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Thread: Tom Cat

  1. #31
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    Default

    If I was in a cheeky mood I would say - that's exactly why I design boats that don't need any of those bits.

    So it is lucky I ain't in such a mood.

    MIK

    C'mon Daddles - you know you just do it for fun!!!

    Haven't you worked out that it is all the pointless things that make life worthwhile. If it's got a good solid reason behind it ... I just don't want to know.

    Its the people that have good solid reasons for doing things that should be first up against the wall when the revolution comes.

    MIK (again)

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  3. #32
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    Quote Originally Posted by Boatmik View Post
    If I was in a cheeky mood I would say - that's exactly why I design boats that don't need any of those bits.

    So it is lucky I ain't in such a mood.
    No need mate, I was thinking of you as I wrote that.

    Flat panels are a very efficient way of using resources. Once you start to move away from the Bolger Box or the Storer Stacker, the first price you will pay will be in material and the second will be in effort.

    Is that a criticism of Bolger and Storer?

    Not on your nelly. Both men understand that if it doesn't work and if the plans don't work, the effort is crap and the result will be crap and both men are masters at making efficient boats, efficient in raw materials, efficient in effort and efficient in performance.

    So does that reduce the more curvy designs to mere aesthetic efforts?

    Nope. Designed well, all the various methods have their virtues and it's a matter of balancing the various inputs.

    Thank goodness some designers understand this and ensure that their plans work at every level. This is why you will find me critical of slipshod designers who's plans do not.

    Richard

  4. #33
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    Default Transom Glue Up

    This was a fairly major exercise and because of that I completed the glue up in two hits. One to glue the two pieces of ply together (fairly simple) and one to glue the NG Rosewood planks on (not so simple).

    I had previously prepared the Rosewood planks by utilising a straight bit router to match the edges. The technique consists of using the router with a square base to run along a straight edge taking off approx 2-3mm from the edge of a plank and then without moving the straight edge bring the next plank close enough to the previously finished edge to take a couple of mm off it. Worked a treat. Keeping the 6mm planks flat without bowing whilst running the router along the edge was the only issue I had but once that was sorted it produced a great result.

    However, gluing the planks had its own problems…….as ever the slippery planks did not want to play ball and I had no pipe clamps or equivalents so I don’t think I achieved an invisible glue line. My saving grace is in the fact that I have chosen a timber grain and colour that almost negates any need to be over critical because of the differences in the planks anyway. That’s my ‘get out of jail free’ excuse anyway! The glue lines you see in the pics are actually the result of oozing of the epoxy under pressure and I certainly don’t expect to see that after sanding. If I could do it again I would use a lot more colour in the epoxy to darken it.

    Transom Glue Up 1.JPG Transom Glue Up 2.JPG Transom Glue Up 3.JPG Transom Glue Up 4.JPG

    Some comments about the stuff that doesn’t hit the water. The object of the exercise for me is the shed stuff first followed by the sailing stuff last. The making of the moulds, jigs etc is half the fun!! If I was in business to make money or get on the water fast there may be a case for simple building but as I said the more complex, the more fun and besides a round bottom on a boat is much more aesthetic than a slab sided craft no matter how good a design (for me anyway). I did a small plywood dinghy and the Stornaway 18 and am very pleased with the results so for me ”I’ve been there, done that!”

  5. #34
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    Default Making Bits

    I have been steadily working along since my last post but I have been away with work. However, I had been able to cut out the rudder, rudder base plate and centreboard from a 12mm ply sheet before leaving. The plans call for the rudder and centreboard to be 25mm so I had a glue job to do before taking off for work. The time away provided an opportunity for the glue to fully harden for my return.

    Considering I was using Pacific Maple ply I precoated one side prior to taking to the sheet with a power saw and jigsaw. It has been 5 years since doing this type of work and completely forgot to set the saw to a low cut so that it would not tear the ply to bits. Luckily I had left plenty of offcut so no damage done. The epoxy coating also minimised major tear outs.

