Suggestions on screwing into fiberglass

[78vip]

I have asked this question in a previous post and the suggestions were to possibly use velcro so my seats and cushions could be removable which is a great idea but come to find out where I am needing to put them is slightly concaved so they wouldn't be flush. Anyways, this is a 1978 VIP 16' fish-n-ski boat that I have redone all of the seats and cushions on which are marked in red on the pic . The blue color on the pic is to represent the round pieces that the screws go in to so the screw doesn't go through the material. Those little round pieces I cannot find anywhere for some reason as I have been to various upholstery places as well as lowes and home depot. My questions are these: What type of screw do I use to go into the fiberglass? Do I need to drill a pilot hole first? Do I need to put some sort of tape or teflon down where I am drilling first? Also where would you all suggest getting the round washer type plastic pieces I spoke of earlier? My thinking was to temporarily put some velcro strips to hold the cushions where I want them and then drill a smaller than the width of the screw hole and then just drill the screw into the fiberglass.. What am i missing? Forgive my ignorance, I am new to this whole deal... Thank you in advance..

 

[Greg Mrozinski]

Re: Suggestions on screwing into fiberglass

Vip,

I see a couple options. One would be to use oval head ss screws with finishing washers. You could use machine screws w/nuts if you can access behind the gunwale or you could use tapping screws and just screw them in place. Predrill the gunwale slightly smaller for the tapping screws or full size for the machine screws. From the out side you would see the oval head of the screw and the rounded edge of the finishing washer.

Second option would be to do the same as above except use pan head screws with plastic screw covers instead of the finishing washers.

The screw goes through the clear piece and color portion snaps over top. You might need to add a little adhesive if using it in deep pleat so the movement of the material doesn't dislodge the cap.

 

[Woodonglass]

Re: Suggestions on screwing into fiberglass

You might consider these

http://www.tech-fast.com/html/pine_tree_clips.html

You could make your covered buttons from your vinyl material and then attach the panel using the pine tree clips in predrilled holes

I'm just sayin...

 

[ajgraz]

Re: Suggestions on screwing into fiberglass

For reference, here is a link to your other thread on this topic:
http://forums.iboats.com/showthread.php?t=446941

I like the pine tree (xmas tree) clip idea of Woodonglass, though may I recommend you consider double-ended like these:

http://www.itw-fastex.com/catalog/index.php/dw/op/a/7/c/17/p/15?m=no

And perhaps do away with the upholstery buttons altogether. All those do is snag fishing line and bathing suits, anyway

(BTW, you can order free samples from that link)

I do wonder though, IIRC you said these are made from vinyl-wrapped foam stapled to wood, yes?
How much wood? How thick is the foam? How large are the cushions?
How heavy are these, and how heavy are they going to be when the foam absorbs moisture (which is inevitable)?

(I'd love to see some photos posted of the new cushions, front side and back, and a description of their construction)

What I'm getting at is, I am wondering if these things will be too heavy for plastic Xmas tree clips, or even for the holding power of velcro?
(Maybe the butt-cushions can use glued-on velcro just to keep 'em from sliding around, but I worry about the "vertical" cushions)

Someone in the prior thread mentioned z-clips or upholstery clips. That works well for holding heavy cushions, but those can get to be VERY expensive, particularly in aluminum or stainless (i.e., non-rusting).

If it's not too late to take apart and re-staple, you may want to consider some sort of through-bolting.
I see from your pic that this is an open bow trihull. I assume you can easily get your hand up under the gunwales in the cabin, but can you do the same with where the cushions in the bow will go?

If so, you could maybe re-engineer your cushions such that you use 1/4" stainless steel T-nuts in the wood, like in this thread:
http://forums.iboats.com/showthread.php?t=397623&highlight=stainless+t-nuts

(BTW, that thread also has links to the thread(s) where the T-nut idea came from)

Then you use 1/4" stainless hex head bolts and fender washers from the rear to through-bolt your cushions into place, length depending on the thickness of the "wall" you are bolting through. Again, this will work only if you can get your hands and tools up under where the bolts have to go.

That's how I re-did my open-bow trihull, and those cushions ain't never coming off unless I want them to.

I considered all those options and more:
Xmas tree clips: fear would be too weak
Velcro: ditto
Snaps: ditto
Z-clips/s.s. upholstery clips: too expensive

Before deciding through-bolting was the way to go.

