Refinishing Hull

Discussion in 'Fiberglass and Composite Boat Building' started by RufNutt, Jan 8, 2013.

  1. RufNutt
    Joined: Jan 2013
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    Location: East

    RufNutt Junior Member

    Hello everyone decided to join your forums today as there seems to be a wealth of info here and some talented people. Been reading here for a few years now.

    Anyhow I decided to flip my Hull to refinish it , the rest of the boat has been restored including stringers and deck.

    I decided to build a boat dolly

    [​IMG]

    I also built a rig to hook to the transom to assist in the flip

    [​IMG]

    and herer it is flipped and ready to go to work

    [​IMG]

    The biggest concern I have is the spots I found on the hull. They seem to be up to an inch and a half in diameter but most are under an inch. I took the pictures to the local recreation dealer and he said it looks like the spots had contamination as the fiberglass is dry or there was a problem with the chop gun and catalyst mixture as it seems to be pretty consistent as to how far apart they are. They are all dry like I said and the fiberglass is dry.

    Here are a couple pictures

    [​IMG]

    and a close up

    [​IMG]

    I was thinking of doing a complete spray of gelcoat on the bottom but am looking for suggestions on how i should prep and finish these areas.

    Maybe i should look at other options instead of gelcoat?

    Any suggestions?

    Thanks
     
  2. RufNutt
    Joined: Jan 2013
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    Location: East

    RufNutt Junior Member

    After investigating further it seems to me gelcoat is out of the question. There is going to be a bit of fairing to do. So I figure I will go with an epoxy resin.

    Question I have is since we don't use csm with epoxy what type of mixture should I be looking to use to fill in the voids before i do finer fairing?

    Should I fix these areas before I sand the whole hull or do the sanding first then fix these areas?

    I figure I might go with like a flexible barrier coat say IP2000 . After reading some info on the net some people suggest to put a coat of IP2000 in the voids first before trying to fill the areas , then fair.

    I suppose I should use something with some strength to fill the voids before fairing.



    Any info would be appreciated

    thanks
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    Grind out the bad spots (blisters and what appears to be some impact damage) back to good, intact laminate. Then fill the depressions with a mixture of milled fibers (milled, not chopped), silica and epoxy. Trowel it on until it's just shy of the surface, leaving something for the fairing compound to live in. If the depression is especially deep (more than an 1/8") you can cut some patches of light cloth (4 - 8 ounce) and bulk up the depression before the milled fibers go in, saving some filler. The milled fibers (and cloth if necessary) will restore the strength to the area and the silica is used to control resin viscosity.

    As to sanding the hull, well prep is always done first, right. A barrier coat needs the surface "toothed" up so it has something to grip. The repair areas will be ground with an aggressive grit, say 16 to 40, but the gel coat just needs to be scuffed. It all depends on the level of finish you want. If you want a mirror finish, you'll have to prep the surface so it's both fair and mirror smooth. If you can live with less, you'll be able to decrease the amount of surface prep necessary.

    Don't "pre-treat" the imperfections with barrier coat, it'll just have less stickum ability, than a direct epoxy bond.
     
  4. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    Thanks for the reply Par,

    I have to order some milled fibers as I only have 1/4 chopped here.

    Another question I had before i start prepping and sanding the complete hull.

    Right now I am just finding my repair spots and digging them out with a pick and scraper. I will hit them with my sander or dremel after..

    What should I wipe the hull down with and do i need to get all the stains off from being in the water all summer. I have some surface cleaners used for before paint work to remove grease and wax and some acetone. Have read about contamination being spread by sanding compromising the bond of materials.

    Should I wipe the hull down with a cleaner before sanding and again wipe down after prepping then continue?



    UPDATE!

    After my trip to town to look for some milled fibers and no luck I ordered some on-line, but the guy got me thinking again.

    The guy questioned me what I was doing, I said just refinishing my hull, next question what are u going to be putting on it, I said an epoxy , he said you have to protect the epoxy from the uv rays or it will turn chalky.

