Friday, September 12, 2014

Dock slip Cat Catcher and set of eight docklines to keep Blueberry clear of the slip sides

 My slip at the Oakland Yacht Club has 8 carefully adjusted dock lines, each with a spliced docking eye at the Nonsuch end. The dock end of each line is shackled to the dock. There are two bow lines, two stern lines, two starboard spring lines and two port side spring lines. These 8 lines are trimmed so that they prevent the Nonsuch from contacting the sides of the slip no matter how severe a surge of water sweeps through the dock slips. No fenders are needed on either side of the slip, when reasonable sized wind waves, storm surges or wake surges pass though the slip.

If the storm waves are large enough to severely damage the marina where your slip is located, all bets are off such as this map of storm wave heights, shown below:

"GRAND HAVEN, MI — An unseasonably strong storm system is poised to churn up the Great Lakes during the afternoon Wednesday.

National Weather Service forecasters expect Lake Michigan breakers to build to an impressive — yet dangerous — 10 feet or greater, especially out to mid lake. However, shoreline communities from about Saugatuck north to Holland and Grand Haven could see wave heights surge to at least 6 to 8 feet.

Considering Great Lakes water levels around long-term averages, the expected surf easily could inundate piers and other structures, meteorologist Bob Dukesherer said.

Winds are forecast to blow in excess of 20-30 mph from the south southwest.

"With 10-footers on top of water levels near normal, (that'll) swamp the piers more easily," he said. "

Sailing or motoring into the slip need not be an adventure in preventing a 5000 lb Nonsuch 22 from ploughing into the dock end of the slip. I have installed two 1.5" three strand dock lines, crossing the end of the slip, creating what I call a Cat Catcher, to take care of that situation.

With the blessing of the dock manager, I started with four galvanized, 1" eye bolts, each 6 " long. The 6" length was dictated by the 8" height of the timbers along the sides of the slip. Each bolt was sunk into epoxy filled, 1 1/2 "holes, along the edges of the dock. The epoxy was allowed a day to harden around each bolt.

Each end of the crossing dock lines are spliced onto galvanized thimbles, and fastened to eyebolts with galvanized shackles. The two crossing lines are pulled as tight as I could pull them by hand so the is very little sag in the two lines.

Docking is simply coasting into the center of the slip with enough speed to maintain steerage into the Cat Catcher. The bow slides along either of the fixed dock lines to the center of the crossing lines and the boat stops, with the bow in the center of the X, and the boat will then be gently sprung back a few inches from the X of the fixed lines.

One side of the stern will be closer to the edge of the slip than the other. Get off onto the dock on that side. Before you touch any other lines, walk forward along the dock and take care of the bow lines. This sequence, described below, is most important for ease of single handed docking.

The position of the bow lines on the dock, well forward of the bow when the Nonsuch has all 8 lines in place provides enough slack for the bow lines to be attached from the dock. To do so, position the bow cleat, or Sampson post, on the bow of the boat, straight out from the dock end of the first bow line to be attached. Pull the bow close enough to stand on the dock and drop that bow line over the post. Then walk around the dock end of the slip and drop the second dock line over the same cleat, or Sampson post, as well. This is easily done as long as none of the other six dock lines are yet attached to the boat. With both bow lines in place, walk along the windward side of the slip and attach the two spring lines over the midship cleat.

Continue along that windward side of the boat and drop the stern line over the stern cleat. The slip I am using is a few feet shorter than ideal so that the stern lines are not led quite as far behind the boat as would be ideal, but the 4 spring lines are more than heavy enough to keep the boat from surging forward and back in the slip without any further help from the stern lines.

Then walk around to the leeward side of the boat, and drop the two spring lines around the mid ship cleat, and then drop the stern line over the stern cleat.

How did this method of docking become important to me? When I first brought a much larger 36' cat rigged ketch to San Francisco Bay from the Great Lakes in April 1979, The only slip I could find in the Bay area was at the San Francisco Pier 39 marina. The floating strings of truck tires for the breakwater in use the first years after construction of that marina were useful for keeping wind wave chop out of the marina, but useless against the wake surge waves from passing  naval ships, oil tankers, and container ships. When I came to the Pier 39 marina office, the damage to boats hurled onto one or the other of the pier fingers by wake surges, and winter storm swell surges, had reduced the number slip occupants from an estimated 10 year waiting list down to one slip available, so I took it.

