Crack Repair

I can use some help with advice on repairing a couple cracks in my 2013 Hobie Oasis. After taking on some water in the hull, I performed a leak check (vacuum exhaust + soapy water) and discovered that bubbles were coming from one of the front seat's twist lock holes. I noticed that the twist lock receiver in the leaking hole was seated lower in its hole than the other 7 receivers on this kayak. I don't know if this contributed to creating the crack or not. The leaking hole is shown on the right in the following photo.


https://1drv.ms/i/s!AnlnaVcTyQWTrX1WoY_wdNqD-MCQ

I removed the receiver and examined the hole, and sure enough there was the crack.


https://1drv.ms/i/s!AnlnaVcTyQWTrXs9d5bVXvAAO5Gy

Now the problem is. . . what is the best way to fix this problem? It is not easy to get to the bottom side of the hole (easy for a contortionist, I suppose, but kind of hard for an old man) and repairing it from the top side could easily result in messing up the threading for the twist lock receiver. Plus, do I need to be concerned about the crack getting bigger after the repair?

In addition to that crack, during my leak test I was soaping down everything while looking for leaks and discovered a crack on the hull where rudder block attaches. Shown here in the following picture.


https://1drv.ms/i/s!AnlnaVcTyQWTrgAzPwoHDgNsJFmJ

This crack does not leak. . . yet. But I am afraid it will leak unless I do some preventive maintenance soon. All suggestions and advice is greatly appreciated.

As a side note. . . Help I have received from this forum contributed to my finding this leak and solving other problems I have encountered with kayaking. You all have my sincere appreciation for all that help.

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All is well, life is good.

Tag,
The seatpeg hole crack is an easy fix. Coat the threaded insert in marine sealant, screw it back in , then fill a pvc cap (1" I think?) with extra sealant and stick it over the seat peg hole nub from inside. Roughen the nub up with sandpaper first.
Using the bayonet fitting as a screw driver will prevent excess sealant getting into the fitting.


More info here https://www.hobie.com/forums/viewtopic. ... 5&start=15
Hobie sell an upgrade kit you could use to fix it that contains the caps and epoxy. Part#81276201-TWIST LOCK SEAT ADAPTER KIT. It might pay to drill a small hole at either end of the crack to stop it spreading.

The stern crack is a bit of a concern and rare. I'd be removing the rudder gudgeon for a closer inspection.

Or you can just put a rubber cap on it:


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Access is easy. Put the boat on its side, against a wall on a couple of saw horses, find a seat so your shoulder is about hatch height, and it's an easy reach to the seat pegs (and beyond), as you can see:


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Stringy, I just saw your thread cutter for the seat peg conversion:


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Brilliant! Thanks!!

PS. I wonder if you could just heat a standard bolt in boiling water and let it soften the plastic as it "threads"; hold the insert in place with a dab of Loctite Blue?

Thanks to Stringy and Roadrunner for their replies. Good advice, as usual.

As a follow-up, I took Stringy's advice and removed the rudder. Only the one crack radiating from the bolt hole. I think I will drill a small hole at the end of the crack and fill it with ??? Any suggestions?


https://1drv.ms/i/s!AnlnaVcTyQWTrgIO3afPCsK5WOZO

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All is well, life is good.

That crack looks minor but I think I'd be taking it to my Hobie dealer and get them to inspect it. It's an unusual crack. There is a molded in brass fitting in the cracked area but I'm not sure if the crack is beyond that?

I like that rubber cap solution RR!

[quote="Roadrunner"]

Thanks, cheapness is the mother of invention!
I too thought boiling water might soften the plastic enough and I did try that first before cutting the grooves in the bolt. Unfortunately it didn't work. Probably needed to be hotter than boiling. I was surprised at how well the modded bolt worked in cutting the thread!

Thanks, Stringy, but there are no local Hobie dealers anywhere near me. The closest one is about 350 miles away. I'm going to have to try something myself, I'm afraid. Thought I'd drill a small hole at the end of the crack then fill it as best I can with some epoxy.

Wish me luck.
Thanks again.

_________________
All is well, life is good.

Tag, since your crack is above the water line, I don't think it will present a serious problem. I doubt that epoxy will stabilize it because most common epoxies don't have good bonding strength with PE. Here's a recent example using G-Flex (advertised to work with PE), even after flame treatment of the surface. It pops right off with just moderate resistance.


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Additionally, the PE is pretty thick there and without good penetration, a surface bond would likely crack as well. I suspect the crack would like to slowly grow due to expansion and contraction, so your arresting hole should keep it under control; a dab of clear silicone calk will have enough adhesion to stick and not crack. Since the crack is not structurally stressed, the lack of strength should be of little concern.

Stringy, the grooves in your "thread cutter" look very clean! How did you cut them?

Thanks, Roadrunner. I'll try that first.

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All is well, life is good.

Clean, but not very straight! Cut with one of those very thin cut off discs for stainless using a handheld 4"angle grinder.

Thanks stringy!

Personally I'd be filling it with Scotchweld DP8005/8010 (I think that's the right product). This is an amazing glue for sticking plastic to plastic and it has many of the properties of epoxy as far as I can tell. It is very pricey but just about as good a glue as you can get in my experience. I have used it on one of my Hobies and the bond is unassailable. If you do go for this you should get the plunger that goes with it or it will be tricky to dispense - no point getting the mixing nozzle: you can just stir it up yourself like epoxy.