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Tartan 34c 1968-1978 Centerboard Repair and Maintenance By ... · Tartan 34c 1968-1978 Centerboard...

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Your Heading Goes Here file:///C|/T34_tech_articles/t34cb/index.htm[8/24/2011 2:04:06 PM] Tartan 34c 1968-1978 Centerboard Repair and Maintenance By Dan Batchelor (clicking any thumbnail below will open the full- size image in a new window) Stainless Lever CB Cross-section CB Lifting Spool The following information was obtained from Joe Palmer, posts from T34c owners on Sailnet’s Tartan email list and my own personal experience. Overview The Tartan 34c is equipped with an easily operated centerboard control system giving positive control in both raising and lowering the board. The nature of the system allows precise control of the centerboard position, permitting you to take full advantage of the Tartan 34c fine sailing qualities on all points of sail and in all wind and sea conditions. Due to rating considerations at the time the T34c was designed, the board is of minimum weight, therefore a positive system is needed to make the board go down, as well as pull it up. The heart of the system is a 15" stainless steel lever rigidly attached to the centerboard at the pin through a stuffing box in the trunk. A well is cast into the starboard side of the lead keel that allows the lever to rotate freely. Any rotation of the lever thus results in a precisely equal rotation of the center-board. The lever itself is controlled by means of a continuous circuit of 1/8" stainless steel cable, which is lead to and winds around a drum located just behind the forward wall of the cockpit. A removable handle (which doubles as the roller reefing handle) turns the drum from the cockpit. Counterclockwise raises the board. Clockwise lowers it. A look at the accompanying diagram will reveal that, if the ends of the cable circuit were fixed, a greater cable length would be required at the half-up position (with the lever vertical) than in either the full-up or full-down position. Consequently, the forward end of the cable circuit is not fixed but is attached through a. turnbuckle to a stainless steel spring. The spring allows the system to accommodate itself to any position of the lever. When the turnbuckle is set properly, proper tension is maintained on the cable at all times. The centerboard cable turnbuckle is set at the factory during building, but due to the effects of use on the system, this setting should be checked occasionally. Excessive slack will be apparent in the full-up and full- down positions, and would result in imprecise control of the board setting. Excessive tension would be most obvious in the half-up position, and would result in difficult operation of the system and possible component failure. Therefore, the turnbuckle should be adjusted at the full-up position so that there is only a slight extension of the spring (1/4 " to ½"). Then tension should be checked manually at the half-up and full-down positions, and the system checked for smoothness of operation. Access to this part of the system is through the lift outs in the main cabin sole. It is important to insure that there is sufficient friction in the system to prevent the board from changing position on its own because of its weight or wave action. This is done by adjusting the pressure of the drum bracket on the drum by means of the two nuts on the lower bolt on the bracket (see diagram). Backing off on the after nut and tightening the forward nut will increase the pressure on the drum end consequently the friction on it. At the proper setting, the drum can be turned easily by the handle but will, not move at any other time. This setting is done at the factory, but should be checked when the owner receives the boat and occasionally thereafter. Access to the drum and drum-bracket is gained though the hinged door just aft of the top of the companionway ladder. As a safety measure, an additional separate length of cable with shackles at both ends has been provided. Whenever the boat is hauled, this cable should be shackled to the pad-eye at the forward end of the spring and to the shackle already present at the forward end of the centerboard lever. This will insure that the board is securely locked in the up position. The vertical actuating arm visible in the bilge is connected to a horizontal axle. The connection of the arm to the horizontal axle has changed during the course of production of the T34c. Early boats had an arm with a square hole in it, and the end of the axle was square. Later boats had an arm with a round keyed hole, and a round axle with a keyway milled in. On all models, a set-screw is incorporated to hold the arm from sliding off the axle.
Transcript
Page 1: Tartan 34c 1968-1978 Centerboard Repair and Maintenance By ... · Tartan 34c 1968-1978 Centerboard Repair and Maintenance ... bracket on the drum by means of the two nuts on the lower

Your Heading Goes Here

file:///C|/T34_tech_articles/t34cb/index.htm[8/24/2011 2:04:06 PM]

Tartan 34c 1968-1978 Centerboard Repairand Maintenance By Dan Batchelor

(clicking any thumbnailbelow will open the full-

size image in a newwindow)

Stainless Lever

CB Cross-section

CB Lifting Spool

The following information was obtained from Joe Palmer, posts from T34c owners on Sailnet’s Tartan emaillist and my own personal experience.