Why were so many boats damaged? It seems that many of the boats had moved to Pier 39 from a well sheltered marina where there were modest sized wake surges. The owners were used to using only 4 dock lines, with almost no slack in those lines, and some fenders, to keep the boat off the sides of the slip. In my year there, before the newer Pier 39 breakwater walls were constructed, my light weight, high top sided 36 footer, never touched the sides of the slip fingers.

Since I was usually sailing single hand or double handed, into a marina with currents and surge waves, catching the bow in the X of dock lines and then, before the boat was  pushed against the down wind or down current side of the slip, (which ever was dominant in slip) it was important to secure the bow lines first, followed quickly by the spring lines and the stern line on the windward side of the slip. The spring lines and stern line on the leeward side of the slip are connected last.

Saturday, June 20, 2009

Replacing the mast head sheave

After 18 months of 2 to 3 times a week racing on San Francisco Bay, the main halyard sheave on Blueberry, my Nonsuch 22, sail # 48, gave notice of quitting. A call to Mike Quill Rigging (a specialist in Nonsuch rigging and the source of many Nonsuch replacement parts) outlined for me what I was up against in the replacement of this sheave.

With three races in the next week, I was reluctant to pull the mast. Pulling the mast was estimated to be cheaper than having the same pair of riggers (one operating the crane, the other at the mast head) doing the repair without pulling the mast for work at the ground level. If I could source a replacement sheave, before beginning the surgery (the mast head has to come off to get at the sheave) I might be able (if lucky) to keep my racing schedule intact.

Mike explained that some of the 22's had single sheaves and some had dual sheaves. Mine is a single sheave. Mike would need to know the dimensions of my single sheave to see if he has a sheave that might fit. A classic Catch 22 for my Nonsuch 22

So the call went out: Anyone have the dimensions of the single mast head sheave for a Nonsuch 22? The consensus was that another source of custom stainless steel parts was Murray Cressman. Murray is a jewel of a resource, and he is highly recommended by many as well as by me after this project.

Given the choice of sheaves from various suppliers in various sizes, Murray took his best guess, based on sheaves supplied to other Nonsuch owners, and arranged for a Garhauer sheave to be drop shipped from southern California. With a great looking sheave in hand, then came arranging to get the mast pulled. Wonderful service by Murray and I thank him for that.

In the San Francisco Bay area, only a very small percentage of the boats on the water year round, (even those which are dry sailed) have their masts pulled each year. The quotes from the three nearby yards, to my yacht club, included the cost of two riggers at $90.00 each per hour, and crane charges each time for a total out and back in the next day, of an estimated $600.00 US. about another approach?

Since I am a Green Card Canadian, with the first 30 of my 62 years of boat owning in the annual boat haul out great white north, mast pulling was familiar enough for me to use a couple of family and friends. With their help I was able to use my local yacht club dry sail haul out crane, at lower low tide. We were able to pick up the mast at the balance point, at a crane and salary cost of gratitude to those involved.

The base of the haul out crane is just above the word Encinal. The tide is much higher at the time of this picture than during the mast haul out.

Same location at Lower Low Water, Large tides ( mast haul out conditions) the next day.

The picture below shows the mast head with the mast head cap removed. The piece of paper taped to the saw horse shows the tidal heights for the day, and a note explaining when the mast would be put back in.

The picture below is a view looking up from the tube of the mast into the mast head cap. The stainless steel pin, through the two flanges of the aluminum casting holds the mast head sheave in place.

The picture below is a view showing one end of the pin in the aluminum casting flange.

The picture below shows the other end of the pin, with a small stainless steel plate welded to the pin and held in place with a flat head screw tapped into the flange. The sheave is resting in the gap between the flanges. So the plan was to remove the old sheave, replace it with the new one, insert the pin, secure the pin in place, and put the cap back into the mast. Easily done eh? Mmmmm....maybe not.....