    Well the reasoning for me to go with epoxy is there is a problem on the bottom of this hull let it be blisters and there is some impact damage. So I figure with the new technology epoxy is the way to try and keep things sealed.

    Reason for not going with gelcoat after doing lot's of reading is really it was intended to be used on a mold and not to be sprayed on and sanded back down to get the orange peel off then to buff it up to get a shine. First of all you have to thin it and the shine is in the pigments so you are compromising the gelcoat right away with less pigments to shine. Also it is known to yellow alot quicker.

    So it comes down to maintenance after the finish.

    Most likely this boat is going to end of in Newfoundland in 5 years tied to a mourn bobbing around in the salt water for a couple months But over the next five years it is going to be used in some black water as u can see by the lines on the boat now.

    My biggest question is what do I put over the epoxy ip 2000 below the water line. I want something white . I am going to go with a white topcoat above the water line.

    Any options would be great.

    I never worked much with epoxy before but I know I loved it when I put the deck down.

    Thanks again and sorry for all the questions.
     
    Last edited: Jan 10, 2013
  5. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    Par you were exactly right 85%- 90% of the blisters I am getting into today are from some sort of impact damage. Maybe tied to a dock in a wild storm etc. I got to remember I never knew how the previous owner actually treated the boat :) After I start chipping away at them you can almost peel off chunks surrounding the blister , a layer of gelcoat with a few fiberglass fibers and it will quit chunking back when you get to good fiberglass.

    It is great to have people like you with the knowledge to help us out. I guess my biggest question is from my last post. When should I clean down the hull and what should I use, before or after sanding.

    I also need to know my best root of attack so I can order some supplies as to what I should put on the bottom after all the fairing. Is IP 2000 ok with some type of uv protection or should I use something else.

    Thanks again Par and anyone with any suggestions please make a post as you are the fellows with all the experience
     
  6. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    picture of what I figure is impact damage

    I included a picture of what first looked like a blister then after further investigating and poking with my pick it sort of come off in big pieces about 1/16 of an inch in thickness .
    [​IMG]


    Looking at the picture you can see where the blister was as it is the white spot in the fiberglass. I figure after grining the area to good glass, which will not take much I should be left with about 1/8 of an inch depression. If I end up with more I will back it up with some 6 oz cloth I got first.

    Can I put my filling putty mixture right in the area just after i put the cloth in or should I wait for the cloth to set up first.

    Thanks again
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    When I'm faced with these types of repairs, the very first thing I do is clean the hull. Surface contaminates, can get ground into the laminate and screw with bonds other wise. A heavy pressure washing, then a hand scrub with a strong detergent. Now you have a level playing field to start with.

    The first decision is local patches and gel coat repairs or wholesale accommodation of the defects and paint. Most boats this size don't have bottom paint, because they live on a trailer, so this is a big decision. Seeing the amount of blistering and damage, I don't think you have mush choice and a wholesale approach is very probable. With this decision made, I'd just work on the "spots", grinding and feathering as needed. Filling and rough fairing operations first, then sanding the whole bottom of the boat comes along. Finish fairing and smoothing, in prep for paint is next.

    Log onto westsystem.com and Systemthree.com, then download their free user's guides. These cover blister repairs, filler choices, etc. the processes employed are the same, regardless of brand and your increased knowledge, will explain and answer the majority of your questions.
     
  8. thudpucker
    Joined: Jul 2007
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    thudpucker Senior Member

    PAR makes that sound so easy I almost went out and bought a Bashed up Glass boat to fix.
     
  9. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    Thanks Par for the info, now to make some decisions.

    LOL @ thudpucker....the boat looked to be actually in pretty good shape, had a guy look at it and he said the same thing I thought it needed some blisters fixed and the price was right (free). never thought blisters were from impacts. Anyhow my labour is free and don't mind doing the work and I have to look at what I have when I am finished and if it breaks off the mourn down home in a storm I will only be out my cost of material to get the boat looking good again as my labour is free when you are retired :) . Damn I have seen boats beat up alot worse then this fixed and if you never seen pictures of the before you would never know
     
  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Blisters aren't from impacts, though a few spots do look like they might have been. Blisters are from the crappy resins used in your era boat.
     
