Registered users don't see ads


Summary of Hunter 170 gluing the floor to foam trials (for all Hunter Luran shell boats)

Discussion in 'Day Sailers' started by Shorefun, Nov 18, 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 now have a few different areas of the floor that have been re-attached to the underlaying foam by using 3M 5200 or Gorilla Glue.
    Please understand the Hunter 170 is a plastic shell construction for those who do not know.

    So between some very detailed and wonderful converstations with Dave, some comments from others, and my previous experience from car restoration I came up with ways to do the repairs to the Hunter plastic (Luran S) shelled boats.

    First off you have to always bare in mind that the Luran S just will not adhere well to anything except that special epoxy. That being said some really sticky stuff over a large area and you have a lot more holding power. The problem that needs to be fixed is getting the plastic shell to be stuck to the foam underneath. The glue can not have any real solvents or cure at a high temp as that will melt the foam. I believe that foam comes apart from the plastic because nothing wants to stick to the plastic well. It is just too smooth so there is nothing for the glue to grab. So you have to take a moment to imagine the complex shape of the deck side. Then think about if you get some heating and cooling expanding and contracting the plastic. Plus you have to think the plastic may shink a bit over time (my guess). The results are the cracks and the plastic separating from the foam. This separated stuff is annoying. It can make an area spongy and likely weaker (it is a pretty strong boat).
    My 170 most of the floor had separated from the foam. It was like a bounce house. Some areas closer to the center bump felt like there was wide separation and the foam seemed lower.

    I need to add my location. I am in southern NJ near Atlantic City. It is getting colder and the temps are (as of writing) kind of at the bottom edge of the of safe for the 2 glues I am using. I am kind of trying to rush a bit as I want to get the hardware back on so I can move the boat off the trailer to work on the trailer while it is cold.

    So let me start with Gorilla Glue. Dave recommended that as a way to glue the plastic to the foam. I did not get more details so my idea was to inject the Gorilla Glue using new empty caulking tubes. I drilled the holes like 3-4" apart and made sure I got plenty of glue in there. Do not do it that way!!! I put a board and some weights on top and the glue came out and made a mess. Luckly the glue really is easy to peel off the plastic. You just get a razor blade under it and it comes up. Of course this makes me curious if long term it holds well. Dave assures me they hold up long term.

    So I learned to use duct tape on my drill holes to keep the stuff in. The area was also not perfectly down. I did not do a very good job.

    Next I tried the 5200. You need a good quality caulking gun and you will need to duct tape it in the gun. This worked well but took over a week to cure. I changed my weights to a couple of 1" thick iron and a bunch of dumbells I have. I squished a bunch of 5200 out of the one uncovered hole. It did a great job and made a very solid area.

    I retried Dave's method with the Gorilla Glue. I used air to move the glue around. Put weights on it. The temp was in the low 60's and to be honest I did not feel I got good flow out. I went back to using the 5200 (I had another tube why let it go to waste).

    So my second attempt with the 5200 I put some water in (very small amount) and blew it in with air. 5200 needs moisture to cure. It has gotten dry here with the winter approaching. I widened the hole distance to like 5" and worked the 5200 in some holding the hole closed with my finger while I pressed and let the 5200 flow. Put duct tape over the hole then weighted it down with my pile of plates and weight. This time it cured faster in just under a week. The area is very very solid.

    EDIT- I forgot to put an important detail in with 5200. I drill a 1/4" hole thru the plastic. The tip of the 5200 has to be cut such that it does not stick past the Luran on the other side. If it sticks too far thru the foam will block the 5200. I also recommend a good quality ratchet caulk gun.
    I found that you need to keep the tube in the hole and allow time for the glue to spread. I also work the area by pressing with my hands. The key is to find the edge where you do not here the cracking noise from the plastic pulling away from the foam. The duct tape limits the 5200 from coming back out the hole. Weight on the area should continue spreading the glue.

    I thought about the Gorilla glue and felt it was too cold to flow easy. So I tried an experiment. I got my hot plate and special garage pot with some water in it. I got the glue up to 80 degrees and found it flowed MUCH better.

    I also had a long wonderful talk with Dave. There I learned he would put the glue in a hole and blow it to the other hole about a foot away.

