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 Post subject: HULL REINFORCEMENT
PostPosted: Tue Dec 19, 2017 9:19 am 
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Joined: Sun Sep 04, 2011 7:37 am
Posts: 31
I am looking at a used 2015 Hobie Tandem Island and it appears to be in decent shape scuffed on the bottom all equipment etc. It does have an area of concern that I have a question on. on the front bow on the side under front hatch it looks like it got chewed up pretty bad by rock or something. it is not punched thru the hull but has some really deep dents the area is about the size of a closed fist. It looks like a sharp rock hit that area about 30 or 40 times. I looked from the inside of the hull out and it is nice and smooth on the inside as it should be. however I realize the kayak walls are not that thick and this one appears to be very thin in some places from all the damage. It is being sold at a very good price. My question is is there a way to reinforce a Hobie kayak from the inside on the inside wall opposite of the exterior damage? Can I fiberglass or something like that on the inside to help strengthen that area I went all over You Tube and it is all pretty much welding videos to do holes. This area I feel would need a patch any ideas or suggestion would be appreciated.


Thanks,
Butch Lafargue
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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Wed Dec 20, 2017 5:55 am 
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Joined: Sun Apr 26, 2015 3:13 pm
Posts: 297
Rotomolded polyethylene hulls exhibit low surface energy (LSE) properties. This means very few materials or adhesives will effectively bond to it. Trying to use something like fiberglass to reinforce the inside of the hull will not work.

If repeated abrasions have considerably thinned the hull, you need to be very cautious in your decision to purchase this boat. That said, TI hulls are quite tough and it takes a lot of abuse to severely damage them to the point of failure. Unless it was severely abused, a 2015 TI should have many, many more years of service. Would it be possible for you to post a photo of the damaged area so we could help you assess the damage?

It's perfectly normal for any used kayak to have many scrapes and scratches, they're impossible to avoid in normal use, but few such abrasions weaken the hull to the point of failure. What concerns me about your description is that you feel enough material has been eroded that you believe the hull is very thin in some places. That is not normal and would be a cause for concern. This is where we would require a photo to help you make a decision.


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Wed Dec 20, 2017 10:58 am 
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Joined: Sun Sep 04, 2011 7:37 am
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Thanks,
I will try to get a few photos tomorrow and post them up and get your view on it



Thanks,
Butch


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Wed Dec 20, 2017 11:08 am 
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Joined: Sun Sep 04, 2011 7:37 am
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I also was told there is a patch material that is hard and you heat it and it becomes pliable and you peel and install over the area in question. Which i would do on the inside of the hull and once it cures it becomes hard and you can actually sand if you wanted. I would just use this to reinforce the hull where the exterior damage is. To give you an idea it is a 2015 Tandem island new vantage seats drive and everything is in good shape and I can get it for $3000.00 and it all looks good except for the one area which is a little scary looking. But I am figuring at that price if I can reinforce the inside it would be worth buying vs a new one. I will post some pics as soon as I can and thanks for the response.

Butch


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Wed Dec 20, 2017 12:56 pm 
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Again, there are very few adhesives or patches that will stick to polyethylene. There are a few expensive adhesives made for low surface energy materials I can tell you about you if you want. But I believe the best way to repair this is from the outside via plastic welding.

Hobie sells a plastic welder for hull repairs. This might work for this purpose as long as the damage is not too extensive.

Image

You can get one here. And here is a YouTube description of the welder.

Even though Hobie provides color matching plastic rods, don't expect the repair to blend in perfectly, it'll show. But welding (melting) new material to the hull to reinforce the damage is probably the best way to repair it. You may also wish to talk to a local kayak dealer to see if there's anyone near you who does this kind of repair if you don't feel comfortable doing it yourself.


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Wed Dec 20, 2017 1:18 pm 
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Joined: Sun Apr 20, 2008 6:18 am
Posts: 2898
Location: Sarasota,Key West FL
We have had several TI's, and some experienced damage here and there, from ramming rocks and boulders when going down class 2 rapids. We also ran over lots of oyster beds and rocks over the years. We only ever flipped the boat over and looked at the bottom once a year, and cleaned up scratches, any deep scratched we always filled with our Hobie welder. You would be amazed at just how durable these hulls are.
Of course without seeing the damage it would be hard to judge. In that area just a guess at the wall thickness right there around that area, I'm guessing around .150", if the gouges are less than 1/16" I wouldn't worry too much. A flashlight can be used to find dangerous thin spots, shining on one side and looking through the hull.

