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Thread: Vintage Pirate Restoration - Mast design

  1. #1
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    Default Vintage Pirate Restoration - Mast design

    This is my first post to the wooden boat forum although I’ve been utilizing it very often for design inspiration, good boat building advice and guidance in my current project. I’m presently in the process of restoring a vintage wooden Pirate sailing dingy and have reached a point where I need some specific guidance on how best to proceed with the the mast fabrication, My mast blank is a solid, two piece laminated sitka spruce fabrication which will become (hopefully) a finished mast, 576cm (about 19’) in length above deck, and having an oval racetrack shaped design. The above-deck profile is shown below at its approximate midpoint.
    Mast Profile.jpg

    I have three initial design questions concerning this fabrication (and probably many more depending on how this discussion unfolds:


    1. I laid out the athwartship (67mm) dimension on my flat-sided blank and feel confident in being able to round it out (8-side to 16-side, etc) but what is a good method for layout of the fore/aft (80mm) dimension? I have an idea but any knowledgeable community input here would be much appreciated.
    2. I feel ‘fairly’ confident in cutting in the bolt groove (initial straight dado bit to depth followed by a 5/8” ball end router bit) but in doing so the bolt groove slot/opening ends up a bit wider than the spec’ed 4mm slot opening (by a little over 3mm) due to the router bit shank design. I don’t ‘think’ this small increase will impact the captive efficiency of the associated luff bolt-rope but I’d like some reassurance to that effect.
    3. Having received several negative opinions on the merits of using a bolt rope for wooden spar attachment I am considering using alternate methods but the options are many; bolt slugs, slides, internal track, external track, etc. I want to keep it simple and relatively foolproof but at the same time use a design that looks good and is in keeping with the vintage nature of the boat (and don’t forget cost). What design is eventually chosen may also negate the work required for #2 above. With that in mind I would welcome any suggestions based on the vast community experience that is out there.

    If you are interested in viewing photos of this ongoing vintage Pirate restoration please visit www.lisec.org and navigate to ‘Boat Shop’ then ‘Builds and Restorations’. You’ll see the 1954 Pirate Restoration under ‘Current Projects’. My thanks to everyone in advance and I look forward to any replies. JohnJ

  2. #2
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    Default Re: Vintage Pirate Restoration - Mast design

    The 80mm dimension can be laid out from your first flat face, once straight and true.

    Re. Bolt slot, many ways to skin a cat, but I would perhaps use screwed on slats of wood for easier repair if needed. This will allow for accurate slot sizing.

    Or tracks with slides... Just make sure whatever you do does not trap water underneath...

    Welcome to the forum.

  3. #3
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    Default Re: Vintage Pirate Restoration - Mast design

    I've always cut the bolt rope groove in the two halves before gluing up, which is a much simpler operation. In this way you get the correct width for the slot which is very important – the one major thing that makes a bolt rope groove system fail is if the slot gets to be too wide so the luff starts to jam or even pull out of the groove. Other than that bolt rope grooves work pretty well in my experience.

    The only downside of this is that you do have to be careful when gluing the spar up to clean excess glue out of the groove straight away, though that is not so difficult to do.

    If you've already glued the blank up, then I would go for an alternative system.

    Cheers -- George
    Last edited by debenriver; 05-13-2019 at 05:21 AM.
    To be truly free to live, one must be free to think and speak.

    A C Grayling

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    Default Re: Vintage Pirate Restoration - Mast design

    All of my spar builds have used lacing or external track, so I can't help. Welcome aboard, see you on the water.

  5. #5
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by lupussonic View Post
    The 80mm dimension can be laid out from your first flat face, once straight and true.

    Re. Bolt slot, many ways to skin a cat, but I would perhaps use screwed on slats of wood for easier repair if needed. This will allow for accurate slot sizing.

    Or tracks with slides... Just make sure whatever you do does not trap water underneath...

