thirdchildhood

iTrader: (6)

You got a lot done in 6 hours.

madbouyz

Kinda hard to tell for sure compared to your 1st set of pics , but you may be ok . The first pics looked like serious gel coat failure . In the 2nd set it looks like it was simply a case of 'mud cracking ' (or alligator skin) of the anti fouling paint due to heavy buildup or incompatible brands applied over each other .
You might find , after all , that when you get down to the gel coat it looks fine and there is no cracking at all .
You're lucky with that new paint . The Vivid alone cost me $410 where I am ! !
It would be a whole lot easier though if the boat was off the trailer and on blocks .
When it comes to applying the barrier coat the temptation is to roll it on , quick and easy . The problem is that due to its consistency when you apply the 2nd coat (on the timed basis 6 hours later or whatever it is) you get a very coarse 'peaking' of the finish . Maybe not a problem on a sail boat or displacement cruiser but it'll really create a speed robbing surface .

dunnitagain

Vivid is Awesome..... Spray it on Though , it will get rough if you roll it . It can be burnished to a nice slick finish if sprayed , but put on 3 or 4 coats.

scottgjerdingen

I'm sanding all they way down to the glass working under the impression that if there was a gel failure, thisi is the best thing to do. While I have all protectants off the hull, is there anything else I should do to it besides the Pettit protect and vivid, it is a 1969 hull. I have reached the fiberglass in some areas I have sanded, it is grey in color almost like the backerboard you lay down before tiling a floor...it is by no means they yellow/goldish color of fiberglass I am more familiar with....it also isn't the yellow/goldish color showing through in the areas where paint flaked off. What do you make of this ? Is this normal? Here are some pics.

[ATTACH=CONFIG]554656[/ATTACH][ATTACH=CONFIG]554657[/ATTACH][ATTACH=CONFIG]554658[/ATTACH][ATTACH=CONFIG]554659[/ATTACH][ATTACH=CONFIG]554660[/ATTACH][ATTACH=CONFIG]554661[/ATTACH][ATTACH=CONFIG]554662[/ATTACH][ATTACH=CONFIG]554663[/ATTACH][ATTACH=CONFIG]554664[/ATTACH]

madbouyz

I'm still having trouble exactly figuring out some of those pictures. It looks pretty obvious in at least one that you're going down to the original first layer of glass that the gel coat is supposed to bond to .
Take what could be called 'picture 3' above .. That doesn't look like a bottom painted surface to me , it looks like the bare yellow gel coat . Is that accurate ?
If it IS the untouched/unpainted gel coat of the bottom then I'd say that you're looking at completely stripping the original gel . And somehow it's caused the bottom paint to crack through as well.
I would consider it a pretty major job to remove all of the bottom gel coat properly , but at least it'll make a good surface to start off with a few good coats or barrier coat as long as it's spotlessly clean and roughed up a bit.
The problem is , you're not going to have a surface that is true and straight like the hull was when it came out of the mold . There's going to be a whole lot of dips and high spots all over .

Interceptor

You are using a respirator ?

scottgjerdingen

I am taking this all the way down to the fiberglass because there were cracks and blistering down to what appears to be the gel coat (and isn't this what would happen if it was soda blasted?). It's not fun but I am fearful that just painting over this will result in future cracks. If this is not the case, please let me know, this has been a lot of work. I am wearing a respirator, thanks for asking!

scottgjerdingen

interesting last few weeks. I bailed on the sanding, it crossed the safety line and I wanted a professional to do this. The place that does my repairs says they got a guy that will soda blast it. the boat sat there 4+ weeks trying to get someone to blast it. I found a dry ice blaster that said he would do it, so I grabbed the boat to take it to him....then he went silent. So, the boat is back in my driveway and I just gotta suck it up and sand this thing myself.

As was predicted above, taking all paint/gel off and going down to the fiberglass is resulting in some ripples in the glass which can be mitigated by sanding them out....but then I am also taking off some amount of fiberglass so should I be flattening these out within reason. Where ripples are deep, I am thinking I should go the other way and "bondo" these areas with Marine Tex Mighty or Bondo 762 Bondo-Hair Long Strand Fiberglass Reinforced Filler http://www.amazon.com/762-Bondo-Hair...omotive&sr=1-2 or
Any of these recommended for patching hull indentations (and fixing some sloppy sanding mistakes)...seems like Marine Tex Mighty is the way to go.

As I continue to look ahead I am wondering if there are rationale things I can do to strengthen the hull, it is roughly a 50 yr old hull and is driven in a spirited manner. I don't even know why this thought came to mind other than when I am designing and building something I always over engineer for strength. I did take a lot of gel/paint ott, it may sound like a fish story but there were at least 5 different coats that measured from a good 1/16" to a bit under 1/8", is there strength & durability that I have sanded away? I am in a bit of a rush to get this in the water.but if there is something that should be done before it is painted, now is the time.

Lastly the paint - Pettit protect - white & Petit Vivid - white (2 coats of each)

Any suggestions to keep me on the right path?

dunnitagain

I would only use a Good Filler rated for Below the WaterLine . Like 3M , or any of the other Marine Grade materials . GlassDave has all the right answers with his vast experience , read his Posts or PM him .

scottgjerdingen

It's been a while since updating this so I will do so now., the boat (hull) is all sanded (such an ugly job) and I am now on the 3rd coat of pettit protect with 2 more to go, then 2 coats of the vivid. Rotating the grey and white pettit protect sure makes it a lot easier to see each coat as it is going on. I'm going to close this thread and continue my questions in another thread.