We had an AMA come off while trailering, (strap came loose), and the trailer tire melted a huge swirly on the side of the AMA, that was years ago and about half the wall thickness had been melted away, (friction). Snce it wasn't leaking, we elected to not try to repair, (a repair might have weakened it further) so we just left it un repaired.

Hobie sells a welder for making repairs, most dealers have scrap returned hulls in their back lots, if you can get some scrap pieces to practice welding on to sharpen your skills beforehand, it would be a pretty good idea, ( that's what I did).

Most kayak shops do kayak repair on such things, and are usually pretty experienced at it. Hobie supplies the matching welding rod material. They aren't going to do it for free, but if your not comfortable doing the repair yourself most dealers have the expert staff that do this kind of work sometimes daily. Hey I'm a pretty handy guy, and have taken several kayaks to the dealer and paid them to do some pretty difficult repairs, (we have owned around ten hobies over the years). Economy tackle here in Sarasota is a very competent dealer, pretty much everytime I go in there, they have a boat on the rack doing some repair, (beyond anything I would try on my own). I would assume most kayak dealers have similar capabilities, (even non hobie dealers).
Hope this helps


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Fri Dec 22, 2017 12:36 pm 
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Joined: Sun Sep 04, 2011 7:37 am
Posts: 31
Thanks for all the responses I originally looked at the island at nite after a rain under a street light. I have since went back and looked at it in the daylight and it did not look near as bad as it did before. So I bought it and I think based off of what everyone has said I will let the sleeping dog lie and not address it at this time. I plan on cleaning her up this weekend and checking and touching up anything that needs addressing. I am pretty excited with the vantage seats for my old back. Thanks again for all the tips and hope you all have a safe and Merry Christmas!!!



Butch


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Sat Dec 23, 2017 11:01 am 
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Joined: Thu Aug 21, 2014 6:43 am
Posts: 87
Location: Chalfont Pa
I have a harbor freight welder, have used it to fill screw holes and such. Practicing on a scrap boat is a great idea, too easy to melt a big hole. I have used JB weld to do, and other repairs, and it bonded well to the hull. I put it on in layers and sand smooth each coat. I got some of the very expensive adhesive, it was 40 bucks for a tube and did not work well. it did fill gouges but half peeled off and had to be redone.
Good luck with the boat, they are pretty tough and this forum is a great support network


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Sat Dec 23, 2017 4:27 pm 
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Joined: Sun Apr 20, 2008 6:18 am
Posts: 2898
Location: Sarasota,Key West FL
There really are no adhesives compatible with PE.
If I was going to make a patch,(like a rubber patch for a tire).
I would get silicone film, drop it in a fry pan, then lay some pe sheet on top. Heat it up on a stove till the pe melts, the apply the hot patch to the damaged area, and press in place until cool. Kind of like fixing an innertube.
You may need to flame warm up the patch area first. More surface area equals better bond.
Your not using any adhesives, just the polyethylene thermoplastic itself with heat, (pe bonds to itself, but nothing else).

An example repair using this method would be repairing the bottom of the bow on a TI that has scrubbed onto too many boat ramps, (yep we had that happen to us). Basically you just melt several 1/8" or 3/16" thick by 2" by 6" polyethylene sheet, (we used cutting boards from Walmart) strips in a fry pan.
Once melted in the fry pan place them one at a time onto the keel end to end. Of course you need to hold the hot silpad (silicone cooking film) with gloves because it's very hot. Working with the hot polyethylene would be like working with pizza do or play do, it will conform to any shape you put it over.
After placement the edges can be filed down and blended and feathered into the hull shape/contour.
I'm quite sure this would be very difficult and time consuming, and likely not worth anyones effort, and you really have to monitor the temps closely, (around 450f is the max you ever want to get Polyethylene). I'm only using this as an example application of the technique.
If I had a hole in my hull, I would put one of those patches on the inside if possible, or outside as a last resort, ( it won't be pretty)
Hope this helps
FE


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 Post subject: Re: HULL REINFORCEMENT
PostPosted: Sat Dec 23, 2017 6:59 pm 
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Joined: Sat Nov 05, 2011 1:58 am
Posts: 2783
Location: Forster, NSW, Australia
May I suggest, before you take any draconian measures, you shine a light inside the hull (obviously when it is relatively dark outside) and you will immediately be able to gauge how deep the damage is. It could well be that you might only need to use Hobie's welder to fill in the deeper scratches. You might even decide that there is still enough "meat" in the scratches to not need any repair at all!

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker and Hangkai outboard
only cool people follow the (non-magnetic) titanium weight-loss program! lol.)


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