Can I fiberglass over existing glass / mat ?

Hello everyone.
Sorry if I'm asking about something covered in another thread somewhere else but, I'm tired of searching the threads

I have zero fiberglass experience. Nada, None !!!!!!!!!

I'm removing the existing glass & mat on my wooden boats cabin sides and roof ( to replace the roof itself which is rotted and riddled with what seems to be hundreds of holes). The surface around the cabin (which extends from the transom forward reaching around the cabin and out over the bow) is covered with a layer of glass too. (see my gallery pic's). I only have to replace the roof so, I would like to remove only what is necessary.

My question is this: Do I need to remove all glass & matting everywhere ? Will the new resin and mat or cloth ??? adhere to the old glass and fiber left intact?

Thanks...

 

yes to ur ?, u will need to grind the glass down for the new to stick, the thing to find out is what resin was used before,

 

Hey Jack, thanks for the info. Unfortunately, I don't know how to tell what kind of resin was used. The boat was built in 1960 and I don't even know if the builder actually put this fiberglass on or maybe it was done at a later date during a previous restore / fix-er-up stage.

Any hints or advise here :?: :?: :?:

 

Probably poly resin. Grind with 24 grit for a mechanical bond. Should have no problems with poly resin but if your not sure, use epoxy.

 

to test for poly resin take a piece and burn it if it smells sweet its poly epoxy wont, i can tell the difference in the smell of the grinding dust, after u grind blow and vac the dust off, wipe down with some acetone to clean it up, what i ussually do is brush some resin and let cure, make sure the resin is unwaxed (laminating resin) for the first layer use chop strand matt this will help to bond ,cloth layedup with poly tends to delaminated ,do your self a favor and get a steel roller to bust the air bubbles out, 3 inch the best and a 6 inch will help to fair the glass out, try and finsh the layup a little shy , this will allow u to throw on some mud to fair with out sanding down the glass, and have a big bottle of water beside you for eyewash nothing worse then resin in the eye, take your time and work in sections nithing worse then resin kicking on u

 

one other thing when you lay up with poly the laminating schedule is matt cloth matt cloth this helps to stop delamination

 

Copy all that guys...
Thanks a bunch but, I have had a change of plans. All of the glass is coming off now.

Found a bit of rotten wood under glass here and there and remembered a few places that seemed to be "bubbled"... the glass was no longer (if ever) attached to the wood underneath.

Have removed 80 % of all glass at this point now and found more "bubbled" spots as well as entire sections that seemed to not have any resin sticking to the wood at all. A couple more rotten spots as well.

Dug out a book about fiberglassing for beginers from my collection of things that I bought when I first bought this boat.

The Fiberglass Repair and Construction Handbook
by:JACK WILEY​

Have done a little bit of reading... boy am I in for a lot of learning

Anyway, thanks everybody for all your comments. I'm sure I'll be looking back on these posts for future guidence.

When I purchased this boat, I had not realized that I was going to be so highly educated when it was all said and done. All I wanted to do is go fishing ​