Nada's re-rigging: finally getting it rightJan 1, 2003
Recently we converted our wooden-sparred ketch Nada to an aluminum-sparred cutter. The idea was to remove weight aloft from what had always been an overly tender boat.
However, I didn't get things quite right when I calculated the new location of the mast. It turned out that I moved it too far aft, giving Nada excessive weather helm. We have a relatively small main (303 square feet), and a relatively large genoa (550 square feet), but, even so, any time we set the full main it completely overpowered the headsails and Nada simply rounded up. The boat did so with sufficient determination to confuse the autopilot or overwhelm the wind vane.
Even when I set a jib and staysail to shift the center of effort of the headsails as far forward as possible, the result was the same. In fact, I had the balance so far off we had a little weather helm under full genoa alone! For much of our circumnavigation of Cuba we sailed under headsails alone, or with two reefs in the main. We never had less than one reef, even in light airs. It was quite a handicap.
The rig conversion had been an enormous project that, among other things, involved cutting down the bowsprit from eight feet to two feet and re-rigging it, modifying the bow pulpit, moving all the chainplates, moving most of the deck fittings (which in turn required removing the lining on the overhead in the cabin), filling and fairing all the holes, repainting the hull and deck, constructing a compression post inside the saloon, and rewiring the mast. The thought of having to do all this again was overwhelmingly depressing.
Clutching at straws, I increased the length of the bowsprit by four feet in order to move the center of effort of the headsails forward in hopes that this would counterbalance the main. A cruise to Belize showed a distinct improvement, but we still could not take the first reef out of the main without Nada wanting to round up. Under full genoa alone we now had a neutral helm, but nothing to counteract the effects of the main. Under main alone, in any kind of a breeze, you couldn't hold her. With extreme reluctance I slowly faced up to facts: the mast had to be moved. Again.
This time I smartened up a little and consulted naval architect Bill Crealock. It was small consolation to me to find out that I had made no gross errors in my earlier calculations. He wrote: "I must confess that your balance problem with the Ingrid puzzles me. At worst, the boat's 'lead' appears to be greater than 20%, and as a ketch it approached 30% which, by normal standards, is huge." We were not dealing with a boat that fits normal standards.
We looked at sail combinations that had worked well under the ketch rig. We looked at sister vessels such as the Alajuela 38 (built on the Ingrid hull, but with significantly more ballast). We chewed over the limited options I had in terms of siting a compression post inside Nada. I could put the post either 24 inches or 46 inches farther forward, or go back to the original mast step, still in place 68 inches forward of the current location. Any other position would involve major interior and structural work.
Given the restricted choices, we decided to move the mast forward 46 inches. Bill recommended we also restore the bowsprit to its original eight-foot length. However, I decided to leave the bowsprit at six feet for the time being because extending it is something that can be done at any time without other modifications to the hull. Lengthening the bowsprit is also a surprisingly expensive proposition that I wanted to avoid if at all possible. It requires not only a new bowsprit, but also a new forestay, new whisker stays, a new bobstay, and reworking the lead angle on the various chainplates for the whisker stays and bobstay. In addition, the bow pulpit would need to be rebuilt to put it back in its original position, well forward.The new location set the mast on top of a fore and aft bulkhead whose forward face butted up to the original mast step. This gave me a good starting point for dealing with the mast's compression loads. I was able to design two large steel frames that were hot dip galvanized and painted before being bolted to either side of the bulkhead and then through-bolted to the forward face of the old compression post. The net effect is a tremendously strong structure that creates very little obstruction within the boat and is visually quite acceptable: I was pleased with the way this worked out.
Then came the work of stripping chainplates and deck fittings, filling and fairing all the holes and scratches, and painting. (We've gotten quite good at this!) The last paint job had been something of a debacle as a result of painting out of doors late in the year. In fact, after three attempts it still didn't look too good. Since then, our local yard (Northshore Marine in Mandeville, La.) had changed hands, and at the time we began our conversion had never done an Awlgrip job on a boat.
With a considerable amount of disconcerting experience behind me, I was extremely apprehensive about having the new team learn on our boat. I needn't have worried. They approached the job with enthusiasm and a commitment to excellence. We had some teething problems (the deck had to be painted twice when the dew got to it before the paint was fully cured) but the end result is that Nada looks considerably better than she ever has.
As best I could figure it, the new mast position would shift the weight far enough forward to set Nada down a little by the bow. To counteract this, I had a couple of 200-lb lead pieces cast. These I attached to the rear end of the keel, one on either side, through-bolting them through the hull and the existing internal ballast. If nothing else, this will improve stability under a press of canvas.
In three weeks of hard work we had the job more or less completed. Moving the mast forward effectively shortened all the stays and shrouds, with the exception of the backstay, which needed lengthening. Luckily, as part of the previous re-rig, I had put Norseman terminals on all the lower ends and had converted to a single backstay with a split rig in the lower portion. As a result, it cost very little (new cones for the Norseman terminals) to cut down the overlength shrouds and stays, and there was relatively minimal expense involved in purchasing lengthened stays for the split section of the backstay.
We stepped the mast and temporarily secured it with a series of halyards. It took me the rest of the day to cut the stays and shrouds to length, put the Norseman terminals back on, and set up the rig. By the time this was done, it was too late to go for a test sail. I had an anxious and somewhat sleepless night: in spite of doing much of the work ourselves, the bill for this latest rig conversion work was already up above $10,000, with no certainty that I had got things right.
The next morning dawned fair and clear, with a 15-knot breeze. Perfect conditions. We took Nada out, set the full main and genoa, and put her hard on the wind. I crossed my fingers, made suitable obeisance to the wind, water, hydrodynamic, and miscellaneous other gods, let go of the tiller, and held my breath.
She just kept on going, right in the groove. She tracked so well I could wander round the deck, tweak the shrouds to check the tension, and even go below and brew a cup of tea. This is how it's supposed to be on a short-handed voyaging boat. Success at last!
Over the next couple of days we experimented with various sail plans in winds from 10 to 20 knots, on every point of sail. We found that as we came off the wind Nada still has a tendency to be a little heavy on the helm, but nothing even remotely as bad as before, and nothing that can't be handled by tweaking the sail trim. I have a hunch that, if I had followed Bill Crealock's advice and restored the bowsprit to eight feet, we could get an almost perfect balance on these points of sail as well, but we'll never find out since I've had my fill of rig experiments!
Of equal, if not greater, importance to us is the fact that Nada can now carry a full main and genoa hard on the wind in close to 20 knots apparent wind speed before the rail goes under. We still don't fit well-known naval architect Chuck Paine's excellent 20/20 design parameter (the ability to carry full sail in 20 knots without heeling more than 20 degrees), but we are a darn sight closer than we were before. We can now keep moving to windward at a respectable speed without having the side decks awash. The project has ultimately been a resounding, though horrendously expensive, success.
With Nada's excessive tenderness cured, and a solution to our rig problems, I can finally say that after 15 years of trial, error, and experimentation, and after playing with just about every system and component on board, Nada is finished. My job and ideas list, which has never been below two pages, is down to just a few lines on one page. I don't really have an excuse to fool with anything any more, so Nada is up for sale. We have a Pacific Seacraft 40 under construction, and I've drawn up a seven-page list of ideas for Don Kohlmann at Pacific Seacraft. Somehow I have a feeling it's not going to take quite as long to get this new boat whipped into shape!