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Thread: Solid Round Wooden Mast Repair - Clothes Pin Scarf

  1. #1
    Join Date
    Dec 2018
    Location
    conwy UK
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    2

    Default Solid Round Wooden Mast Repair - Clothes Pin Scarf

    This was a problem brought to me by one of the Conwy One Design owners. The mast was of a rounded solid wooden design tapered for most of its 25 foot length. There was a metal collar about two thirds of the way up providing an anchor for the mast stays. Although the mast was in near flawless condition the wood under the collar had been exposed to fresh water and rotted badly as a result. It was decided that to try to epoxy the wood where possible and replace the worst pieces would not be sufficient to fix the problem. Reinforcing the area would also compromise the flexibility of the mast. A previous mast had broken in this location probably from the same issues.

    Mast 02032019 004.jpgMast 02032019 005.jpg

    I tried to find any information on cutting a clothes pin scarf on round mast in situ without success so I came up with this plan. So far it seems to have worked so in case anyone needs to do the same here it is.

    The section to be replaced was about ten inches long with a taper from 3 1/8 to 2 7/8 inches. I aimed to cut a 14 inch scarf but ended up with 10 inch (this will be explained later). The process was to build a jig with a slot which would fix around the mast and guide a handsaw saw cut with enough accuracy half way through the mast. Then the mast would be rotated 180 degrees inside the jig to cut the other half of the scarf. When making the jig I cut the slots on a table saw after fixing two pieces of wood together to create an accurate mirror. I did not account for the thickness of the wood in making the jig which removed 2 inches from the scarf length.

    Originally I practiced the cut on some spare wood, arranging the jig to make a vertical cut. This was easier on the arm but I was blind to the bottom slot and drifted off. I changed the cut to a side way horizontal configuration and got better results. When cutting the mast I was as accurate as I could be to make the orientation of the jig level so that the second cut would match the first. I used 4 locating screws which pinned the jig to the mast when the position was correct. The actual cuts drifted down within the guide slot which made the scarf end up about 10 inches. With the jig on I stopped the cut about 1 inch before the centre of the mast. When the second cut had been made, the jig was removed and with the mast supported, both cuts could be finished to meet in the centre.


    Mast 15032019 001.jpgMast 15032019 002.jpgMast 15032019 003.jpg

    The picture allowance is full so will post links.

    Full album here.

    https://www.flickr.com/photos/159893722@N07/albums/72157677553125807/with/46811177154/


    https://www.flickr.com/photos/159893722@N07/47534882841/in/album-72157677553125807/

    https://www.flickr.com/photos/159893...7677553125807/

    https://www.flickr.com/photos/159893...7677553125807/

    With the bottom of the mast cut away I took the top half away and cut a similar scarf using the same technique. This left me with the damaged area of the mast which I now used as a pattern for a replacement.

    https://www.flickr.com/photos/159893722@N07/47534882681/in/album-72157677553125807/


    As with cutting the female sides of the scarf, the wedges needed practice. I needed the replacement to be the same length as the old piece and to be exactly the same rotation.
    When fettling the wedges I noticed that I could loose a lot of length (5-10mm) quite easily. This ruined the first attempt so give your self plenty of spare length. I worked from a square profile to get the top wedge a close as possible with an extra 10mm length on the second to give some room for adjustment. Once I was happy with the scarf I approximately rounded the repair section (using a spar gauge).

    The sail track on the mast proved very useful in lining up the mast pieces and by carefully fettling the lower wedge into the scarf on the bottom part of the mast it lined up surprisingly well. I was lucky with the rotation and the time taken on the positioning of the jig was well spent.


    We were lucky enough to get some hot weather in February so I glued the mast using West Epoxy. I wet all surfaces first before mixing some fine sawdust from the new wood with the epoxy to make a glue/filler. The whole thing only needed a tap on the end of the mast to seat accurately. I screwed the sail track into all three pieces to hold them in position. I wrapped the whole thing in cellophane and massaged the epoxy back into the seams. Checking the mast for straightness one last time it was left for 4 warm days to cure fully.


    https://www.flickr.com/photos/159893722@N07/46811172324/in/album-72157677553125807/

    https://www.flickr.com/photos/159893...7677553125807/


    When done the rounding of the repaired section was relatively straight forward.

    Results to date are promising with the mast bending through the repaired section.

    https://www.flickr.com/photos/159893722@N07/40582533673/in/album-72157677553125807/

    https://www.flickr.com/photos/159893...7677553125807/



    PS: In the pictures I put he collar back upside down.

    Thanks those take the time to post up.

    Good Luck.