    So I brought my pot out to the back garage and got the glue toasty warm (around 80) and tried it. This worked very well. I put in a bunch of glue using a small container then blew it around. I dumped a bunch of glue in and 3 days later when I had time I took the plates and weights off and a nice solid area.

    So today the temps were in the 50's. I am out of Gorilla glue and have a tube of 5200. I refined my 5200 techniques. You can get close to 5" of movement of the 5200. When you start the loose areas will make the ripping noise when you press and release. So I would inject the 5200. Keeping my finger over the hole I would work the area listening for when that ripping noise would go away and I knew where the glue had moved. Plus I figure the plate and weights would move it even farther over time.

    So my summary.

    I am partial to the 5200 glue. I feel it is likely a better glue because as best I can figure it has a better stick value to the Luran. It does not expand and it can move some as it is rubbery. It is slow and relatively expensive.

    In reality either solution will work so long as you are aware of temp issues. The Gorilla glue worked nice once I got it up to temps. I recommend getting a smaller bottle for injecting and a really large bottle to refil. I believe in very warm weather the Gorilla glue will flow better for areas that are tight. For areas where better adhesion might be required you are better off with the 5200.

    Keep in mind my 170 seems to be on lighter end of problems. Some seem to have more problems.

    If you need to do a full floor area then at least 2 large bottles of Gorilla glue or 5 tubes of 5200. Home Depot has the best price on 5200 at $17 or so.
     


    Last edited: Nov 24, 2018
    justsomeguy likes this.
  2. Hunter216

    Hunter216

    Joined Sep 22, 2018
    62 posts, 5 likes
    Hunter 216
    CA Kingston
    Shorefun
    Nice summary of your results and a good reference for me as I have a 216. Thankfully I haven’t noticed any “delamination” issues yet but the boat is 2004 and new to me so time will tell.

    I do have one question on your overall approach to resolving your cockpit floor issue.

    If the area(s) involved were quite large and already separated from the foam did you ever consider cutting - scoring the Luran material so that you could lift off a large section, spread the glue and then set it back on with appropriate weights?
     


  3. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    The option of cutting and gluing was something I initially thought of and decided against. Kind of a very drastic action and I do not like the structural implications. The strength of hull is from its form and the 3 layers being held together in a system. Having the separation from the foam and plastic causes the floor to bounce. Once you connect them back together the stiffness increases substantially. The deep draw form of the upper half also give a lot of structure.

    What bothered me is the plastic gets its strength by being a whole. If cut and glued back it may not be as good and cause other issues. Like induce stress and create more cracks. My experience tells me that glued plastic does not always hold as you might like so be conservative.

    So as I researched I found Dave's comments on the Gorilla glue. I was skeptical at first because I know just how hard it can be to get something to stick to that type of plastic. What I wondered about was the long term holding power. After talking with him I feel there should be no problems. My thoughts are that once the glue starts to move off over time the expansion and contraction will allow it to peel off again. Now I believe that may be true for small areas but the really wide area of contact means a lot of holding power.
    When I learned about the 5200 that caught my eye as it is a relative of the glue used to hold windshields to car bodies. That stuff likes to stick to anything and during expansion and contraction it will give a bit. I found a chart for the holding power of 5200. It can hold a lot on many sub-straights, I think it was like 3000 units holding power to stuff like wood but for the plastics like Luran it was like 400 units. I could not find anything for the Gorilla glue but a quick experiment with a couple of pieces of Lexan showed it held well, but eventually did come apart at the plastic glue border. I also found that if you get under the gorilla glue with a razor it will peel off nicely. The 5200 wants to stay in place and the razor has troubles getting it all off.

    I want to stress that I am not saying the Gorilla glue will be a problem. I have no problem with using it. While the 5200 is much more expensive, I like how it works better and there may be a couple of times where it would be a better choice like when you have a larger gap between the foam and the luran. I belive here the gorilla glue will be too much foam and not a solid connection. I found the area near the center and in the transom area where it curves up there is more gap. The transom area I believe suffers from it being a curve and the plastic I think (I do not know) shrinks a tiny bit pulling it taught across the gentle curve.

    I hope that all makes sense.
     


  4. Hunter216

    Hunter216

    Joined Sep 22, 2018
    62 posts, 5 likes
    Hunter 216
    CA Kingston
    I appreciate the mindset of taking a conservative approach as things don’t always work out the way you think they will!! I am by no means questioning your wisdom on the approach you took as it has been successful and the most important part is you have done no harm.

