Ford Focus Boat Tail design

[HydroJim]

I'm looking to make a boat tail for my ford focus. I want to make a permanent boat tail and was looking for ideas because I have no idea how to tackle the tough angles and curves on the focus.

Coroplast is cheap and seems easy, but it's hard to make curves in and I'm not sure how I would support it. I was thinking fiberglass on foam, but I'm not sure how I would go about putting that together.

I've attached 2 pictures of what I'm dealing with.





Any Ideas?

[BamZipPow]

I'm guessing you don't have a lot of fabrication experience...I would start with cardboard (free is good) and work with that first. Git some ideas working and then progress into the more durable materials...

[Daox]

I'd do some searching on the forum. A bunch of people have made boat tails and kamm backs for their cars with numerous techniques. Find one that you like and give it a shot.

[ecomodded]

With a mini car maybe a mini boat tail.
A glorified Kammback.
Say 3-4 ft long, attached in such a way as to retain a functioning hatch.
Having the bottom shaped around the bumper & free hanging.
Constructed using your favorite ecomodder's proven technique.
I like the idea of mocking it up in cardboard, to help develop a good design and address the fabrication idiosyncrasies, of which their could be many.

[redorchestra]

i dont know if it would be perfect benefit but i would build a kamm back between the tail light s. attach to the glass portion of the hatch, and over the little spoiler. it would allow the hatch to be functional and the tail lights to be used as stock

[redorchestra]

For a boat tail I would follow ecomodded advice.


I know my angles are off, but just to show you the alignment

[euromodder]

If you want to keep it simple and straightforward (or rather straightaft ...), how about a box cavity ?

http://ecomodder.com/forum/showthrea...-cd-21175.html

It also includes a picture of a base plate - the end plate of a virtual boattail on a stick.

[HydroJim]

I've been looking at the car and I have a pretty good idea of what I'm going to do.

I'm going to use aluminum bar. I'll use the bar to build a frame and then attach coroplast to the metal frame. Do you think I should use bolts, self-tappers, or rivets for that? I have a picture of my rough idea attached

In order to make the hatch still functional, the gap between the car and the coroplast will obviously have to be unsealed permanently. Since I am keeping the hatch installed, I don't have to worry about water, but I am worried about the airflow getting under the coroplast. I was thinking of getting adhesive rubber foam so that when the hatch is closed, the foam will act like a weather strip and keep air and excessive water from going inside the boat tail. I chose the foam over rubber because it will glide across the paint easier and it won't destroy the paint when it rubs during opening and closing. I have a picture included to show what I'm talking about.

PS excuse my poor skills in paint

[aerohead]

If the tail is going to swing away with the hatch you'll need to know if the geometry of the existing hatch hinges will cause interference and binding as the tail swings from closed to open position.The top of the tail may want to collide with the roof when raised.
If you had a sturdy hatch-mounted bicycle rack the tail's superstructure could be attached to that and then 'skinning' only the perimeter of the tail,where it must interface with the Focus' body,you could move the tail through it's entire range of motion to be sure that everything will clear.
If you like what you see,then you're good to go with a permanent shell.
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Cardboard and masking tape can be used to construct a mockup for actual on-road testing (tufts and mpg).
If you're pleased,graduate to coroplast and aluminum.
Fiberglass over foam is also a great way to construct.
You can also do fiberglass wet layups over cardboard directly on the car ( with a suitable 'release area prepared) and later soak the cardboard out from 'underneath' the glass layup after completed,leaving only the glass shell.

[HydroJim]

At the top of the hatch, the hatch is about 8 inches from front to back and it lifts up over the roof, so there is plenty of clearance.

Thanks for the tip, I would have been unhappy to find out that the hatch wouldn't open up!