.  So a big rudder certainly helps.  Here is what it looks like.  You can click on the image to see a bigger version.

Thank you for your reply Arne. I too have been unable to find out anything on the internet, although I have seen the stock fibreglass version many times around our coast – evidently the Pelorus design has been quite popular here. (If anyone is interested, I have added a photograph of a grp production Pelorus to my album here.) I have been unable so far to make contact with any owner and as winter approaches I have been hiding away up a tidal creek where I live (on the boat.) and have not yet tried her out under full sail.

A local fleet of fine and much-loved displacement motor boats has evolved here on the North East Coast over the last 100 years, and if she were a “motor boat with an auxiliary rig” I would be quite content. However, in fact this boat does not quite belong to that category. Her hull shape is more that of a sail boat than a motor launch – I am sorry I was unable to send you a lines drawing so that you could see. It is a motor-sailer type of hull, a type which has been refined quite well in this country.

However the draft is shallow, she has been given a small sail area, and (I agree with you) not a very suitable rudder. The size of the rudder is, hopefully, not such an issue – it is somewhat larger than a motor boat of this size would have and she seems very manoeuvrable, with a tight turning circle. (I drew the rudder in freehand as my side-on photo does not show it side on – maybe my artistry is not very good.) However, you are quite right to judge that this boat’s windward performance will be not very good. She is dragging a 4-blade propeller in an over-large aperture, with a balanced rudder which I do not like very much and would have preferred hung from the transom.  I expect she could potentially sail moderately well off the wind, and be rather sluggish to windward under sail alone. Clearly now, before any further speculation and before any changes to her rig, I must go and do some sea trials with what she has – and I will report back. I think she will tack under the Bermudian rig – we shall see. Does a junk rig tack with more difficulty than a Bermudian rig? I do hope not to be modifying the rudder or adding a mizzen.

I understand and agree with all you say about expectations, and have noted your recommendation that the sail should be moved forward, and that generous camber could be allowed. I would like to ask you some more detailed questions, but clearly it is necessary first to get some better information about how she performs with the current rig. I too would expect that your junk rig design will be an improvement, especially off the wind and with the larger sail area. Thank you for your advice and I will report back.

Rob – thank you too for commenting. I threw the tabernacle pin into the drawing at the last minute simply to indicate there would be one, and although I had given it quite a lot of thought I was not thinking when I made that last addition to the drawing and only realised after I had clicked “send” that the pin was above the boom. I guessed someone with sharp eyes might notice that – and I was not disappointed!

I like the look of Arne’s high-peaked, modified HM sail design but am open to other planforms if mast-positioning or other factors warrant a re-think. In the meantime, before any further speculation, I had better put on some warm clothes and a woolly hat and go find out how she handles under her current, rather tired Bermudian rig.

Thank you all.

Hi Graeme,

It looks to me as if you are on the right track and getting some good advice. The sailplan looks fine to me and the sheeting back to the stern will work. My only comment, and someone may have the answer, is that the tabernacle goes above the boom level. I can see the sail bundle being pulled over the tabernacle but when the sail comes down it could be a different story.

Rob

Graeme.

I suggest you fit your drawing with some sort of dimension, a metre or foot scale or something. This would make it a lot easier to add constructive comments. It would not hurt if you add the basic dimensions including, displacement and ballast on the drawing as well.

Cheers,

Arne

Hi Graeme,

I had another look at your proposed sail plan and think that the mast should stay where you show it, and the sail should be moved forward, on the mast, so that a sling point on the yard 45% from the forward end is located just aft of the mast. If you install fixed luff parrels on the lower four parallel panels, a preventer from the forward end of the boom to the base of the mast, and a yard hauling parrel, this should be all the control you will need on the sail.

If you feel that there may be a lee helm problem if you do this, then I would suggest installing a small mizzen on the transom with boomkin sheeting. This would also be useful, when at anchor, to reduce the amount of "hunting" that boats with masts well forward tend to do. It can also be designed as a wind vane self steering gear if you want, like Chichester had on Gypsy Moth for the first OSTAR.

All the best, David.