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July 1, 1999 Issue
July 15, 1999 Issue
July 1, 1999 Issue
Of Leeboards & Simple RigsBy Luc Casaer
Perhaps your readers might be interested in my experiments with leeboards. My particular kind of leeboard clips over the gunwale. The advantages are numerous: Nothing in the way for the rower; no centreboard case, so the craft is easier to build and lighter to carry; the waterflow is not disturbed by the centerboard slot; the waterlogged craft can easily be bailed, because no water is coming through the case, and you can finely trim the lateral plane to a neutral helm by shifting the board's position along the gunwale. A huge gain for a small investment. But there's more to come!
I first experimented with this leeboard on a Canadian canoe, which I found too good a boat to hamper with a centerboard case. The Canadian canoe has some tumblehome in her sides so the board was angled out, as on most traditional Dutch craft, to give an efficient lateral plane when heeling.
But on my Swampscott Dory the sides are flaring out above the waterline, so the board is angled inward, which at first didn't seem to offer a favourable lateral plane to sail efficiently to windward. But it worked splendidly; the dory even gained stability and heeled less when sailing faster! I gratefully accepted the results without thinking much further. Some months later I came across an article about the forces in action, written by J.P. Brouns, a Belgian architect working in France. I was in fact sailing my dory on the same principles as Tabarly was sailing his Paul Ricard. Only the lever of my foil was a couple of feet, while the lever on Paul Ricard was several metres.
The big advantage of this kind of leeboard, which I first found on a design of Bolger in his book Small Boats, is that it can be fitted on all kinds of open boats, from canoes and wherries to ex-lifeboats, without much alteration for the boats character! A boon for boating enthusiasts under the shadow of inflation. It is, of course, essential to reinforce the sides sufficiently to stand the strains of the leeboard.
A further point is that on short tacks the board can remain on the same side because it is clipped over the gunwale and will not float up as a traditional leeboard would. So one has not to worry about shifting things on every tack, provided the gunwale is reinforced in such way that it can stand the reversed stress. The foil shape of the board is, of course, not adapted for this new tack but over a short distance the loss is less than when taking the trouble of lifting the board clear of the water and putting it in the water again on the other side.
A second experiment was the rudder, which had to be fairly deep to give enough grip in a seaway because of the long underwater body of the dory. The first rudder was in one piece and I had to lift it off the gudgeons every time we came into shallow water, then steer with an oar. Lifting the rudder was not much of a problem but fitting it back on the steeply inclined transom was difficult, so I made a rudder with a lifting rudder-blade, which however proved too awkward to stow easily on board.
Another of my hobbies is building model aircraft and here I found the "end-plate" effect in the chapter on the aerodynamics of wings. End-plates limit turbulence on the wingtips and increase wing efficiency, so I fitted an endplate to a very shallow rudder. It worked beautifully. Even in rough water the rudder kept good control without problems. And the small rudder was easy to stow on board. From what I understand in the yachting-press the keel of the Australian 12 metre works partly on this end-plate principle. This rudder adaptation can be very useful on craft sailing from a beach or in shallow waters.
A third experiment was tried with the rig. The first weeks I sailed the Swampscott dory it was rigged with a boomless spritsail. This was good to windward and on a beam wind; it was however difficult to handle in a strong following breeze because it induced rhythmic rolling. On a beamier hull this is of less consequence than on one with the fairly narrow waterline of a rowing hull.
I found a sailboard rig the most obvious alternative to my traditional spritsail. Thousands of these have been sold over the world, so there is a big choice of different quality masts and sails readily available at competitive prices. Since on a sailboard the tack of the sail comes near the foot of the mast, I had to find a way to lengthen it. I took a section of GRP tube from a set of fishing rods and slid it over the mast top. It has been strong enough.
Instead of the wishbone, I adopted a horizontal sprit on one side of the sail only. Hence the name of this rig could be "horizontal sprit rig" but other suggestions are welcome. I first met this kind of rig in a monograph on the Chesapeake Bay by Brewington, edited in 1953. 1 am, in fact, quite surprised it never has been adopted somewhere in Europe, certainly now that on sailboards it is a more than familiar sight in most sailing areas. Sailors must e a very conservative lot.
In my opinion this rig has many advantages on a small boat over the common boomed sail we all know so well: A clean airflow in the fee of the sail; because of the high clew the sail is not pinned on the water in case of a knockdown; built-in-downhaul, which I find the most striking advantage versus the boomed sail. It eliminates rolling and puts no strain on the sprit, which is in compression only, so all the gear can be light. There's no need for a sheet traveler; you have good control of the sail shape, and there's no hardware, only a few pieces of plywood, bits of rope, and two blocks.
