According to Small Boats magazine its displacement is 575 pounds.

I made the classic mistake!

Thanks for the correction.

I think the boat is 500 kg empty of provisions, isn't it? In fact, I suspect that is just the trailer weight, but Bill can settle that.

The displacement ratio in voyaging trim might not be as high as you suggest, though in any case I don't think that is a very meaningful parameter to generalise with, especially on a dinghy. (I think what matters more is wetted surface area/sail area - that's another discussion for another thread).

I wouldn't suggest over-canvassing a dinghy, generally - I was more suggesting an optional under-canvassed rig for voyaging or sailing in predominantly rough conditions.

But, you are absolutely right - best not to go overboard with ideas  - just keep it simple and get sailing. (I wish!)

The tubular "tabernacle" (or "mast socket"). I did have a similar idea some time ago for a smaller boat (my Golden Bay dinghy) but the mast on my 17’ Serendipity is much too heavy to lift that way, so I was not sure if it would be suitable for Bill. Now that Arne has confirmed that Bill’s mast will be light enough to manage that way, I think he has put together all the elements Bill needs for an outstandingly successful conversion.

Congratulations Arne on designing the complete sail and rigging package for a truly practical junk-rigged camper-cruiser – another “first”. I think Bill will be well satisfied when he realises what a great advance Arne has made in the ability to (quickly and conveniently) de-rig and re-deploy a junk rig for a trailer boat.

From the side-line, if I may, I would like to make a couple of very minor additional suggestions.

(1)   There was a hint somewhere that the halyard might be a 1:1 arrangement. This would require going to the mast in order to hoist sail or shake out a reef. Sounds nice and simple, but not always as simple to do as it might seem while out on the water, single-handed in an open cockpit dinghy. If Bill can re-arrange the design of his cabin top, or find some other way to re-route a halyard through a turning block and back to the cockpit (along with any other running lines) I think the extra convenience (and ultimate safety) of being able to tend to the rig without leaving the helm or risking upsetting the dinghy, would be worth the extra effort. This would probably require the extra small complication of a multi-purchase halyard. I have a 3:1 halyard on Serendipty – the double block just clips onto the yard with a single quick-release clip, and the tail comes back to the cockpit via a turning block – I think it is worth it.

(2)   My other suggestion is – if the mast tube comes long enough to reach down to the keel, then as Arne points out, the bury is excessive. However, I suggest, do not cut it short as shown in the diagram. Never cut anything short until you have to!  If for one reason or another Bill finds that he needs to raise the masthead a little, then it is a simple matter to do so, and just drop a short spacer into the tube. You never know –  I had to do this on Serendipity due to a miscalculation (I didn't allow for sufficient halyard drift - a common mistake I suspect) and it was very convenient to be able to raise the L.A.P. without the bother of having to lengthen the mast.

..........

This brings another possibility to further enhance the brilliance and versatility of a junk rig as a cruising sail. How’s this for an idea – a summer day-sailer rig and a winter voyager rig all in one. 

Arne’s “mast socket” rig makes the "extendable mast" a practical possibility.

If the sail is made just a little less in area, and the mast made just a little shorter than shown in Arne’s diagram it will be very convenient for sailing in rough conditions, or voyaging in potentially rough waters. There are times when it pays to be under-canvassed from the start, and to keep the mast a bit shorter if possible.  Then, when reefed down, there will be less naked mast up there causing windage and degrading the boat’s ability to windward in these conditions. It would be a “conservative rig” and perhaps a little dull at times.

However, the sail could have an extra panel which is unused in the “mast down to the keel” configuration – the boat would be sailed with this "secret panel" permanently reefed. (What do you think Arne – the high aspect ratio rig with one panel permanently reefed?)

During the summer, or when day-sailing in balmy conditions, it is much more fun to be slightly over-canvassed. A spacer tube (equal to the width of one lower sail panel) could be dropped into Arne’s mast socket at the time of launching – raising the mast and enabling the extra panel to be used. The standing lifts, which clip on at the time of launching, would need a little surplus length and a second clip position, so they can be clipped on for the “mast raised up” configuration. The same rig is then instantly converted into a high AR, light-weather rig for day sailing.

I think one should have one’s cake and eat it too, whenever possible. Arne’s mast socket makes this a very simple possibility, with almost nothing to lose. Even if caught with too much sail in the light weather configuration, a double reef is just as easy as one. The real advantage, as I see it, is to be able to have plenty of sail area most of the time, but at the same time to have a very snug, compact rig when venturing into conditions which will be mostly heavy weather.

There is a further minor detail to attend to at the position of the upper GRP "waist band". A couple of solutions come to mind. Are we starting to "build God into" the boat, as Arne puts it? Its a trap I often fall into, and I suspect Bill suffers from the same affliction. What do you think Arne?

Trailerizing a JR

Today I drew up and sent another 2-drawing sailplan for Bill, this time at AR=1.80 instead of a taller one at AR = 2.00. I also introduced a tube-type mast socket. Since some of it may be of interest to some of you, I let you have the whole letter I sent him;

*****

Stavanger 20221227

Hi again Bill

Now I had a second go and made a lower sail with AR = 1.85. This sail is quite similar in shape to Johanna’s sail (AR = 1.87).
The lee helm issue I had with Johanna (no big problem) was because the mast was so short that the halyard drift became very short. With full sail set, the sail had to be canted a good deal forward in the top. As soon as I took a reef, the sail could be set properly, and there was no longer any lee helm. On the sails I draw these days have, I ensure the halyard span (drift) is long enough (18% of B).