This shows the elegant Garhauer sheave, the favorite of myself and the choice of Murray Cressman, and a second sheave, sourced locally at the last minute, on the right. And the reason for that would be....shown in the picture below this one......sigh.....

Remember the comment that some Nonsuch masts had single sheaves and others had double sheaves? Well it seems there was some variety in castings as well. My favorite Garhauer could not be fitted even if I had the casting milled out enough to fit into the slot as that would leave the flanges too thin. This was a situation neither Murray nor I had imagined might be the case.

OK, if we are not going to fit the Garhauer, what is Ken Blake doing with the milling machine? Ken Blake runs a small custom metal parts manufacturing company with machine tools ranging in age from the 1940's vintage milling machine being used in the picture to a modern 5 axix CNC machine used for longer runs of small parts production. Ken can be reached at 510-258-3592. Over the years I have used Ken's ability to visualize what has to be done, without a drawing, to create a number of boat related metal parts.

The locally sourced sheave, that would fit betwen the flanges, would not fit far enough into the slot between the flanges because the slot was tapered slightly when cast. The original sheave apparently just barely fit, for a while, but as the bronze bushing wore in use, the sheave tried to drop further into the slot, and in the effort to do so milled, or at least tried to mill a wider slot for itself until it jammed. The jam got my attention, from some 30 feet below the mast head, when pulling up the main sail.

So Ken milled out the slot to the width at the top of the taper, all the way to the bottom of the slot. This allowed us to position the sheave on the stainless steel axis pin, with three thin mylar washers on each side as low friction spacers.

Great, all done now?.....maybe not.... It seems that the stainless pin was not quite square to the stainless plate holding it in between the flanges. Tighten the screw, the sheave jammed....loosen the screw, the sheave spun as it should. OK, some shim stock under one end of the plate, tighten the screw, and all was happy again. Oh yeah, all of the stainless screws threaded into aluminum on this casting were well coated with Forespar Lanocote to prevent electrolytic corrosion in the salt atmosphere.

At the next lower low tide, the spar was picked up just above its balance point, and reinstalled in Blueberry. The next couple of hours were spent re-rigging the wishbone, bending on the sail, and cleaning up the clutter for a beer can race that evening.

After going to all the trouble to source a Garhauer sheave that would fit the size of the line at full hoist of the sail, why was I able to settle for a narrower sheave instead? The high tech halyard had a wonderfully strong mast head shackle spliced into the line. The bury of the splice, tapering from 1/2 inch at the shackle down to the 3/8 inch line beyond the burried tail of the splice, was all on the sheave . So the splice was cut off, the rope end whipped and the dinghy method of fastening the halyard was used.

A loop of the halyard is pushed through the ring in the top of the sail. The short end of the loop tail, with a stopper knot tied in the end, is passed over the top of the sail and pushed down through the loop, the loop is pulled tight. Now only the 3/8 inch line is loading the mast head sheave instead of the fatter spliced section of line. Elegant solution, eh?

Friday, January 9, 2009

Wyliecat width of wishbone on Blueberry

Link to earlier blogs in blog order
Links to earlier blogs in chronological order:
Nonsuch 22 Brochure
Forward looking sonar on Blueberry
MarsKeel stability bulb torpedo on Blueberry
Wyliecat width of wishbone on Blueberry

Some 50 years before Mark Ellis designed the Nonsuch, and Tom Wylie designed the Wyliecat, Sidney Herreshoff was designing small sailboats with wishbone booms, sometimes referred to as "wishboom" rigs. Wishbone boom design has flourished among suppliers of wind surfing equipment.

Tom Wylie's racing oriented boat has a wishbone design considerably wider than the wishbone design of the Mark Ellis Nonsuch cruiser, to allow for some light air sail shape racing advantage. So, "It seemed like a good idea at the time." came into play one more time in my life

The drawing below was based on my "back of the envelope" sketch for the estimator at Accurate Tube Bending in Newark CA. My sketch required a new nose piece and a new tail piece of mild steel bent to fit the original Nonsuch aluminum side tubes. Mild steel was selected for this design instead of the carbon fiber nose and tail pieces that the Wyliecat used with their aluminum side rails. A lot of thought went into electrochemical isolation of the aluminum and steel components.

