DIY Carbon whisker pole

Discussion in 'Boat Design' started by Gashmore, Dec 25, 2009.

  1. Gashmore
    Joined: Feb 2008
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    Location: Macon, GA

    Gashmore Junior Member

    I am a veteran scavenger and need a whisker pole. Over the year I have accumulated a Forespar 3" UGPS and a 3.5" UTS pole ends. I also have 4 roles of 6 month old prepreged 12K carbon tow looking for purpose in life. The prepreg needs to be used soon or it will be useless so so I have talked myself into building a couple of tubes.

    I have some experience building my rudder stock but it is wound over a core of H100 Divinycell so there was no need to extract a mandrel. Also the stresses were in torque and bending while in a whisker pole the stress is more in compression.

    Here is the plan and I am looking for feedback. The basic idea is to lay it up on standard aluminum pipe and tube, vacuum bag it and cure it by blowing super heated steam through the tube. It happens that a 2.5" schedule 40 aluminum pipe is exactly the OD to fit a 3" end fitting and a 3.25 OD aluminum tube is right for a 3.5" end. I plan to cap the ends, run a 1" tube drilled every few inches through the middle and support it all on pillow blocks so it can rotate. Wrap each end with adhesive backed Velcro hook to hold the tow in line.

    First spin the mandrel to wind on a couple of transverse plys. Next run 6 plys end to end hooked on the Velcro. Finally wind on 2 more transverse plys.

    After all the prepeg is laid lay on some peel ply and bag the whole thing. Pull the vacuum and blow super heated steam through the pipe and let it vent out some holes in the far end. Roughly figuring a 16,000' spool will make a 3"x12' .065" wall tube. The 3.5" tube would probably have the same section modulus with one or two fewer longitudinal plys. After it cures wet lay and bag a cover of harness weave, sand and add a couple of coats of clear poly for UV protection.
     
  2. mark775

    mark775 Guest

    You are way ahead of me. At what temp does your pre-preg cure? I thot superheated steam doesn't transfer heat very well. Did you mean simply "steam" (saturated steam)?
    I have two questions about the rudderstock. How? Will you post pics?
     
  3. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    A whisker pole mostly takes bending and compression loads, somewhat like a mast. This is rather unlike your rudder post, which takes bending and torsion. For a rudder post, most of the fiber oriented at +/- 45 degrees is probably ideal. Not so for the whisker pole. Fiber at +/-45 is about useless for compression loads. You can still fiber wind a compression spar like this,, but the traverse speed has to be very high so you can achieve fiber angles ~5 degrees off of parallel to the long axis.
     
  4. Itchy&Scratchy
    Joined: Jul 2008
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    Location: Oxford & South Africa

    Itchy&Scratchy Senior Member

    Hey Gash

    Its such a pity you have prepreg, I would be inclined to ditch the prepreg and go for a wet layup instead, which should make the whole thing pretty straightforward.:)

    I shall be watching this thread to see how you get on though-interesting idea. Epoxy and dampness dont go well together:mad: , but I do understand it will be bagged.;)

    Im sure guys who know pre preg will be along soon and give you the do's and dont'sfor this application.:D
    Have fun
    J
     
  5. Gashmore
    Joined: Feb 2008
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    Location: Macon, GA

    Gashmore Junior Member

    The main advantage prepreg has for a DIYer is you can take your time doing the lay up so you get it right. With wet lay up you are always in a low grade panic trying to get it in the bag before the resin kicks.

    Cure temp for this stuff is 120C for 90 minutes but the complicated part is the ramp up and cool down. I need to do some more thinking about how to control the steam. Actually super heating might work to advantage as above 100C there are few calories per KG so heating will be slow. OTOH, if I need more heat I can just pressurise the pipe to about 15 PSI so it stays saturated.

    Jimbo, Are you saying to lay the long fiber alternating slightly off axis?

    Some pictures of the rudder and stock are here.

    Glenn
     
  6. wet feet
    Joined: Nov 2004
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    Location: East Anglia,England

    wet feet Senior Member

    Is there no company in the heat treatment or composite business close to the job?I know that there is a composite facility in Braselton and it would be worth the cost of hiring their facility to be sure of a successful job rather than improvising a steam setup with no control mechanism to follow the necessary cure cycle.It may be that a stove enamelling or heat treatment company would have a suitable oven if you could run in vacuum lines capable of withstanding the heat.Even a sign company,working with acrylics,might have a suitable oven.Why not make a few calls?
     
  7. Gashmore
    Joined: Feb 2008
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    Location: Macon, GA

    Gashmore Junior Member

    Unfortunately in my neck of the woods I appear to be the composites expert which does not say much for the state of the art locally. :(

    I could cobble together a make shift oven from a length of A/C duct wrapped in insulation. I still have the heating elements and PID controller from curing the rudder shaft. That would definitely be easier to control. I was attracted to the steam however because it would heat and expand the aluminum mandrel before the epoxy sets. When it cools it shrinks and hopefully would pull away from the tube. My nightmare is to end up with a perfect carbon tube with an aluminum pipe embedded in it impossible to extract.
     
