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  #16  
Old 05-25-2008, 12:20 PM
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kach22i kach22i is offline
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Quote:
Originally Posted by northerncat View Post
stianless staples around the edges fired only halfway in so they can be pulled out or tapped in as needed and start rolling from centre out
sean
I like this idea northerncat. I'm going to do similar with the screws and fender washers. I hope the fabric does not twist up.

Would you pound the staples with a hammer into ABS plastic, shower stall panel, wood and existing fiberglass work? I'm afraid to do this, the staples would have to be razor sharp to get away with this. If the staples were not pounded all the way in, the cloth would still move and be able to pull off, if even just a little.

How do I prevent the fabric from stretching and puckering once wet?

Limit the amount of resin saturating it?
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  #17  
Old 05-25-2008, 03:37 PM
SamSam SamSam is offline
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Originally Posted by the1much View Post
and SLOW the craft down by ALOT. that stuff is heavy, and will cause so much drag and friction,,that he may not even get it off the ground,,hehe,,k thats a little overboard,,but,,it does do that stuff.and im not sure how the stuff would handle being in the water all the time
Quote:
kach22i...One thing for you boat guys to remember is that the hull of a hovercraft is not in the water. All the typical quality of finish for hydrodynamic reasons are pretty much out the window.
I think with all the fiberglass panel, aluminum, plywood, screws and washers, glue and other gunk, there wasn't a whole lot of concern with weight, although you may be right in that there might be now. The thing is not meant to sit in water, and although bedliner might be heavy, compared to all the resin needed to adequately cover all those rough edges and sharp corners, exposed screws, etc. it could end up lighter. Coupled with inexperience in laminating, I have little doubt it would be a better idea.
Quote:
I would like to fiberglass over the aluminum, fiberglass shower panel, ABS plastic and wood rails/landing pads on the bottom of my hovercraft hull.
How well does epoxy stick to ABS plastic, anyways?
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  #18  
Old 05-25-2008, 07:41 PM
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kach22i kach22i is offline
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How well does epoxy stick to ABS plastic, anyways?
The resin is sticking to everything much better than I ever expected. Of course it may be a different story after a few hours of operation and several Michigan winters.

Weight is always a concern, the things added should by now equal the weight taken off; battery removed, starter removed, seat removed, etc.....

I need some more advice.

I used both the micro-bubbles (red) and 3M-balloons (white) as filler around my landing pads and landing rails. The thickest part is a 45 degree filler approx. one inch each leg along the aluminum tube seen in the first photo. I do not want impact shock or hull flexing to loosen the bond the filler has. The filler seems seems rock hard and very strong, does not look like it's ever going to go anywhere.

I figure there are three ways to proceed.

1. Do I just grid down and sand any rough edges and call it a day?

2. Do I just brush some resin on it after touch up finishing and call it a day?

3. Do I finish it with a layer of fiberglass cloth and resin?
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  #19  
Old 05-25-2008, 11:14 PM
Jratte Jratte is offline
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Ok, I'm coming into this a bit late but my first large fiberglass job was an upside down repair on the bottom of a hull. Here's how I did it.

The first thing that was key to this working was being able to vacuum bag the repair.

We erected a good size table, larger then the laminate we would be adding. Covered the table in plastic. On top of that we laid the vacuum bag material with bag tape applied to the edges. Next we laid down the breather material, a layer of release film, and then peel ply.

Under the boat we had a few jack stands set up with some plywood laid across them.

We wet out as many layers as we felt we could handle, usually 5-8 layers of glass. After being wet out, each layer was laid on top of each other on top of the peel ply, breather, bag stack. Once all the layers were together, we shuffled the whole pile onto the plywood and jack stands.

Then we wet out the underside of the boat with un-thickened and thickened epoxy and proceeded to screw the stands up until the pressed the laminate on the boat. The we pulled the edges of the laminate up, made it nice and did the same with the peel ply, breather, etc. until we got to the bag. Having the tape already on the bag made it go very quickly as placing darts were no problem.

Turn the pump on, check for leaks and let it cure. I can't imagine doing any substantial glass work upside down any other way. If doing something similar is an option I would consider it. Best of luck.
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  #20  
Old 05-26-2008, 07:43 AM
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Quote:
Originally Posted by Jratte View Post
Under the boat we had a few jack stands set up with some plywood laid across them..............proceeded to screw the stands up until the pressed the laminate on the boat.
Your method sounds top rate, I'm not in a position to do it the same way, but it's given me some ideas.

I'm considering a layer of sponge rubber or acoustic foam with wax paper on one side and plywood on the other. If I lay resin soaked cloth on the wax paper and press the assembly to the face of my anti-plow plane it should press flat on the flat area and still be able to form around the odd fluted edges which are all around the half-circle anti-plow seen in the second photo. I would have to figure out the best way to screw/strap/tape/bungie or maintain pressure during the curing process.

It's just an idea.


EDIT: Pictures...........needs sanding and coat of fiberglass cloth.
Not going for looks or finish awards under here obviously.
http://s184.photobucket.com/albums/x295/kach22i/



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  #21  
Old 05-29-2008, 10:46 AM
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I did some glassing last night. Problem areas as expected were the many flutes and curves on the ABS plastic. The flat areas were easy. Even the funny folds and bends on and adjacent to the landing pads went up quickly.

The little bit of chopped strands I used as a filler on my diverter/splitter sanded down just fine with a stick on pad triangular power sander.

I went to the local/wonderful Stadium Hardware in Ann Arbor which stocks West Systems this morning. I picked up some fine filler to finish my fan cone/spinner with (410). I also picked up some low friction mixing powers (graphite) 423 & 406 to coat "first contact" areas and problematic intersections on the bottom of the hull.

I'll post pictures, verbal descriptions will not suffice for the "seat of the pants" method I came up with.
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  #22  
Old 06-02-2008, 03:22 PM
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UPDATE: June 02, 2008

The key to working upside down I found is to get your resin into a paste-like state. You do this by adding fillers. Use the graphite additives for a slippery hull bottom and the recommended filler for body. It also helps if you duct tape one end of the cloth so you can have a good starting point which does not move around on you. Also the duct tape allows you to pull on the fiberglass cloth so there is no stretching or slack.

Much of the cloth texture is left exposed using this method, even if laying it on thick. I used one thin layer of paste-like resin followed later by a thinner finish coat to really gloss it up and seal it good.

http://s184.photobucket.com/albums/x295/kach22i/
Duct tape both ends and each side so that the fabric is stretched flush.


After curing, cut away with a mat knife unresined or unused cloth and any lose parts which you can pull off with a little tug.


Cut away openings so that a second lap layer can be done.


I used 2 inch wide cloth at the edges and pressed in with more resin mud. Reinforce high wear or high stress areas too. Then the whole thing gets painted with resin to soak in and protect intersections of differing materials.


Just another picture angle, this area received more colored resin in the air lift supply holes to seal the open cell foam. Open cell foam is bad, some of the expanding foam in a can is almost as bad when it comes to absorbing water.
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