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| Hobie 18 soft hull repair http://www.hobie.com/au/en/forums/viewtopic.php?f=13&t=54377 |
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| Author: | jrwyble [ Thu Apr 09, 2015 7:45 pm ] |
| Post subject: | Hobie 18 soft hull repair |
Looking at a very nice Hobie 18 Magnum....has the soft hull on top of the starboard hull just ahead of the rear crossbeam. No port access hole behind the rear crossbeam like I've seen in some other Hobie 18s. Instead of epoxy injection, wouldn't it make more sense to put in an port access just behind the crossbeam and work on the inside instead of drilling holes on the outside? |
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| Author: | SabresfortheCup [ Fri Apr 10, 2015 9:41 am ] |
| Post subject: | Re: Hobie 18 soft hull repair |
The area just forward of the rear crossbar is a common problem area, due to the frequent weight at that point. The problem is that one of the layers of fiberglass has become detached from the inner foam layer. Drilling holes and injecting resin allows you to re-bond the fiberglass and the foam by "gluing" them back together. No matter how you go about it, you need to drill through the outer layer of fiberglass to inject the resin, or else the area will remain "soft" and continue to grow. However, if you feel so inclined, some guys actually insert plywood frames beneath the deck in that area for further reinforcement. In that case, you do need to cut holes aft of the rear crossbar for access, and turn them into inspection ports when finished. |
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| Author: | srm [ Fri Apr 10, 2015 5:55 pm ] |
| Post subject: | Re: Hobie 18 soft hull repair |
There was a hotline article several years ago that explained how to install partial bulkheads in the aft deck area. Probably worth looking that one up. One thing to note from that article was that in the case of the boat they repaired, the inside skin was actually cracked and they had to get in there and actually reinforce the fiberglass. It was not just a case of delam. The inside skin of glass is very thin (one layer of glass on my 1985 boat) and I can see how it would pretty easy be cracked. Injection will work well if the composite is delaminated. If the skin is cracked, injection isn't going to do anyhing. So you really need to ge a handle on specifically what is causing the soft spot before you dive into the repair. The first thing I would probably do would be to drill one or two very small test holes into the deck right in the middle of the soft area. Drill thru the outer skin and foam but not through the inner skin. Then get in there wih a small toll like a piece oc coat hanger wire and see if you can get the skins to spread apart. If they spread apart, then likely there is delam and injection would be a good starting point. If the skins are solidly bonded to the core, then probably the inside skin is cracked and you will need to get inside the hull to repair. The other thing to keep in mind is that there is a very large foam block in the hull behind the dagger board trunk and this will severely limit hull access in that area. Placing your access port behind the rear crossbar is not going to give easy access to the area in front of the rear crossbar. Between the foam block and the crossbar saddle, you are not going to have much room or visibility of the repair area. I would probably put the port somewhere just aft of the daggerboard trunk. In the hotline article, they actually cut access holes in the bottom of the hull and then patched them up after the deck was repaired. sm |
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| Author: | OlderBowman [ Sun Apr 12, 2015 1:30 pm ] |
| Post subject: | Re: Hobie 18 soft hull repair |
Steve is right about this. I have the same issue with my port hull, just ahead of the rear crossbar. In my case the inner layer(s) of fiberglass is split open, which I found out the hard way after the Git-Rot I injected from the top wound up all over the bottom of the hull. Fortunately it peeled right out. I will be cutting a port behind the rear crossbar to affect the repair as I do not want the hole or port in front of it. I have been forewarned about difficulty getting to the repair area, but that is my plan. I avoided the it last season, but hopefully will get done soon. |
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| Author: | shakyrudder [ Fri Apr 17, 2015 8:01 pm ] |
| Post subject: | Re: Hobie 18 soft hull repair |
I just finished an overhaul repair of my port hull this winter. The hull was soft along the top cap nearly the entire length of the hull. I installed a port to inspect in inside of the hull for cracks but worked from the outside as most people do using the drill-fill-tape method. I also reinforced the chain plates, crossbar points, and dagger board slots from the inside with fiberglass and cabosile. I first thought the hull was too far gone but after about 50 drill holes and some git rot it seems to have another ten years or so left in it. If you can get the boat for the right price its hard to go wrong. I paid $500 for the 1985 boat last year ready to sail. |
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| Author: | raisehull [ Sun Apr 19, 2015 10:33 pm ] |
| Post subject: | Re: Hobie 18 soft hull repair |
i get the basic theory here. drill only part way into the glass layer, and injecting the "git rot". questions are: what kind of vessel is recommended to inject with; how far apart do i drill the holes? my repair is on the top deck, behind the front crossbar, the soft spot is about 24 inches long by approx 10 inches wide. |
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| Author: | shakyrudder [ Mon Apr 20, 2015 12:20 am ] |
| Post subject: | Re: Hobie 18 soft hull repair |
During the repair process of my H18 and H14 I drilled holes 3 inches apart but it really depended on the size of the soft spot and how much epoxy it needed. The idea is to totally fill the void between the foam and the fiberglass exterior of the hull without breaching the interior layer of glass. This video gives you a good idea of how to complete the job. He uses a pneumatic injector. I simply used the mixing bottle provided with the git rot kit and cut the bottle nipple to fit tightly inside the drill holes. https://www.youtube.com/watch?v=KhYKg0IRpv4 |
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| Author: | srm [ Mon Apr 20, 2015 7:45 am ] |
| Post subject: | Re: Hobie 18 soft hull repair |
About a 3" spacing between holes is probably a good starting point. The general idea is that you want to be able to pump epoxy into one of the holes you made in the sandwich until it starts to flow out of the other holes. You go around through all of the holes and keep pumping in epoxy until it flows out of all the holes. Then you know that the entire area has been fully saturated with epoxy. I belive the Git Rot bottle is designed to allow you to inject the epoxy straight from the bottle. I actually like to use a plastic syringe because you can squirt epoxy out, but you can also suck it back in. So you pump epoxy into the hole and it starts to ooz out of another hole, then you can suck the oozed epoxy back into the syringe and use it in another hole. Less waste and less mess this way. This is also why masking off the whole area is so important. Epoxy ends up everywhere. It's also a good idea, once you have injected the hull, give it a few flexes with your hand. This will help work the epoxy around. Then go back and top off the holes. sm |
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