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The lifting keel on Analie, my Seal 28, had been showing an increasing tendency to encounter high spots in lifting and lowering. On one occasion it jammed in the down position. We decided to nudge it gently from the bottom on the slope of a concrete launching ramp. I misjudged the position of the ramp, and we ran into the end of it at around one-and-a-half knots. This rattled the crockery on board but did free the keel. Subsequently, it jammed completely in the ‘down’ position. The boat was lifted out, and I asked the yard to lower it slowly on to the keel allowing the weight of the boat to push the keel up somewhat, hoping that this would clear the jam. Instead, it simply wedged the keel more firmly, a little less than halfway up. Finally, allowing optimism to overcome common sense, I applied the winch with increasing force to try and move the keel, and succeeded only in fraying one of the strops. Analie resides at Bradwell Marina on the River Blackwater Estuary in Essex. She rarely takes the ground and then only in the soft mud endemic on that coast, so the keel-jamming was unlikely to be due to trapped stones. The culprit was thought to be a build-up of rust blisters both on the lifting keel and the inside of the stub keel. After liftout, the boat was placed in a cradle on the hard with the keel clearing the ground by a few inches, just too little room to get a hydraulic jack underneath. I acquired some lengths of bandsaw blade cut to suitable lengths and attempted to ‘saw out’ the rust blisters by passing the blade between the stub keel and lifting keel—daylight was visible around about half of the keel on both sides. I had already flooded the area with phosphoric acid in the hope that it would transform the rust into something softer. It was hard work and little progress was apparent, so I motorized the process by attaching the bottom of the blade to a return spring fixed to a block of wood secured to the base of the keel with a clamp and attached the top to a reciprocating electric saw. I still could not get the sawblade round much more than half of the keel periphery. A group of friends, Chris, Cliff, and Ewan, all owners of Parker yachts, took pity on me and organized a Friday afternoon working party. The application of a sledgehammer, and persistent sawing away with short lengths of the bandsaw blades at the bottom—together with an electric chisel—seemed to do the trick. We ‘borrowed’ a 2-inch square beam from one of the unused cradles in the boatyard, and using the edge of the steel cradle as a fulcrum, managed to lever the keel up and down by a few inches. The jam had been broken. Figure 1 shows the keel and beam; the keel and stub keel show some signs of the force applied to encourage movement. 
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Removing the Strops The lifting keel on a Seal 28 is a daggerboard designed to slide vertically up and down through a suitably shaped slot in the stub keel. The horizontal profile is a symmetric aerofoil. Two wide vertical grooves on either side of the centreboard box are engaged by large nylon block sliders fixed to the keel with three studs in line vertically and secured with nuts on each side. The sliders serve to keep the keel vertical with respect to the transverse and longitudinal axes as it slides up and down. The top stud threads two wire rope strops via slots in the top of the keel; the strops each pass over pulleys turning the cable through 90º, and then 180º, and are secured via copper end stops in a brass block which moves on a screw within a rectangular tube. When the keel is down, the bottoms of the nylon sliders sit on top of the stub keel preventing the lifting part from falling out. To remove the lifting keel from the bottom of the boat, the studs must be withdrawn and the nylon blocks removed. The daggerboard keel weighs in at 454 kg—nearly half a tonne—so it must be treated with a considerable amount of respect. Any process involving moving it when it is not fully and securely supported, must be done in a fail-safe manner. Clearly, replacing the strops was a job for the boatyard using professional people and proper heavy-lifting gear. As well as replacing the strops, the keel and the inside of the stub keel needed to be de-rusted, cleaned, primed, and antifouled. To do this properly, the keel needed to be dropped out of the bottom of the boat; the inside of the stub-keel would have to be cleaned by hand. To remove the daggerboard keel, first it must be lifted right up so that the top 20 cm or so is clear of the keel box. This allows the stud securing the strops, and the two studs below it which secure the two nylon sliders, to be removed. For me, getting the yard to do this was a bridge too far. There was the uncertainty of exactly how to proceed—would the keel jam as it was lifted up? How would it be lifted? More obviously, since it was almost certain to jam going down—the problem in the first place—how would it be unjammed then? Open-ended engineering issues lead to potentially unlimited financial commitments. Given my circumstances—and the value of the boat—this meant that any remedial work would have to be a do-it-yourself undertaking. If extra muscle other than my own meagre ration was needed, I had three enthusiastic members of the Parker Seal Association to call upon. First things first; whatever process was adopted, it would be necessary to access the keel both inside and outside the boat many times. A safe and secure method of climbing in and out was needed, and this was accomplished by using a stepladder fixed to the central cleat as shown in figure 2.  