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OK, so I'm Sanding My Bottom...

12K views 97 replies 23 participants last post by  Squidd 
#1 · (Edited)
But I'm from the Midwest and not so sure what I'm looking at...(all we paint out here is houses barns and tractors...)

Is this supposed to be so "lumpy"...



Doesn't look like any "paint" I've ever seen before... It looks "thick"... like an 1/8" thick and like it was put on with a spatula and back brushed with a whisk broom...that's just the "Red" layer...



And it's "Soft" almost chalky or powdery...some of it flakes off (in the blistery ares and the "layered" areas.. and then the rest is stuck on tight...

Below that is a light blue/gray also "Thick" powdery layer...





I think it had popped blisters as well and then the red went over that...

Below the Gray is a greenish chopped fiberglass layer that is hard...

The whole thing down to Glass is almost 1 1/4" thick...



But you can see some of the red also goes all the way down to the glass matt..

So what do I got here and what do I do with it...??

I'm thinking continue sanding all the blisters/bubbles down to the green glass matt and then fair and fill with some sort of epoxy/poly "filler"...?

Then fair the bulk of the bottom to smooth out the "lumps...

Prime (type) ??

Bottom paint...

What I'm looking for is advice on getting it to the "primed" stage...There's enough arguments/threads on bottom paint choices already...

Thanks in advance...
 
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#37 ·
Exactly...

My goal is to fill, fair, put a sealer/barrier coat on and biocide paint...

See what it looks like next spring and "maybe" in a couple years a total redo...

But really it's a $3k boat...I'm not planning on putting $5k bottom job on it...
 
#40 ·
If you'll look at the photo of the strainer, it is surrounded by white surface. I think that's your gelcoat. Everything on top of that surface is either old paint, or dirt or algae covered with old paint. I don't think most of the pits you are seeing are "boat pox." I think they are simply many layers of peeling paint. If you get all the red and brown and blue stuff off, eventually you'll get down to the white gelcoat, which is where you want to be. You don't want to remove the white gelcoat.

I wouldn't apply any filler to try to smooth it out, because I believe you'll be filling pits in old bottom paint and dirt, sealing them there forever. You have done a terrific amount of hard, nasty work, and smoothed out the original mess fairly well. My suggestion is that you apply one coat of ablative antifouling and enjoy sailing the boat for the summer, and then, next spring, have another go at it, and finish the job. After it's finally done, if you use no more than one coat of good quality ablative each year, you'll probably never have to strip it again. After you get rid of all that old paint, you'll be able to see whether there really are any osmotic blisters under it. At that time, you can decide whether you need to do anything about them.
 
#43 ·
Mon has it right - where there is bare glass showing, it is surrounded by white - almost certainly gelcoat. I would at least paint some epoxy resin over the bare glass that's showing before putting on bottom paint.
 
#48 ·
I know everyone is just trying to be helpful which is what makes this a great place. I know that Squid has done a lot of research on this and actually read these articles on blister repair (posted earlier): Hull Blisters on Boats and Yachts - by David Pascoe, Marine Surveyor
and: Sea Lake Yacht Sales (Kemah, TX) (posted by Brian/Mitiempo)
written by surveyors with quite a bit of experience in hull blisters.
If you guys and gals read the articles you will find that neither surveyor has a high degree of confidence in conventional blister repair techniques recommended by most boat yards. Can any of you say that you have heard of, seen, or experienced a blister repair job that was effective and lasting, whatever the method?

Squiddo is in Wisconsin and wants to sail his boat this summer during the short sailing season. I can't blame him. Given the likelyhood of eventual failure of the patches (no matter what method or materials) I'd be thinking of using the cheapest, quickest method (polyester) to fair the bottom and go sailing - hoping the patches last a year or two before needing to be readdressed.

I've seen it time and time again on my boat and on other boats in my yard. The owner diligently applies an epoxy patch to the keel or hull and in a few years that same patch needs to be redone. Faulty method you say? Perhaps, or perhaps that is just the way it is.
I hope I'm wrong as my friends Endeavor 32' got a case of the blisters after being left in the water in the Chesapeake for 5 years. One hundred twenty dime sized blisters in that thin laminate would make Squidd's hull look pretty good.
Anyone know of a sure fire method for fixing blisters? Anyone?
Didn't think so. Conventional wisdom is so... conventional.
 
#49 ·
So if the theories are correct, that the blisters are caused by unsaturated mat, is there anything to be said for applying penetrating epoxy (in the hope that it will penetrate and seal the mat better) before the thickened epoxy filler?
 
#50 ·
Blisters are not caused by unsaturated mat. The mat looks unsaturated after osmotic wicking has destroyed the resin that used to be in the fiber. Caleb - we have a couple boats that were done in the early 80's and still look great. Does that count?
If EVERY step is done correctly, a proper blister job will last decades. EVERY SINGLE STEP!
 
#51 ·
Well that's helpful. How about telling us what the steps are?

