Fiberglassing advice for project

Discussion in 'Materials' started by Zachary9893, Jan 19, 2023.

  1. Zachary9893
    Joined: Jan 2023
    Posts: 1
    Likes: 0, Points: 1
    Location: Chugiak, Alaska

    Zachary9893 New Member

    Hello, first and foremost, I’m sorry but this is not a boat. This is a high roof van topper that I am looking to extend as well as reinforce the 75 bolt holes for mounting around the base.

    I was able to get a parts van with a 24in fiberglass topper but unfortunately it was for the std wheelbase. I have the extended wheelbase so I’ll have to stretch it about 2 feet. What would be the best way to go about doing this? It only has to look nice on the outside, the whole inside is getting spray foam for insulation and sound deadening. It is very thin so I am wondering the best way to extend it. I was thinking cut it about 3-4 feet from the rear and stretch as necessary with an interior side mold.

    the next thing that I need to do is reinforce all the way around the mounting points. Most of them are cracked because there is only about 3/8 inch between the hole and the edge of the fiberglass. I was thinking some sort of metal flashing cut and bent as needed to reach around the base going up the inside around 3 inches of coverage inside and out with basically a full epoxy fill and just wipe off the excess spillage before it dries. Let me know what you think.

    The photo is the top strapped to the top of my van for transport to my buds heated garage. (It’s strapped on backwards)

    Attached Files:

  2. wet feet
    Joined: Nov 2004
    Posts: 1,396
    Likes: 435, Points: 83, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    Everything depends on two factors;how complex the shape is and how good a woodworker you are.The process is quite easy to describe and quite demanding to carry out.You need to set up what you have on a level surface,cut in in two,move the two pieces apart and find a way to fill the gap.You may have figured out that last part!Either build a temporary mould in place or make one remote from the job and then graft the extension into it's new location.Your piece seems to have several swage lines and these complicate matters as you will have to create a duplicate in either positive or negative form.For flat panels,melamine faced chipboard is a useful material and you can use polyester filler for the corner fillets or even plasticene if you are careful.

    For reinforcing the bolt holes,there is no need to use epoxy and it may not work well with the material you have on hand.Emulsion bound chopped strand mat may not break down in it's company and it costs a good bit more than polyester.You may find it sufficient to remove a bit of the old interior glass and brace the flange with a short piece of wood clamped in place while adding two or three layers of glass mat with polyester resin at each damaged hole.You can use cloth if you have it.
  3. fastwave
    Joined: Jan 2007
    Posts: 128
    Likes: 24, Points: 18, Legacy Rep: 36
    Location: europe

    fastwave Senior Member

    If there is a section which is an extrude (Maybe the middle) you can take a mould before you cut it in two. Then hopefully when you cutout in two that section will fit nicely between the pieces.
    Last edited: Jan 20, 2023
  4. wet feet
    Joined: Nov 2004
    Posts: 1,396
    Likes: 435, Points: 83, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    That would be a much simpler process if there weren't so many swage lines and recesses.From what I can see of the shape,the mould wouldn't release vertically and would need to be made in two halves that come away laterally.The two areas worth further study are the section directly above the join in the blue and white doors or the plain section between the green strap and the sloping panel at the rear of the carrier vehicle.these are the zones with the smallest number of geometric features.
  5. mudsailor
    Joined: Mar 2013
    Posts: 88
    Likes: 17, Points: 8, Legacy Rep: 25
    Location: United States

    mudsailor Junior Member

    Pick the cut location (in the middle and the simplest shape) cut it, then install the two parts. The bridge between the parts with 2x1 wood battens extending maybe 24” into each existing half on the inside, use multiple battens. Then remove the whole assembly from the van. Then use thin plywood to create a flush outer surface, paint and polish and then build a temp mold over the outside. Flip it over, remove all the wood battens and plywood and lay up the fiberglass as needed in the new mold and overlapping into the existing part.

  6. Blueknarr
    Joined: Aug 2017
    Posts: 1,451
    Likes: 414, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    The biggest hurdle you face is maintaining alignment of the two pieces.
    My approach---
    Cut at simplest shape.
    Mount both pieces
    Bridge the gap from the inside with sheets of 1/16" vinyl and duct tape.
    Lots of wood backing up the vinyl.
    Move to saw horses.
    Grind an eight to one bevel.
    Start laying glass.
    When nearly thick as original
    Remove vinyl and wood
    Fill screw holes with final layers of glass
    Fair and paint
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.