The tail piece casting is shown below. The side tubes are fitted over the tail piece casting, and held in place with screws drilled through the tube and tapped into the casting. The stainless steel screws have to be coated with some dielectric barrier such as Lanocote to prevent the aluminum, in contact with the steel to "rot" into a crumbly white material.

The new tail piece, shown below along with the old one, is not a casting, but is, instead a bent tubing, the same size as the side tubing, with a pair of ferrules slipped inside these tubes to bridge the joint.

The nose piece casting is shown below. As with the tail piece, the side tubes are fitted over the nose piece casting, and held in place with screws drilled through the tube and tapped into the casting.

The new nose piece, shown bekow along with the old one, is also not a casting, but is, like the tail piece, a bent tubing, the same size as the side tubing, with a pair of ferrules slipped inside these tubes to bridge the joint.

Shown below is the new tail piece fitted, but not yet drilled and tapped for the the joint screws.

Shown below is the new nose piece almost fitted, with one of the ferrules visible on the right hand side.

Shown below is the longer front to back extent of the new tail piece compared to the original tail piece casting.

Shown below is the longer front to back extent of the new nose piece compared to the original casting.

Shown below is a side view of the new nose piece.

Shown below is the new wishbone in place on Blueberry. The original Nonsuch rubber bumpers were retained on the side rails to cushion occasional slamming of the wishbone against the mast when all wishbone control lines happen to be slack.

The length of the original mast to wishbone hangers was retained, though provision was made for an alternative attachment position further forward, as in the Wyliecat design. I was concerned about the length of these hangers until I realized two things:

First, the twin topping lifts could be used to effectively lighten the weight of the wishbone on the leech of the sail in light air conditions.

Second, in all but the lightest air conditions, the front of the wishbone was essentially supported by the choker lines, at least on the Wyliecat, leaving the mast to wishbone support lines slack.

There are wishbone hanger length, hanger position, choker line attachment and wishbone angle design details involved here that are yet to be explored.

The picture below shows the double topping lift of port and starboard lines, running from the mast head towards the rear of the wishbone, similar to a pair of running back stays.

The green, starboard topping lift, and red, port topping lift, are each spliced to a shackle. A shorter length of line is spliced to the shackle and continues on to another splice on a shackle at the mid point of the rear of the wishbone. Those two fixed lengths combine to hold the wishbone safely above the cockpit. The lower fixed length lines each have an adjustable length line beside them, to use as a topping lift for raising the wishbone.

Either side of the topping lift may be used to raise the rear of the wishbone for hoisting the sail, or reefing the sail. After each of these procedures, the topping lift is released, with the leech of the sail supporting the wishbone.

In light air sailing conditions, the windward topping lift can be tensioned to ease leech tension enough to allow a desired amount of twist to the sail. When the windward topping lift is tensioned, this moves the wishbone towards the leeward side, providing slightly more room for the draft curve of the sail inside the wishbone in light air sailing.

When tacking in light air, the leeward topping lift is tensioned to match the position of the windward topping lift, the tack is initiated and the windward topping lift is released, to become the slack, leeward topping lift.

Each topping lift has a two part tackle of blocks at the rear side of the wishbone. The topping lift line then runs through hanger blocks along the side of the wishbone two a second two part tackle of blocks running from the wishbone to the deck and back to the cockpit.

The resultant four part tackle makes the level of effort for topping lift adjustment quite reasonable. This is shown in the choker line picture, below this one.

The two choker control lines start at a pad eye on each side of the mast, pass through blocks on either side of the center of the nose piece, and through blocks at the beginning pad eyes, then down through a single block in front of the mast.

The picture below shows the single block supporting a triple block below it. The choker line is slack, allowing the wishbone to relax to a fully forward of the mast position, drawing the triple block up as high as it ever gets. Pulling on either the port side or starboard side choker line draws that triple down the front of the mast closer to the double block between the two cheek blocks on the mast near the deck.

Having port and starboard choker lines, port and starboard topping lift lines, and a double ended main sheet, with port and starboard winches, makes single single handed sailing rather convenient.