OverviewThe Tartan 34c is equipped with an easily operated centerboard control system giving positive control inboth raising and lowering the board. The nature of the system allows precise control of the centerboardposition, permitting you to take full advantage of the Tartan 34c fine sailing qualities on all points of sail andin all wind and sea conditions.

Due to rating considerations at the time the T34c was designed, the board is of minimum weight, therefore apositive system is needed to make the board go down, as well as pull it up.

The heart of the system is a 15" stainless steel lever rigidly attached to the centerboard at the pin through astuffing box in the trunk. A well is cast into the starboard side of the lead keel that allows the lever to rotatefreely. Any rotation of the lever thus results in a precisely equal rotation of the center-board. The lever itselfis controlled by means of a continuous circuit of 1/8" stainless steel cable, which is lead to and winds arounda drum located just behind the forward wall of the cockpit. A removable handle (which doubles as the rollerreefing handle) turns the drum from the cockpit. Counterclockwise raises the board. Clockwise lowers it.

A look at the accompanying diagram will reveal that, if the ends of the cable circuit were fixed, a greatercable length would be required at the half-up position (with the lever vertical) than in either the full-up orfull-down position. Consequently, the forward end of the cable circuit is not fixed but is attached through a.turnbuckle to a stainless steel spring. The spring allows the system to accommodate itself to any position ofthe lever. When the turnbuckle is set properly, proper tension is maintained on the cable at all times.

The centerboard cable turnbuckle is set at the factory during building, but due to the effects of use on thesystem, this setting should be checked occasionally. Excessive slack will be apparent in the full-up and full-down positions, and would result in imprecise control of the board setting. Excessive tension would be mostobvious in the half-up position, and would result in difficult operation of the system and possible componentfailure. Therefore, the turnbuckle should be adjusted at the full-up position so that there is only a slightextension of the spring (1/4 " to ½"). Then tension should be checked manually at the half-up and full-downpositions, and the system checked for smoothness of operation. Access to this part of the system is throughthe lift outs in the main cabin sole.

It is important to insure that there is sufficient friction in the system to prevent the board from changingposition on its own because of its weight or wave action. This is done by adjusting the pressure of the drumbracket on the drum by means of the two nuts on the lower bolt on the bracket (see diagram). Backing off onthe after nut and tightening the forward nut will increase the pressure on the drum end consequently thefriction on it. At the proper setting, the drum can be turned easily by the handle but will, not move at anyother time. This setting is done at the factory, but should be checked when the owner receives the boat andoccasionally thereafter. Access to the drum and drum-bracket is gained though the hinged door just aft of thetop of the companionway ladder.

As a safety measure, an additional separate length of cable with shackles at both ends has been provided.Whenever the boat is hauled, this cable should be shackled to the pad-eye at the forward end of the springand to the shackle already present at the forward end of the centerboard lever. This will insure that the boardis securely locked in the up position.

The vertical actuating arm visible in the bilge is connected to a horizontal axle. The connection of the arm tothe horizontal axle has changed during the course of production of the T34c. Early boats had an arm with asquare hole in it, and the end of the axle was square. Later boats had an arm with a round keyed hole, and around axle with a keyway milled in. On all models, a set-screw is incorporated to hold the arm from slidingoff the axle.

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CB AssemblyDiagram

CB Assembly

Centerboard

CB Assembly,Disassembled

The horizontal axle passes through a stuffing box and through the centerboard trunk to a bushing on the portside of the centerboard trunk. Where the axle passes through the centerboard, the axle is square, and there is asquare hole in a piece of brass embedded in the board. In time, a few thousandths of an inch of wear willhappen to the square hole in the piece of brass embedded in the centerboard. Because the sides of the squareare only about an inch on a side, the small amount of wear will let the aft end of the centerboard many feetaft, drop lower than the bottom of the keel, even when the board is hauled up all the way (with the verticalarm all the way forward). There are two remedies for this condition:

1. Remove the board and bush the square hole in the board to be a tight fit on the axle again.

2. Remove only the vertical arm and cut it and re-weld it with a dogleg so the axle turns further before thearm hits the forward end of this travel. The disadvantage of this fix is that the board will not go down all theway.