    I had previously made templates of the bits from the lofting on 3mm MDF and so after cutting out the rudder, etc I gave the reverse side of each piece a coat of epoxy, let it go off, sanded and glued the matching pieces together. So with the “bits” all glued up its now time for cleanup and profiling the sections. I’ll have to complete some research on the best method for the chord profiles. Maybe that's overkill but its fun to research.

    I have also sanded back the transom and am quite pleased with the result. Another couple of coats of Non Yellowing epoxy before I can put it aside ready for the backbone construction.

    First two pics are of the transom...sanded and first coat of NY epoxy on.

    DSC01163 (Small).JPG DSC01164 (Small).JPG

    Pic 4 are my "bits"... barn door Rudder and Centreboard.
    Pic 5 is the Rudder base plate.
    Pic 6 is the Rudder being glued.
    Pic 7 is the glued up Centreboard and the Rudder on the trestles.

    DSC01169 (Small).JPG DSC01170 (Small).JPG

    DSC01174 (Small).JPG DSC01171 (Small).JPG

  6. #35
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    Default Components

    There has been plenty of activity with nothing much to show for my efforts. Been routing and profiling the rudder and centreboard and have reached a point where the effort appears to be not giving any positive return so have ceased this and will await the purchase of some 200gsm glass before proceeding any further. I'm thinking it a good idea to give each a layer on each side ro provide further stiffness and strength. The areas are quite large and the glass will make me feel more comfortable going forward. However, I will need to figure the total glass requirement for the boat as I don't think it practical to buy a couple of metres when I may be able to get a better deal if I buy in bulk. You never know your luck!

    So......I have moved on and cutout the rudder cheek pieces after deciding on the type of tiller attachment to use. The design provides for a number of different choices and I have chosen the full rudder design with plywood cheek pieces that will hold the tiller in place.

    This choice was made after going back to the lofting to work out the tiller placement etc. The tiller is quite long and protrudes thru a cutout in the transom into the interior of the boat. The plans show a straight tiller from the rudder but in checking the lofting the clearance is not what I would call "plenty" so I have decided to form a tiller with some nice curves to clear the bottom of the coaming. I think you should be able to pick up the tiller in previous pics to appreciate what I'm alluding to. Some more laminating work there and the plan is to use of cuts from the NG Rosewood and maybe a top and bottom laminate of T.Oak to beef it up. Haven't decided yet.........some of those tillers with different coloured laminates can look a bit cheap, I think.

    I have also begun work on the centreboard case. Fwd, Aft and Bed logs have been cut from raw stock but I still need to laminate the Fwd and Aft logs to get the width and thickness required. I'm using T.Oak 32x185 stock and need to get to 50x75 for the Fwd log and 80x75 for the Aft log. The Bedlogs are 23x80 so you can see the case structure is pretty hefty. The case sides, however, are ply and again I want to add a layer of glass internally to beef them up as I am using ply one size smaller than the design requires. I couldn't see myself buying a full sheet just for these when there was sufficent left over from the transom laminates to meet the requirement.

    No pics this post.....next time!

    However, help is sought from those out there who have done this before. What is the best method for the pivot assembly for the centreboard? What is assumed to provide the best outcome in a no leak, robust and easy serviceable pivot pin arrangement?
    All responses gratefully received.
    Rgds all
    Laurie

  7. #36
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    Howdy Laurie,

    Leakless and protects all the wood. Prevents any undue load on the case.

    PIVOT STRUCTURE
    Nice way is to make a pin out of a bit of SS rod for the pin (must have not thread cut on it!) that is just a little bit short of the thickness of the case structure it has to go through. Then make a ply pad to cover each end of the hole. Use a bit of sika under each pad and screw in place to cover the hole each side.

