CENTERBOARD ASSEMBLY TEST

Centerboards are probably the most neglected component of MATILDA sailboats[out of sight-out of mind]. Neglect your centerboard at your OWN PERIL.

Objectives - Centerboard Assembly Test #1

#1 Epoxy paint durability-the original centerboard was badly rusted and had numerous DEEP depressions from rust? and had been touched up with TREMCLAD [no anti-fouling paint had been applied]. Leading edge of centerboard was very rough [acting like a saw blade on front wooden centerboard guide every time centerboard was raised or lowered] - especially with over half of the centerboard's weight of 300lbs. resting against the front wooden centerboard guide.
There is not any coating that can withstand this much pressure for any length of time.

#2 Reduce wear on front lower centerboard guide- the existing pulley system used the mid- point of the centerboard as the fulcrum for raising and lowering the centerboard and bulb [this was a good system for the early MATILDAS that had a bulb with material in front of and behind the centerboard, but is certainly not suitable for LATER MATILDAS [SEE INSTALLING CENTERBOARD] which have material only beyond the rear of the centerboard, which causes the newer style centerboards to be very tail heavy] Being TAIL HEAVY causes EXTREME pressure on front centerboard guide[ in fact, in excess of 160lbs. is required to pull centerboard back from front centerboard guide] If allowed to remain in that state the front guide would have to be replaced shortly.

#3 Durability of revised centerboard lift wires -would changing from a 4 to 1 ratio to a 3 to 1 ratio raising system over stress the existing wire and pulleys?

#4 Increased lift requirements of raising centerboard- would changing from a 4 to 1 raising system to a 3 to 1 raising system cause the winch operator difficulty?

#5 Revisions to winch- the hazards of a winch RUNAWAY have been discussed in great detail in previous MATILDA WEBSITE FORUMS and the general conclusion is that the current winch is the least expensive solution as well as the best use of the existing winch - EDUCATION is the answer rather than replacing existing winch. But for complete peace of mind, install a BRAKE winch and you will never have to worry about WINCH RUNAWAYS again.



Details -Centerboard Assembly Test #1
A. Becket for wire rope [2 stainless steel straps 1/8 " X 1 ½"] pivoting on pulley axle ½" diameter [3/8" thru bolt]
B. One of the two original centerboard straps [note bolt above B thru bolted under pulley to prevent wire from jumping off pulley]
C. Safety strop [1/8" 7x19 stainless wire-1700lbs breaking strength ]-clevis pin safety wired. Limits centerboard movement to 1" below stop bolt position
D. Bridge made by a previous owner to overcome problem of center pulley splitting top support wooden frame
E. Centerboard which has been sandblasted and painted [2 coats epoxy primer + 2 coats FOREST GREEN AWLGRIP paint]



Installing MATILDA centerboard after
#1 Sandblasting centerboard and bulb
#2 Fairing board with INTERLUX watertite epoxy filler
#3 Priming with epoxy primer [AWLGRIP] 2 coats
#4 Painting [2 coats] with AWLGRIP FOREST GREEN
Weight of centerboard and bulb = 297 lbs.







RESULTS

#1. The epoxy paint has surpassed all expectations. The centerboard, after a wash with MURIATIC ACID [to remove the mineral deposits that adhere to all underwater surfaces at WILDWOOD LAKE], has stood up well after 2 seasons and looks almost as good as the day it was painted.

#2. Revising the centerboard pulley system has worked well to reduce the wear on the front centerboard guide lower corner. The epoxy paint on the leading edge of the centerboard is still in good shape and the lower portion of the centerboard front guide has not deteriorated any further. A good test to determine how freely the centerboard is suspended in the centerboard trunk, is that, if the centerboard is lowered 2 ratchet teeth on the winch from full up [when the boat is on it's trailer], the centerboard can be moved quite easily, fore and aft, in it's cavity, where as before, it was almost impossible to pull the centerboard back from the front guide. THIS IS DEFINITELY A MODIFICATION THAT ALL MATILDAS WITH A TAIL HEAVY CENTERBOARD SHOULD CONTEMPLATE. Another observation that should be made, is that some MATILDAS experience a STUCK centerboard[ centerboard can not be raised]. This condition[ only with TAIL HEAVY centerboards] is likely caused by a centerboard being jammed in the cavity because the aft top corner is digging into the rear centerboard guide because of the tail heavy centerboard. The only way to remedy this problem is to lower the centerboard slightly and somehow apply forward pressure to the wires on the aft pulley in an effort to prevent the top corner of the centerboard from digging in to the rear guide and SERIOUSLY CONSIDER CHANGING THE PULLEY SYSTEM.

#3&4. The centerboard goes up and down much more smoothly and freely [because pressure is not being exerted on the top rear corner and lower front corner] than with the previous setup which has actually made it easier for the winch operator to raise the centerboard. It has also reduced stress on the wires and pulleys, because the centerboard no longer is dragging on the top rear corner and lower front corner.