That doesn't explain why some brands have terrible blistering, and some get none. For an example of none, see my Bristol. They have the same bottom paints and gelcoat, and are in the same water. So clearly there's something different about the construction technique. What, is the question.

What we need is more wisdom, not information. Wisdom is backed by information, evidence, and reasoned argument.
 
#52 ·
There are very good, informative articles and threads, but start with the W.E.S.T. System how-to section on blisters. Instead of going over it inch by inch I'll just tell you the most common mistakes we see.
1. Individual blister grind instead of peel. When you grind out individual blisters there are a million smaller ones you didn't get.
2. Fresh water rinse every other day for the first 2 weeks. Glass fiber is like cotton fiber in your shirt. If your shirt goes over the side are you ever going to get it dry without washing the salt out of it? Of course not. The bottom of your boat is no different, the salt in the fibers will inhibit drying and screw up the epoxy bond.
3. More fresh water rinse to wash away the glycol compounds (one of the results of polyester osmotic decomposition) as they blush to the surface. Once these glycols have dried on the surface they're really hard to remove. Nothing sticks to glycol.
4. polyester or vinylester fillers - why mix chemistry? All epoxy all the way.
5. Nobody seems to want to prime the surface (with neat epoxy) before applying barrier coat. When Interprotect first came out, they wouldn't guarantee the 2000/2001 barrier coat unless you primed with 1000/1001. Now, nobody seems to care about it. We still prime because the neat epoxy soaks in, the barrier coat doesn't.
6. Insufficient millage - most barrier coats require 12 mils cured minimum. That's 4 or 5 coats. Not 2, not 3, FIVE! You know damn well the millage is not going to be uniform, why cheese it?
Hope that helps.
 
#55 ·
In the 60's all the Miami builders had a guy who mixed the resin for that day. He would adjust the cobalt, promoters, styrene levels for the moment they were about to use the product. It was a very custom, accurate way to do it. Today, we get summer resins and winter resins, that's about it. And there were no chopper guns then, wet out guns yes, but no resin rich gun chopped glass went into those boats. Then, the fuel crisis with rising prices and shortages. When was that, maybe 1973 or 74? Funny thing is....I don't remember any blister problems before the early 70"s. Coincidence? My view is, the resin got "watered down" and ****ty fillers were added to get it back to normal thixotropic properties which resulted in much worse hydrolytic damage. There are plenty of pre 70's boats around with original bottoms.
Also, Bristol was a pretty good organization back then. They didn't allow sub par work. The better the laminating crew, the lower the chance of bad blisters.
 
#57 ·
Appreciate all the input I'm getting on this bottom factor...Kinda like "discussing" the best anchor to use...

Here's what I'm seeing...There is no gelcoat on the bottom of this boat... I know what gelcoat looks like, there is gelcoat on the cabin and deck...the topsides are painted, but there is gelcoat below the Britesides ( I saw it when I touched up fender rubs)...

Just below the waterline, (green tape) is a blue line of gelcoat <w/some dark blue paint> and then it goes to the gray "Filler"....

There is no hard gelcoat "solid surface" to sand down to without going all the way down to the fiberglass matt.I don't know where the hard coating went, but it ain't there no mo..



I do not have the time, ambition or money to do a "Full Bottom Job" before I launch this season..I may do it in the future, but I have yet to see a full repair schedual I can believe in.

So I will be forging ahead on a Fill and Fair repair job, resin coating the entire bottom to tie it all together and then a couple coats of hard biocide paint for color and to keep the slime down...

I already have and will use a polester fiberglass filler...The can I have has a picture of a boat on it, says Marine on the label, waterproof and for above and below the waterline use...I'm fairly certain the gray matter on the boat is a poly filler (as do most opinions offered) and see no reason not to continue with it to fill divot holes...

At this point "spot coating" the exposed matt is a non starter if the filler right next to it is permeable, so after filling fairing and smoothing out (with wide spreaders, flat sanders and long boards) I will coat the entire bottom below water line with "Epoxy" resin witch should bond and tie in with whatever chemical soup is underneath... 2 coats and scuff sand for adhesion of 2 additional coats of hard Marine Biocide paint...

That is good enough for me for now and the bottom line is I'm the only one I have to placate anyway...

Will post pics in the Fall...
 
#59 ·
Here's what I'm seeing...There is no gelcoat on the bottom of this boat... I know what gelcoat looks like, there is gelcoat on the cabin and deck...the topsides are painted, but there is gelcoat below the Britesides ( I saw it when I touched up fender rubs)...

Just below the waterline, (green tape) is a blue line of gelcoat <w/some dark blue paint> and then it goes to the gray "Filler"....

There is no hard gelcoat "solid surface" to sand down to without going all the way down to the fiberglass matt.I don't know where the hard coating went, but it ain't there no mo..

What is the white layer next to the exposed mat? That sure looks like a glecoat layer.
 
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#60 · (Edited)
Thanks for that information FG1. Am going to do a barrier coat job on my old A35 this summer. Is good to hear experienced advice. I'm thinking of just using coats of West instead of Interlux and maybe even incorporating a layer of fine cloth between layers.
 
