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 Post subject: Crack at Rear Crossbar
PostPosted: Tue Sep 01, 2020 1:56 pm 
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Good afternoon

I've got a 1988 Hobie 18 Magnum, and I've discovered a crack approximately 5 inches across where the rear crossbar meets the hull. The crack itself goes through both layers of fiberglass and is approximately 1/8' wide. Although this crack has likely been here for some time, the hull surrounding the crack feels solid. The crack is on the outside of the port hull. It is just beneath the crossbar bolt inside the hull flange. On both front crossbars and shrouds, I have the reinforcement plates, but the rear crossbars have the older style bars.

My question is, could I attack this problem from the outside? I found a hotline article describing how to do this by Rick Buchanan. Link here: https://static.hobiecat.com/2010_archiv ... 1598563657

By going after it from the outside, I would be able to avoid putting a port in the deck to reinforce with fiberglass from the inside. My concern is, this area is too structural and prone to cracking again if I don't make this repair correctly. I've seen in the forums where people have reinforced the crossbar/ hull connection but wanted to see if there was an alternative that didn't involve putting a port on the deck.

Thanks in advance!


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PostPosted: Tue Sep 01, 2020 4:33 pm 
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Inside is best. Requires you install inspection ports. Especially critical if you have wings.

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PostPosted: Tue Sep 01, 2020 4:56 pm 
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Location: Jersey Shore
I agree, just install an access port behind the rear crossbar and reinforce from inside. You may also want to try to get some glass on the outside as well. A 4” port is very tight to work in, but is doable. 5” will be a lot easier. Cut the hole for the port, do the repair, and install the flange for the port last. This will give you an extra 1/2” to work in. It doesn’t sound like much but makes a huge difference between being able to move your arm around inside the hull and not. Also easiest if you take the boat apart to do the work. Here is a write up I did several years ago on reinforcing the front but the aft would be the same process. Also keep a look out for a set of updated reinforcement plates. They can also be installed in the rear with a little tweaking.

https://www.hobie.com/forums/viewtopic.php?f=13&t=49780&hilit=Hull+reinforce&start=0

sm


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PostPosted: Tue Sep 01, 2020 8:24 pm 
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I suspected this was the case. My boat does have wings, and I do use them, and I'd like to make this repair correctly. My plan is to start with a 4" port and if I can't get the job done with that, I'll widen to 5". Srm, I saw your reinforcement post and that has been my guide thus far, although, I will probably just use fiberglass as opposed to carbon. One question I did have, I've read to start with larger sheets of fiberglass and work my way down to smaller sheets to distribute the load. Is that something you're a believer in? I was going to put the largest piece of mesh directly against the crack and work my way down to smaller pieces, coming in towards the center of the hull. This is how I interpreted the West System instructions, although, I will admit, this is my first time doing a true fiberglass repair. I've worked with the epoxy in the past, but the jobs I've done did not involve the glass.

I've read elsewhere that the 18 has a foam block inside the hull beneath the crossbar. Can anyone verify this? If so, what is the proper course of action to get behind it to administer the repair?

I may have exaggerated a bit with my estimate of a 1/8" gap. It's probably more like a 1/16".

I'll try to attach photos here:

https://hosting.photobucket.com/images/ ... fit=bounds
https://hosting.photobucket.com/images/ ... fit=bounds

The first photo is of the actual crack. The second is where I was able to bring it together with a ratchet strap. My thought is to fill the crack with West System G-Flex, ratchet the crack together on either side of the crossbar with ratchet straps, then go inside the hull through the port and put up 3 layers of fiberglass.

I'm open to any thoughts. Let me know if you can't view the photos.

Thanks!


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PostPosted: Wed Sep 02, 2020 8:06 am 
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Location: Buffalo, NY
andrewphelan11 wrote:
I've read elsewhere that the 18 has a foam block inside the hull beneath the crossbar. Can anyone verify this? If so, what is the proper course of action to get behind it to administer the repair?

Can confirm, the foam block extends from about the aft end of the dagger well to the rear crossbar. Source: I installed aft hull ports.

I love having the aft hull ports! twice the storage, easy access to inspect & ventilate hulls, and I installed bottleports back there which are super handy! http://www.dinghyshop.com/product/S-A04.html

I agree with the others, the repair ought to be made inside the hull.

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PostPosted: Wed Sep 02, 2020 10:51 am 
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Location: Jersey Shore
I am not able to view the pictures.

The foam block does extend past the rear crossbar and will somewhat impede your ability to work inside the hull. It is loose in the hull though so you can kind of move it out of the way but it is a bit of a PITA. If it really becomes a problem, you could cut it into two pieces and slide one section forward and the other aft to give yourself more room to work.

Regarding laying up the glass, yes, you should stagger the overlaps and edges of the plys so it doesn’t create stress points. It doesn’t really matter if you go from small pieces to large or vice versa. My preference is to make the last piece be the largest so it covers all of the prior plys and gives a generally cleaner result with fewer exposed edges.

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PostPosted: Tue Sep 15, 2020 2:30 pm 
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I have done this repair also, sounds like a similar size crack I had on an old boat. I cut the access port hole behind the cross bar. One piece of advice is get shoulder length obstetric gloves from a ranch supply store. That really helps keeping resin off your arm hair. I would then put a latex glove over it to maintain some feeling in the fingers.

I did most of the repair from the inside, I went small pieces first to make sure I had good surface contact, then added larger pieces and at different angles, so not all fabric going the same direction. Also did 1 or 2 layers on the outside up in the lip.

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Hobie 18 w/wings
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PostPosted: Thu Sep 17, 2020 1:53 pm 
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Joined: Sun Sep 01, 2019 7:24 am
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Just wanted to thank everyone for their input on this matter. I did put a 4" port behind the rear crossbar and reinforced it with some West System G-Flex and 4 plys of fiberglass mesh.

I also wedged open the crack prior to putting the fiberglass in and filled that with epoxy and clamped it down to bring the crack together. That way, when I went behind it with the glass, I was able to ensure the hull was in its correct shape.

I did also wear long sleeves and gloves, so, fortunately, I didn't run into any epoxy on skin issues.

The repair feels solid and seems watertight.

Time to get it back on the water.


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