home made mast tube

Discussion in 'Sunfish Talk' started by pthayn, Nov 23, 2009.

  1. pthayn

    pthayn New Member

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    I have just purchased a sunfish made is the 70's by viking. When I got the boat home I realized that the mast tube is badly damaged. Large pieces of the fiberglass are missing and it is no longer attached to the bottom of the hull. I was wondering if anyone had any experience or ideas about for repairing this. I was thinking of constructing a new mast tube from aluminum tubing and attaching it at the bottom of the hull over a circular wood disc that fits the inside diameter of the tube. This disc would be glued to the bottom of the hull. I am going to put in an inspection port about 6 inches from the mast tube, but off center since there seems to be a support fore and aft of the mast tube.

    Has anyone heard of a similar repair, or have any ideas?
     
  2. Wayne

    Wayne Member Emeritus

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    Though I have not done any sort of extensive repair work on an Intl. Fiberglass Co., Viking, reports are their construction is very similar to the Alcort, Inc., Sunfish.

    Why not simply reconstruct the fiberglass mast tube and maybe beef it up a little with some additional layers of glass fabric. That would be the typical repair method used to fix an Alcort Sunfish with the same damage.

    How did you discover the Viking has internal supports near the mast tube, are these now exposed with the damage? It would be interesting to see just how similar or different these two boats are. Can you post some pictures?


    Photo - Courtesy of the Sunfish_Sailor Archive
     

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  3. pthayn

    pthayn New Member

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    Here are some drawings of what the situation is. I can't really get very good pictures until I cut the inspection port. It may be a while before that happens since it is raining here and probably wouldn't be a good idea to cut a hole and then get it all wet inside. There is already some water in it.

    I have no experience working with fiberglass and have no equipment. It sounded kind of expensive to get everything I would need, plus there is no only about 2/3 of the original tube left, hence being able to see the inside of the boat to choose a inspection port location. If that is in fact a better idea, there is some one local who repairs boats, but I would rather do it myself to save some money.

    My idea is to epoxy the disk of wood to the previous location of the mast tube attachment. then set the aluminum tube around it and put some thick epoxy around it for support. I would also epoxy around where the tube would come through the upper hull, with some added support of a wooden ring cut to fit around the new tube.

    the original fiberglass tube remains would be cut out, which kind of concerns me.
     

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  4. pthayn

    pthayn New Member

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    Thanks for the picture. I drew the missing areas on it. I can't get a good look at the attachment at the base of the tube, but it moves freely, so I am not sure it is attached at all.
     

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  5. Wayne

    Wayne Member Emeritus

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    My concern with port placement is the deck area perpendicular to centerline at the mast tube supports a portion of the mast's lateral force. Offset at 45º might work better. \ /


    Your proposed approach looks workable. It would not be my first choice, but considering it utilizes materials you are more familiar with I don’t see a functional problem.

    In boat repair circles, when epoxy is discussed, the reference is to “laminating epoxy” rather than pre-thickened A-B epoxy like you find at the hardware store for household repairs. The difference being, laminating epoxy alone is less viscous and will therefore run into crevices the squeeze tube stuff won’t…, and you can add additives to create different sorts of extra hardening. There are thickeners, structural strengtheners, and aerating fluffers so you use one can of resin to create your own variations for all parts of the job.

    One consideration when you are done, a metal mast will wear quickly against a metal tube. You could consider using a thin plastic insert like the cover off a flexible notebook as a liner between the two.
     
  6. 67stang

    67stang Member

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    ...heres is my 3 cents worth... watch for the Styrofoam blocks when you go to put the inspection port in. You will want to be on the inside of the factory foam block layout, as well as what Wayne had mentioned about the 45 degree offset.
     
  7. pthayn

    pthayn New Member

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    Thanks you guys for your advise. I can already tell you've helped me avoid several mistakes. I will have to read up a little about epoxy, before I try anything. I am open to trying a fiberglass repair, but am not sure how much I would be able to do if there are parts of the original tube missing, and if its not attached at the bottom. Can you use fiberglass to replace missing areas?

    I am having a hard time seeing the actual extend of the dammage, but will try and get a inspection port soon. If the tube looks similar to the picture you posted, fiberglass may be more doable.
     
  8. Webfoot

    Webfoot New Member

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    Saving the mast tube depends on how much it's damaged. Plan 'A' is to reattach the mast tube to the bottom of the hull then wrap layers of fiberglass cloth and mat around the mast tube. If the mast tube is not shattered or crushed, coating the mast with release agent and inserting the mast in the tube should allow you to repair some large holes. The real trick is getting the mast tube attached to the bottom of the hull so the mast is straight and not at an angle. Best way would be to make a jig off someones SF that you could use on your SF. You idea for a wooden block at the base of the mast step is good however it might be a challenge since you have the keel depression and V shape of the hull to deal with. For extra strength I'd go with triangle gusset blocks after (A) the mast tube is fiberglass 'Scotch-Taped' to the hull and (B) the mast tube is wrapped in layers of fiberglass cloth and mat. The whole idea is to always go the 'down and dirty' or the simple route unless other considerations prevent it.
     