The keel needed to be lifted so that the top stud could be withdrawn, and the two strops removed and replaced with new ones. The remaining unbroken strop could not be trusted to take the weight using the winch, so the keel had to be lifted from below.[1] I made some blocks by cutting up some 4 x 2 timber—44 mm x 93 mm by my measure—together with some spacers of 18 mm plywood. A substantial lever was essential—I could not rely on borrowing one from the boatyard—and a custom 50 mm square box-girder, 2 mm wall thickness, 2.5 m length was acquired by Chris from a local metal shop (I could just get this length in my car). Using this I was able to lift the keel and get a hydraulic lever-arm jack underneath—see Figure 3. [1] The breaking strain of the wire rope when new is around two tonnes, but the unbroken strop had been subject to considerable strain. Also, using just one strop would unbalance the brass block which could then jam or strip. In any event, I could not take the risk of damage to the jack or the strop breaking.  Using the jack, I could lift the keel and block it sufficiently high enough so that there was room to get a vertically lifting hydraulic bottle jack underneath. I could now raise and lower the keel to the extent of the jack’s lift without worrying that the small transverse movement of the end of the lever-arm jack might allow it to slip off the keel. I lifted the keel until it was flush with the stub keel—see Figure 4. I didn’t feel that the pile of blocks was sufficiently stable, so I replaced them with two axle stands—Figure 5.
So far, I had been using pieces of wood roughly sawn on site, but the keel needed to be lifted by another 15 cm or so to access and undo the nuts and withdraw the stud threading the strop thimbles. I photographed the keel from the top—Figure 6—and made a scale drawing of the central part—Figure 7. I wanted to make three stacks of blocks, mostly from 4 x 2, precision square-cut using a radial-arm saw, sized to fit within the stub-keel slot without too much room for transverse slop, while allowing the stacks to move up and down without catching on each other or the sides of the slot. The central stack would sit atop the jack; the stacks either side would support the keel while the central stack height was being adjusted and vice versa. I dare say there may be simpler and better ways of doing this, but I could not think of any.  The process was as follows starting from the point shown in Figure 5:
 (Berridge, in his book The Girder Bridge, describes this as ‘giggling’. He used the reverse process in the controlled dismantling of the old Brunel railway bridge at Chepstow, where a large wrought-iron tube was slowly lowered by steadily reducing the height of the supports at either end from the bottom. The Oxford English Dictionary does not recognize the term.)
The process was not entirely without issues or risk. A steady hand was needed to avoid the stacks toppling as new blocks were added at the bottom of the stack. To limit this tendency, I used double-sided tape between some of the blocks. As a safety measure, one of the stacks was always securely in place under the keel, with a second stack no more than 7 cm or so below the keel. I manipulated the stacks from the side, avoiding placing my fingers anywhere where they could be in danger should one of the blocks slip catastrophically. The method worked well. I was able to lift the keel so that the stud and its securing nuts were above the keel box. Using the largest socket in my set—32 mm—to undo the nuts, and with a bit of encouragement from a drift and hammer, the stud was withdrawn and the strops removed. Replacing the strops. Analie was built in the 1970s, so it is not surprising that Imperial measure was used—it is a Seal 28 (feet) after all. The strops have probably been replaced a few times over the years, and by measuring up the unbroken strop I determined its specification as follows:
Two cables each of two tonnes breaking strain lifting a 400 kg weight provide a safety factor of ten which may seem like overkill, but since each cable passes over two pulleys, radius of curvature around 2.4 cm—one bending the cable back on itself 180°—some substantial derating is necessary. The first problem was to acquire suitable thimbles. These are sized according to the diameter of the wire rope for which they are designed. Unfortunately, 6 mm thimbles have a clear aperture diameter of only 15 mm, 8 mm thimbles will accommodate 18 mm. 10 mm thimbles have a clear 25 mm aperture, but they are much bigger and would not fit the slots on the keel. Examination of the existing thimbles indicated that they were likely to have been of the 8 mm size. Two new 8 mm thimbles were purchased and modified by my Parker Seal mate Chris, by the expedient of banging a 20 mm diameter socket into the hole. This opened the jaws sufficiently to accommodate the 19 mm stud—Figure 8. The original thimbles could have been reused but the one from the broken strop was badly corroded and pitted—worn right through at one point—and I wanted to keep the remaining strop in one piece as a precaution.