  2. #2
    Join Date
    Nov 2004
    Location
    Port Townsend WA
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    12,382

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Nicely done Joe! That is a lot of work to do without a spar bench indeed! I can only congratulate you for being resourceful in your planning and execution of the job! I have only one comment which is not of much consideration at this point and, most likely, will not cause a problem for you.
    Mast scarfs are normally made with the angular portion of the joint facing downward so that the slant of the sun does not affect the glue as much as an upward facing shim end of a scarf. This keeps any moisture from wicking into the joint should the shim end degrade or crack.
    Go Sailing and enjoy!
    Jay

  3. #3
    Join Date
    Apr 1999
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    Hyannis, MA, USA
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    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Finastkind.

    I leave the tip of the male end circumsized, as it were, cutting the tip flat about 1/32". That leaves a pilot hole for boring out and plugging with a stop water. With an epoxy joint, especially on a mast, a stopwater may seem a bit silly, but I find that the little flat at the end of the male piece makes of an easier exact fit as I cut the male end a hair large and plane to the final using carbon paper or chalk to show me the high parts.

  4. #4
    Join Date
    Nov 2011
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    5,937

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Boat builders can be very clever people. Nice job JP.

  5. #5
    Join Date
    Dec 2003
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    Sound Beach, NY
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    3,729

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Nice job, with a handsome result.
    I've repaired rot in a standing mast by carving it out on one side, fairing the curve with spokeshaves, and springing in thin stock laminated in place. I worked my way around the stick until it was all new. Your method looks better and probably went faster.

  6. #6
    Join Date
    Dec 2003
    Location
    Portland, Oregon
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    54,218

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Looks good.

    Next step -- make sure that the future attachments are well bedded, so as to avoid what sounds like a recurring issue.
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  7. #7
    Join Date
    Aug 2014
    Location
    Westchester, NY
    Posts
    200

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Thank you for sharing! I too wondered why you opted for this orientation of the scarfs: <==> rather than <==<

    Also, were it me (although I know nothing), I would not have bothered even roughly rounding the "dutchman" until it was glued in...
    My Goat Island Skiff Project Photos:
    https://www.flickr.com/photos/999065...7648295059621/

  8. #8
    Join Date
    Dec 2018
    Location
    conwy UK
    Posts
    2

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    Thanks to all those who have taken the time to reply.

    I shall try to address a few of the points made.

    I did not trust myself to be able to cut “same direction scarfs” because of the accuracy involved and only being able to easily fettle the male wedge. If we look at the mast after the damaged piece has been removed we have a top and a bottom which have to line up on the rotation, length and be straight. Also I have to line up the top half of the sail track with the bottom half (on the bottom half of the mast) and if possible all the screw holes (bonus).

    Let’s say for example I cut the top part of the mast with a male wedge into a female part of the scarf on to the repair (top scarf) to give same directional scarfs pointing down. When going for the second scarf (bottom scarf) I cannot adjust the top scarf without reducing the length of the top part of the mast (wedge). If the rotation is out or the mast not straight I have to adjust a male wedge somewhere and now I only have the bottom male wedge. Also if I have to remake the repair piece I have to cut a female scarf into the end which is much more difficult compared to a wedge and I would have to cut the top mast wedge again to fettle it.

    This even stopped me gluing up the top scarf before the bottom because to get that bottom one exact with all the other considerations may have been impossible after a mistake, and then I would have had to cut off the top scarf and start again.

    The easiest option therefore was to cut two female ends on the original mast pieces then I don’t need to touch those again and I can concentrate on the blank. If I make a mistake on the blank (which I did) I just have to make a new blank.

    In conclusion then, this way all the mistakes were focused on to the new piece as the two wedges could be fettled on both ends. It just gave me a bit more slack because I thought this may not work.

    Good question though.

    The rounding is how the jig cut the pole. It came out like that.


    This mast is laid up in the winter and is stored horizontally on the ground exposed to the elements. This action may need to be revised in future as I think the damage may have been caused in the winter months. I have also noticed condensation as being an issue in the mornings. I have asked the owner to consider removing the collar in the winter and before varnishing. A regular wash with saline may also help.

    Unfortunately all wood left out in the elements without maintenance deteriorates. Unless it is Greenheart but that is another story.

    Thanks again.

  9. #9
    Join Date
    Apr 2019
    Location
    Massachusetts
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    29

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    That's some nice work. I wish I could do that as noicely as you!

  10. #10
    Join Date
    Nov 2011
    Posts
    5,937

    Default Re: Solid Round Wooden Mast Repair - Clothes Pin Scarf

    I have always figured that if I had to do this job it would be like this, >>--<<, where the center portion, the dutchman, would be in 2 layers so that all 4 of the pieces would be wedge shaped at their ends. I would use a jig similar to your cleverly designed unit for all 6 of the cuts, essentially a big miter box, and undoubtedly have to do a little bit of block planing, but without the jig the whole thing could be fashioned with just a plane(s).

    Hopefully the joinery and gluing would be good enough with no place of entry for moisture that it wouldn't matter at all whether the joints were oriented up or down, easy with epoxy.

    Perhaps as insurance you can saturate the new wood with clear Cuprinol, wet on wet until it won't absorb any more.

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