(Please ignore date on posting as that date was necessary to have this post appear where I wanted it.) This post was actually started on Jan. 6/2011. One of my objectives in installing new guides would be to install guides made of material that could stand up to being immersed in water. I considered the installation of wooden guides to be a major design flaw of MATILDAS in that even the best wood available e.g white oak could not be expected to last even 30 years when the hull has the potential to survive for 100 ?? years if properly maintained.
Another objective was to eliminate the tenon and mortise joint in the upper corners as one has to have room to slip the tenon into the mortise and that is impossible without the guide projecting out the bottom of the centerboard trunk.
Another goal was to eliminate the original wooden cross support that had been split and repaired by a previous owner.
This the basic concept of new approach.
A steel plate bolted from mast step.
Welded section containing pulleys.
Front and rear guides made from ULTRA HIGH DENSITY POLYETHYLENE or by another name ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE because of the outstanding attributes of this material. U.H.D.P.E. has extremely low moisture absorption, has a very low coefficient of friction, is self-lubricating, and is highly resistant to abrasion (15 times more resistant to abrasion than carbon steel).
Sketch of top plate made from 1/2" steel plate. Cutouts are to allow clearance for pulleys.Mast step bolts will thread into this plate which will eliminate problem of holding mast step locking nuts while bolts tightened. Mast step bolt holes are approximate on this sketch.
Details of front guide made from UHDPE.
Basically a duplication of original front guide except for top corner.
Length of guide will have to be adjusted to fit in cavity.
Rear guide made from UHDPE.
Notice wide area of guide walls to assist in supporting centerboard below limit bolt.
Original rear guide did not offer any side support to centerboard below limit bolt cut out, as a consequence, the slot that the daggerboard extends from was originally 3/4" wide, the front of the slot is 3/4" but the rear of the slot is worn to almost 1" wide. Hopefully the extra material added to the guides will keep the rear of the daggerboard better contained.
When centerboard was fully extended, there was only 6 " still in the rear guide groove even tho there was still 12" of centerboard inside centerboard trunk. There was no side support for rear of centerboard below limit bolt. Length of guide will have to be adjusted to fit cavity.
Support plate
Basically two pieces of angle iron, 20" in length welded together to form a 1 1/4" by 2 1/4" box and tabs added for bolting to guide
3/8" X16 stainless nuts were welded to the back to anchor pulley axle bolts securely.
The new guides made up to the specifications detailed earlier.
The guides were obtained from C.B.S. Equipment, Stratford, Ontario at a cost of $640.71 completely made to my specifications.
Delivery was received 2 weeks after they were ordered.
If these guides were made in any significant quantity , the price should be improved.
They certainly did an excellent job of making up the guides.
The top plate support painted and ready to install
The pulley support assembly
painted and ready to install.
Now the challenge is how to install guides in centerboard trunk ?????
#1 Cut hole in top of trunk under the mast step plate and use cut out section to glass back in under the mast step plate?????? (The mast step plate should hide any imperfections in glassing).
#2 Cut hole in bottom of slot in bottom of daggerboard trunk?? (Not a great idea as the upper half of the guides have a width of 1 3/4" and the lower half of the trunk is only 1 1/2" in width plus the slot at the bottom of the trunk is only 3/4" wide).
#3 Remove side of lower centerboard trunk to allow access to bottom of trunk for repairing hole punched by centerboard in front of trunk???????? (Not a great idea as most fibreglassing repairs never turn out as well as the original factory finish + should be able to patch the hole if a suitable method can be found to properly support a piece of U.H.D.P.E. , which resin will not adhere to, inside the trunk)
#4 Install guides by inserting guides in centerboard trunk from inside the cabin. (So far looks promising as the U.H.D.P.E. can be flexed a bit).
2 comments:
I wish I knew you were cutting these Lorne I would have gone in and ordered a pair. Might have reduced the costs some. Tom
Amazing Post, Thanks
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