    I was just thinking about the relative merits of taking the Luran layer off IF it had already separated in “large areas” from the foam layer thereby destroying the integrity of the sandwich layup.
    1) if the foam is exposed it would be “relatively” simple to spread a consistent layer of glue.
    2) if the foam layer had deficiencies “gaps” during layup you could add some foam in those areas.
    3) you could perhaps “scratch” the underside of the Luran to get better adhesion to the glued foam.
     


  5. BobbyFunn

    BobbyFunn

    Joined Apr 16, 2017
    404 posts, 165 likes
    Federation NCC-1701
    US Riverside
    Shorefun, keep up the "Mythbusting". The experience is appreciated.

    The 170 is a throw-a-way boat. The grand failed experiment to build a boat to the same standards as a 1980's GI Joe toy vehicle, using the same automation rubbermaid uses for garbage cans, but without the durability of either.

    Cutting the skin probably is the way to go. A surface doesnt really need most of it to be strong. Sail shades are a good example. A surface needs corners and folds for strenght. Wet rudders and centerboards are repaired this way all the time, by skinning, then repairing, the reaatching the skin.

    The next step in logic says...but the skin wont stick...then use another skin.
    , or stop trying to repair it. The parts on a 170 will easily transfer to another hull form.

    The delaminaion under the grip tape is bad design. Cut all that off, put some real decking material underneath, then reskin.
     


  6. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    It would be too much extra work for no real advantage to do that level of work to this boat.

    Even with the unfixed cracks my boat would have sailed fine and worked a long time. I have sealed the cracks and I am fixing the floors. I was going to paint the cracks but the Krylon plastic paint does not seem to want to stick to the sanded epoxy.

    I am going to finish up the floors (about 1 hour more work) and then start re-attaching all the hardware I took off. I need to pull up the keel and then get the boat off the trailer. I am going to deal with a few issues on the trailer then put it back on and practice putting the mast up on warm days.
    I am hoping to locate a used mast float at a cost savings, buy some better life vests, a VHF radio that floats, the CG required items, a new pair of tires, and fix the Nissan 2.5 outboard (the older lighter 2 cycle model) I picked up cheap. I also need to clean and lube the mast. Once it gets warm enough out I go with my boys. I live in the shore area so I hope to pick up stuff used to save more $$. Need to save up for the new Leopard 45 for $500,000 plus another $250,000 to fit it out (just kidding, I do not have the cash for one of them but I saw youtube people telling the costs)
     


  7. Hunter216

    Hunter216

    Joined Sep 22, 2018
    62 posts, 5 likes
    Hunter 216
    CA Kingston
    Yes never fails that once your done someone like me comes by and backseat drives your approach <grin>!!

    I have a Uniden handheld vhf that floats - excellent range and has rechargeable battery. It also has an adaptor that lets you use normal 2A batteries. Kids, boats and life jackets are a challenge IF the adults aren’t wearing them and the why should I conversation inevitably occurs, especially on the hot days after dropping the hook and going for a swim. I just always put mine on to shorten the debate time.
    Again thanks for the detailed analysis of the fix.
     


  8. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    For life preservers I plan on all people wearing them all the time. Too many wild PWC's in the area we will be going. I used to have one and I got rid of it cause it was just too nutz.
     


  9. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    6,871 posts, 660 likes
    -na -NA
    US Anywhere USA
    Folks

    I do not suggest 5200 for repairing the floors. When working with gorilla glue, gelcoat, 5200, spray paints, etc, you need warm weather or an enclosed area that is warm for 24 hours. Cold weather will create issues. As for the floor separating I always used gorilla glue spread with an air hose in 1/2inch holes every foot. This is what I taught hunter.
     


  10. Shorefun

    Shorefun

    Joined Sep 5, 2018
    89 posts, 7 likes
    Hunter 170
    US Northfield, NJ
    I was out on the boat today. It is well above 50 and I finished up the other side transom area and a couple of small areas elsewhere to finish off the tube.

    I was very pleased as before I started the floors were very flexible. I would stand with my feet on either side of the center hump and the floor would rock as I shifted my weight. Now it is very stiff with almost no rock.
     


  11. JimInPB

    JimInPB

    Joined Aug 22, 2017
    1,315 posts, 383 likes
    Hunter 212 & 170
    us West Palm Beach
    +1