#64 · (Edited)
Also good news in my case as the boat will be "dry slipped" mast up on a trailer for a 5 month season then brought home and stored indoors for the winter...

That's about as dry as you can get it/keep it...(and still go sailing)

At that rate my "patch job" may last a good long time...
 
#63 ·
I asked about the colors above, because I wasn't sure I was seeing the gelcoat either.

It seems likely that a prior owner stripped the gelcoat off when trying to address the blister problem and then did a bad rebuild.

Squidd has a good plan. If you're not going to go all in on drying her out, getting the salt out and relaying a bottom (and I wouldn't on a 3k boat), then just get it done quickly and go sailing. See how you make out.

If it really requires a 5k bottom, I would sooner junk the boat and buy a different 5k boat that already has a good bottom.
 
#65 ·
OK I have applied my first coat of filler to many of the deeper divots, I'm sure I'll do a second for the ones I missed...



Next I laid out my weapons for fairing the surface smooth...I would prefer the random orbital for the dust collection aspect, but the sanding pole with the abrasive screen is supposed to produce a smooth finish with minimal mess when "wet sanded"... My fall back is the 1/3 sheet orbital which is known to produce a smooth finish , but creates a lot of dusty mess...



I'll do test spot comparisons before I get fully into it to see which tool actually works the best for my situation...
 
#67 ·
I'm kinda likeing the effect of wet sanding with the pole sander and abrasive screen...

Going from filling to wet sanding is really blending and smoothing the surface without multiple coats of primer and glazing...(I've bondo'ed a lot of old cars up here in rust country)

I don't know if you can see it in the picture but the filler has been blended.faired down to surface level high spots are coming down and sanding scratchs are dissapearing...



All with minimal mess and from a comfortable standing position...Thanks for the tip Gary...
 
#69 ·
Trav

Thanks for tip on the sanding screen, I have some heavy bottom work to do next fall and will keep it in mind.

John
 
#71 · (Edited)
Yeah, not too late, but unfortunatly I won't be needing the ace paper...

The 1/3 sheet sander "bit the dust" a minute after I started it up...I didn't even get to do a test patch..it was an old machine, been sitting on the shelf for many years (I prefer the RO) and must have rusted/corroded up from sitting so long...screeched and locked up...

The ACE "screens" seem to be holding up, I did one side the one side of the boat with 4 sheets (2 packs)... about what has been reported in some of the other "sanding" threads...

The RO is using some german made "klingspore" contractor sheets "Finish Line" brand....I only used 25 sheets to get the red off...and I bet I had 15-20 lbs of "dust" in the shop vac...

I will have more sanding to do, got at least one more round of filler to apply and fair out...
 
#73 ·
The 1/3 sheet sander "bit the dust" a minute after I started it up...I didn't even get to do a test patch..it was an old machine, been sitting on the shelf for many years (I prefer the RO) and must have rusted/corroded up from sitting so long...screeched and locked up...
Believe me, it did you a favour. That was the first sander I ever bought - it was so horrible I trashed it - I wouldn't even sell it on to some unsuspecting victim. All it did was vibrate your hand - completely useless.

The RO is using some german made "klingspore" contractor sheets "Finish Line" brand....I only used 25 sheets to get the red off...and I bet I had 15-20 lbs of "dust" in the shop vac...
I've been using Klingspore for years on my DeWalt R.O. - they are very good disks.
 
#72 ·
Glad your getting there! Sandpaper really varies in quality! The best seems to be available to the auto body business. But, most all auto-body sanding is done with 6" psa instead of the 5" H&L with vac holes in them. Norton bluemag and or green zirconia (3m?) is worth the cost though, I've used it. Home centers seem to sell low quality sandpaper. Also storage makes a difference, long term storage in a damp basement for example,the paper gets soft and weakens the paper's bond with the grit.
 
#74 ·
It's coming along nicely... two coats of filler dry sand, wet sand and now starting to apply first coat of epoxy barrier coat...

Really smoothing out from the lumpy mess I started with...



And I will admit I have more "gelcoat" layer than I first thought or reported...

The light blue layer was under yet another layer of paint, but is helping me carry a smooth line...there are large "patchs" of filler from previous repair attempts and I guess maybe I was concentrating on them and blinded to how much is still solid...
 
#76 ·
Nahh, I'm way ahead of where I started..another coat of epoxy... two biocide to keep the slime down and I'm going sailing...

Remember this is just fill, fair and seal for this year...too many variables laid down to get too excited over for now...


Seems the only way for "permenant" repair is going to be blast or grind "everything" off down to bare fiberglass matt and "rebuild hull" with epoxy and cloth and then start refinishing from there...

Dollar and time wise may be better off with a different boat...If I'm gonna put $7,000-$10.000 in a hull job on a $3,000 boat I' be ahead to sell this for a $1,000 add it to the $7,000 and buy a better looking $8,000 boat...(or a nice downpayment on a $30,000 boat...)
 
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