Unless operating in very shallow water, most owners ignore the drooping aft end of the centerboard.

NoteYour T34c centerboard should not move up or down unless cranked with the proper setup. If your stainlesssteel lever arm with cables attached (located in the bilge) is all the way forward, then your centerboardshould be in the up position. If the centerboard hangs...then you have the dreaded droop. If this is the casethen the centerboard shaft pin is worn, or the hole in the centerboard itself is worn at the axis point. I justcompleted full removal and rebuild of the centerboard shaft pin this spring. My cb also drooped. The cbshaft has a square section that fits into a square hole in the cb. Sometimes this hole get enlarged.....andsometimes the hole is ok, but the shaft pin is worn.Dan BatchelorT34c "Chance"

NoteMy 1972 T34C board has always been tight (no droop) with no apparent wear - i.e. no sag with the arm inthe forward position. This year after a downwind surf to the cape in May (35-45 NE winds), I noticedbanging as the boat would roll side-to-side from the CB hitting the trunk (and with the board all the wayup). I had never had this before. My initial conclusion: I WAS FINALLY SAGGING like the rest of theCLAN.. Upon investigation, however I found the CB pin had slid to starboard about 1/2-3/4 inch (noticedthe polished metal on the pin which had previously been inside the packing gland). There is a small SS boltwhich threads into the end of the pin to keep it from sliding awthwartships. My bolt was still there but wasnow hard up against the access plate on the starboard side of the keel which it had never been before. Additionally the bolt which hold the SS arm onto CB pin was loose.

I took a long crow bar and with some wood in the bilge as a brace/bearing fulcrum, and tried to push the pinback into the board. It wouldn’t move until I grabbed the CB SS arm and moved it up and down a bit whilepushing the end of the pin with the crowbar. A miracle, it slid back in. I now had slack in the arm (it wasn’tfully forward now with the pin pushed in) I installed a longer screw and put a small plastic wedge to take upthe rest of the gap between the screw head and the inside of the plate and hoped for the best. The boardstopped banging and when the water warmed up a tad, I went for a swim and found I again had NO sag inthe board.

Therefore, before you conclude you have a CB rebuild this winter (which you may need), take an inspectiontour and see if my problem , might have happened to you. I ultimately concluded that after launch this springI had never checked the board position and it must have been in the slightly down.

Our sail to the Cape was one you read about with 6 - 10 ft following seas and a lot of rounding up andgenerally rock-em sock-em rolling. With the board partially down, and the rough conditions, it was enoughto work CB and hence the pin through the packing gland until the screw hit the plate and stopped any furthermotion. From talking with the guys on the list the pin really doesn’t engage the hole in the board by verymuch. I figured that it was barely engaged and near completely out of the hole in the board. When I movedthe CB arm in the bilge and pushed with the crow bar, I luckily got the alignment just right again, loweredthe friction enough so that I was able to fully "reengage" the pin into the hole in the board and viola NODREADED DROOP. Laird BrusterWindfallT34C #246

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CB Access

Removing the Centerboard

This can be done with the boat supported by normal jack stands and a center support under the keel, justforward of the centerboard slot. Dig a trench under the centerboard. Dig it deep enough so the centerboardwill drop out horizontally. Depth of trench should be approximately 18 inches. Disconnect the cables fromthe vertical arm. There is an inspection plate in the hull, starboard side of the keel area. The inspection plateis glassed over with one layer of mat to help insure watertight integrity. If you cannot find the plate visually,the metal in it will cause a different temperature to be felt in the area of the plate. You can hit the area with aCO2 fire extinguisher, and the frost pattern will tell you where the plate is. Another approach is to place astraightedge up inside the keel until it strikes the horizontal axle and then measure the distance to the base ofthe keel (aprox. 8 inches). Move the ruler and measure up on outside of the keel and mark the location soyou can sand away the fiberglass until you locate the plate. The middle round section will unscrew. It hastwo holes in it that are filled with a non-hardening putty. Remove this putty so the holes can be used to helpturn the plate. Unscrew the round, middle portion of the inspection plate or remove the entire plate (it'sbolted on).

