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PostPosted: Sun Jun 24, 2018 7:58 am 
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Sardinian Islander wrote:
Hi. For the ones who used dp-8010 can you confirm that in order to use it you need to buy so add o the tools and in this way the cost becomes similar of that for the Hobie KC welder?
You can buy a mixing nozzle and plunger, but it is not necessary. I mix by hand (with a stick) as with other 2 part epoxies -- it is less wasteful, but does take several seconds off your short working time. I use dowels to individually plunge the tubes, indexed so each tube gets pushed the same distance.

I just tried a new similar product, Loctite 3035 and am very impressed with the results. It also has a very short working time, but has one advantage -- a 1:1 mixing ratio rather than 1:10 ((easier to blend accurately).

Plastic welding, IMO, is not as strong and is limited as to access depending on location (many drivewell cracks are better addressed from the inside of the hull). Drivewell repairs should be reinforced to be made stronger than the original material, since it obviously failed already. If the crack is in the back of the drivewell, corrective action needs to be taken on the Drive so it is no longer a point of contact. Good luck with your repair! 8)


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PostPosted: Sun Jun 24, 2018 10:29 am 
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Joined: Sun Apr 20, 2008 6:18 am
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Location: Sarasota,Key West FL
If I owned that boat here is what I would do to repair.

Yes if can reach in there and try to weld the crack itself, it will help, but is not really necessary to do so, (no welding will ever be strong enough to fix leak), it will start leaking again quickly.
However the problem can be mitigated so it will never leak again. There are two distinct problems here, one being a crack in the hull (which really can't be fixed effectively), and the other and more serious problem of water coming into the hull. These are separate issues.....

First off there is a flaw in the design of every mirage drive boat made, which is called a point load against the thin web of plastic at the front edge of the mirage pocket. The pressure from your pedaling flexes that little web of plastic till it fails, there is no plastic made that withstand that type of load, (speaking as one of the top plastics experts in the industry).
You can verify the problem yourself easily. Just put the kayak (any Hobie), place in any pool with the bow pointed towards the sidewall. Now with you standing next to the boat, place your finger under the thin web in the front of the mirage drive. Now have someone else start pedaling the boat as if underway. You can feel with your finger that little web of plastic flexing up and down. That's the root cause of the issue, no un-reinforced plastic in existence can withstand that load.

In the beginning of time, (early 2000's) before turbo fins, on the original design the load on that point was much less). Of course Hobie has done much to strengthen the area, but failed to address the root cause.

The simplest solution of all is to eliminate that point load and flexing altogether. It's very simple to fix.

If you go to home Depot or walmart and pick up some bondo body putty, (a small can).
Next remove the mirage drive and clean both the mirage drive well, and the front of the mirage drive, (the front tang) well.
Now spray some mold release, (cooking spray will also work, siran wrap also works), into the front area of the mirage pocket, where the mirage tang sits).
The front tang of the mirage drive, if you rough up the outside surface of the tang on the frame a little, the bondo will stick better.

Now mix up some bondo, about the size of maybe two golf balls, and gob a small amount of the body putty around the front of the mirage drive tang. Now drop the mirage drive in and click it in place, (but don't push it down too hard in the front till it bottoms out in the pocket front).

Now take the rest of the bondo and work in and around the front tang so it completely fills the space in the very front of the mirage well, (covering the tang on the front, top , and sides, (basically filling in the space), and hopefully climbing up the walls a small distance).

Of course the type of putty you end up using is up to you, (I'm outlining the method, not necessarily the material), use what you like. There are several epoxy based repair clays out there that would work nicely, as long as it sets up rigid, and sticks well to the front of the mirage drive tang your golden. I also used white Locktite marine epoxy on one boat, (but it's thinner, you need to make a tape or clay dam to control where it goes). Anything you use, if you ever sell the boat, you can usually chip and sand it off the front of the mirage drive.

Now to test it in the water. Put the boat back in the pool, put your finger back on the same spot, (on the thin web at the front of the mirage well). Have someone else pedal the boat to their hearts content, you will not feel any flexing in that area at all. Job is done.

We used the flex 90 fins on our TI, (same fins used on the eclipse), which are much larger than turbo fins, (on older V2 mirage glide drives, not 180 drives), If you don't do that fix you will wreck the hull. Of course your still going to snap more cables, and the strain on all the mirage drive mechanisms is greatly increased, (shortening the lifespan).
This fix only address's one boat, matching one mirage drive, (the fixed drive can't be used in other boats without re-doing the fix.

Of course this is only one of a hundred ways to address the root cause of the problem.

Now to fix the water leak. It's not worth trying to fix the crack itself, (there is no longer any load on that area, (from the previous fix), basically what we did was enlarge the point load from a 1/4 to 1/2 sq in surface area out to a 2 to 3 sq inch surface area, (well within the flexmods of the plastics being used).
You can fix the crack if you like, but I wouldn't bother, (too difficult, the material is already wrecked, and can't be recovered). So the best thing to do is just make sure it doesn't leak water, ever.
Easiest way to fix is to clean the entire repair area very clean, out to a couple three inches away from the repair area. Once dry just spray a thin clear coat of Krylon for plastics spray paint, (the active ingredient in the paint is heptane, (which melts almost all plastics). Then just get a tube of clear GE silicone and glob it over the entire area, say 1/4" thick, so it's spread out 2 to 3 inches away from the crack with an even coat, (doesn't need to look pretty).
The hull will never leak water again.
The Krylon paint sticks very well to the polyethylene, and the GE silicone sticks very well to the Krylon painted surface so bonding is as good as anything out there. THe silicone is nice and flexible, so any banging around or impacts on the hull don't break the water seal. Think of it similar to a bike inner tube repair kit.

People can talk about all the fixes and repairs they like, (there are a million opinions), not a single one I've ever seen on the forum address's the root cause of the original problem...... Which is a basic flaw in the original design itself, which applies to all mirage kayaks ever made, past and present, (extreme point load).

FE


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PostPosted: Tue Oct 23, 2018 1:23 pm 
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Joined: Tue May 27, 2003 12:44 pm
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fusioneng wrote:
Which is a basic flaw in the original design itself, which applies to all mirage kayaks ever made, past and present, (extreme point load). FE


Except that the failure rate does not at all support this. Failures to drive wells are very rare these days. We make a LOT of boats, so we will see a few though. Murphy's law and all.

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