Cracked drive well; can't afford hull replacement; advice?

Matt,
In my experience the failure rate has been very high. As I have said before, my first AI an '08, lasted a year before the drivewell cracked and was warranty replaced with an '09. This too only lasted a year and was warranty replaced with an '11. I also had a second '08 AI which I got for friends to use. It had much less use and I sold it when I got my '10 TI. I heard a few months later that it too suffered the drivewell crack. I know of two similar vintage local AI users who had theirs replaced under warranty as well.

I agree that Hobie has fixed this issue as my '11 AI is crack free to date.

What I'd like to know is how Hobie fixed it? More plastic? Re-designed brass insert?
Knowing how it was fixed might make it easier for recycle to achieve a successful repair.

My opinion is you should try to fix it first so you can at least continue using the boat. One thing about polyethylene (PE) is the only thing that sticks to PE is PE via melting. I would not try to introduce any other adhesive or filler into the crack itself besides molten PE from the outside. If it was me I would remove the grey plug and toss it. If you don't already have a Hobie welder, go buy one (IMO every Hobie owner should have one. If you buy it from the dealer (recommended) most are pretty expert at kayak repair, and for a pittance most will repair the kayak for you if you lack the skills. If I were to attempt this repair I would use the Hobie welder with the supplied color matching rod ( with my dealer if I run out of the right color I just asked for more and they gave it to me), they also give great advise as to how they would try to fix it (customer satisfaction is their most important asset so you will come back and buy new boats in the future from happy customers, they don't make their living fixing our crap. I've watched the local Hobie dealer around here (Economy Tackle in Sarasota fl) expertly repairing damage much worse than yours, just about every time I go in they are performing surgery on yet another hot mess (mostly other brands of kayaks), these guys are really expert at it, as I would assume most Hobie dealers are. Obviously there is never any warranty on a repair, but they do their best.
If you try to fix it yourself, realize the goals, the main goal of the repair is to stop water intrusion into the hull primarily so you can continue using the boat, secondary is to repair the crack enough so as it doesn't grow and get worse. Appearance is not important (it's the bottom of a very old boat). What makes this type of repair particularly tough is the constant pounding from the mirage drive, if you do nothing the crack will just keep getting bigger and bigger.
If it was me I would start out with the edge of the Hobie welder (no filler yet), and plunge the edge if the welder into the crack melting down as deep as possibe turning the crack into a V trench by melting. Try your best not to let the plastic exceed 450 degrees (if it turns black it is ruined). Once you have a nice V groove (by melting) you then start filling in the groove with the filler rod. just fill in the area where the grey plug was with filler (take your time though and don't let the area get to hot (resting often)). It works best to just do really small areas at a time. What I do is heat the area I plan to fill by touching and melting the surface to be welded first, then apply filler to fill the groove just in that spot, then I move to the next spot and repeat. Take your time and don't allow the entire area to get too hot. Spraying water inside the hull can help on a really big repair. Next I would cut a piece of the stainless mesh so it overlaps the repair area at least one inch on a side larger than the crack (this is your main strength component to isure the now weakened joint can't move. The more surface contact area you have the better in a high stress area like this. Now you just take the Hobie welder with the flat face place it on the screen and melt the screen into the outside of the hull ( just like in the video) take your time and try not to overheat the entire area (resting often) appearance is not important at this point, just be sure not to overheat the plastic over 450f, or allow it to turn black. Places like Michaels or Hobby world sell hot air guns that are good to around 400 to 450f, in certain areas using them is more productive than the Hobie repair iron (just FYI). Personally I would during this repair I would be spraying a light mist of water inside the hull with the boat upside down. Now with the Hobie welder and the filler rod start Ironing on the Top surface, I would build it up at least 1/16 to 1/8 inch thick over the entire area feathering out thinner near the outside edges (past the screen), the patch area will be large. When done just sand and go over with the heat gun to smooth it out and make it look pretty. Don't worry if the area sticks up a little, that's not going to hurt a thing. All the work you have done up to now is for structural integrity (because of the mirage drive), but not much to do with water leakage. Basically you can't fix the split in the wrap around web area where the mirage drive sits, the area is just too small and confined, and it's best to just leave that alone (this is the reason you added all that stainless mesh on the underside). Now comes the most important part of the repair that will prevent water intrusion. You will need a big tube of GE silicone some denatured alcohol (or Bestest rubber cement thinner (if you can find it at the hobby store). The rubber cement thinner is heptane which melts and softens PE so things bond better. And you will need a scrap piece of some type of cloth (I like thin ripstop nylon the most. With the boat upright clean the area around the mirage drive well so it is squeeky clean with either the alcohol or the rubber cement thinner, and let it dry. Now take the entire tube of silicone and dump it into the area in front of the mirage drive. Now take the cloth and place it over the blob and kneed the silicone over the entire area around 1/8 to 1/4 inch thick (like your making a pizza crust), going 4-6 inches past the repair area. The more contact area you have to the PE the better (this is your water seal). I usually use those plastic trowels they use for autobody repair to spread the silicone under the cloth with. This is all inside the hull nobody cares what it looks like. The stuff is incredibly sticky, this is why you cover it with the cloth so you can massage it around withoit getting a huge mess all over your hands. Try to do this with fans blowing over you because the acetic acid in the silicone can burn your lungs. Now just let it dry a week or so and you should be good to go. The reason for the silicone is it is very flexible and will breath with the boat. The silicone bonds well enough to the PE so it creates like a bladder inside the hull with a huge contact area. And even if the crack comes back, at least you won't have water intrusion. I highly recommend not using anything but GE clear silicone, I definately would not use 3m 5200 for this (great stuff but not for this repair, kind of more suited for general marine repair ( like fiberglass boats).
I have never done a repair like this, but If I had to repair my own hull, the way I discribed is exactly how I would fix it. Sounds complex but there are very good reasons for every detail and step involved because it's the most difficult area to repair on a Hobie because if the high stress in that area.
Hope this helps you
Bob