  8. mark775

    mark775 Guest

    Gashmore, I read your site right down to how to E-bay, and enjoyed thoroughly. I was going to buy a rudderpost but may reconsider now. THX
     
  9. Itchy&Scratchy
    Joined: Jul 2008
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    Location: Oxford & South Africa

    Itchy&Scratchy Senior Member

    Gashmore
    I owe you an apology,

    I thought that you were just having a go at this for the first time, I neglected to actually take the time to look at your site, before opening my big mouth.
    After Mark commented on it I went back and had good read, very interesting.
    I especially like the power long boards that you made, very nice.
    With your experience so far, prepreg is definitely an option.

    The build looks excellent so far and I for one will now definitely be keeping an eye on it.
    Hope you have an excellent vacuum filled New Year, with no dry spots.
    regards
    Justin
     
  10. Gashmore
    Joined: Feb 2008
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    Location: Macon, GA

    Gashmore Junior Member

    Thanks, but I have to apologize for the condition of the site. I have been very negligent in keeping it up over the past 2 or 3 years. I have lots of pictures of finishing the keel, installing the engine and fabricating the stainless stem fitting/bow rollers that I need to put up but time has to be divided between building and earning the cash to buy more material.

    I am getting close enough though that the neighbors are worried about when the animals will start arriving. Status now is down to laying the teak on the side decks in sessions my knees can handle, installing a rack full of bits and pieces and an enormous amount of sanding and varnishing a couple of acres of interior cherry. All of it drudge work which is why I need an exciting project like a carbon whisker pole.
     
  11. mark775

    mark775 Guest

    That is funny, you are completing a monumental task, almost there but can't stomach the thought of sanding those finger-tips off. So you take on a fun little project that has not much to do with getting the boat done. I have been there!
     
  12. wet feet
    Joined: Nov 2004
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    Location: East Anglia,England

    wet feet Senior Member

    Seems like a sensible plan,and it would give a chance of remaining close to the temperature gradient on the way up and on the way down.Steam would be a bit difficult during the parts of the process that occur below 100 deg C.
    The surface finish of the tube is quite important and I have heard anecdotal accounts of a man who laid up a carbon mast over a tube that had a very small dent.Extracting the tube was a huge battle.
     
  13. Itchy&Scratchy
    Joined: Jul 2008
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    Location: Oxford & South Africa

    Itchy&Scratchy Senior Member

    You might find this interesting, although not exactly what youre doing.

    If you do a search on youtube for 'building a carbon spinnaker pole.'
    J
     
  14. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    This may or may not be true. Prepreg is not necessarily forgiving on time, especially prepreg that is out of date. And with the right curing agent, you can get just about any working time you want for a wet layup, if you are willing to do an elevated temp cure cycle, and the fact that you are considering prepreg means that are are willing.

    With an imidazole (like EMI-24) or lewis acid (like boron trichloride amine) you can get anything from 24 hours to six months room temperature gel time. Typical room temperature gel time with EMI-24 is 2-5 days (depending on ambient temps) but with even modest heating to 120F it will cure in 6 hours. It has an unlimited post-cure window, also. (This is NOT necessarily true for the amine agents you typically see in commercial prepreg; if you get the cure cycle wrong, it may be impossible to EVER achieve the full 'as advertised' cured state properties, no matter what you do later with post curing.)

    These type of agents do not have a critical mix ratio either and will work in any resin. The typical 'starting point' mix ratio is 4%. Either will work as low as 1% PHR.

    Jimbo
     

  15. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    The trick to making these shop-built ovens work right (nice even heating) is adequate air circulation. Grainger sells a high-temperature rated blower that when combined with you heating elements, a distribution duct within the 'oven' and your PID controller will make a very serviceable composite curing oven. Most Controllers built recently can read several thermocouples and do one of two things with the data: either average all the inputs, or associate each individual thermocouple with a 'zone' within the oven, and cycle (distributed) heating elements appropriately to keep each zone at the right temperature. This is especially useful for a very large or long oven. Standard rain gutter makes a great hot air duct material, BTW. You just punch a bunch of holes in it, feed hot air in one end and cap off the other end. Your mandrel might also work as the duct, though I'd be a little cautious about that as you could wind up with some hot spots inside the tube and no thermocouple in there to alert you of the problem.

    You can have one central location for the heating element, like a heat box with the blower attached to it, or distribute the heating elements within the hot air duct within the oven, or even a combination of the two. My oven used the combination method and could maintain up to about 200F +/- 5F along its 45 foot length.

    Jimbo
     
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