  11. RufNutt
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    RufNutt Junior Member

    Actually last year after doing some reading about blisters some people say even though they cleaned up the blisters they came back again. I wish I would have taken a picture of before. Actually last year after reading a guide or something , it said to take a dremel and clean out the blister then take your sander and feather edge it , then start the repair.

    The other day I read another guide that a boat yard put up he said to take a pick or blade and clean out the blister until you get to good fiberglass , so that is what i decided to do. Then use the dremel and sander.

    The thing is the blisters i started with last summer were like a half inch, I did the dremel tool idea and sander, after getting rid of the white fiberglass and got to good I stopped, most ended up being 2 inches or so after cleaned up. Basically cleaning up the white circle you see in the picture.

    So today just for kicks and giggles I decided to hit these same prepped spots with my pick and blade and I was able to remove as much of the gelcoat as in the picture I showed.

    So what this is telling me maybe I am being fussier then most repair yards just using the dremel tool and sander method on a blister. They should investigate a blister farther and actually pick at it and maybe they would not get as many re blister repairs in the same areas.

    I know if I filled in the spots I prepped last summer they would have looked good but I know now I would have had blisters back in the same areas again sometime. I know this working at a truck body manufacturing plant back in 1980. Now don't get me wrong I had to work to get these areas to lift it just never come right off, I spent about 10 minutes finding the spot to get it to delaminate, it was not just flapping and there was no difference in the tapping sound with a malet before or after the bad area was removed from around the blister.

    Anyhow just letting others know my findings and like i said these areas i am showing were not showing up as big delaminations on the hull they are showing up as blisters say up to one inch.

    Hope this helps out a fellow diyer
     
  12. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Repairing individual blisters is sort of a waist of time because as time goes by more and more will show up, before too long your repaired blisters will be surrounded by new ones.
     
  13. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    Well everyone seems so optimistic , I guess this is how alot of people look at old cars too and I have a few ...I have ones I prepped myself and am happy then I have ones that I have paid big to get restored . I guess it is all a difference of how much work one wants to put in in prepping . We will see what everyone thinks when I come back with the finish product.

    as to not fixing blisters i can't see myself at least trying and what happens after I have tried is out of my control and I can say at least i tried :)

    i just want to make a boat that I can call my own and not spend 5 grand on something that is half rotten and half to do this type of work in 5 years anyway. I don't want a new boat just one I can have when I want to relax .

    So I will post back when I get er done

    10-4 I am out of here
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Blister repair is all about the prep. Focus on getting the damaged laminate replaced and you'll be good to go. New blisters are possible, but if your boat spends most of it's time on the trailer, much less likely than a berthed craft.
     

  15. RufNutt
    Joined: Jan 2013
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    RufNutt Junior Member

    stripping gelcoat

    Just an update .

    Well like I said earlier I have some friends that have restored autos for a living. Dropped by yesterday and today. His first thought was to get the boat down to the fiberglass and start from there. He figured there were too many spots to fill. Might as well check the hull out . I said whatever you think.

    We spent the afternoons just playing around with the scrapers and voila we got the gelcoat off one side except from the chine to the waterline.
    [​IMG]

    You can see where the waterline is as it is marked by the dirty water. I placed some tape just above it.

    Where do most people stop peeling the gelcoat off the hull, an inch above the black line ?

    I am going to refinish the whole hull in the end with something, just undecided yet.

    All depends if I am sanded out after we get into sanding the hull.

    My plans right now is to use an epoxy base just for the barrier protection but maybe I will just go with interlux vcm performance then a topcoat from waterline up with a nice wild type of strip in midnight blue just above the water line just to hide the transition of products.

    Thanks
     
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