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-   -   Giving Your Boat Some Legs (http://www.sailnet.com/forums/gear-maintenance-articles/20077-giving-your-boat-some-legs.html)

James Baldwin 07-27-2004 09:00 PM

Giving Your Boat Some Legs
 
<HTML><P><TABLE cellSpacing=0 cellPadding=0 align=right border=0><TBODY><TR><TD width=8></TD><TD vAlign=top align=left width=250><IMG height=325 src="http://www.sailnet.com/images/content/authors/baldwin/020802_jb_beached.jpg" width=250><BR><DIV class=captionheader align=left><FONT color=#000000><B>Careening a boat for the purposes of periodic maintenance is often risky and always awkward.</B></FONT></DIV></TD></TR><TR><TD colSpan=2 height=8></TD></TR></TBODY></TABLE>As many cruising sailors know, one drawback of a typical single-keeled monohull sailboat is that it will not stand upright on its own when you intentionally take the bottom on a falling tide. During the 22 years that I've owned my 28-foot Pearson Triton, <I>Atom</I>, I have often looked for a practical method of standing her upright when drying out between tides to clean or paint the hull, or simply to make repairs below the waterline. <P>Most of the time I have made do by careening, which is to let the boat lay over on its side as the tide drops and, if necessary, heeling her over even further by hauling on a halyard connected to a secure point on shore. But this means that only one side of the boat is accessible at a time. Safe careening requires a firm, smooth shoreline, such as a sloping sandy beach. Even so, the hull is vulnerable to damage from pounding against the bottom if an unexpected swell or wake from a passing boat should arrive. It is also extremely uncomfortable to live on the boat while it's laid over at a crazy angle. And getting up in the middle of the night at high tide to move the boat out or to turn it onto the other side is no fun either. </P><P>While in Madagascar, I even experimented by standing <I>Atom</I> bow-on to the beach with an anchor set out to each side connected to halyards at the top of the mast. This system sounded fine in theory, and may even have worked if I had not upset the balance by stepping off the side of the boat, causing one of the anchors to move slightly from the increased load. Moving in slow motion, <I>Atom</I> rolled gracefully and unstoppably over on her side. Fortunately, the only real damage done was to the skipper's pride, as witnessed by a group of curious local fishermen who gathered around.</P><P><TABLE cellSpacing=0 cellPadding=0 align=right border=0><TBODY><TR><TD width=8></TD><TD vAlign=top align=left width=350><IMG height=300 src="http://www.sailnet.com/images/content/authors/baldwin/020802_jb_boatlegs.jpg" width=350><BR><DIV class=captionheader align=left><FONT color=#000000><B>The author's "dry-out legs" include safety lines run from the base or foot forward and aft to cleats on deck.</B></FONT></DIV></TD></TR><TR><TD colSpan=2 height=8></TD></TR></TBODY></TABLE>But in all my voyaging, I have rarely found a quayside or dock suitable to lean against for drying out. The alternative, of course, is to haul out at a marina. Again, these facilities are not always available when and where I need them and the costs and hassles involved are not justified by the kind of minor jobs I often need to do. <P></P><P>While on that six-month cruise around Madagascar a few years ago, I began to seriously consider designing some type of dry-out legs. Besides keeping the boat upright for maintenance work, I wanted a method where I could enter shallow coves and tidal rivers at high tide, drop my anchor, set up the legs and let <I>Atom</I> look after herself as the waters receded. Some European sailors who keep their boats on moorings where huge tides turn the bays and estuaries into narrow channels and vast mud flats use what they call dry-out legs. However, the only types of legs I had seen in use were bulky and difficult to stow. Most of them lacked any height adjustment and I didn't care for the way they were attached to the hull, requiring special fittings and reinforcements.</P><P>Eventually I came up with a design using two sets of adjoining stainless steel pipes connected together with a standard pipe coupler and attached to the existing shroud chainplates. Their height and angle of inclination are fully adjustable and the plywood feet that I designed for them pivot in order to be used on an uneven seabed. Because they attach to the existing chainplates, they do not require any modifications to the boat at all. In addition, the chainplates are better designed to take heavy loads than most fittings that you might add on later. When not in use, the legs disassemble and stow easily in the bottom of a cockpit locker. An added benefit of these legs being fully adjustable and attaching to the chainplates is that I can loan them out to friends with boats of similar size and draft.</P><P><TABLE cellSpacing=0 cellPadding=0 align=right border=0><TBODY><TR><TD width=8></TD><TD vAlign=top align=left width=250><IMG height=365 src="http://www.sailnet.com/images/content/authors/baldwin/020802_jb_boatlegs2.jpg" width=250><BR><DIV class=captionheader align=left><FONT color=#000000><B>An adjustable braket on the upper portion of the leg attaches to the chainplates for a more secure set-up. Note the protective black rubber sleeve that keeps the leg from marring the boat's topsides.