Before I start, I must give a little warning: If one tries to “build God” into something, it will never be finished. This is your first sailboat ever. I strongly suggest you don’t over-load the boat with tall and complicated superstructure. It will just add windage and weight. Rig the boat as it is and then learn to sail in it. When you gain experience, you may well find that you need a different boat, or you may find that sailing is not for you, after all. Then you have not spent too much time and money on this one. Highest priority should be to get under sail early next summer.

I have not had a junk-rigged boat set up for trailer sailing, but I have owned and sailed my 5.5m/200kg dinghy Broremann, so the dimensions are well known to me.

You mention that you will use a carbon mast. That is good. This will most probably end up at well less than 10kg. My second mast for Broremann, of solid spruce, was 10kg. This could be plonked into position each spring, quite easily.

This is what I have done to ‘trailerize’ the JR for your boat:

• ·         I suggest installing a permanent mast socket from a slightly oversize aluminium tube (blue). Since the mast is so light, there is no reason for using a tabernacle, which brings the centre of the sail much higher up. The socket, as described below, will also be helpful in keeping the rig tidy when trailering
• ·         As shown on the diagram, I also suggest terminating the mast somewhat higher than the bottom of the boat (at B). This lets you get away with a shorter mast, which is convenient for transport (and keeping the weight down. I suggest that the mast rests on a 10mm bolt at B.
• ·         Two waistbelts of GRP are wound and glassed around the mast at A and B to get a close, but still not too tight fit in the socket. This ensures quick stepping and unstepping of the mast.
• ·         The distance between A and B has been chosen to give about 10% bury, which is the recommended minimum.
• ·         I strongly suggest not to reduce the number of battens. Thanks to having seven panels, they will be so narrow, that you can get away without lazyjacks, apart from the double topping lifts and mast lift at the mast. This makes life easier when trailer-sailing.

This would be my procedure when lowering the rig after a sail:

• ·         First, bring the boat ashore on the trailer. The boat is steadier to work on when on terra firma.
• ·         With the sail dropped, start with securing the sail bundle with a few ties (different colour than other lines you use).
• ·         Bring out and erect the boom crutch, about as tall as the shown cuddy.
• ·         Unclip the two topping lifts and lower the boom and bundle onto that crutch.
• ·         Unclip the halyard (single part?) and secure the halyard, topping lifts and also the mast lift to the mast with a tie.
• ·         Unclip the mast lift  so that the fore end of the bundle can be lowered onto the deck (cuddy). With only a bit slack in the batten parrels, these will slide down the protruding stub of the mast socket.
• ·         Even the standing tack parrel should be willing to slide down the mast socket.
• ·         The mast is now free from the sail and can be lifted out and lowered at leisure.

The brilliant thing with this setup is that the all the parrels can stay on the sail (..yard hauling parrel, YHP, throat haulig parrel, THP, and as said the batten parrels and the standing tack parrel, TP). In addition the sheet can stay connected.

Now it is just to tidy up the slack lines, lower the mast and add a few more ties to ensure that the mast and sail bundle don’t get airborne at 60mph along the road.

I would insult you if I now started to spell out the rigging process...

Good luck!

Arne

*****

(diagrams on Arne's sketches, Section 7)

Hi,

While I'm no expert on the SJR rig,. regarding the Aspect Ratio of the SJR, the fact that it consists of 2 separate surfaces, each with their own camber built in, taking each surface on its own, both jiblet and main actually have a very high aspect ratio individually.

So I wonder if, what might look like a low aspect ratio sail  at first glance, (because we are thinking of jiblet and main as one sail, instead of two separate sails, each with a high aspect ratio), will actually work quite well.

Another advantage of SJR, i think, is that it is better balanced, in that when the sail is in any position other than close-hauled, the fact that a good portion of the sail is on the upwind side of the mast, producing its own force more inboard than a Hasler/Arne type sail, means that, with less sail area producing force on the leeward side it probably suffers less from weather helm and produces less heel.

Another thing to remember about a dinghy with no ballast for cruising , as opposed to one used mainly for racing, is that one isn't looking to extract maximum performance at all times, so a smaller sail than the racing size is probably more than adequate for cruising. Extracting the last 5-10% performance to win a race is not necessary when cruising.

Cruising is about relaxing.

A taller mast exerts more leverage  in your dinghy, with no ballast to counteract that leverage, so reduced sail size and reduced mast height as a consequence is a bonus.

Graeme has a lot more practical experience of using the SJR than I ( this year, this year, I promise myself), but the little i HAVE sailed mine with 95-100sqft rather than the usual 140-145sqft usual on the Wayfarer, i didn't feel there was a lack of sail area, solo at any rate.

If the wind dies, fire up the outboard, or break out the oars.

Regarding building the SJR, I managed to build mine using Slieve's notes and drawings and quite a few questions on the forum.

Never having built a sail or used a sewing machine before, the sail still turned out well, setting nicely on the mast

I used paper and sticky tape to draw out a panel model and get my head around what Slieve actually meant in his notes, which once i begán to understand them, are actually very good.

Try making a single panel from paper first. That will bring better understanding. You are building both camber AND sheeting into the shape of the upper and lower lense panels.

The 45 degree shelf makes for a sail which looks better and hangs better when there is no wind than a 90 degree shelf foot which IIRC, was one of Slieve's criteria when he designed it. To look better and less "baggy" and need less wind to fill out.

It also happens to perform very well.

So I wouldn't rule out the SJR as a smaller sail, as for cruising you won't be needing a racing sail area and the SJR is a good performer anyway.

But there are many happy customers for the Arne type sail also.  

Down to personal preference, and if the mast position and sheeting angles work for you.

Cheers, Dave D.