    Welcome to the forum.
    Thanks. That was my thinking once the width was tapered and planed flat to its correct dimension. Then scribe the width radius (33.5mm) onto the 80mm flat face at points along the spar, strike a batten and viola', the elongated flat side should then take care of itself. Rounding over should be straight-forward from there. I thought maybe there was some fancy modified spar gauge that I didn't know about that would work.
    The screwed on wood slats (perhaps metal to minimize wear) is a good idea and one I'll have to think closely about. I could then be able to more closely control the slot depth and width in one shot. Whatever is done will be well sealed to avoid trapping water. Thanks for the quick reply and suggestions.

  6. #6
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    Default Re: Vintage Pirate Restoration - Mast design

    Thanks. Hope to be out there soon.

  7. #7
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by debenriver View Post
    I've always cut the bolt rope groove in the two halves before gluing up, which is a much simpler operation. In this way you get the correct width for the slot which is very important – the one major thing that makes a bolt rope groove system fail is if the slot gets to be too wide so the luff starts to jam or even pull out of the groove. Other than that bolt rope grooves work pretty well in my experience.

    The only downside of this is that you do have to be careful when gluing the spar up to clean excess glue out of the groove straight away, though that is not so difficult to do.

    If you've already glued the blank up, then I would go for an alternative system.

    Cheers -- George
    Thank you for your reply. Unfortunately, it's already glued up. Not having built a mast before I failed to forsee the issue. I intuitively was thinking that the bolt slot could be more critical then first met my eye and you confirmed that. Thanks for the heads up on that. As for alternative systems; I was thinking in lieu of a bolt groove I would dado out for an internal track (thought it would look cleaner) or proceed with the bolt groove and may use a track system such as the internal round track system from Tides Marine. Any thoughts on either approach?

  8. #8
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    Default Re: Vintage Pirate Restoration - Mast design

    Sounds like a fun project If you're planning on being able to reef, I'd be inclined to go with the trach thought. Bolt ropes make for very inefficient reefability unless you cut the sail so you have slugs below the reef points. Looking forward to pics of the project,,,you're teasing us John!

  9. #9
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    Default Re: Vintage Pirate Restoration - Mast design

    Welcome to the Woodenboat forum John!
    George in post #3 is correct about making two halves first and cutting the bolt rope groove on them and then gluing up the halves. This should be done prior to making any taper or shape to the mast blank. This insures that the bit will not choke and over heat in the cut from chip build up. Once the ball has done its work on the two halves and they are glued up. You can be followed with the ball bit to smooth out the groove a bit. A mahogany or other hard wood insert at the heel of the groove prior to using the ball bit will create a stronger point of insert for the head board and bolt rope. This can be slightly flared/rounded off, on the very bottom by hand to make inserting the bolt rope easier. The two halves should have the vertical grain aligned athwart ships to give the strongest resistance to the bending of the mast off to leeward. The fore and aft flex will allow the sail to be flattened when working to weather.
    Jay
    Last edited by Jay Greer; 05-13-2019 at 11:24 AM.

  10. #10
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by Hugh MacD View Post
    Sounds like a fun project If you're planning on being able to reef, I'd be inclined to go with the trach thought. Bolt ropes make for very inefficient reefability unless you cut the sail so you have slugs below the reef points. Looking forward to pics of the project,,,you're teasing us John!
    Thanks Hugh. Your point on reefability is well taken. Since the sail has not been made yet the comments re: slugs will be noted if that is the route taken.
    I didn't mean to tease. My original post had a link to where photos are posted of the project. I volunteer at the Bayles Boat Shop in Port Jefferson, NY and I am in charge of this pirate restoration. It has been a lot of fun and I've learned a lot and not without a lot of anxious moments thrown in. This is my first ever attempt at this sort of thing so I've been proceeding cautiously.
    If you want to see photos of the Pirate project please paste the following link into your browser: www.lisec.org. Then go to the 'Boat Shop' drop down menu and select 'Builds and Restorations. You'll find the Pirate listed under 'Current Projects'. If you run into any problems accessing the site please let me know. Besides working on boats I'm the webmaster for our organization also. Hope you visit us!