Replacing the lifelines along each side of the cockpit with stainless steel tubing that matches the tubing of the pushpit, provides improved comfort and safety for those of us who race with our bodies perched on the cockpit combing for better visibility and heel angle trim.

Thursday, December 18, 2008

MarsKeel Stability Torpedo Bulb on Blueberry

Link to earlier blogs in blog order
Links to earlier blogs in chronological order:
Nonsuch 22 Brochure
Forward looking sonar on Blueberry
MarsKeel stability bulb torpedo on Blueberry
Wyliecat width of wishbone on Blueberry

For Blueberry, light air, flat water sailing is pure bliss. Sailing on San Francisco Bay can provide, on most summer days, conditions ranging from light air and flat water to near gale force winds with waves to match.

For most sail boats, including Blueberry, reaching downwind in heavy swells can be "interesting". Over the years, photographers have documented truly spectacular knock downs, round ups and other results of sudden changes in apparent wind. Such "interesting times" are more a matter of "when" than "if" for those of us interested in racing. To improve the recovery from "when", a Mark Ellis designed, MarsKeel built, 450 lb split bulb torpedo was bolted and faired into the bottom 4 inches of keel so as not to increase draft, but to add stability in case of knock down. Original keel lead was 1800 lb. Total keel lead is now 2250 lbs.

The pictures below document the installation process.

The split bulb, threaded rod, with nuts and washers to fit, arrived on a pallet. Each half bulb weighed 225 lbs. The piece of door skin veneer shown on the pallet was traced from one of the bulbs and used to transfer the positioning location of the torpedo and the bolt holes to the keel.

Bottom paint was ground off the keel to allow room for the keel and fairing epoxy. The door skin template tracing for the keel and the bolt hole positions is shown below. The template was applied to both sides of the keel.

The bolt holes were drilled from each side, to meet in the middle. Small pilot holes were drilled and adjusted to a single, corrected, pilot hole before the holes were very gradually enlarged to fit the threaded rod supplied by MarsKeel. Why so gradually? Drilling through a lead keel is marginal entertainment, with ample opportunities to snap off a suddenly stuck drill bit.

Wrestling each half bulb onto the keel bolts is truly an exercise in heavy lifting. The plank holding the split bulb was lifted, one end at a time, to the level of the template mark. The half keel bulb was then slid on to the keel bolts. Much easier said than done.

With the bulb half loosely in place, before the bolts are tightened, a layer of thickened epoxy is applied to the keel and the keel bulb half. The hole through the keel was lined with thickened epoxy to firmly grip the threaded rod when the epoxy hardened.

The bolt holes through the keel bulb halves were supplied already countersunk to the width of the flat washers and nuts for the threaded rod. The holes for the threaded rod were drilled slightly loose at the thin ends of the bulb to allow for the change in position as the bulb half was pulled into the shape of the keel.

The keel bolts were gradually tightened, a little on each bolt, to avoid bending the thin ends of the bulb halves. The keel bolts were then cut off flush with the keel bulbs.

The countersunk holes, with their threaded rods, washers and nuts were filled in and faired to the shape of the outer surface of the torpedo.

The joint between the keel and the bulb halves was filleted with thickened epoxy.

From the sides the bulb does not look all that massive. From the rear the maximum width make the bulb look more massive than it really is.

The same is true for the view from the front as well.

Since the two forward looking sonar transducers were mounted where one might normally find a pair of transducers, one for speed and one for depth, there was a design question of where to put the usual transducers.

The answer was to use an Airmar triducer, set off to the side of, and about 3 ft behind the keel, to provide NMEA signals for speed depth and temperature.

The bulb was faired with thickened epoxy filler, sanded, and given a rather thick coat of barrier epoxy over all.

As supplied, the bulb was beautifully smooth. Wrestling the halves into place rather marred that finish, hence the fairing compound on both halves.

Next came a layer of epoxy and filler over the halves and the keel section that had been sanded free of coating so the epoxy would stick to the lead of the keel.

More sanding and another barrier coat of epoxy as a preparatory surface for the bottom paint.

Finally the bottom paint over the lot. View from the starboard side.

View from port side.

View from the stern. Just before the travel lift took it away for launching.