Couple Questions on Glassing and Bogging

Discussion in 'Boatbuilding' started by CatBuilder, Feb 22, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    Nice strategy on aligning the bulkheads. Thanks!

    Great info.
     
  2. CatBuilder

    CatBuilder Previous Member

    A cruddy weekend:

    Here's some annoying stuff...

    I have way too many screw holes to patch up with bog. I have 7 holes for ever 11 inches of boat. I have this many because in the bilge, I really needed to pull the 1" foam down to each and every batten to get things in alignment. Also, the foam tends to "pucker", or rise up from the batten at its center point, while the edges touch. I had to pull it down in the middle with each of the 7 screws per sheet.

    On top of all that, my bog sucks. It keeps sagging, leaving a small dimple in screw holes or a trough in between sheets. How flat does everything need to be?

    100% flat for glassing, right? No dips, or I'll have air bubbles, right?

    I hope to find a better way to hold the sheets in place on the next bilge. I also hope the topsides (pretty flat) don't require as many screws from the front. Maybe none?!?

    Well, I'm kind of irritated this weekend from driving 6 hours for some peel ply, having to do dishes, cooking, groceries, etc... and not having enough time for the boat.

    What time I do have was spent sanding my first bog application to do a better job, then vacuuming the foam. Now, I see my 2nd bog job kind of sucks too and I am going to have to sand, vacuum, re-bog, sand and vacuum before laminating - IF the next bog comes out right. WTF?

    Any suggestions?

    [​IMG]

    [​IMG]
     

    Attached Files:

  3. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    You're doing good work so stop telling yourself otherwise. You have not been doing this for 30 years so let up on yourself. Dimples, indentations can be filled by a "flood coat" after everything you have done is thoroughly DRY. Use a medium to semi medium coat of epoxy with a hard roller. Do a test on the thickness. The rest is all top sanding. You do not need a chemical bond for dimples or indentations so let it dry and hit with 80 grit and go over with the flood coat. Just my 2 bits on it. If you want perfection , go with the flood coat then lay a film plastic down on it and hard roller or hard squeegee then when dry pull off the film. Don't know the name of the film but will look for it.

    Here is the film. http://duckworksmagazine.com/03/r/articles/glass/bottom.htm
     
  4. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    Cat are you trimming the edge of the sheets for a close fit?
     
  5. CatBuilder

    CatBuilder Previous Member

    Thanks, Rasorinc.

    Yeah, I tend to try for perfection in just about everything I do. I just want to improve my process a bit to get it more efficient, but maybe just doing the extra work and plugging along will be faster overall. I'll fill those little dimples at the screw holes in as I put the laminate on (with bog).

    War Whoop:

    I'm not trimming the edges of the sheets. I'm bending them and sticking them together, than squirting bog into the cracks using a cake decorating frosting bag.

    They are fitting together well on their edges. The area I'm having some problem with is the very center of each panel, down a vertical line in the center.

    All along the center, the foam shrinks a bit, while the edges stay 1" thick. So, the long edges of the foam come into nice contact with the battens, but the very center of the foam isn't in contact with the battens - hence, those 7 screws from the front with plywood washers to force the center of the foam down to contact the battens.

    There are a hundred screws holes in each batten to allow you to screw into the foam from behind, but those don't seem to work for me until after I put the screws in from the front to pull the center line of each foam panel down to the batten.

    I think the topsides will be a lot easier. This is why Andrew suggests I do the bilge in a different way... using long pieces longitudinally. However, I see lot of Farrier builders dong it the way I am.

    If I could just get less screw holes, I think it would be better.... then again, I guess all those screw holes don't matter too much - but they are extra work.
     
  6. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    The sheets should be seated on the battens before you fasten from the back side,also that is why I use long pieces of batten to draw the face side down and avoid the dimpling,Then screw from the back side with large self tappers like a #14 screw also the joints are scribed to a dead fit.
     
  7. CatBuilder

    CatBuilder Previous Member

    That's exactly how I'm doing it, except I used plywood washes instead of batten pieces to seat the foam from the front. After seating it, and it cooling, I went around back and put those screws in. Not sure what number they were though. They were fine thread drywall screws. They don't grab well though. They strip very easy in the foam.
     
  8. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    Here is Cleanup on a 11 Meter hull just pulled ,that is going together built with 1" Core and NO Bog or whatever,The fixture was built very close and the core fastened tight from the inside,Hint Drywall screws do not make it.

    [​IMG]
     
  9. CatBuilder

    CatBuilder Previous Member

    Now I get it. Small battens across the front and number 12 screws. I'll try that.

    I owe you beer next time I'm in ft lauderdale. Thanks!
     
  10. CatBuilder

    CatBuilder Previous Member

    Now I get it. Small battens across the front and number 12 screws. I'll try that.

    I owe you beer next time I'm in ft lauderdale. Thanks!
     
  11. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    I wound up using #14 Screws they tightened well also one has to use caution against dimpling Via point loading when mounting the sheets.
     
  12. CatBuilder

    CatBuilder Previous Member

    Agreed. I have some dimpling from point loading when I was mounting the sheets. They were still soft from heating and got some dimpling.

    I'll check on the #14. Thanks.

    Also, I decided to just foam up the topsides in addition to the bilge that's already done. Then, I can glass the topsides (walking through the deck area of the mold). Then, I can stand on the already-glassed topsides to glass the bilge and then turn around and do the same to finish up the deck.

    Andrew thought of this sequence a while back and showed it to me, but I never got it... until today. I think I can save on materials this way with less waste.
     

  13. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    The drywall screws are fine for pulling the sheets down as they are quick,But the fastening is better done with a larger screw from the back once in Place.
     
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