Perhaps an interesting topic?

[Mark]

Water and GRP. On several sections of my yacht the gelcoat has small cracks. Of course I am concerned about water getting in and ruining the fibre glass. However having recently spoken to a yacht builder he has said that the only time you get a problem is where the glass has not been completly saturated with resin. In other words if water comes into contact, over a period, with "dry glass then a problem will develop however if the glass has been laid up with the resin well and truly saturating the glass this in itself will prevent any water damage. Anyones thoughts??

 

[Capt J]

Correct

I agree with the yacht builder you spoke to. I used to work in the industry and as long as the fiberglass has a full penetration of resin there will be no water damage or leaks. The resin is the "water blocker" and the fiberglass is the strength. All the cracks are, is an exterior cosmetic blemish that can be fixed if you so desire. I do not know what brand boat that you have but it has been built using one of two methods of laying the glass. One is a chopper gun that sprays in a combination of resin and chopped fiberglass that is than rolled into the mold over the gelcoat or it has been hand laid in mat form then the resin is sprayed into the mold and rolled. Either method will usually yeild a completely saturated fiberglass hull. If I were you I would not worry about anything other than the cosmetic aspect of the cracks.

 

[crazy dave]

info

Mark;Generally you will find cosmetic gel coat cracks in angles which is common with all boats. If it is below the water line with the boat in the water, I would address that as the glass and resin is in contact with water all the time. Contrary to what others may say, constant contact of fiberglass and resin with water all the time causes a chemical reaction and thus large blisters do occour over a period of time. If on top, not a worry.I would address those on top. It is not difficult to fix. Take a dremel and cut the gel out from one end to the other end of the crack. Clean and then put in two part epoxy and let dry. You may have to sand it and put more on if on a vertical surface. When smooth, take some gel coat and brush it on and then resand smooth as this will fill in the pores.Then take a Pre Val sprayer and mix with gel coat, hardner and acetone (20%). If that mix does spray out smoothly you are fine but if not just add a little more acetone. First spray in the affected area. Then overlap with additional layers. Let dry and sand lightly using wet/dry sandpaper like 400 grit. Then compound.Cracks in the curves do require some more time as to the sanding versus on a smooth flat surface.