I sent the modified thimbles to GS Products, whose applications engineer, Lewis, had been most helpful via several emails and a telephone call. After three weeks, they had not arrived there… Chris modified two more thimbles for me, and I sent them Royal Mail Priority Tracked—they arrived the next day. Within a week I had two brand new strops—Figure 9. A week after that, the first two thimbles arrived at GS Products... Moral: if it’s important or time critical, send it tracked (or don’t use Royal Mail). With the glorious benefit of hindsight, it might have been wiser to make a new, smaller diameter stud, say 17 mm diameter, to fit the unmodified 8 mm thimbles—see below re strop length—but I was loath to modify anything unless absolutely necessary. Also, a new stud would need machining, with threading at each end and the central part supporting the thimbles left smooth—more delay and expense. Meanwhile, the winch had been stripped down—Figure 10 shows the constituent parts. The box was cleaned and painted, the screw, slider, pulleys, and cables were regreased with waterproof grease as used in my MaxProp propeller. The thrust-bearing was loaded with as much grease as it would take, the whole reassembled, and the strops fitted into the keel.[1] There was one irritation: one of the strops was a few mm or so longer than the other. This almost certainly arose from my request to the supplier not to clamp the cables tightly round the thimbles in order to preserve their modified opening. Some copper wire was wound around the cable next to the copper end stop until the tension in both cables was judged to be the same—see Figure 11. [1] I could not see how to disassemble the thrust bearing; it may have been pressed into place. The plastic ring sealing the end adjacent to the handle could be removed. I used a thin blade to lever it out, and crammed the space inside with bicycle grease, hoping that pressing the plastic ring back in place would force grease into the business part.   Lifting the keel The most problematic part of the whole business was the need to lift the keel sufficiently high enough to allow proper cleaning. Although it had been unjammed, extensive use of both the lever and the bottle jack showed that it would still jam about three-quarters of the way down. Since the keel could not come down to be cleaned—the option already ruled out because it could only be done by the boatyard—it had to be lifted up. The bottle jack and blocks had been very successful in lifting the keel safely from below, and sufficiently high enough to allow the strops to be replaced. But the two nylon guide blocks had always been fully engaged with the slots on the keel box. Even with the strop stud removed, the two remaining studs clamping the blocks to the keel ensured that it was always secure from toppling. Lifting the keel another 10 cm or so would see the blocks rise above their guide slots, and all transverse and longitudinal stability would be lost; the risk of a topple in either axis was too awful to contemplate. It was clear that the only safe way to proceed would be to suspend the keel from above. I considered three options:
There is a semi-permanent hatch, for’ard of the sliding coach roof, secured by four screws and sealed with silicone rubber. When this was removed, it revealed what appeared to be a small ‘removable’ panel suggestive of a port originally designed to admit a lifting strop for the keel… Unfortunately, on Analie it was attached with permanent bulk adhesive, probably epoxy, and quite definitely not removable. To execute option 3, a hole of suitable dimensions would need to be cut through this panel, some wood spacers underneath, and the ceiling moulding. In various states of euphoria, depression, sobriety, and inebriation I considered these three options, favouring first one and then another. I had to get the keel in an operational state; I might need to sell the boat. Marina fees were accruing relentlessly and my indifferent health meant that my confidence in sea-sailing was waning. On the other hand, a bodge would be worse than useless; it had to be a decent job. The ‘A’ frame solution allowed access to virtually the entire keel with no timber framing in the way. Also, it should be possible to lift the keel entirely above the keel box, allowing some timber cross-pieces to support the keel on the box securely. This would enable some decent and safe cleaning of the inside of the stub keel also. Chris had a half-ton chain hoist I could borrow, and GS Products sell a range of galvanized wire rope and clamps enabling the various strops needed to be fabricated at minimal cost. The downside is that a substantial hole would have to be cut through the coach roof and the ceiling moulding under it. The position of the hole and apex of the double ‘A’ frame would have to be determined by dead reckoning adding to the difficulty. Furthermore, the ‘A’ frames could well