Outside sanded, ready for fiberglass..a few lessons learned

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Grumple
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Outside sanded, ready for fiberglass..a few lessons learned

Post by Grumple » Mon Jul 13, 2015 7:52 am

Hey Guys,

So I spent my weekend preparing the outside of my hull for glass. The big tasks were shaping my second outer stem and sanding the hull. I ended up sanding more material than I planned for a few reasons but I think I'm ok as long as I only take off a minimum amount of material when I sand the inside.

I few anecdotes to hopefully help others avoid mistakes I made:

When I glued my outer stems I left a mess of epoxy squeeze out on the sides of the bow/stern underneath all the straps I used to hold the stems in place. This was a big mistake as it took me forever to clean it all off being careful not to damage the strips.

Prior to sanding, I tried a few ways of removing the ridge where strips meet each other, but was getting tear out using my scraper, plane, etc. I thought I was being clever when I realized I could hold my random orbit sander at an angle and 'feather' the edge along the ridge between strips. This removed the ridge without touching the strip centers as was suggested in CanoeCraft.

HOWEVER, as I got progressively more tired/impatient after hours of this process, I started to make mistakes, and in one area in particular I started feathering into the strips a bit too much here and there. I freaked out a bit wondering if I had really just ruined my project after all this time and effort! I was able to sand this smooth again later, but I suspect I removed a solid 1/16" of material from the outside of my strips in the process. Now I'm going to be paranoid sanding the inside!

I also found that in my final sanding I had a few tiny gaps open up in strips that hadn't shown themselves before. Anyone else finds this can happen? I'm planning to try to just 'inject' a bit of epoxy into these gaps prior to laying on the fiberglass. I don't want to make a mess filling cracks as I don't want to have to sand anymore...

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Cruiser
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Re: Outside sanded, ready for fiberglass..a few lessons lear

Post by Cruiser » Mon Jul 13, 2015 8:25 pm

Hi Grumble,

This post is where I posted pics of the same issue and I dealt with it as you intend. If you go down near the last part where the Kipawa stuff is posted, you will see the pics.

viewtopic.php?f=3&t=637&p=28690#p28690

My advice to you is to just leave the gaps alone, it's a lot of effort, the epoxy can bleed to other strips and it is a %^$#@ to get it back off, so unless it's really bad .... I would consider just letting the initial wet out take care of the gaps.

I did do it, it can work, it is a lot of extra work and I don't think I would repeat it. Just my opinion.


Brian

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Grumple
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Re: Outside sanded, ready for fiberglass..a few lessons lear

Post by Grumple » Wed Jul 15, 2015 8:00 am

Hi Brian,

That's probably a good suggestion. I'm waffling back and forth about whether to try to tackle the cracks before the wet out. They really are relatively small and there are only a few, and I would love to avoid any sanded I can at this point as I'm paranoid about strip thickness.

My only concern that makes me tempted to try to inject some epoxy is that I might trap air under the cloth at the cracks if they aren't filled. Having no real world experience with this phase I'm not sure how serious of an issue this is. =P

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Cruiser
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Re: Outside sanded, ready for fiberglass..a few lessons lear

Post by Cruiser » Wed Jul 15, 2015 7:39 pm

Unless they are very sizable, the fiberglass wet out should allow then to fill and disappear. That's what happens to all the staple holes when you build with staples. The epoxy soaks in and fills the holes, you don't get hundreds of tiny bubbles...just filled holes.


Brian

alick burt
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Re: Outside sanded, ready for fiberglass..a few lessons lear

Post by alick burt » Thu Jul 16, 2015 1:28 pm

Hi Grumple
I would make this the guide to whether or not you should fill the cracks.
1.If the crack is big enough to go right through to the inside of the hull fill it.
2. if it is only visible on the outside of the hull don't worry about it.

If you fill with epoxy and sawdust trying not to put too much on to begin with is the key to an easy clean up job.
As an easier to sand alternative you can use ordinary wood fillers but getting the right colour can be tricky, which is why I still use epoxy and sawdust mixtures mixing up different quantities of light and dark dust to get the colour I want.
If you fill with epoxy alone you will have some clear cracks that will show and without microfibres or dust the filled crack may be weak.( just a thought).
Cheers :wink
Alick

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Grumple
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Re: Outside sanded, ready for fiberglass..a few lessons lear

Post by Grumple » Thu Jul 16, 2015 3:15 pm

Ok thanks guys, that sounds like good advice.

Based on your input I should be able to get away with just letting the wet-out cover the few cracks. None of them go through to the inside of the canoe, and they are small enough that I'd have a hard time cleanly feeding epoxy into them in the first place.

I've some final prep work to do, then Saturday the outside fiberglass goes on....wish me luck!

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