  9. Wayne

    Wayne Member Emeritus

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    With a fiberglass repair (using either epoxy or polyester resin as the medium), the job is similar to paper-mâché, for big kids. You would wrap resin soaked strips of fiberglass fabric around the existing pieces of the mast tube, using the remaining portions of the tube as your form. Once a new tube has been built in layers the depressions left on the inner diameter by the broken out parts would get filled with a paste of resin and chopped glass fiber.

    Re-attachment of the bottom of the tube to the hull would be accomplished in the process of building-up the “new” tube by forming a gusset with each layer of wrap. If the upper end of the tube needs a connection to the deck it can be made in the same way.

    Any good book on fiberglass boat repair can provide the details of handling resins and fabrics. For example:

    Fiberglass Repair and Construction Handbook by Jack Wiley

    Fiberglass Repair: Polyester or Epoxy by David Aiken

    The Fiberglass Boat Repair Manual by Allan H. Vaitses

    If you have a specialty plastics supplier (fiberglass outlet) in your area, they can be invaluable for advice on which materials to select and how to apply them. Something a recent graduate from Mac Big Box Hardware’s School of Counter Service Excellence won’t likely be able to provide.

    These are some on-line examples…

    Fiberglass Supply Co.
    http://www.fiberglasssupply.com

    Jamestown Distributors
    http://www.jamestowndistributors.com
    (look in their help area for video overviews)
     
  10. pthayn

    pthayn New Member

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    Here are some better photos of the mast tube. There is also a metal ring that is missing that should be screwed to the mast tube opening, as the manual (not missing) states it to takes strain off the top. One thing that I have noticed while looking at other photos of mast tube repairs is that there is an overhang from the tube opening and the actual tube. I will attach a drawing to show what I mean. I don't believe this is the case on normal sunfish boats.

    The bottom of the tube is not attached. I also have attached several pictures showing the support post about 6 inches in front of the mast tube.
     

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  11. Wayne

    Wayne Member Emeritus

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    THANKS..., those help to understand your boat's construction much better.


    I've seen that in other pictures of the Viking.



    It's not clear from the photo, but does it appear the bottom of the mast tube might have been set into a block of dense foam? Laser uses a method something similar to secure their mast tube at its base.
     

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  12. Wayne

    Wayne Member Emeritus

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    Those supports ahead of and behind the mast tube... Could you be seeing the ends of some emergency flotation blocks running down the center of the boat?
     

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  13. rob herschel

    rob herschel New Member

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    i think i'd go with a new set up of heavy pvc pipe, a dougnut shaped wood ring bottom and top and a good epoxy bond. you can also make a nice deck ring to fasten to the inner deck ring you make. fiberglass coatings (fgci)in fla. makes a great 2 part epoxy i have used for years called superbond. it's 50/50 mix like peanutbutter. a pint of each epoxy/hardener) will do the job.
     
  14. Porpoise2

    Porpoise2 New Member

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    Working with epoxy is easy and the paper-mâché analogy is perfect. This is a highly-stressed part of the boat, and epoxy is extremely strong.

    There is a lot of sanding involved and surfaces must be rough, very clean and very dry. By using measuring spoons, you can save on buying the expensive West® System pumps that seem "necessary".

    In your case, epoxy can "create" everything you need (step, tube, and deck support) and will give you knowledge for future repairs elsewhere.

    It doesn't appear that the mast tube is worth saving. A new and much more durable tube can be "created" out of epoxy. Use the old mast as a female mold and tape a couple of layers of wax paper between it and the new built-up epoxy tube.

    Rather than cut a new port, why not cut out an eight-inch circle using the mast tube as the center? Retain the cutout piece and build up a new support ring using epoxy ("created" out of multiple layers of epoxy and cloth). A replacement metal ring can't be available any longer and epoxy won't corrode, loosen, and can be made still stronger, lighter and more durable.

    The large hole will allow direct access to the necessary sanding that would precede the "creating" of a new epoxy mast step. That bottom part of the hull is almost always wet, and a wood step is vulnerable to swelling, splitting, or breaking loose. You could still make a "PT" wood support that is bonded to either side of the mast tube with epoxy.

    Save the cutout piece and epoxy it back in place and add a layer or two of cloth to reinforce the deck, which probably could use it anyway.