BTW, good online source for inexpensive stainless hardware, buy anywhere from individual pieces to mega-packs:
www.boltdepot.com

 

[78vip]

Re: Suggestions on screwing into fiberglass

This is the material I used to cover the seats/cushions with (Tan color):
http://www.joann.com/joann/catalog/...e=search&flag=true&PRODID=prd23669#pro_colors

This is the 2" foam I used for the seats/cushions:
http://www.joann.com/joann/catalog/productdetail.jsp?pageName=search&flag=true&PRODID=xprd1130462

I used 3/8" treated plywood for the backing:

The construction process:
I took off the old seats and ripped off the old vinyl material down to the wood and used that for a template to trace onto the new 3/8" treated plywood. I then cut all of the marked pieces out. I then cut all of the 2" Nu Foam material to fit the plywood and spray glued them to the plywood. Then I just basically cut the marine vinyl and wrapped it around the Nu Foam and plywood and stapled it on the backside of the plywood.. Attached is also a crude pdf that I had originally created in autocad in order to figure how much material I needed and the sizes. As far as the weight of the cushions/seats they actually range from being very light to pretty heavy.. Really the heaviest pieces are the long side rails that are to be put on and also the one long piece that is up front that is a seat. As far as being able to get behind anything that I am screwing in to: The seats/cushions up front I would not be able to get behind the fiberglass for a nut or whatever.. Now the side rails I can get behind to hold a nut for a bolt or whatever type.. I know the pictures are horrible and I apologize but my phone is not made for pictures. Thank you for all of your replies/suggestions so far.. I hope this explains a bit more of what I am trying to accomplish. Let me know if you need any more info.

 

[Greg Mrozinski]

Re: Suggestions on screwing into fiberglass

Now that I see what your cushons look like, it's too late to consider going through the material because the vinyl will not stretch enough and will tare too easily if you try to put a fastener through it. I suggest for the gunwale pads to put a threaded insert into the wood and then put a corresponding hole through the gunwale and run a machine screw from behind into the back of the pad where the insert is located. In hind sight you should have installed tee nuts in the wood and marked the locations before foam and wrapping. For the bow area it is a little more complicated. I would take a piece of aluminum sheet (1/8") and cut two pieces about 3" wide and roughly the length of you cushon. Put small off set bends along the length so that they can hook together on top of each other. Attach one piece to the pad back and the other to the fiberglass. Then slide the cushon on, interlocking the two. See the diagram below.

 

[Woodonglass]

Re: Suggestions on screwing into fiberglass

Gregs suggestions will work. Or you could still use the Pine Tree Clips. All you would have to do is cut out a piece of 1/8" Fiberboard drill to match the back of your panels drill your holes in the boat thru the panel just like you were mounting the backs and seats. then Mount the Fiberboard to the back of your Backs and seat using screws and Gorilla glue. Coat em with some polyurethane and snap-em in place.

Not sure how many clips you'll need. I'm guessin 5 on top and bottom and 3 along the sides..

I'm just sayin...

 

[Woodonglass]

Re: Suggestions on screwing into fiberglass

deleted

 

[Greg Mrozinski]

Re: Suggestions on screwing into fiberglass

Wood,

That's a good idea also.

 

[ajgraz]

Re: Suggestions on screwing into fiberglass

At this point I think I'd agree with Woodonglass' post above, using a piece of fiberboard or some such as a template to transfer the hole locations, and using A LOT of Xmas tree clips per panel to hold the weight (maybe one every 4 to 6 inches around the perimeter).

Difference is, I'd use the template to also drill the holes into the wood backing of the cushion, use those double-ended Xmas tree clips, and not bother with sealing the template and adhering it to the cushion.

You could use cheap scrap cardboard for templates that way, and also not add weight to the cushions.

EDIT: as to actually drilling into fiberglass, here's what I do:

1. Put a little blue painter's tape on the gelcoat
2. Start with a small pilot bit to make the initial hole
3. Follow that with a bit slightly larger than the desired hole, and spin it backwards with some pressure to create a "chamfer" in the gel coat
4. Finish with the desired bit size.

 

[78vip]

Re: Suggestions on screwing into fiberglass

Those are all excellent suggestions.. I appreciate all of you taking time out to reply to my post.. Thank you for your time.