White spots on fiberglass

 

Hi, I'm building my first shearwater 17  I accidentally drop the boat on stairs  Now white spots appear   Is it common?  Is it that easy white spots would appear?  Im worried it's my building fault caused the weak bonding between wood and fg   What is the proper way to fix this?  Sandto wood and patch them with fg and epoxy?

Thanks in advance,

Chi

https://photos.app.goo.gl/gX2PpbxPymfJPiKb6

 


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RE: White spots on fiberglass

Hi Chi, 

ouch...  its frustrating when that happens....and yes you damaged the epoxy/fibreglass skin.....it is not necessarily indicative of a weakness in the bond but what happens in this type of composite construction if they take a point impact like what hapened by being dropped on a stair.

the good news is you built it...so repairing it is easy and can be done as you described.  that said, when i look at the picture, this is a very small dent and i would use a bit of sandpaper to remove the damaged glass/epoxy and just paint some epoxy over it and sand/smooth it in.  i don't think its worth the effort to put new glass in.  

also, before i put the epoxy down to repair it, i would wipe it with denatured alchohol.  if when wet, the 'whiteness' disappears....you will know you have removed all the damage.  if you still have whiteness after it is wet with alcohol, you still have some damaged glass/epoxy you need to remove.

otherwise, while it is a little picture, what i can see looks really good.  so keep up the good work.

h

 

RE: White spots on fiberglass

My take is that those marks - the big one at left, then the smaller group to right - are where your S17 encountered a stair's edge first, then again after a bounce or three.

They'll need to be carefully sanded away to bare wood, faired out a bit beyond the obvious damage so you don't end up with a thicker patched area once you sand the patch's edges later.

Looks to be mostly cosmetic not structural flaw. Important to ensure water can't make its way past damage, into the ply underneath.

RE: White spots on fiberglass

just a little note on repair without glass vs glass.  usually i will not go to the trouble of new glass until a problem is larger than 3/4 inch round.   i am assuming, based on the picture that it is a significant enlagement and the long side of the 'big dent' is a little less tha 1/2 inch and the width is less than a quarter.

to make an efficient "epoxy only" repair, once you have removed the damage material, put a couple drops of epoxy into the depression and place a piece of clear packing tape over it,   this will keep the epoxy in place and ensure the little void is filled.  when the epoxy hardens, just pull the tape off and finish it up with a little 120/150 grit sandpaper.  the tape helps you get  repair done in one session.

h

 

RE: White spots on fiberglass

 

 Thanks for the answers and advices. 
 

yes, the dents are small. I'd go for the epoxy only fix. 
 

Sounds like the damage is just cosmetic. The damage is on the bottom panel. I'm thinking of putting graphite/epoxy coatings on it. Does it means I don't need to fix them? 

Chi
 

 

 

 

RE: White spots on fiberglass

Hi Chi, 

i would still fix it - epoxy only.  what the white color means is that the glass has pulled away from the wood and now you have a little gap.  it's important in this construction technique that you do not create a pathway for the water to get to the wood.

if you go over it with more material, you will still have that little void....and you want to avoid those as over time, voids have a way of expanding and attracting moisture.  kind of like a little windshield nick on a car can expand and become more serious if the little nick is not addressed.

sand it out.   wipe it down with denatured alcohold to confirm you have the broken bits out, mix one pump of epoxy/hardener....place a drop or two of epxy in the little depression, place scotch tape or packing tape over it to hold epoxy in place till it cures......about a 15 minute job or less not including waiting for the epoxy to cure and a 2 minute sanding job once it has hardened.

not a bad little skill to develop.....every season i have an 'oops' with one of my boats......and i end up using this technique to quickly address it.

h

RE: White spots on fiberglass

   Hi h,

I'll follow you advice fixing it   thanks for your excellent explanation and advice.

 

Chi

 

 

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