Fixing foam block

Discussion in 'Sunfish Talk' started by mdelaney, Nov 30, 2009.

  1. mdelaney

    mdelaney New Member

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    I am wondering if anyone has ever tried to fix a loose foam block from the bottom of the boat? I have read how to fix them, but was thinking about drilling holes in the hull itself, using the foam can spray to adhear the foam to the hull and then reglassing the hull. I realize that you never want to drill a hole in your hull, but this seems easier to me than trying to pour the foam through a port hole.

    Also, has anyone tried the foam spray from a can and what were the results?
     
  2. Webfoot

    Webfoot New Member

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    It's a lot easier to create an inspection port that repair a series of holes in the hull. The number of holes needed would be many and the time needed to do a proper repair on the holes is prohibitive. The block needs to be refastened it's entire length top and bottom to provide support to the deck and hull. Drilling holes in the deck would be ugly with no way to hide it except a total repaint of the deck.

    I've use Foam-In-A-Can but would not recommend it for reattaching blocks. You need Two-Part-Foam that will flow in between the hull and block. Not much flow to Foam-In-A-Can. In fact, Canned Foam like 'Good Stuff' expands so much you can break the hull if the foam is not able to find a way to squeeze out of an opening.

    http://www.windline.net/project3.htm
     
  3. rob herschel

    rob herschel New Member

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    i think there is also a water absorbtion problem with some of the spray in foams.
     
  4. Wayne

    Wayne Member Emeritus

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    There are prior posts saying spray foam has worked for some and not for others. I believe some of the differing experiences have to do with how actively the boat is sailed, whether or not the foam was shot into a clean dry space, and what grade of foam was used.

    In reading through the DOW Great Stuff MSDS, tech specs, and even trying some myself, I have discovered the following…

    Spray foam comes in several varieties and brands. The density ranges from a light weight, high expansion insulator to a contractor grade low expansion sealer. The highest grade (and lowest expansion) has a density around 1.8 lb per cu ft.

    DOW Great Stuff
    http://greatstuff.dow.com

    Density has to do with the ratio of the plastic forming the bubbles to the air trapped within those cells. The lower the density the larger the bubbles and the thinner their cell walls. Thin cell walls are subject to crushing (Compressive Deformation is the test category) at lower loads and are more easily permeated by water vapor over time.

    Marine grade A/B polyurethane pour foam has a minimum density of 2 lb per cu ft to meet USCG requirements. We aren’t governed by the rule since we aren’t builders and our boats are sailboats under 20’ long, however that measure does provide a benchmark. The original foam used in a Sunfish is no doubt at least 2 lb density and several Sunfish owner’s, myself included, prefer using a 4 lb density foam in repairs.

    Examples of different grades of A/B foam.
    http://www.uscomposites.com/foam.html
    (scroll down the page)

    Closed Cell Foam
    [​IMG]
     
  5. Porpoise2

    Porpoise2 New Member

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    How about this alternative?

    My Sunfish has both forward blocks loose, and a 6" port, but I'm thinking of a mechanical repair, such as making a couple of springy fiberglass struts. They'd be designed to keep both blocks pushed outboard in support of the deck. (And maybe gradually move back in their former place with wave action). Otherwise, I'm not inclined to do a proper foam repair for my "recreational-use" Sunfish.

    My Porpoise II had good foam "glue", but the aft foam blocks themselves were like soaked sponges! Two of us could barely lift it after I'd purchased it. Handful by handful, I've since removed all the foam blocks aft of the cockpit.

    Because the Porpoise is quite narrow (compared to the Sunfish), the aft blocks aren't missed. Flotation was restored with as many empty and sealed 2-liter plastic bottles as I could cram into the space. :eek:
     
  6. mdelaney

    mdelaney New Member

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    Thanks for the responses. The last question I have is, has anyone tried to spray the two part foam in between the blocks and the hull? I am not sure how this could be done, but would think that a wand of some sort with an airless sprayer would be ideal and less mess. Any thoughts?
     
  7. rob herschel

    rob herschel New Member

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    without doing a lot of research in archives has the possibility of separating the top and bottom hull sections ever been tried? i've seen this done on a number of other boats, on a small hull like this it seems like it's doable. not having a fiberglass SF i don't know if it is. just a thought.
     
  8. Wayne

    Wayne Member Emeritus

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    It can be done, but unless you own the equipment, the pre-packaged commercial spray kit for 2 lb density marine grade comes in sizes uneconomical for a small job.

    http://www.marinefoam.com/handi-foam.html?page_type=flotation-foams
    [​IMG]



    Have you looked through the pour foam procedure guide at the Wind Line Sails web site? http://www.windline.net/project3.htm

    Wind Line Sails, Sunfish and small boat repair pages - Fixing a Loose Block
    [​IMG]


    There is also a companion photo essay to the Wind Line Sails guide showing how to get good access inside the hull and details about handling the materials. It can be viewed and/or downloaded from Sunfish_Sailor.
    http://groups.yahoo.com/group/sunfish_sailor




    It's do-able, but due to the complexity it's considered a last resort best reserved for someone with either prior small boat hull repair experience or the patience to climb a very steep learning curve. Not recommended for anything less than full flotation block replacement or very extensive hull/deck repair.

    Subtleties like maintaining hull "squareness" and deck crown creep into the picture, not to mention repairing anything marginal discovered along the way. That approach can turn a $40 weekend job into a $400 month long restoration.

