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Where to Glass a 170 and I would like to hear results of repairs after a few years, what has worked?

Discussion in 'Day Sailers' started by Shorefun, Oct 5, 2018. Add this thread to a FAQ

  1. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    So I am trying to figure out when I need to grind a wide channel and lay some glass for the repairs. I have several very long cracks into the forward area the will be glassed. I have included some pictures of other areas. Do you think they need to be glassed?
    The tabernacle has the aft crack that goes onto both sides. Do I need to glass the whole area?
    Cracks that go up and around the curved area on the sides?
    Cracks in the area where the jib cleats mount?
    Cracks around the motor mount or rudder mount?

    My thoughts are I can always grind and add glass later. A lot of the cracks really look more like they are from the plastic shrinking more so then structural. Even the one around the tabernacle seems to not be structural. The tabernacle is very solid in its position. The boat has never had a motor mounted to it and there are cracks. But I could see the differential movement of the metal vs the plastic in temp changes causing issues.

    What have you done and what has failed over time?
    I real a lot about doing repairs but almost no comments about how they have held up over mulitple seasons.

    Thanks
     

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  2. Joe

    Joe

    Joined Jun 1, 2004
    6,577 posts, 372 likes
    Catalina 27
    US Mission Bay, San Diego
    Those look like gel coat cracks to me... not fiberglass failure. google "gel coat crack repair"
     


  3. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    It is a Hunter 170 which is made of a Lexan like plastic on the outside, some foam and then thin fiberglass. It needs to be repaired differently.
     


  4. cagreen75

    cagreen75

    Joined Nov 6, 2017
    20 posts, 5 likes
    Catalina Catalina 30
    US Stratford
    Since I’m not an expert on this subject I’ll not offer any advice on that level but I will offer my opinion on what I would do. First I would continue to look for an expert opinion and if that did not work I would grind very carefully through the gelcoat to see if there is any damage to the underlying structure. Small cracks on the surface could be nothing or could also be something totally unexpected. Either way you will never know unless you grind it out to see what is going on. The other thing is if there are cracks I would look at the area to determine if I could see if there are any point loads from the rigging that may have caused these cracks. If there is I would try to devise a plan to not only repair any fiberglass that is damaged, I would look for ways to add reinforcement to those areas to prevent any further cracks in the future. Following this method should eliminate any future repairs of the same areas if you have indeed identified the reason for the cracking in the first place. My feeling is that unless you know that you have done everything possible to strengthen and repair the cracks you will never know that you have a safe boat that you can trust to take you on the journeys you wish to take. God luck with your repairs, but most of all keep looking for expert advise.
     


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  5. JimInPB

    JimInPB

    Joined Aug 22, 2017
    1,315 posts, 383 likes
    Hunter 212 & 170
    us West Palm Beach
    You can find my 2-part post about motor mount repair on a 170 here - https://hunter.sailboatowners.com/mods.php?task=model&mid=11&mn=170 That was done nearly a year ago & so far, all looks good.

    The hump in the middle of the stern, that the rudder attaches to, has a block of wood inside it, if it is anything like it's bigger brother, the H212. I did a quick little repair on my 212 a little while back. Details can be found here - https://forums.sailboatowners.com/index.php?threads/h212-gudgeon-repair.191936/ The wood spreads out the stress from the gudgeons. The crack that you have in the top of the hump will probably not give you any immediate structural issues, but it will probably allow water to intrude & rot the wood. That would create a major problem. I would V-out and patch that top crack as soon as is practical. I would try to get the insides bone dry before sealing it up.

    I would expect that the cleats & tabernackle have backing arrangements that are similar to the rudder mount hump, but I do not know that for a fact.

    I am not real sure how similar Luran S (H170 skin) is to Lexan (poly-carbonate) Lexan feels more rigid & tends to hold a sharp edge more easily. I am not sure what other properties may also be different.
     


    Last edited: Oct 9, 2018
  6. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    6,871 posts, 660 likes
    -na -NA
    US Anywhere USA
    ACP skin in a sense in layman’s teens is plastic and any repair you must keep that in mind. One thing, acetone and resin/hardner should never be used. Period. Two part epoxies do not hold. Not sure about newer materials. I made many repairs over the years and have discussed that in the past.
     


  7. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    The ACP skin is very smooth at the molecular level. Many glues work by getting a chain of chemicals into a molecularly rough surface and grabbing hold. The old plastic glues were really just solvents that melted the edge of the plastic. So any glue such as epoxy or gorilla glue do not get a very good bond. Now the MA300 is an epoxy type glue that has solvents to create a grip point for the epoxy.
    I found the gorilla glue does a surface bond of sorts to the Lexan piece I had for testing. But I found I could easily peel the glue off if it got a blade between the two surfaces. It would just peel off.
    My guess is gorilla glue is ok to use for filling or holding the Luran to the foam because there is a wide surface area. But I feel that if there were proper stresses over time the gorilla glue will peel away from the ACP. My guess says it likely will hold for a very long time and is fine for the job. The job being holding the back side of the ACP to the foam.
    The 3M 5200 I believe will have a much better grip to the ACP but also would likely peel off if you worked at it. This just knowing how the polyurethane glues work, think the stuff that structurally holds the windshield in your car, yes it is part of the cars structure. They use a similar type adhesive. But it is also stiffer and harder to move around. It is also much more expensive. I plan on getting a small tube an trying it out. The big thing is once you open the tube you have to use it all pretty quick cause it goes bad. It might even go bad sitting on the shelf. I used a similar product attaching felt to the door window channels on my 31 Model A Ford Cabriolet. http://www.cabriolet.piklefactory.com

    Probably too much information.

    Oh FWIW I did a quick test sanding. I had some 220 on a stiff sanding block and it leveled the glue some. It cut pretty quick, faster then some autobody stuff I have done.
     


  8. BobbyFunn

    BobbyFunn

    Joined Apr 16, 2017
    404 posts, 165 likes
    Federation NCC-1701
    US Riverside


  9. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    The G-Flex will not work for crack repair. It does not have a solvent to create adhesion. For it to work you need to sand the surface with the correct grit paper.
     


  10. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    6,871 posts, 660 likes
    -na -NA
    US Anywhere USA
    I have tried so much over the years and what worked for me is what I report on plus conversations with those building these plastic boats. New materials I do not know relying on those to report back as to repairs holding.
     


  11. JimInPB

    JimInPB

    Joined Aug 22, 2017
    1,315 posts, 383 likes
    Hunter 212 & 170
    us West Palm Beach
    If you put an opened tube of 5200 in the freezer, it will last for many months.
     


  12. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    6,871 posts, 660 likes
    -na -NA
    US Anywhere USA
    Make sure it is in a plastic bag with air squeezed out