</B></FONT></DIV></TD></TR><TR><TD colSpan=2 height=8></TD></TR></TBODY></TABLE>The legs and their assorted fittings I fabricated myself in a friend's shop in South Africa using stainless steel pipes and plates that I purchased for $40.00 (US) from a local scrap yard. A sliding, clamping sleeve that can be adjusted by a turnbuckle, attaches to the two-and-a-half-inch diameter, thick-walled pipes. A larger boat than <I>Atom</I> would, of course, require heavier materials, but most marine yards or steel fabricating shops can make up a similar set of legs according to your own dimensions. <P>The feet are made up from one-and-a-half-inch thick, epoxy-laminated and sealed, pieces of scrap marine plywood. I was initially unsure as to what size would be best for the feet, wondering if I might even need a second set of wider feet for muddy bottoms. To calculate the correct foot size I began with the rough calculation that my full-keeled, 10,000-pound boat (fully loaded) would put, say, a maximum load of about 2,000 pounds on each leg. So I conservatively guessed that I'd need to keep the foot pressure load under 20 pounds per square inch, and I found that this could easily be handled by a surface area of 10 inches by 12 inches, or 120 square inches. </P><P>After testing, I was pleased to find that the feet do not sink in excessively, even in the muddy river bottoms of Brazil where I used them recently. In practice there is normally not much load on the legs, but they still should be massively overbuilt to withstand the possible shock loads from waves that arrive just as you are taking the ground or starting to refloat. On one of the legs I later added two small steps to facilitate getting on and off the boat at low tide.</P><P><TABLE cellSpacing=0 cellPadding=10 width=160 align=right border=0><TBODY><TR><TD><IMG height=2 alt="" src="http://www.sailnet.com/images/content/authors/bullets/black_1pix.gif" width=160 border=0></TD></TR><TR><TD vAlign=top align=middle width=160><FONT face="Arial, Helvetica, sans serif" color=black size=+1><B><I>"To lessen the chance of pounding on the bottom it's prudent to choose a spot that is well protected from waves and wakes."</I></B></FONT></TD></TR><TR><TD><IMG height=2 alt="" src="http://www.sailnet.com/images/content/authors/bullets/black_1pix.gif" width=160 border=0></TD></TR></TBODY></TABLE>Now, when I'm setting up the legs, I've found that it's important to first determine the angle of slope of the sea bottom. If the angle is steep, such as along a beach, it is best to position the boat's keel so that the bow is pointing straight up the seabed's incline by using a bow and stern anchor. On a tidal flat where you know the bottom is nearly level, the boat can ride to the wind and current on one anchor and take the ground where she will. To lessen the chance of pounding on the bottom it's prudent to choose a spot that is well protected from waves and wakes. <P>I prefer to set up the legs while still afloat to avoid a panic trying to get them set up before the falling tide heels the boat. I begin by loosening the aft lower shroud turnbuckles and removing the pins. With the legs assembled on deck, I then lower each one over the side, and attach it to the chainplate. A rubber block slid over each leg protects the hull from scratches. The legs are clamped at a pre-marked position so that the feet are level with the bottom of the keel. Lines attached to the forward end of each foot are tied to the bow cleat, and then the aft lines are pulled tight and tied to the stern cleats. (I occasionally use the cockpit winches if necessary for final tightening.) These four lines tend to pull the feet inward at the bottom. To oppose this force, and to ensure that the legs will incline slightly outward, I pull a line tightly across the deck between the top of each leg. </P><P><TABLE cellSpacing=0 cellPadding=0 align=right border=0><TBODY><TR><TD width=8></TD><TD vAlign=top align=left width=350><IMG height=300 src="http://www.sailnet.com/images/content/authors/baldwin/020802_jb_boatlegs3.jpg" width=350><BR><DIV class=captionheader align=left><FONT color=#000000><B>Perhaps the best aspect of this invention is that each leg collapes to the stowable size shown here.</B></FONT></DIV></TD></TR><TR><TD colSpan=2 height=8></TD></TR></TBODY></TABLE>When the tide is up I bring the boat to the beach using a stern anchor and a line strung from the bow to the shore. If the boat should lean to one side as the tide drops, the leg's height can be adjusted by the turnbuckle. If more adjustment is needed than the turnbuckle allows, the sliding clamp is tightened, the turnbuckle temporarily taken off, and shackles or a short length of chain added under the turnbuckle to make up the required distance. The foot lines are then readjusted, if needed. Bigger boats may need additional support, possibly by using four legs rather than two. And an owner with a ketch-rigged boat might attach the aft legs to the mizzen shroud chainplates.<BR><BR>The legs have proved a valuable addition to <I>Atom's </I>cruising gear, opening up shallow waters that were previously out of bounds, and making her a more versatile and self-sufficient boat. Even in areas where the tidal range is less than your boat's draft, setting up the legs can be useful when replacing a thru-hull fitting or the prop, or just cleaning the bottom. And, when you want to anchor in that enticing deserted cove that is just a little too shallow for your boat to remain afloat at low tide, the legs will make that possible. </P></HTML>


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