Maxime,

I suspect you may have already seen this but, to be sure, I wanted to share this website titled COLVIN GAZELLE: A Junk-Rigged Cruising Icon.

The rig used on this boat supports the center of effort needs described by other JRA members. This boat is 'junk rigged' but still has a triangular foresail attached to a stay, like a jib.

If you are interested in my opinion, I would like to see your boat rigged with 3 masts as shown in the photo that Graeme shared. I think your Colvin Gazelle will look like a very serious ship if it is converted this way.

Scott.

I am not sure that constraint (2) is impossible. My gut feeling is that keeping the existing rig height you could probably achieve a sail area something like your current ketch rig, by making a junk ketch along the lines discussed. But I don't have the accurate software to try it. If you were to increase the rig height a little it would certainly be easier to achieve and give a little flexibility in how you were to go about it.

The SJR main will get your CA a bit further forward than any other plan form, for a given mast position, which may help a little - you've got that.

The centre of area of a junk sail will generally be higher than that of a bermudan sail of the same area, but not a lot, if any - try the geometry of it. (The weight of the bundle is greater and the centre of gravity is higher). But that issue is not as important as some people think, and more importantly it is not normally a problem in practice. Weight and CA come down as the sail is reefed. You are right to favour low aspect-ratio for this boat, but "all things in moderation" is a safe code of practice.

I may have been wrong to deride the use of double-sheeting. I am sure it is better to avoid it if possible (for obvious reasons) and I would personally prefer not to have it, but there are plenty of examples where double sheeting is resorted to, in order to overcome a sheeting problem. It's a last resort, in my opinion- but not a "game changer" and it surely does the job. To achieve other goals, it may be worth it.

I would leave it to others to comment on the "downside of camber". These days not having camber would only be accepted by someone who has good and special reasons (and there are some). Dave Zeiger preferred not to camber the mizzen sail because he likes to use it as a riding sail, in the manner of a yawl, and an uncambered sail will sit quietly without flogging when holding up into the wind - ie when at anchor or hove-to, as fishermen have known for decades, if not centuries. [And some form of double sheeting the bundle would be good there too - you are right!] For a largish junk mizzen of ketch proportions, it seems to me a compromise might be to leave the top triangle or top couple of panels uncambered, for that purpose. I suppose the camber in a mizzen should be a little less than for the main, for obvious reasons, but I have never had a ketch so I don't know.

I totally agree with Scott (in the other thread) in getting advice and doing the calculations before using your existing poles. I had noted that you described them as having plenty of wall-thickness and that your main pole was 165mm diameter (slightly more than the standard 150mm which is a pretty standard pole used in New Zealand (cf FanShi for example)) - but when suggesting you look at extending your original poles in this current thread, in the concluding remark. I did add the caveat "... if their scantlings are shown to be adequate..."

I don't think you need any advice from me, on the contrary, I suspect - and I look forward to one or two of the really qualified experts to chime in with mast and sail plan suggestions. It's a very interesting challenge indeed and I am sure very achievable. I am looking forward to reading of your successful conversion.

(PS I never figured out how to use the "quoting mechanism" trick either - I just cheat and use the highlight editing button.)

[I also think it is annoyingly over-used by some people, quoting and re-quoting entire lengthy posts like some sort of horrific echo-chamber, graphics and all. Mostly OK on the JRA forum where it is normally used more discriminately, thank goodness. Says the grumpy old man.]

If I am re-rigging I may as well go all the way. The critical point is to eliminate these blasted running backstays on both masts! And might as well eliminate all stays while I am at it.

By implication this also eliminates the fore-stay sail - and the bow sprit. (And, for the sake of discussion, let's try to get rid of the port/starbd sheeting as well).

I would like to join the discussion not as an adviser, but merely a sideline commentator who is interested in what I see as basically a problem in geometry.

If I understand the problem correctly, there are four constraints:

• (1)   The centre of area of the new rig to be in the same position as original
• (2)   The new rig not to exceed the height of the existing rig.
• (3)   The new sail area not to be less than the existing sail area.
• (4)   The masts to stay in their existing positions (negotiable).

After fooling around for a while with simple graphic software (I don’t have CAD) my conclusion is that there is no 2-masted junk ketch or schooner solution which meets all four above constraints.

Eliminating the fore triangle and bowsprit (which were designed to match the underwater profile of this hull) creates difficulties and makes it impossible to meet all four constraints.

I presume constraints 1-3 are not negotiable. It is necessary, then, to consider change to mast(s) position(s).

A 3-masted solution (ketch or schooner) may be possible but only if a small fore sail is placed very far forward, and also, due to lack of deck space, port/starboard sheeting may be necessary – and the cost and complexity goes up - these factors all render a 3-masted solution to be a step backwards in my opinion and not worth considering on a boat this size, I would have thought.  (Having said that, there is a good example of  3-masted junk Colvin (Madam Wong - see Boat of the Month archive, scroll down to May 2023).

(In fact there are a number of Colvin-design 3-masted junks described in detail in this link here ( https://www.boatdesign.net/threads/hello-and-a-thomas-colvin-junk.62500/) eg Colvin's own Kung Fu Tse, Oothoon, Mysterious Ways and others - but all are larger vessels than the Gazelle, and they possibly have a slightly different under-water lateral plane.)

A junk ketch solution is possible if the main mast is moved forward. A split mainsail would not bring the centre of area far enough forward and would still require moving the main mast forward. How far forward the main mast would have to be moved, would depend on the balance given to the main sail, which presumably would carry the greatest sail area possible on the height of the existing main mast – and presumably would be within what would be normal bounds as regards aspect-ratio. (Low aspect ratio, but not extreme). Such an arrangement could also make it possible to consider using the original masts keel-stepped, with top extensions to compensate for the necessary bury.