I am not entirely sure what hull I would get... at first my dealer said it would be a 2011 and then he hedged and said it would probably be 2009, and then he said he really didn't know (he's not exactly a "detail" person ). He was really focused on trying to sell me a 2015 AI. I guess he didn't believe I didn't have the money, so I finally pointed out the new model was too heavy for my car rack anyway (he said the hull only weighed five pounds more, but finally agreed with me after calling his rep).

If I had the $1000 I probably would do it, although I would be very leery if it might be another 2009 hull (it seems 2010 is when they seemed to mostly/totally? solve the drive well cracking). Like you said even as an investment for resale it probably would be worth it. I just can't responsibly spend that much now. It's nice that Hobie will pro-rate a product after warranty, and even a 2-year warranty is better than you would typically get for most products. If the boat originally cost $2,500 I would be fine with it all. For a $5,000 boat though... we have a very short season up here (upstate NY); I didn't even use the boat one year because of a broken arm, so I estimate I used it once a week for about 10 months in total. So if I took it out say 40 times in that period, that's ~$125/trip.

Wow, thanks Bob that is definitely useful!

I came to the conclusion as you said that almost nothing sticks to PE but hot PE so I am going the welding route. I appreciate your approach with making a V, making sure the surrounding area gets hot enough, filling that in, and then putting the mesh over. That is what I'm going to do. I had a couple questions on some of your points:

• My friend owns a Dewalt heat gun that actually has a digital temperature control. Do you think that might be more effective/quicker (and safer for the plastic) than the Hobie welder? I am going to be careful about ruining the plastic though -- that was something I didn't realize was a risk.
• So you are saying to not even attempt to repair the vertical crack up into the well because it's too small and confined (not sure what you meant by "web area")? My plan was to actually wrap the steel mesh around from the bottom up into the well over the crack. I figure since the crack is already there I need to reinforce that area to stop it from spreading... ?
• From what I've read GE silicone will hardly bond at all with HDPE. That's why I was leaning towards the 3M DP8010. But the 3M stuff will be like $60 a bottle -- I would love an alternative. If I use silicone, I figure it would just sit on the surface of the plastic and water would eventually be able to permeate between the two. But you think the rubber cement thinner will help with that bonding?

I have to admit I'm very jealous of your Hobie dealers there. It is not like that up here. I actually had an absurdly comical experience just buying the boat in the first place. No way I am going to get help with repairs, although I do appreciate they were quick to help with the warranty claim.

Thanks again for your advice!

Recycle:
You may need both the Hobie Welder and the hot air gun, the one you are describing sounds way better than mine.
The web I was discribing is the thin area where the mirage drive sits. If you can wrap the mesh over that area great, but knowing how tight and thin that area is you may melt it into an un controlled blob, I'm just not sure I could be succesful (actually I'm pretty certain I wouldn't be). An alternate approach might be to take some 1/16 x 3/4 wide aluminum form it into a U shape then slide it over the web area (where the mirage drive sits), it may take a hammer and channel locks to conform and bend the aluminum to get it to conform to the shape. After all conformed just gob the whole works with silicone and shove it on. Once the silicone is dry, the aluminum piece will never come off and protects the area by distributing the load to a much larger area. The silicone is hydrophobic so water can't wick. This shouldn't affect how the mirage drive fits. Basically you are coverting the load from a point load to an area load (huge difference engineering wise....). Actually I'm really suprised Hobie didn't figure this out a long time ago (they can be quite stubborn designwise at times), their simplest solution to all their mirage drive point stress issues on all of their kayak lines was always to just add a small molded delrin insert (a $.05 cent part) glued in place with silicone to convert the load from a point load to an area load, but thats Hobies problem not mine.