  11. #11
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by Jay Greer View Post
    Welcome to the Woodenboat forum John!
    George in post #3 is correct about making two halves first and cutting the bolt rope groove on them and then gluing up the halves. This should be done prior to making any taper or shape to the mast blank. This insures that the bit will not choke and over heat in the cut from chip build up. Once the ball has done its work on the two halves and they are glued up. You can be followed with the ball bit to smooth out the groove a bit. A mahogany or other hard wood insert at the heel of the groove prior to using the ball bit will create a stronger point of insert for the head board and bolt rope. This can be slightly flared/rounded off, on the very bottom by hand to make inserting the bolt rope easier. The two halves should have the vertical grain aligned athwart ships to give the strongest resistance to the bending of the mast off to leeward. The fore and aft flex will allow the sail to be flattened when working to weather.
    Jay
    Thanks Jay. Unfortunately, as I replied to George, that train has already left the station. I like the hardwood insert at the heel of the groove and will surely use that idea (assuming I go with the bolt groove at all). After I cut the sitka plank to it's rough dimension, and before gluing it up I flipped it around so the grain is opposing athwart ships Is that what you were emphasizing in your reply?

  12. #12
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by johngsandusky View Post
    All of my spar builds have used lacing or external track, so I can't help. Welcome aboard, see you on the water.
    Thanks. Hopefully we will. She'll be moored in Mt. Sinai Harbor when finished so it's a distinct possibility.

  13. #13
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    Default Re: Vintage Pirate Restoration - Mast design

    Do you know this German website?

    http://www.holzpirat.org/die-segeljolle/bauplane/

    They have a lot of detail pictures and hints...

  14. #14
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by JohnJ View Post
    Thanks Jay. Unfortunately, as I replied to George, that train has already left the station. I like the hardwood insert at the heel of the groove and will surely use that idea (assuming I go with the bolt groove at all). After I cut the sitka plank to it's rough dimension, and before gluing it up I flipped it around so the grain is opposing athwart ships Is that what you were emphasizing in your reply?
    The vertical grain, if the wood is quarter sawn, the run of the grain should face the beam and not fore and aft. The verical grain will resist bending of the mast.
    The flat grain will face fore and aft and allow the mast to bend, thereby flattening the sail when the boat is sailing hard on the wind with maximum tension on the sheet.
    Hope all works out well for you and your little ship!
    Jay

  15. #15
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by tobias View Post
    Do you know this German website?

    http://www.holzpirat.org/die-segeljolle/bauplane/

    They have a lot of detail pictures and hints...
    Tobias. Yes we have been contact with Malte and his group quite extensively. They are excited to have news of a Pirate here in the U.S.A. and we have been keeping them abreast of the restoration. The detail plans have proved invaluable to moving this project along.
    Thanks for the reply.

  16. #16
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    Default Re: Vintage Pirate Restoration - Mast design

    Here's a thread that may be of interest; http://forum.woodenboat.com/showthre...-mast-boom-etc

    Thinking of reefing - I'm inclined to agree with Ian in post #7 of that thread.
    It's all fun and games until Darth Vader comes.

  17. #17
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    Default Re: Vintage Pirate Restoration - Mast design

    I would seriously consider getting an .025 kerf band saw blade, making a fixture to keep the mast oriented to the blade and just sawing it back in half. Then the groove with the correct tooling and glue it back together. It will save time and agony.

  18. #18
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by JohnJ View Post
    Thank you for your reply. Unfortunately, it's already glued up. Not having built a mast before I failed to forsee the issue. I intuitively was thinking that the bolt slot could be more critical then first met my eye and you confirmed that. Thanks for the heads up on that. As for alternative systems; I was thinking in lieu of a bolt groove I would dado out for an internal track (thought it would look cleaner) or proceed with the bolt groove and may use a track system such as the internal round track system from Tides Marine. Any thoughts on either approach?
    In that case, I think I would go with an internal track set flush as you describe - that would be a neat solution.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  19. #19
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    Default Re: Vintage Pirate Restoration - Mast design

    Quote Originally Posted by JohnJ View Post
    Thanks. Hopefully we will. She'll be moored in Mt. Sinai Harbor when finished so it's a distinct possibility.
    We will for sure. There are only a few wooden boats there and I have one. Her pic is my icon, name is Wandering Star, 39' ketch.

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