Thread:

Crack in fibreglass.... Suggestions of repair method?

Originally Posted by BAHNER79AUSTRALIA

Hi all, thought i would post up another thread. I have a crack issue on the top of the shell, right on the top edge of the hull where it begins to peak, then heads down on the inside. Was wondering if anyone has any advice how to repair. I can V it out no problem, and fill with fibreglass filler.... But should i attempt to lay some glass/mat on the inside? Its quite tight up in there..... Did a quick sketch showing a cross section showing what i mean. Just thinking it might need more strength than just V grinding it out and filling......Any suggestions? I have this exact crack on both sides of the boat.

1 word GRIND, you will need to grind that out well past the fractured area and reglass with matt and cloth. Dish it out good and layup on the inside and outside.

How " Holorinhal " explained it to me and how he fixed some of the crack on his resto of the kona with v grinding " V-grinding is simply that you are making a cut, with a grinder and a carbon cutoff or grinding wheel, in the shape of a V. If You were to take a cut and turn it up and look at in cross section, it would look like a v,smaller at the bottom of the cut and wider at the top. The way you achive a v cut is to simply follow along a crack with the grinder, holding it slightly on its side, at an angle relative to the top of the crack, making a couple of passes with the grindre angled one direction and then the opposite angle direction. all v grinding does os gives the the stress crack some depth and body to expose raw glass and add new material to reinforce the all ready stressed area.Just be carefull on the depth that You grind down as not to grind completly thru the glass thickness. Thry to achive a width at the top of about 1/2" to 1" width then surface grind back past the V edge,in each direction, to a total of about a 3" width for the bite of the last layer of glass. when laying in the fiberglass cut alternating strips of mat and cloth starting with a skinny strip of mat wetted with resin and layed in the bottom of the cut and getting larger or wider fo each successive layer. In other words each layer should be slightly wider than the last until the last layer covers the 3" surface ground area the enttire length of the crack. Remember to grind out the crack a litle longer in each direction past where the crack ends to help stop the spreading of the crack. Build the fiberglass op slightly higher than the surface but not too much to make finnishing a little easier. Finnish the last two layers with matt then when cured grind or sand back down flush with the surrounding surface. You can start out with 36 grit to knock down the heavy stuff untill it is just barely higher, then switch to 60 or 80 grit to finnish then fill and final sand with 80 or finer grit. "

looks like from climbing into boat. thats is a common weak area. make a custom brace from stringer to side and will help it. dont make it to rigid or it will crack another spot

much luck.. Post some pic and detail when you do! Id like to see how it works out. Im worried ill end up with a high spot where i plan to fix mine..

[QUOTE=BAHNER79AUSTRALIA;1509763]Yeah your correct CP. The crack proceeds all the way through the glass. Was thinking of opening up the crack to a decent size, perhaps 5mm, then glassing from the inside as you have mentioned (Thanks for the wax paper trick). After that I was thinking of filling the opened crack with fiberglass filler against the new glass on the inside... Filling slightly higher than the outside surface for sanding down. The glass that has cracked is quite thin at this point... Looks like only 2mm odd![/QUOTE

I think it might be better to lay in a thickness inside first, then you can use your DA to sand a V angle outside and then fill in with matt.