    An outline of the procedure is in the Knowledge Base...
    • Sunfish KB & FAQ > Repairs & Upgrades > Replacing Foam Blocks [PDF]
      (Courtesy of the Sunfish_Sailor Owner's Support Group)

    LP Factory Tour, Photo - Geophizz
    [​IMG] [​IMG]
     
  9. Wayne

    Wayne Member Emeritus

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    addendum (12-08-09):

    Shortly after my last post I emailed DOW and inquired about some of the new foam-in-a-can products they've introduced recently. Products like backyard pond repair foam and their "Pro" contractor grade foams, stuff that comes in an economical size, but we don't usually find in the retail stores.

    I explained the application was for bedding styrofoam emergency flotation blocks in a boat. That the bedding wasn't to be considered part of the flotation - just attachment. However it is desirable the foam have substance in the range of 2 lb density or better. And, if not the home foams then what is their recommendation for a product suitable for use in a marine environment.

    No reply now after a week :(

    If they are just busy and slow to get back to me, I will post the response when it finally shows up.[​IMG]


    ... it is convenient. Hope they now have something that will work for us.
     
  10. Wayne

    Wayne Member Emeritus

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    DOW replied today {Jan 12, 2010}, but not in the way I'd anticipated. They sent a survey asking how their customer service was/is. Considering nobody from DOW ever bothered to address my question, you can imagine the rating I gave them. :mad:

    I left the door open for them to follow-up, we'll see... :rolleyes:
     
  11. Webfoot

    Webfoot New Member

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    Dow Chemical huh?, ask them about directions for use of 'Agent Orange' and see if you get another 'Customer Care' survey.
     
  12. Wayne

    Wayne Member Emeritus

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    Wasn't that Monsanto? Anyway, the instructions are right on the side of the RoundUp bottle under active ingredient 2-4-D. But this is getting off-topic, I just want to fix Sunfish, not defoliate them. ;)
     
  13. Webfoot

    Webfoot New Member

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    Actually it was both companys. Anyway when you submit a email question to a company most of the time it goes into a Rule-Based Auto Answer computer program. The program looks at syntax and key words and then tries to select a 'canned' answer that best fits the question. This may have been the response you got.

    Or....

    The Rule-Based program can't make a match and sends you're question to a computer work-station. Here the temporary employee, who's job is to make customer questions go away so he can surf the internet, mashes together some pre-canned answers that have nothing to do with the question and sends you a useless reply. How do I know this? Don't ask!

    How to bring the topic back to Sunfish? I guess the short answer is that one comes to the conslusion that sending customer questions to most big companys is useless and uses the time to go sailing. Cold weather has had me dreaming of SF Sailing anyway!:D
     
  14. fbjru

    fbjru Member

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    I fixed one of my boats using foam in a can "Great stuff". What I did was found flexible tubing that could fit over the spray nozzle. On the other end of this tubing I attached a stiff tube that could be used to spray foam in otherwise impossible to reach areas. Keeping the can outside the porthole I was able to use the tubing to inject foam exactly where it was needed.
    Though I probably should have used a denser foam this method was easy and economical.
    I am happy with the results. Its been three years and the foam is still firmly attached. Also my boat weighs the same as it did the day I did it. It appears that the foam is not taking on water, although my boat leaks very little and I take time to thoroughly dry it out after each use.
     
  15. Wayne

    Wayne Member Emeritus

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    I agree, that sort of easy application is exactly what's needed. The reason it's been shied away from is, if you dig out the technical info on Great Stuff, the most rugged level, the "Pro" variety in the low expansion grade, it still falls below 2 lb /sq ft density. If one doesn’t care for their boat as well as you do, the light weight foam is more susceptible to compressing from outside pressures and the thinner cell walls are less resistant to letting moisture vapor through over time.

    DOW recently showed the addition of some new types of foam and a whole new level of contractor grade products, now available in cans rather than bulk only. My question to them was/is what’s the density of these new products (they seem to like to keep that a secret) and would any of these products be particularly suitable in a marine environment.

    In my inquiry I never mentioned Sunfish specifically, just boat building and maintenance so DOW could relate the question to general foam block attachment that’s common practice in most all boat’s under 20’ and has, for decades, been the area where 2-part pour foam in the 2 to 4 lb density range is used. I would have thought if they had a suitable product, they’d jump at a chance to explore a new market.
     
  16. Webfoot

    Webfoot New Member

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    Just wondering, did the foam flow around the edge of the block so that it sort of locked the block in place by forming a ridge between the deck and foam block?
     
  17. 67stang

    67stang Member

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    On mine the blocks detached from both tops and bottoms near the dagger trunk. The fronts were tight and attached, so I left them alone. Next, I removed, (with a long hack saw blade), all of the factory expanding foam, from mid way all the way to the back. This left a 5/8” gap on top as well as bottom .I then used a long extension tube attached to the medium expanding foam (not the “Great Stuff” product) and started filling the entire void. It seems to have worked fine for now, the blocks are stable and the new expanding foam seems to cradle them nicely. I keep the boat aired out after use and all looks good.
     

    Attached Files:

  18. Webfoot

    Webfoot New Member

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  19. Wayne

    Wayne Member Emeritus

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    Cabin Fever
     
  20. Wayne

    Wayne Member Emeritus

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    Received today from Dow...

    Less help than I'd hoped for.

    I guess that makes us the guinea pigs for the next decade should anyone choose to try the foam-in-a-can approach.

    For myself, I'll stick with marine 2-part foams because their properties are clearly stated and their performance is known.

    .
     

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