    There are several "caveats" connected with these suggestions, but that's what I would do. :)
     
  15. Webfoot

    Webfoot New Member

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  16. pthayn

    pthayn New Member

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    Here is a drawing of what I believe the foam blocks are like in this boat. Its a viking, so there are apparently some differences between it and a sunfish. I am starting to think that I should not put a access port behind the splash guard since there is only a a couple of inches between the lateral running foam block and the deck. I am thinking that I will put a 5" port on a 45 degree angle in front of the mast tube to gain access. This drawing is made from looking through the gap at the top of the mast tube.

    I was also wondering if I could use the mast a male form/mold to fashion a tube to replace the current mast tube instead of using pipe. If so, do I just wrap the actual mast in plastic wrap or is there something I should coat the mast in?
     

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  17. Porpoise2

    Porpoise2 New Member

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    I'd tear out the remainder of the existing mast tube to see if the foam is worth saving. (The tube's going anyway). Wouldn't this be a good opportunity to refurbish the foam?

    There's nothing wrong with using PVC—especially if the diameter is exactly right. You'd just have to bond it to its fiberglass supports by mechanical means. (Use PVC cement to put a series of PVC rings on the tube for the resin to grab onto).

    Will a 5" port be large enough to get your electric sander through? (An air sander, maybe).

    I've only made flat molds, but you can use something as commonplace as plastic grocery bags. (The new resin won't stick to it). I suspect releasing the two will be difficult, so I'd be generous with whatever wrapping you decide to use. Four or five turns of wax paper might be good. In a pinch, the wax paper could be heated (from inside the aluminum mast mold) to cause the new mast tube to slide off.

    Perhaps a substitute mold would work: something on the order of tightly-rolled aluminum flashing, secured on the ends with hose clamps, would work out better. After curing, you could tighten the hose clamps to reduce the mold's diameter and remove the flashing from the new mast tube. (Or use a PCV pipe cut on one side of its length, and the hose clamps). Swim noodles come in different diameters.

    Using a glass cylinder of the right diameter would be perfect! (You could break the cylinder and shake out the pieces). :D :p
     
  18. rob herschel

    rob herschel New Member

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    i would use the mast itself as the mold and wrap it in a cardboard tube (like a papertowel tube). wrap the papertowel tube with saran wrap then wrap this with wetted strips of fiberglass to the thickness you want for the tube(build up the tube thickness strip by strip). this will give you some space between the mast and new tube you can make it a little long then use a cardboard mockup to fit in the hull and determine the exact length you need. with a little extra effort you can form a flange edge on the end of the tube to attach to the hull and then build wood donuts to fiberglass to the deck and bottom surrounding the new tube. if you prep ahead it could all be built in one step without needing to wait for the glass to dry.
     
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  19. Wayne

    Wayne Member Emeritus

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    All the Sunfish look-alikes have subtle and not-so-subtle differences. Your peek into the hull looks like it shows the bottom is entirely covered by a layer of sprayed in foam. It's going to be educational once you get the port installed and have a good look around.

    From your sketch, off-center and forward appears like an appropriate location for repair access.



    Rob appears to have some good suggestions grounded in experience.

    The mast does need some room for a little pivotal motion so the thought about adding a layer of cardboard to create that spacing is a good one.

    I do not know if all plastic wraps are compatible with resins and their hardeners so a little testing would be a good idea. Waxed paper works great and is a mainstay of fiberglass work. Another material is PVA (polyvinyl alcohol). It's a liquid developed as a mold release, but has also found use as a protectant for surfaces surrounding a repair. It can be brushed or pump-sprayed. Another helpful piece of equipment is 3" wide tape, masking or packing. You can see it being used in the Geophizz video on hull repair from the Laser Performance seminar.

    If you choose a mechanical installation, fitting and sealing will be the challenge. WEST system, G-Flex is a specialty epoxy (other brands as well) that claims to adhere to plastics regular epoxies won't. ...should you go that route.

    For comparison, the Sunfish mast tube uses both a mating flange approach and a flared flange, at least at its base. These are fiberglassed in place making the tube part of the hull rather than a stand-alone piece.

    2¢ …

    I am still leaning toward leaving the broken mast tube in place and building around it. One reason is, there’s a question of perpendicular alignment and I am thinking leaving the existing bits in place maintains that and saves having to devise a way to set a new separate tube.

    The approach I would entertain first is to run tape across all the broken out places from down the tube. Stuff the tube with crumpled paper to give the tape support.

    From inside the hull, wrap strips of (wetted) fiberglass fabric mummy style around the existing tube until a new tube is formed. You can even form a flange as you go at both the top and base to make the tube integral with the hull.

    If you want reinforcement at the deck, make a doughnut in two halves ( ) for below deck and a new metal collar for above.

    As I mentioned earlier, once a new tube has been built in layers the depressions left on the inner diameter by the broken out parts would get filled with a paste you mix up from resin and chopped glass fiber.
     
  20. rob herschel

    rob herschel New Member

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    hadn't thought of the alignment issue. it would be best to leave it then. i agree if it can be reinforced and built up in place that's the best way.
     

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