Plascore Stitch & Glue

Discussion in 'Fiberglass and Composite Boat Building' started by hardcoreducknut, May 11, 2012.

  1. hardcoreducknut
    Joined: Aug 2011
    Posts: 47
    Likes: 1, Points: 0, Legacy Rep: 27
    Location: USA

    hardcoreducknut Junior Member

    I'm in the process of building the duck hunting layout boat of my dreams. It's 13'10" long x 48" wide with a 60" beam and a non-planing hull. I plan to spare no expense and use Plascore PP Honeycomb w/ veil and System 3 Silvertip Epoxy. Fortunately, I have a friend who made an absolutely gorgeous stitch and glue drift boat. His boat utilized Plascore for the bottom and Mahogany plywood for the side panels. Best part is he is very excited to help.

    One of our concerns is that joining the edges of the Plascore might be a problem with getting a good bite when joining honeycomb's seams. Another question we had was flex in the sides after the boat is completed. Should we use carbon fiber as well as cloth in our layup schedule? Would it be too brittle?

    Any insight would be much appreciated. Thanks!
     
  2. Tungsten
    Joined: Nov 2011
    Posts: 454
    Likes: 10, Points: 18, Legacy Rep: 75
    Location: Canada

    Tungsten Senior Member

    this is great as im building the same size boat,only using corecell foam instead of honeycomb.im wondering if you or your buddy did any tests on the plascore?

    also theres a site" phorum drift boat building"that has many driftboats build from plascore.

    sorry i cant answer any of your questions but someone here will.
     
  3. Jetboy
    Joined: Feb 2012
    Posts: 278
    Likes: 6, Points: 0, Legacy Rep: 65
    Location: USA

    Jetboy Senior Member

    I'm building an 18' folding trimaran (sailboat) with plascore as my core material. When speaking with the manufacturer they recommended just butt joining the pieces and fiberglassing the surface. I'm not sure I agree with this. I'm using a hard chined plan so I need 8 20' long 4' wide panels. That requires 2 joints in each one. What i've been doing is laying fiberglass - 12oz - on one side (I'm using epoxy). Then I flip over once cured. The fiberglass then provides a backstop if you will for filling the honeycomb gap. I mix up a batch of epoxy with fumed silica so that it will still flow well.

    I then put it in a ziplock bag and do the cake icing technique to fill the gap. To get the best access I place a 2x4 under the joint on my table. This bends the gap open nicely, but not enough to cause the epoxy to crack or weaken. (usually this is 1 day after the first side so it's probably still a bit softer.). Anyway, it will fill in the voids anywhere that there is a cut that partially cuts open a cell. This ends up making a really nice matrix of filler between the two panals. I can take a picture if you'd like, but it probably fills about 50% of the cells on the edge making a plug type of connection inside the half cut cells. I suspect the joints are stronger than the rest of the panel. I don't have any other great way of doing this. I have also been putting an extra layer of 12 oz tape on one side that will be the inside to add a little extra strength. I don't want to try to fair the hump on the outside of that extra reinforcement.

    I don't see any other great way to do these joints. I'm certainly open to ideas. I believe the Plascore is going to be a great core for my project. Once fiberglassed up, it is surprisingly stiff and impact resistant.
     
  4. rwatson
    Joined: Aug 2007
    Posts: 5,783
    Likes: 265, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    That's all it needs. There is no real 'strength' in this honeycomb panel, the fiberglass needs to do all the work. The core is just there to separate the fiberglass, and resist the compression from surface loads.

    There is absolutely no gain in strong joints of the panels.

    Have you got a professionally designed layup for your boat, or are you making it up as you go ?
     