Once open, there will be a ¼-20 hex head machine screw visible on the end of the axle. Back out thisfastening, and then the vertical arm can be slid off the end of the axle after the set screw is loosened. Onsome models the arm is attached to the horizontal axle with a machine screw.

Removing the ShaftIt is often easiest to thread a long ¼-20 bolt, or piece of threaded rod into the tapped hole in the end of theaxle in order to pull the axle out. (HINT Slide a piece of ½ x 8“ pipe on the threaded rod. Place a largewasher and a nut on the end of the threaded rod. Sliding the pipe and hitting the nutted washer will act as a“slap hammer” making it easier to remove the axle.) If possible, support the centerboard before pul1ing theaxle.

Remove packing nut and replace packing. 3/16 or ¼ inch packing.

Replacing the CenterboardOne trick in getting the board back in is to draw a cross on the starboard side of the board with chalk,crossing at the axle hole, so that the direction to the hole can be seen while your assistant wrestles with theboard. This can also be done by one person ... place a line through the centerboard hole and pull it throughthe axle hole in the keel (starboard side) to move board into position. Hold it in position propped up onbricks or wood and position it with a dowel or long screwdriver. Put a little waterproof grease on the end ofthe axle. This end fits into a bushing and a little lube won’t hurt.

WARNING: Possible ProblemIf the bolt in the starboard end of the axle is not properly installed with the locking nut on it, the bolt mayback out, allowing the axle to move to starboard enough so the square in the axle disengages from the squarein the board. If this should happen, pass a line under the boat, and haul up on both ends to partially raise theboard.

Use a crowbar, or in an emergency, a winch handle, to apply pressure to the end of the axle visible just tostarboard of the vertical arm, down in the hole in the bilge. Wiggle the arm while supplying the leverage, andif you hold your mouth just right, you will be able to get the square on the axle to line up with the square inthe board. (Good luck with this I don't understand how anyone could do this either in or out of the water.)Once the assembly is all back together, you may wish to epoxy a piece of fiberglass or strong wood to theinside of the hull opposite the centerboard axle to prevent athwartship movement of the axle.

This information might not fit your boat's specs exactly

Lifting Drum InformationOn the T34, you raise the centerboard by inserting a crank into a mechanism located on the vertical part ofthe bridgedeck and turn until your arm hurts. This moves some cables which raise and lower the centerboard.The crank arm fits over a solid steel rod with two "pins" or "ears" which protrude at right angles to the axisof the rod at the center of this mechanism to which the crank attaches. The crank grabs onto those "pins" butours have disintegrated so there is nothing for the crank to grab onto. If you have the furling boom

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mechanism, this is almost the same piece that's used to furl the boom.Stanley A. Winikoff

Removal and repair of centerboard lifting drumYou probably taint going to store -buy a replacement. When my pin sheared off many years ago I had afriend with a machine shop drive our the old and install a new pin. It is just a press fit To do this you willneed to remove the wire drum. Standing at the ladder looking aft the CB drum/wire is attached to its mountwith four bolts. The bolts hold an aft plate which also acts as a CB tensioning device and it therefore hasdouble nuts on each bolt. To remove the drum, disconnect the wire thimbles from the CB arm. Pull bothends of the wire back thru the bilge (noting how they are run), remove the nuts on the aft plate and pull thedrum forward. Remember how the both ends of the wire flaked off the drum (Forward run (the wire thatpulls the board up) is longer than the other end.

By the way, while you have the hole mess apart, now is a good to inspect the wire and think about replacing. My Cb cable has parted twice since I bought the T34C in 1983. The first time was right after I purchased(10 years from its original launch by the PO) and the second about ten years later. I treat the board and cablewith a lot of care and seems like about a ten year life is all I get. Laird BrusterWindfallT34C #246

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