A 2-masted junk schooner solution is possible only if both masts are moved forward. In that case one is “starting completely from scratch” and either a ketch or a schooner rig will be possible, including a schooner with equal masts if so desired.

My conclusion, considering Maxime is already predisposed to ketch rig, and with a view to minimising alteration to mast post position engineering, and interior layout etc, and the potential for utilising the existing masts -  is that the logical solution will be a two-masted ketch rig with the mizzen mast remaining in the original position and the main mast shifted forward to bring the centre of area of the rig to its correct position. A split main will certainly work, and this option requires the least movement forward of the mast, but if that main mast position does not suit, then the mast can be moved still a little further forward and then a lower balance, contiguous main will do just as well. In fact, if possible, a slightly more forward placement of the main mast, together with a low-balance contiguous plan form, will allow a little more sail area to be crammed onto the existing mainmast height and this might be considered a gain.

[The Amiina-type split sail with its low yard angle gives slightly less sail area than, say, a Johanna-type sail, for a given mast height. Interestingly, Arne has designed a Amiina-Johanna hybrid which evens that score somewhat. In addition to the Johanna style, the low-aspect-ratio, ultra-low-balance Reddish type of sail that Paul Thompson has been developing recently might also suit a farthest-forward mast position in this case, cribbing a little more area - although that might mean having to revert to port/stbd sheeting. Split or unsplit, in this case it's mainly just a matter of where the new main mast might best be placed with the minimum of disruption to the interior layout.]

I would argue for a very modest increase in mast height, if the existing pole(s) are proposed to be used together with topmast extension(s) – not because of necessity and not for the purpose of gaining more sail area (I never saw a Colvin design that was under-canvassed and the designed sail area of the Gazelle seems adequate) - but simply because if the rig can be raised a little, then the designer has more flexibility in designing the rig to fit within the constraints (1) and (3) above. Particularly if a split main sail were to be considered.

Dave Zeiger designed Wayward with a split junk ketch rig of proportions which are not far away from the case requirements here. He left the mizzen unsplit - and also uncambered, for quite good reasons, I thought.

In any case, without raising mast-head height, a ketch solution is geometrically possible, either split or contiguous main, which matches the top three constraints, with the main mast only being moved (forward), and the possibility of using the existing pole masts (top-extended to allow for bury) if their scantlings are shown to be adequate.

[More or less in agreement with Len, whose post I have just read.]

Len, Arne, Paul, thanks for your responses.

I am willing to do fairly major surgery to the boat. I can go schooner or I can remain a ketch. I'd even consider a third mast if it makes sense. If I am re-rigging I may as well go all the way. The critical point is to eliminate these blasted running backstays on both masts! And might as well eliminate all stays while I am at it.

It would be great to be able to reuse the existing mast tubes. They are cylindrical, not tapered, and tabernacle-stepped. I hope there is a way to reuse the tubes, keel stepped, with a slimmer top-section to provide some taper. I will make a separate post about this too...

The boat doesn't need to remain a ketch, it can go to schooner. However I've been liking that the big main balances well enough and pulls cleanly downwind, without the mizzen raised. I'm not sure how schooners do it downwind.

I would like to eliminate all standing rigging and thus all non-junk sails. Without having done any sketching yet, I was imagining the masts might stay more or less where they are. I have steel cabin tops so an unstayed mast through them would be fine. In order to get enough sail area, and to get it far enough forward, the main might be a split sail. I am willing to work with a bigger mainsail, to the point where I have to use a winch to raise it. The winches for the foresail sheets are already well positioned near the hatch. Another compromise I am willing to live with is double sheets on one or both of the sails, allowing me to crowd them in closer and lower. The sails will have to be low aspect ratio to keep the centre of effort low. The Gazelle is a narrow, shoal draft boat and it cannot stand up to a tall rig.

I've attached a photo of the original sail plan, along with approximate marks for the current positions of my masts. I will soon do something much more precise, along with marks showing all practicable mast positions according to interior arrangement.

Regarding my wife, I like the idea of sailing lessons (as a backup plan). At risk of straining our relationship, I will first attempt to give her those lessons myself... She certainly does have the strength for sailing, and anyway if more strength is required, it means there is something wrong with the rig! I really do want her to have a gentle introduction and minimize stress and bad experiences right from the outset. Her happiness aboard will determine whether we can take up cruising as a major part of our lives, after all.

Anonymous wrote:

Just a shot in the dark:
How would it be to keep the mizzen and replace the main mast and its sails with a junkrig?

Arne

Arne, would that be possible with the current masts on Max's boat?  I had a Gazelle for 11 years, but it was a junk schooner with one small jib - easily single handed.  But the masts were in very different positions.  Max's boat is the first Gazelle I have seen with a ketch rig.  A junk main with the present masts would be a monster sail I believe.  Raising it might require a winch, and handling it would not be trivial.  My schooner main was about 450 sf, and it was as big as I ever wanted to deal with at times.  The ketch rig, with junk main replacing the gaff main and two jibs would have to be a lot bigger.  Your suggestion if it works would be way less expensive than converting to a schooner, but one of Max's goals is easy handling - the schooner rig if he went that route fills the easy handling requirement quite well.  But lots of work and expense to get there.   Colvin's books provide a sailplan for a schooner rig.  Does anybody out there have Colvin's sailplans as originally drawn?  Very useful for a conversion project.

As for finding a similar boat, junk-rigged, to try it out, my former schooner Indigo was in Astoria, OR last I heard.  I have no contact info. for the owner though.