    TO PROTECT TIMBER
    The hole through the centrecase structure and the centreboard can be drilled out oversize for the pin. EG if the pin is 9mm drill the hole out at around 15. Fill with epoxy and the glue powder mix made up to a thick consistency then when it cures redrill with the correct size hole.

    If you can do this before the centreboard is glassed is it extra groovy - but not entirely essential.

    The glue powder/epoxy mix will take a very long time to wear much at all and can be drilled out and refilled and redrilled when and if it gets sloppy.

    The crappiest method is to use a conventional bolt with rubber gaskets under washers because
    1/ it always leaks
    2/ because it leaks there is always someone who tries to stop the leaking by tightening up the bolt and then that cracks the join between the hull and the centrecase ... or somewhere else.
    3/ the threads of the bolt act like a rasp every time the board goes up or down.

    Another way to achieve the top method is to have the pin's end welded to a SS disk with three screw holes in it Then it can be pushed in from one side and sika'd and screwed to one side of the centrecase - the other side gets covered by a ply disk like above.

    Best wishes
    MIK

  8. #37
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    Default Pivot Pin

    Many thanks Mik.............as always you are font of knowledge, Simple, quick and easy. I have read a lot of different methods and I thank you for providing your thoughts and experience to my project.
    Rgds
    Laurie

  9. #38
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    the colour and finish on the transom is awesome, i just hope when i build my Yellowtail i can do work like this

    Great thread Laurie


  10. #39
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    Howdy Laurie, a pleasure to help just a bit. I'd give credit if I could remember where I saw the idea first!

    MIK

  11. #40
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    Default Centreboard Case Bits

    Work continues on the centreboard casing.

    I have succumbed to the local expensive glass so that I can get on with it. Spent some time this week on the cap and support rails. These are in NG Rosewood to give a nice accent (I hope) in the middle of the boat.
    Today I began glassing the casing sides. More coats of epoxy to come.


    I have attached some pics of the bits mentioned earlier.
    1. Centrboard profiled awaiting glass
    2. Aft Log (a sculpture, no less!)
    3. Fwd and Aft Log
    4. Rudder profiled awaiting glass
    5. Rudder with Cheek piece and Base
    6. Ditto
    7. A mock up of the centreboard and Logs

    DSC01185 (Medium).JPG DSC01186 (Medium).JPG DSC01187 (Medium).JPG

    DSC01222 (Medium).JPG DSC01190 (Medium).JPG DSC01189 (Medium).JPG

    DSC01184 (Medium).JPG

  12. #41
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    Default Centreboard Case Continues

    Not much news this post. Stuff like glassing the Centreboard sides, applying a sealer coat to various components etc.

    I finally found a supply of graphite that was in a small enough lot not to break my bank. For those out there wanting to make up some epoxy mix using a small amount I discovered it in the lock section of the hardware store. Who could tell that it is the main lock lubricant?! Anyway a 6.5gm pack was plenty big enough to make a 50/50 mix of graphite and colloidal silica. Now I have a little lot for any other place I might like to use this mix.

    I have used this to provide a bearing surface for the Centreboard pivot pin as suggested previously. I drilled a 20mm hole with a spade bit in the Bed Logs and Centreboard and filled the holes up with the epoxy/filler/graphite mix. After “going off” I drilled a clearance hole for the 12mm SS pivot pin so that’s another little project added to the completion list. I can now happily proceed to assemble the case after some further internal finishing work.

    I guess my procedure will be to ensure I have a couple of coats of epoxy on the wood bits and I’ve prepared the internal surface of the case sides by adding a coat of 200gsm glass and sanded it in preparation for finishing after assembly. I still need to prepare and attach the Cap Supports at the top of the case sides before I attach these but in the meantime I can assemble the Bed Logs to the Head and Aft Logs. Bill Garden has designed the Centreboard case to allow a large dimension between the Case sides to provide access for cleaning and repainting. The Bed Log height is approx 90mm and the Centreboard tongue bears against the Cap slot to keep it aligned. I had visions of applying a rub strip vertically in the case but have decided not. If it happens that this doesn’t work there is plenty of room to work within the case to attach a rub strip at a later date, should the need arise.