You can use whatever adhesive you desire, but the silicone is only 3 bucks a tube and adheres to anything and everything (even glass). The whole key is the amount of contact area, and because the silicone is hydrophobic, water can't wick. The coolest part is if you ever want to redo the repair, you can stick a screw driver under one corner of the silicone to break the seal, then just peel the silicone blob off, throw it away, then redo your whole repair, then just put another $3 dollar silicome skin over the entire area without contaminating the polyethylene. I modified my TI hull with a 4lb urethane expanded foam/fiberglass rear end to turn the back end of the boat from a pointed kayak type displacement hull to a rounded modern planing hull ( so the stern looks like the stern on a WETA, which has a modern planing hull. The mod weighs 6 or 7 lbs but adds 100 lbs of additional flotation to the stern of my boat. I needed that mod to support my normal cruising speeds because of my wing sail and twin big ole outboards (I go offshore a lot). Guess what I used to hold the whole works on , yep just $3 dollars worth of silicone and a couple straps, thats it. That stern mod has been on there a couple years now and still going strong, the coolest part about it is if I ever want to remove it, I just jam a screw driver in to break the seal then just peel the silicone off the hull leaving the hull un touched. Pretty much all those marine adhesives you are discribing are designed for wood/fiberglass boats, not ours.
Hope this helps
FE

Thank you again fusioneng. Yes, I'm leaning toward the $3 silicone over the $60 epoxy!

I had a 20-minute or so conversation on the phone with someone who has done what I am attempting. He is actually a Hobie dealer in a warm climate and has done many boat repairs including three or four with the drive well crack. I don't know if he wants me to mention his name so I will not, but I want to thank him for being so generous with his time and experience. This is what he said...

Basically, don't do it. He has a lot of experience welding boats and has professional welding equipment, and has tried this very repair a few times. In only one case did the repair last about a year, but honestly he thinks the owner barely used it so that may be misleading. He said that my chance of success without the advanced equipment and experience was close to zero. The problem is in part the crack goes both horizontally (along the bottom of the hull) and vertically (into the drive well). He says what always happens is the steel mesh will snap at the bend, and then the crack come's back. And often the crack will continue on beyond where the mesh is. Basically he said you can never get it as strong as the original bond (although the mesh comes close), and the original strength was not strong enough so there is little hope -- and that is if you do a perfect repair job. He agrees that the problem was mostly eliminated with boats after 2009 or 2010.

He also pointed this out to me: right now my AI is worth maybe a few hundred dollars in parts. If I get a new hull, the resale value will be minimum of $2000 and up to $3000. If I were to put the new hull on a 0% credit card for a year (his suggestion), I could recoup the hull cost and make a profit on it, versus having a near total loss now. Even use it for a while and still sell it. So it actually would be silly not to do it...

I agree with what that second dealer recommended.
The drivewell ledge is the point where a lot of forces meet up and not just those from the mirage drive. You can open up the split just by pushing on the side of the hull in certain places. The fact that Hobie haven't come up with a factory kit fix is an indication that a repair is not viable.
BTW- I wouldn't accept a hull earlier than '11 as a replacement. As well as getting the stronger drivewell, you are also getting the stronger transom with the vertical rudder.

Stringy +1. Definitely '11 hull or later.

Good luck!

Keith

_________________
2015 AI 2, 2014 Tandem

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon

Just thought I would follow up... I got the money and ordered a replacement hull ($1024). I will report back on the experience if anyone is interested.

I also did a temporary patch of the existing hull successfully: I just used some cheap silicon filling in the crack from the bottom of the boat, then covered it with Gorilla duck tape. I went for about a 9 mile trip (~4 miles peddling, 5 miles paddling). The tape held completely and there was no water seapage into the hull. If I thought the crack wouldn't eventually grow I wouldn't mind just maintaining the patch. But it was a quick and easy temporary fix.

One final follow-up for future reference should anyone be in a similar situation... I received my hull replacement exactly five weeks after ordering it. To my happy surprise it was a 2014 hull (replacing a 2009). I've taken her out for a couple of sails and a couple of kayak trips and she has been great. I'm happy with the decision to replace the hull and the price seems well worth it now that I've gotten some upgrades as well.

I was a little nervous about a new hull because I was told it would come "bare" and everything from the old boat would have to be transferred over. But as it turned out only the aka-mount bars had to be moved over (the mast seating was already attached -- the bars just screwed onto the top). All the lines and hatch seals and everything were already installed. So it was like a new boat.

Differences I've noticed going from a 2009 to 2014:

• Boat seems about 10 pounds lighter. Apparently they use a new blending of polyethylene that is stronger but lighter.
• New gigantic rudder... at first I missed the twist-and-stow but the larger rudder gives noticeably more control in heavy waters.
• New rudder handle design -- more ergonomic
• Scupper holes have lined tubes to protect the hull from damage
• Hatches seem to close and seal better (may be particular to my old boat)
• Carry handles on sides
• Extra drink holder

That seems to be it. Overall I'm happy with the outcome. Thank you to everyone for their help and advice!

Great result Recycle. Typical of my experience and shows Hobie's warranty policy is still the best!
Those improvements are well worth the $1000 and you now have a much stronger hull and drivewell ledge.
You also have the pin guidance system for easier inserting of the Miragedrive. It may be worth upgrading to the latest Miragedrive spine to get full use of that improvement.
I hope you appreciate those side handles!