foul the shrouds. An initial foray to the boat to measure up the position and size of the A frames was abandoned. The impossibility of making accurate measurements on a three-dimensional structure with curved and sloping surfaces soon became clear. I considered that the deck-loading should not be a problem, with each leg having to support, say 120 kg, but there were two further difficulties. Firstly, the substantial hole in the cabin roof would need considerable remedial work when the keel had been dealt with. Secondly, and this was the killer, the apex of the two ‘A’ frames and the fixing of the chain hoist would need to be around six feet above the coach roof. It would have been quite impossible for me to have worked on this securely and safely, and at the mercy of the weather. I reconsidered options 1 and 2. Option 1, I discounted for the reasons given above. Option 2 used the transverse and longitudinal stiffness of the keel box—itself designed to hold and contain the keel, raised or lowered, under conditions of pitch and roll—to stabilize a frame sitting on the cabin floor. The floor was supported by transverse timbers directly on the hull. Option 2 had further benefits—no holes needed in the coach roof, and the entire procedure contained within the weatherproof cabin. Furthermore, some preliminary tests showed that with the sliding roof open, the winch handle could still be used with the winch quite close to the ceiling. This was the approach I decided to adopt. Figure 10 (previous post) shows the underside of the winch with its mounting flanges and the substantial box girder containing the stainless-steel screw and brass ‘nut’ with its two slots to locate the ends of the strops. The winch is heavy, weighing 12-14 kg. The screw assembly is offset laterally to allow visual inspection of the keel and strops. The strops run to the two end pulleys where they are turned through 180º and led to the nut. It is evident that the centre of weight passes through the two pulleys on the central flange which has a triangular reinforcing web on the top side—visible in figure 12. There are fixing points on the keel box corresponding to the flange holes. The central rectangular flange bridges the keel box above the keel and the two slots accommodating the nylon sliders. Either side of these, the keel box is substantially reinforced—centimetres thick all the way down to the floor. To keep things simple, I supported the central flange closely behind the pulleys with a simple transverse timber beam. The resulting moment on the screw box transmitted just a few percent of the weight to the flange adjacent to the pulleys at the for’ard end of the screw assembly. Figure 12 shows the basic structure. I considered calculating buckling strengths and stiffness ratios for the timber, and the merits of ‘A’ frames rather than four parallel vertical beams. In the end, I opted for simplicity—the Stonehenge design—and decided that if it lookedright, using C24 grade building-quality 4 x 2 and common-sense constructional techniques, then it probably was ok. Furthermore, timber in construction has that quality, well-known to the old miners who used to use it for pit props, that it creaks and groans when pushed to the limit, thereby signalling distress before imminent failure. Note that the bridging transverse beam and the two side bridging beams, consisting of doubled 4 x 2, are arranged with the ‘4 inch’ dimension vertical. The stiffness of a beam varies with the cube of its depth, so a pair of 4 x 2s, not glued or screwed together and arranged thus, have eight times the stiffness of the same pair used with the ‘4’ dimensions horizontal. Each pair of vertical beams was located on a short length of timber on the floor to spread the load. They were braced at the bottom and half-way up. Separation was around 20 cm, this being a compromise between longitudinal stability and room to access the keel, and the need to limit the length of the bridging span at the top for safety. They were clamped to the keel box as shown using four horizontal members, screwed to the verticals and tensioned by studding at each end. The studding was positioned on the keel box using wedges. As before, there may well be more secure and/or efficient ways of doing this, but it was straightforward and was able to provide open access for rust removal and treatment. There was plenty of creaking from the floor as the cables took the full weight of the keel, but the frame seemed to be secure. One further benefit unlooked for as the design evolved, was the fact that the keel, at 450 kg, provides a considerable level of security when the strops are under tension by clamping all parts very firmly together.  