  5. Jetboy
    Joined: Feb 2012
    Posts: 278
    Likes: 6, Points: 0, Legacy Rep: 65
    Location: USA

    Jetboy Senior Member

    I have professional plans, although the plascore is not the original core material. It's a Scarab 18 if you're familiar with them. - I should call it a Scarab 18 "like" boat though as I'm making various unapproved changes like honeycomb and I plan to use foils from production boats that may be slightly larger than design rather than build my own foils. I'm adding a layer of 5oz kevlar to the hull bottoms to improve durability for beaching. I'm also using epoxy rather than polyester. Finally I might build my own beams out of aluminum rather than fiberglass and design new connections with the floats for them, but that's yet to be determined. The plan is designed originally for plywood or foam core. This will not be the first honeycomb version though. At least one other very similar boat - the 16 foot model - has been built in honeycomb and seems to have had success with it. In our email exchanges I mentioned planning to use honeycomb and it wasn't identified as a problem for this boat although it wasn't specifically approved. The key structural bulk heads and beams will not have honeycomb in them. I believe honeycomb will be sufficient for the rest of the boat.

    The joints would be weakened without a "plug" of epoxy in them. Where part of the cell is cut to make the end cut of the sheet of honeycomb the cells can collapse easier as the structure is compromised. So the joint becomes a weak point otherwise. Using the fillet type mix to fill the empty edge cells makes that joint area very strong. Probably considerably stronger than the rest of the panel. Without it I think it would be prone to fail at the joint where the compromised cells would not resist compression as well as the rest of the panel.

    The drift boat makers are using an interlocking puzzle like cuts to join panels. I don't believe that is necessary for my purposes.
    Looks like this: [​IMG]
     
  6. hardcoreducknut
    Joined: Aug 2011
    Posts: 47
    Likes: 1, Points: 0, Legacy Rep: 27
    Location: USA

    hardcoreducknut Junior Member

    The layup schedule we were using was the one that Montana Boatbuilders provided with their driftboats (which use plascore for the bottom, plywood for the sides). Those are designed for whitewater rapids, so I'm sure running my 6.5hp mud motor through grass marshes wouldn't hurt it. I wanted honeycomb because stronger, lighter & cheaper than marine grade plywood. Their schedule calls for 1 layer of fiberglass with epoxy inside and out. Then 3 layers on the bottom or 1 layer of fiberglass + 1 layer of kevlar. I'm leaning towards kevlar.
     
  7. rwatson
    Joined: Aug 2007
    Posts: 5,783
    Likes: 265, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    This makes a lot of sense to me. Its sounds like you have thought it out pretty thoroughly. I will look forward to seeing the final result.
     
  8. hardcoreducknut
    Joined: Aug 2011
    Posts: 47
    Likes: 1, Points: 0, Legacy Rep: 27
    Location: USA

    hardcoreducknut Junior Member


    I could be wrong, but I believe this is called a "scarf" joint.
     
  9. Saildude
    Joined: Jun 2011
    Posts: 84
    Likes: 9, Points: 0, Legacy Rep: 119
    Location: Seattle, Washington, USA

    Saildude Junior Member

    A scarf joint is a joint that has the edges of a sheet beveled to match the sheet it is fastening to - the beveled edges are smeared with the proper adhesive the sheets are then overlapped and clamped - harder to do than the jigsaw type of joint in the picture -
     
  10. rwatson
    Joined: Aug 2007
    Posts: 5,783
    Likes: 265, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Its called a 'puzzle joint' for obvious reasons
     
  11. pittendrigh
    Joined: Jul 2011
    Posts: 7
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Bozeman, MT

    pittendrigh Junior Member

    The puzzle-joint photo above is mine (http://montana-riverboats.com). I do box joints now, rather than dovetails. Not sure if it's needed. Doesn't hurt and it isn't hard to do. And it does guarantee the proper 2-dimensional alignment. To get the panels aligned in the z-axis I place visqueen over the joint, plywood on top the visqueen and weight on top the plywood. Core material, fabric and resin are indispensable. Without them you can't build a boat. For me, visqueen is indispensable too. I use it at almost every step.