#5. The jury is still out on the winch question. People who have switched to the BRAKE winch love their conversion and are confident that NO ONE will ever experience a WINCH RUNAWAY on their MATILDA.

Another observation that should be made is , how much clearance should there be , when the centerboard is fulled raised in it's slot and the boat is on it's trailer. If wear has not occurred , there will be approximately 3/4 " clearance [ allowance for the safety bolt cutout] at the rear of the centerboard and almost ZERO clearance at the front between the centerboard and the edge of the cavity. If the clearance at the front is larger than 1/4", you will know that the lower front corner of the centerboard slot is being eroded and future problems will arise.

AN INTERESTING OBSERVATION

During the winter of 03/04, when we removed the centerboard of our WALTZING MATILDA, for fairing with INTERLUX WATERTITE and painting with AWLGRIP two part paint, we made an interesting discovery that could have far reaching ramifications for MATILDA sailboat owners who have what is referred to as a "TAIL HEAVY CENTERBOARD.
In the process of moving the centerboard around with our forklift, we attached a chain to lift the centerboard as we didn’t want to drag the centerboard and scratch the paint. If the chain was attached to the center hole at the top of the centerboard, it would assume the position shown at the left side of the picture. If the chain was attached to the left hole at the top of the centerboard, the result is shown on the right side of the photo.
As you can see, the bulb is not parallel to the ground on the left view, which it should be when installed in the boat. A force of 160 lbs [applied to the centerboard, just above the bulb] was required to move the centerboard to a position where it was level with the ground. This meant that whatever the centerboard was resting against, the centerboard was exerting 160 lbs pressure against whatever was restraining it from finding its natural resting position. When the centerboard is installed in its trunk in the MATILDA, it is the lower edge of the front centerboard guide that is restraining it.
So, when the centerboard is raised and lowered, the lower end of the front centerboard guide has a force of 160 lbs exerted against it. Now imagine if that force has a rough surface [caused by rust, etc.] what effect it will have on that lower edge.
That’s right, it would rapidly wear , as if you were running a saw blade or rough file, against the lower edge of the centerboard guide every time you raised and lowered the centerboard. Even a smooth painted surface, running up and down, under such pressure would not last long.
This action is reflected in the ever widening gap [when the centerboard is raised completely] between the centerboard leading edge and the front of the slot in the MATILDA trunk. As well, another indication of excessive wear on the front centerboard guide is when you find that the centerboard limit bolt is no longer effective [the winch reaches the end of the wire before stopping] because the centerboard is tilted so much that the notch for the bolt does not catch the bolt. Another factor to consider is what effect the position of the centerboard [being further forward in the slot] would have on the balance of the boat [excessive weather helm?].

So what are the options?

A. Ignore this condition until the centerboard saws thru the oak guide. The centerboard will then proceed to saw thru the fibreglass in front of the guide and eventually the lower front corner of the centerboard trunk. You will probably notice the water flowing in through the hole you have made in the bottom of your boat.

B. Replace the worn portion of the wooden guide with a plastic filler piece. This has been attempted and is successful for a period of time until the plastic [U.H.D.P.E.-Ultra High Density Poly Ethylene] is chewed up as well and the centerboard spits it out the bottom of the trunk.

C. Replace the worn wooden guides with new wood. This will solve the situation of the worn guides but is expensive and very time consuming [approx $100.00 for material and 20-30 hours of work once you have removed the centerboard, a major job in itself]. This will solve the symptoms of the problem but the problem will rear its ugly head in the future as you have not eliminated the problem.

D. Try the solution outlined in our BLOG of having only one hanger on the centerboard positioned in the rear holes on the centerboard. We have utilized this solution for two years now and have not experienced any problems. In fact, our centerboard is probably easier to raise than the original set up as the centerboard is not being dragged against
the lower corner of the front centerboard guide as configured originally.

P.S.
This photo illustrates the evolution of how we arrived at the left side of COMPARISON photo shown previously.





For additional information on MATILDA centerboards
see
http://matildacenterboard.blogspot.com/






KNOCKDOWN PIN

May 10,2006
Morning Keith, ABSOLUTELY concur with your observation that MATILDAS have a reputation for great stability and deservedly so. However, the fact remains that even the most stable keel boat can get knocked down but they survive. It is my firm belief, that if John Wright's Matilda [ TARDIS II ] had a knockdown pin installed, he would still be sailing his MATILDA today. His boat's fate was sealed when the centerboard slid back into its trunk when the craft was knocked down. In my opinion, the installation of a $4.00 pin is a small price to pay to guard against such a "CATASTROPHIC" event occurring.
CHEERS
LORNE
This message is part of the topic "sticking keel" in the Google Group "Matilda Sailboats"
Please visit the topic at http://groups.google.com/group/Matildasail/t/dcf063bb558313f0