In the eyes if the aerodynamic purist there's one big handicap. On one tack the sail is pushed against the sprit and the foil shape is spoiled! In my experience this disgrace is softened if the sprit has enough play near the mast; only the after part of the sail will be thus affected. But, if you dip the sprit each time when coming about the foil shape is maintained on both tacks. Once assimilated this maneuver takes no more time then sheeting in a jib and certainly less than tacking a genoa. Besides, it is only a refinement and no necessity.
My sprit was made by two mated sections of my GRP fishing rod. Joined from one end, they make a boom of the right length; from the other end they telescope into each other to a short tube that can be stowed inside the mast. Any tube the right length and of about 5cm diameter will do. As you can see from the drawing the system for passing the sprit under the sail is very simple, providing the boom is not too long.
An additional advantage of this rig is that any triangular sail with a luff shorter than the mast can be used almost without alterations If this sail has no eyelets for the lacing around the mast, I stitch a number of velcro tape,, along the luff instead of punching holes. So far it has never come undone.
Perhaps all this looks too simple to work. but I can assure you that, having sailed this rig for several seasons now, I am not disposed to return to the good old boomed and goosenecked mainsail with either its Chinese gybes or straining downhauls.
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July 15, 1999
The Coast Guard Auxiliary And Aids To NavigationTom Shaw
There are literally thousands of federal aids to navigation marking the safe channels in bays, harbors, rivers and the Intercoastal Waterway. There are thousands more private aids that delineate the clear channels to marinas and anchorages. The average boater who stays fairly close to home will rely on approximately 200-300 of these aids. The cruising boater depends on several hundred more. Local Auxiliary Flotillas conduct annual chart updating patrols each spring to make sure that winter storms have not damaged these aids.
Aids to Navigation, or ATONS, include lighthouses and radio beacons, but the vast majority are buoys or day boards, some of which are lighted and show a characteristic flash indicated on the chart. Accidents happen to ATONS. They are damaged by storms, struck by vessels out of the channel, subject to electrical failure and (sadly) from time to time hit by vandals. Maintaining all of the public and private aids to navigation is a major task and the Coast Guard has special units dedicated to this work. These buoy tenders are kept busy all year round.
Every boater, commercial or recreational, has a role to play in seeing that the ATONS are watching properly by reporting problems to the Coast Guard, but the Auxiliary has a special responsibility, not only in checking ATONS during regular safety patrols, but in special patrols at the start of each boating season. Early in April three Auxiliary boats from my own Flotilla will have checked all public and private aids for some thirty five miles of the Intercoastal Waterway. A little later, we will be verifying the position of off-shore aids using GPS. Other Auxiliary flotillas assume responsibility for areas to the north and south.
Not only do the Auxiliary crews check existing aids, they also keep a very close eye on their depth finders to make sure that there has been no new shoaling in what had formerly been safe water. At least one local buoy in my area has been installed because of Auxiliary ATON patrols and, unless current trends alter, another will be soon be added.
Each spring, as part of my duty as an Aids Verifier I check the PATONS, private aids to navigation, on three private marina channels in addition to the federal aids along a 35 mile stretch of the Intercoastal Waterway, and each spring I file discrepancy reports (with photographs) for all three. Two of these channels do not concern me, they are short (two red and two green markers) and they lead to marinas fully occupied by local boaters The fact that the dayboards are in discrepancy with red letters on white rather than white on red and with deterioration of the plywood does not significantly affect boating safety.
The third channel does concern me. It is long (16 aids). It is narrow. It leads to four major marinas and it attracts a significant number of cruising boats. Were I a stranger to the area, I would have real difficulty attempting this channel at dusk, let alone after dark. Many dayboards are missing. Those that are in place are approximately 1/3 the approved size and have no retroreflective tape. Each year, when I check this channel, I have a brief regret that the Auxiliary has NO law enforcement authority. Here is a situation that could and should be remedied. All I can do is file a report.
Aids that are charted, whether public or private must, to be correct, be on station and watching properly. You and I need to have reasonable assurance that if an aid to navigation is shown on the chart we can count on its being there to guide us to a safe mooring.
The moral of this story is that if the private aids to your marina are not correct and well maintained, you need to fuss a little and get any/all discrepancies corrected. Some boater you have not and will never meet will rely on those aids. You can make sure that his trust is well placed.
And, if and when you see an aid that is missing, off station or obscured by a bird's nest, report it at once to your local Coast Guard Station. You can be confident that an Aids-to-Navigation team will be out to make proper corrections. When they know it's broke, they fix it.
Checking on Aids to Navigation is only one of the many activities that makes the volunteer Coast Guard Auxiliary the principal boating safety organization in the country. Why not join us? Call 1-800-336-BOAT for the flotilla nearest you.
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