More height Having established that the basic structure shown in figure 12 (previous post) was stable and secure, it seemed appropriate to see how far it could be safely extended vertically, and lift as much as possible of the keel up for cleaning. This could be achieved by placing further blocks under the existing beams. Every operation described so far was relatively straightforward and called for no great strength, with one exception, and that was the lifting up and positioning of the winch assembly on the frame. I have mentioned that it weighed between 12 and 14 kg. Lifting it on to the structure—head height—remembering that the strops were attached, is definitely a two-man job. I managed it on my own by lifting one end, propping it, then lifting the other and so on. The process was not pretty, and not thought-out beforehand; it was the only part of the procedure with which I was not completely satisfied. Going any higher would have been impossible without mechanical assistance. The solution was to use those small lever-arm lifting jacks designed to lift washing machines etc. Figure 13 clarifies the process. Firstly, the keel was lifted until the nylon blocks were well above the keel box. Pieces of timber either side of the keel, long enough to bridge the keel-box slots, were placed appropriately, and the keel lowered on to them. This provided a safe and secure support for the keel and allowed the support structure to be modified. The keel could then be used as a platform—as shown in figure 13—to support the jack. It is important to note that the jack is only lifting the winch and its associated timbers, not the keel…  By slackening the strops, one end of the winch and its bridging timber can be lifted. Blocks are placed underneath, and the jack is then transferred to the other end and the procedure repeated. One note of caution: Slackening the strops can, in extremis, cause the cable end-stops to come out of the end of the slots in the winch nut. In applying subsequent tension, it is possible for the shoulder of the end stop to then catch on the nut causing the strop in question to be shorter than the adjacent one by the length of the stop. Worse case, the winch might need disassembling. The way to avoid this is to keep tension on the strops as much as possible, and only to unwind the winch a few turns at a time. The ultimate height I was able to achieve in this way is shown in figure 14. With the keel this high, all but 30 cm or so of its vertical length was visible above the keel box and available for cleaning etc. Since at least 60 cm is accessible below with the keel right down, this procedure allows all parts of the keel to be accessed for cleaning, derusting, and antifouling. Some further precautions are, however, appropriate when the keel is lifted this high. It is important to ensure that the blocks used are square and regular in the vertical dimension, and the stacks are vertical and stable. At this height the keel is entirely free and will pendulum in all directions, only loosely constrained by the keel box. For cleaning, and to improve security, the keel can be slightly lowered on to two Stonehenge type supports under the nylon blocks. The verticals can be sized to accommodate different heights. One side can be removed to allow full access for maintenance, with the keel partially lowered on to the support on other side. This stops the keel moving around, while most of the weight is held by the strops for security.  Cleaning and derusting
Analie’s daggerboard keel and its stub companion are made of cast iron. Fifty years of immersion in salt water have taken their toll, and both are badly pitted. Over the years various remedial work has, no doubt, taken place using goodness knows what treatments or fillers. (My dear old granny used to use Polyfiller to repair the rusty bodywork on her old A35 motorcar…) Visual inspection was inconclusive, but whatever was on there, apart from rust and antifoul, was quite hard. A stiff rotary wire brush or abrasive pads on my angle-grinder took a long time to do anything and were very hard work. A rock hammer, or an old chisel and hammer likewise had some success but were also very hard work for little progress. Use of the electric chisel was alarming. The chisel was quite blunt, and it was necessary to use it at 90º to get any response, at which point it proceeded to dig a pit… I tried a pneumatic needle gun next. This only seemed to tickle the surface, producing a series of parallel scratches. The method that worked best was a small, sharpened chisel in a Wickes Pneumatic Hammer Drill. The secret was to keep the chisel sharp and present it at an angle to the work to avoid digging in. By weighing the material removed, I’m guessing around two-thirds of a kilo of rust and ‘other material’ came off. A trial lowering indicated that the keel was free, certainly to the constraints of the cradle. Once I am satisfied that all suspicious extraneous material has been removed, the keel will be coated with Jenolite rust converter, Primocon primer, and antifouled. Peter Maggs, May 2026 |
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