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Hull bubbles?

Discussion in 'Technical Discussion' started by bamyacht, Nov 11, 2009.

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  1. bamyacht, Nov 11, 2009
    #1
    bamyacht

    bamyacht New Member

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    At haul-out my surveyor said the boats bottom paint was "sick" & that the paint had "adhesion failure". There were ?100's of tiny "osmosis blisters" & 10-12 larger ones. The seller credited me $ to remove all coatings, grind back the 10-12 larger blisters/ repair, coat with three coats of epoxy barrier and two coats of anti-fouling paint. The boat is in the shipyard now & it seems the workmen have ground most of the blisters flat, which maybe they shouldn't have done? Currently the gray primer in the gel coat is the predominant color however where the blisters were ground flat there is not color, just a fiberglass appearance. Some of the ground blisters emit fluid when pressed. With some I can actually break through the remaining glass into a void beneath as they are thin. The yard claims that it is not necessary to open/ clean/ fill all of the thin & or water emitting spots – the plan to paint over many, repair some. They explained that this is caused by a polystyrene bubbles from the hull fabrication ?a defect - gas moisture. My concern is that I want it done right. If these spots are too weak they might fail causing me to re-do what I have done additionally causing a complete bottom job. What is the correct approach at this juncture?
  2. K1W1, Nov 11, 2009
    #2
    K1W1

    K1W1 Senior Member

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    Hi,

    None of what you have written sounds good at all.

    Did you get the surveyor you used pre purchase to have a look at these and give his opinion?

    It sounds from your brief description that you might really have a dose of the Pox ( Osmosis) on your boat.
  3. bamyacht, Nov 11, 2009
    #3
    bamyacht

    bamyacht New Member

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    Yes tried to get the surveyor out but doubt he'll make it. I have a tight window as they may try to roll primer it tomorrow eve. The yard is really reputable, & they of course are warranting their work.
  4. Capt Bill11, Nov 11, 2009
    #4
    Capt Bill11

    Capt Bill11 Senior Member

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    If going to do it, have it done right the first time. Remove all the blisters and let the hull dry out properly before filling and barrier coating.
  5. Henning, Nov 11, 2009
    #5
    Henning

    Henning Senior Member

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    You can, but it won't make a difference unless you bring the hull matrix back up to 90*C for about 10 minutes. The problem is with Polyester resin after the formulation change in 1972 to get it to meet the new VOC rules. The styrenes in it will not fully cure catalytically at room temp, it has to be post cured to 90*c. Unless you do that, you can strip grind and peel all you want, next year you will have more blisters. The yard is doing right by the guy by not bleeding him for money for a doing work that will have no true effect. If you don't want blisters, don't buy a polyester boat from 1972 or after. Vinylester and epoxy don't have this problem. Grind the big blisters and fill and paint over the little stuff. Rinse and repeat every year when you haul out. Peeling/grinding and fairing hulls, barrier coats... it's all a scam to make money. If the blisters go deep enough, grind them out with a 12:1 or greater edge bevel and lay in some new layers of glass scarf style.
  6. Capt Bill11, Nov 11, 2009
    #6
    Capt Bill11

    Capt Bill11 Senior Member

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    Leaving behind small blisters is one thing, leaving behind weeping blisters is different. A blister problem can also be the sign of poorly saturated mat and/or the use of chopped mat. Not just poly resin.

    In fact there are quite a number of reasons why a boat may blister. Improperly wetted out glass being just one. Also a boat that has water permeability of the laminate can get blisters due to water seeping into the laminate from inside the hull.

    From what I've seen if you can get out the weepers then dry the hull with heat or dehumidifiers and then fill and prime properly using the proper products to the proper thickness, you can keep the vast majority of blisters from coming back. Look at the old Hatteras's that were repaired under warranty. Very few had reoccurring blisters from what I've seen and read.

    But if the job is not done right the first time, you can pretty much guarantee blisters will return.

    The only worth while way to do it is to do it right. Which of course is the expensive way.

    You can of course ignore it all if you want. (And that might be the better way than doing it on the cheap.) Because in most cases blisters are "deal breakers, not boat sinkers". :)
  7. bamyacht, Nov 11, 2009
    #7
    bamyacht

    bamyacht New Member

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    Okay Henning & Capt. Bill11 great input but a little over my head. How do I “bring the hull matrix back up to 90*C for about 10 minutes”. Will I ever be able to get the styrene’s in the hull to fully cure catalytically? if so, how? Is “Leaving behind small weeping blisters” a mistake? If I have “a poorly saturated mat and/or the use of chopped mat”, “Improperly wetted out glass”, “water seeping into the laminate from inside the hull.” are these curable? how to i.d. them?

    Seems to me the raised blisters had some glass/ resin thickness between them & the hull. By grinding them flat there is now either a thinner glass/ resin membrane between them & the hull or the blister hole beneath is now exposed (an obvious repair). My desire is of course to do it right but what of these recently created thinner membranes that may or may not be weeping. Can they just be painted over? Also this boat is a 1992, past repairs seem to be holding well so seems there is an effective method for repair.
  8. Loren Schweizer, Nov 11, 2009
    #8
    Loren Schweizer

    Loren Schweizer YF Associate Writer

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    Can you give us a clue as to the manufacturer? That may help given the (possible) knowledge here regarding sisterships.
  9. bamyacht, Nov 11, 2009
    #9
    bamyacht

    bamyacht New Member

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  10. Capt Bill11, Nov 11, 2009
    #10
    Capt Bill11

    Capt Bill11 Senior Member

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    Offshore, well you aren't the first from what I've heard to have that problem on an Offshore.

    After the hull is properly dried. And if they truly are mostly small blisters with a few large ones, I'd probably have the yard repair the large ones using epoxy with little or no sanding filler and fair out the small ones as best as they can. Again leveling them with epoxy with no filler in it. Then be sure they have removed all the old bottom paint and apply the proper number of coats of barrier coating to seal the hull properly.

    Gougeon Brothers' has a couple of books you might want to pick up:
    Fiberglass Boat Repair and Maintenance (Model 318485)
    Gelcoat Blisters: Diagnosis, Repair, and Prevention (Model 384420)

    Many West Marine stores carry them.

    Also check out: http://www.yachtpaint.com/Images/15_6819.pdf

    And let me add this disclaimer, I do not claim to be an expert in blisters and their repair. I am just passing along information I have learned over the years.