PROBLEMS

 


MATILDA centerboards, as the boats become older, are becoming a problem for MATILDA owners.
The problem is not so much the centerboard itself but the centerboard guides, although a rusty, pitted centerboard adds greatly to the problem of wear on the guide.

Basically, there are two types of problems with the guides. Even though the guides were made from high quality wood, white oak, they are subject to


#1. DRY ROT from being in a moist, poorly ventilated environment.


#2. WEAR from being subjected to guiding the centerboard as it is raised and lowered.

The centerboards can be broken down into 2 types.










#1. The "EARLY" centerboards, which have a bulb with material ahead and behind where the bulb is attached to the centerboard. Steel was used to cast these bulbs.








#2.





The later centerboards, "TAIL HEAVY", as they only have material in the bulb behind where the bulb is attached to the centerboard. Lead was used to cast these bulbs. Centerboard type 2 are much more susceptible to problem #2.







UNITED KINGDOM MATILDA WITH FULL LENGTH KEEL

This is an interesting photo of a U.K. MATIDA with a full length keel.











Sunday, October 01, 2006 1:37 PM

Afternoon Onde,

Thank you for your favourable comment on our BLOG,http://pamsmatilda.blogspot.com/

Glad to hear that it is of value.You have raised some excellent questions regarding the "ACHILLES HEEL" of MATILDAS with "TAIL HEAVY" centerboards. I am sure that many a MATILDA has been rendered UNSAILABLE [consequentially unsaleable to the informed buyer] because of this condition.

Repairing a MATILDA with rotted centerboard guides is a major undertaking but if the guides are only worn, a revised pulley system may prevent the problem from progressing further.In order to determine the best course of action, you have to evaluate the condition of the wooden guides. Certainly removing or lowering the centerboard would make this inspection easier.

#1 If you have found a bit of rotted wood on your centerboard guides, you can rest assured that dry rot has set in and it is only a matter of time until the entire wooden structure deteriorates completely [in spite of the high quality original material -oak- being used]. In this case, the wooden guides must be replaced completely.

OR

#2 You may find that the wooden frame in the area of the limit bolt has had the wood fibres crushed as a result of impact, etc. Replacing the bolt, with proper washers, may solve the problem.This might be an opportune time to check the wear on the lower front corner of the guides. If wear is evident then you might consider changing the pulley system to minimize wear on the lower corner,. See our blog. Specific answers to your questions will follow in another posting.Hope this information is of value to you.

Cheers

Lorne

--~--~---------~--~----~------------~-------~--~----~This message is part of the topic "Oak keel guides" in the Google Group "Matilda Sailboats"for which you requested email updates.To stop receiving email updates for this topic, please visit the topic at http://groups.google.com/group/Matildasail/t/ec552571cd84095d-~----------~----~----~----~------~----~------~--~---




"TAIL HEAVY" centerboards are much more suseptible to wearing of the front guide because of the extreme pressure exerted against the lower corner of the front guide as 160 lbs pressure is always pressing against the guide, even when the centerboard is winched up to the top of its trunk. This causes the lower corner to deteriorate even when the boat is sitting at its dock, if the boat is rocking, from wave action. From observing wear on actual guides, the worn portion extends from the top to the bottom with the greatest wear at the lower end of the groove.



As a result of this deterioration, the board is prone to jam in the trunk when the front guide is worn sufficiently that the pivot bolt is bypassed by the portion of the board that is designed to rest on the pivot bolt. The only thing holding the board from sliding to the bottom of the trunk is that the winch cable has reached the end of its travel. As a result of the board jamming against the bolt, the bolt bends more and more.











DIAGNOSING FRONT GUIDE WEAR

How much clearance should there be, when the centerboard is fully raised in it's trunk 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.




FROM BROOKS NORTHERN

One other thought. The "keel guides" also support the mast. One photo in the previously referenced link shows a gap between the top of the keel/mast support and the top of the cabin. If you have such a gap,your keel guides/mast support should be replaced.--~--~---------~--~----~------------~-------~--~----~This message is part of the topic "Oak keel guides" in the Google Group "Matilda Sailboats"for which you requested email updates.To stop receiving email updates for this topic, please visit the topic at http://groups.google.com/group/Matildasail/t/ec552571cd84095d-~----------~----~----~----~------~----~------~--~---

The separation of the centerboard trunk from the cabin top may have two factors contributing to the problem.

#1 The weight of the centerboard, on the cross piece (pulling the cross piece down against the rotten front upright which is no longer supported by the lower part of the trunk).

#2 When sailing to windward, in a fresh breeze, the increased tension on the upper shrouds increases the compression load on the mast which forces the cabin top down against the front support. When you are no longer hard on the wind and tension on the mast and shrouds is reduced, the cabin top will spring back to its normal profile, causing the gap to appear. This undue flexing of the cabin top causes the inner and outer layers to separate (delaminate?) creating spongy areas in the cabin roof and deck.




When your centerboard guide starts looking like this, you know it is time to replace your guides!!!!
A note of caution regarding the worn out portion of the guide. If the groove is worn so badly that all the wood at the bottom of the groove is missing or deteriorated, as indicated in the photo, the only thing separating you from a major disaster (read a hole in your craft) is a 1/4" of fibreglass around the front of the guide.
A slight grounding or hitting an object with the bottom of you centerboard bulb will force the top front corner of the centerboard right thru that thin 1/4" layer of fibreglass without any great effort, resulting in a major leak. The time to remedy the problem is before it happens rather than wait for when it does happen.

The challenge is to do something about this problem before your guides deteriorate to this state