    I have to admit I agonised over the type of fastening system to use – epoxy or flexible glue of some description. I have finally decided I will assemble the case using epoxy but when finally fitting it to the Apron I will use a flexible polyurethane adhesive.

  13. #42
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    Howdy Dry Water,

    Why change - do you expect the load to be different between these two parts?

    Best wishes
    MIK

  14. #43
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    Hi Mik
    I have visions of a future requirement to replace it so thought using some sort of bedding compound may be more suitable should the need arise to get it out of the boat. Happy to take any advice.
    Laurie

  15. #44
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    Default Centre Board Case Assembly Begins

    I have finally reached a point where I am in a position to begin to put the bits together. I have finally glassed and filled both sides of the Centreboard and it ready for fairing and finishing. This is a job that I am doing outside to reduce the amount of dust in the shed. Stuff gets everywhere! The drawback is by the time I get off work and home it’s dark so it’s a job for the weekend. It’s slowing me down but hey! there is no deadline so it’s good to take one’s time and think things thru as you go along. Research is half the fun!

    In the end I decided to apply some glass to the inside bearing surfaces and top of the Bed Logs for peace of mind. This took up more time but am now ready to glue the Logs and sides together. As an aside, I mentioned in my last note that the Bed Logs were 90mm but the full CB bearing dimension will be the Log height plus the Apron, Planking and Keel. All up about 155mm plus the tongue at the top. (I’m still not sure about adding some internal rubbing strips) .

    Getting the Pivot pin aligned in all directions will be the number one priority so to facilitate that I will glue one Bed Log to the Fwd and Aft Logs together with one Case side. This will provide the internal room necessary to completely finish one side and provide a stable base from which to square up the other side prior to fixing it in place. Refer to Pic 1.

    My pics today show
    • The part assembled case. Trimming still required with no glue at this point. The Bed Log on the side closest the camera will be removed after the initial glue up of the other side components to facilitate finishing.
    • A close up of the graphite/filler/epoxy hole. It looks rough around the edges but this is due to the fact that I have coated the hole with candle wax in case I get either epoxy or paint in there. It should be easy to clean if I do.
    • Another view of the pivot pin holes.
    • A mock up of the Case and “ready for fairing” Centre board. Note that the board is not level in this pic.


    DSC01195 (Medium).JPG DSC01196 (Medium).JPG DSC01198 (Medium).JPG DSC01199 (Medium).JPG

  16. #45
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    Don't despair if you are following my thread..........things are progressing on the Centreboard, Centreboard Case and Rudder front. However, not much to show as I have been busy undercoating the interior of the Centreboard Case bits and am now ready for a few top coats prior to assembly.
    I have also completed the epoxy coats on the Centreboard and am ready for the paint build up process.
    Finally decided on how I would handle the Case Cap Supports. Straight bits of wood seemed somehow too simplistic for the position they're in in the boat. I thought it would be nice to give them some shape and deciding on just what the shape should be took some research and muckin' around....had to consider the seat support shape as well to ensure it all worked in together. Thought I might even do something tricky with some applique work on the Rudder Cheeks to suit but haven't really decided onthat yet. One thing about applique, you can do it anytime. Need to come across some scrollwork or something....plenty of time.
    I have also purchased my silicone bronze gudgeons and pintles which has facilitated movement with the rudder as well. Fairing is complete and am onto epoxy coats. Fitting the hardware has been a bit of fun and taken up an inordinate amount of time. Needed to consider where and how the fixings would go, where the tiller would go etc. I certainly appreciate the lofting underfoot!
    Also took a week off during the school holidays and took the family down the coast so no work done week before last.
    Will take some new pics tomorrow to bring everything up to date.

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