    Some drifboat builders make panels as above, and then proceed to build a stitch and glue one-off boat, as if they were working with plywood. IE just slap it together, perhaps with a few temporary formers to keep the shape, prior to stitching and/or gluing.

    I like to make a temporary male mold out of plywood, especially so when working out a new hull shape. Then I drape 4mil visqueen over the mold, lay the Plascore on top the mold and then glue it together. This extra step is NOT required. But it is easier to make incremental shape adjustments to a wooden plug, until you get the desired shape. And then apply the Plascore. A knock-down plug also makes it a whole lot easier to make several identical hulls, perhaps at a later date.
     
  12. Jetboy
    Joined: Feb 2012
    Posts: 278
    Likes: 6, Points: 0, Legacy Rep: 65
    Location: USA

    Jetboy Senior Member

    Thanks Pittendrigh. IIRC you are are based out of Livingston. I'm from Bozeman. I live in SLC currently for work. Hope to get back soon.

    I'm not sure if you're aware, I've spoken with plascore and they will make single panels as large as 7x50 feet. The price gets really high for them though if you're only ordering a few. If you have a large enough order like a production facility might, you may be able to purchase single sheets large enough to do a whole boat side or bottom. Might save time and $ for a production set. I sometimes wonder if I should have just bought 20'x4' panels and skipped all the joining work. If I were building a dozen boats I would.
     
  13. pittendrigh
    Joined: Jul 2011
    Posts: 7
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Bozeman, MT

    pittendrigh Junior Member

    There are two of us. Jason Cajune used to be Montana Boat Builders, in Pine Creek, just south of Livingston. Jason is still around and still building boats. But he has downsized his operation some. But I think Jason still does sell both boats and blueprints. He's a cool guy. And a hell of a craftsman.

    I am Montana Riverboats. I've been here the longest. Since the early 1980s. But I'm retired now. Build only for the fun of it. I do sell "online plans" for several stitch and glue dories. I don't use much plywood any more. Mostly Plascore. I will be experimenting with CoreCell and DiviniCell foams for seat parts, etc. I have built seats with fiberglass over construction worker's foundation foam. And that works well too. I think my future direction will be no plywood at all. With the hull mostly Plascore and everything else foam.
     
  14. rruth
    Joined: May 2012
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Salt Lake

    rruth New Member

    Plascore boats

    I was thinking about building a composite boat last year and came across a guy in Salt Lake. His name was Larry. He was just completing a second all plascore drift boat. The first was a totally killer all plascore fully decked, self bailing whitewater boat. It was the lightest dory I have ever seen.

    He had a web site with the construction history of both but I have lost the link.

    This dude really knew his stuff.

    Randy
     

  15. pittendrigh
    Joined: Jul 2011
    Posts: 7
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Bozeman, MT

    pittendrigh Junior Member

    That's my buddy Larry Hedrick. I went through Desolation Canyon with Larry last year, a week off peak high water, in his all-Plascore boat. Nifty boat. Larry said is was a "stretched-out" montana riverboats' Honky Dory. Same frames with an extra two feet cut and pasted into the middle somehow.

    Good boat. Fine river. Good bunch of people.

    Mountain dogs dot net or something like that. Here's Larry in another boat he built.

    [​IMG]
     
    1 person likes this.
Loading...
Similar Threads
  1. Deadrift
    Replies:
    10
    Views:
    1,780
  2. reelpleasure
    Replies:
    0
    Views:
    3,163
  3. reelpleasure
    Replies:
    1
    Views:
    1,642
  4. mwwinklerdc
    Replies:
    20
    Views:
    6,082
  5. Mardonis
    Replies:
    3
    Views:
    733
  6. Roy Berntsen
    Replies:
    33
    Views:
    4,174
  7. Tungsten
    Replies:
    10
    Views:
    1,537
  8. Bluesphere
    Replies:
    6
    Views:
    2,773
  9. muzungu
    Replies:
    6
    Views:
    2,695
  10. MattStudent
    Replies:
    2
    Views:
    1,900
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.