Tandem Island Dolly Cracked - Design Flaw

My Tandem Island Dolly is a little under I year and has developed four stress cracks with one being major (see photos).









I believe the cracks were caused by a design defect such that the axel isn't strong enough and the load of the Tandem Island is being supported by the plastic dolly instead of the axel (see photos). The bevelled back corners have stress cracks in four places with one significant crack in under one year. Plastic welding is probably only a temporary fix until a revised axel can be produced?





Also, the tie down webbing have significant wear.



I also have plastic cradles on my trailer (travelled 5,000 km) and those cradles have no cracks since they are supported by a rigid cross bar.

Has any one else had this problem and what are Hobie going to do. I paid a significant amount of money for this dolly and didn't expect it to have such major flaws.

I guess I have to ask - is posting this issue here your way of initially trying to contact Hobie? Or have you already contacted Hobie and they have rejected your warranty claim?

Posting here first is like standing outside a shop with a protest banner instead of walking inside and talking directly with the company. Maybe I am just old-fashioned, especially since I have never heard of Hobie ever being unreasonable regarding warranty issues.

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

I was trying to see if anybody else was having this issue, there is no point getting a new Dolly only for it to crack again.

I have also contacted the local dealer and don't expect a replacement for about four months since that seems about the average time it takes for Hobie to get orders fulfilled in New Zealand.

Looking at your boat pictures it looks like you have the Dolly well loaded. It was designed to carry a empty boat to the beach. You can see a flex in the shaft from the load. Also mud will add uneven loads on the cart. Plastic can flex only so many times. Your trailer is a rigid installation so it holds the weight better.

Recommend using the dolly with only the unloaded TI. Hobie cannot predict the additional loads that you submit your gear to...

Just a observation.

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Paul
DogsLife
2011 Adventure Island


http://dogslifeadventures.blogspot.com/

@Snakebite--from your pictures, it does look like that dolly is pretty loaded down. What does the picture look like when the dolly is only loaded with the TI and nothing extra. Just curious.

I can understand your desire to load your gear onto the TI/dolly. It saves a trip or 2 from the car hauling that gear down. Still, how much "extra" weight are you loading onto the boat? What does your cooler weigh? And, the bag of stuff in the rear storage area? How much do your anchor(s) weigh?

Keith

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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

Snakebite:
I'm just saying if I owned one of those carts ( I don't) and saw that when I have my heavily loaded TI on there and the axle was bending as what it appears to do in your pics, I would be looking for a way to strengthen the axle by adding a carbon or aluminum tube or rod down the center of the axle. Or a piece of U shaped aluminum channel mounted between the axle and the cradle.
Another option might be to add spectra string from the upper ends of the cradle down to the center of the axle (creating a bridge truss to take some of stress). Basically 6 small screws screwed into the sides of the cradle on the front and back of the cradle. 4 near the top on the outermost posts, then 2 screws down near the bottom center of the cradle. 8-32 screws should be sufficient with washers. To lace the spectra string ( like a shoe) you basically shim up the center with a block of wood ( a couple inches) you then make a cinch knot and slip it over the center screw, then pull the string around one of the outer screws( loop once around the screw) and run the string back to center loop around the center screw then continue over to the other outer screw wrap once then return to the center. Now if you make another cinch knot on the end if the string and slip it over the center screw. It doesn't have to be perfectly tight since the unit is pre- loaded for stress with your 2x4 shim. Tighten the screws so there is a slight gap between the spectra and the washer ( don't tighten everything yet). Now do the same pattern on th back side leaving the screws loose. Now remove the 2x4 shim, the string will become very taught, if you have any loose ones you can adjust the loops on the ends to get equal force to all the strings. Now you tighten all the screws to trap the strings.
Congrats you just created a truss that can support 1000 lbs. The 8/32 stainless screws should be able to withstand the sheer force, if it is possible to put nuts and washers on the inside strength will increase, but if not feasable just threaded thru the abs should be sufficient.
Each strand of spectra can withstand 300 lbs, and you have 8 strands.
I do the same as you do and load my TI fully at the car then roll it to the water, that includes my motor, anchor, inflatable lifeboat all the coolers and gear for the day and sometimes as many as 4 scuba tanks ( probably more than 200 lbs of stuff). I made my own cart (part of my trailer) but I see no reason you couldn't re-enforce your cart to do the same. This goes way beyond what Hobie designed the cart for, the designed it to shuttle an empty 200 lb TI to the water, I wouldn't expect it to be able to haul over 400 lbs ( my boat weight) as designed. Your air tires may not be up to the task ( I know mine weren't so I went to standard trailer tires)
Hope this helps
Bob

PS I wouldn't worry about the stress cracks in the ABS, once you fix the problem of the axle bending, the cracks won't get any worse (put it in your log as lessons learned, (that's what I do)). If you drill a small hole at the end of each crack it will stop them from continuing. Since the unit is ABS (not PE), it's easily repaired with ABS repair cloth (available at hobby shops). They usually sell ABS solvent glue (kind of like PVC glue), basically you just brush it onto the area, it melts and liquefies the surface (with butyl alchohol as the active ingredient) then you just plce the repair cloth over the tear and let it dry (do it only on the underside). To fill the crack you can melt some ABS shavings in the solvent, then make a paste filler to fill the cracks on the top side. Hope this helps.
I believe the rated capacity of the cart is 242 lbs (basically an empty TI), and if loaded over that capacity, Hobie has no obligation to honor a warranty claim, I'm just guessing but looking at your pic I'm guessing your tipping over 300 lbs with all that gear and cooler in the boat ( I've transported mine with a lot more weight than that (LOL)), but I have a custom designed cart designed for that kind of weight.
The wear on the webbing is caused by the axle bending, and the webbing rubbing on the tire sidewall (the tops of the tires are bent inward), normally the straps clear the tire. Once you fix the bending problem, so the webbing doesn't rub the tire, the webbing won't get any worse (you can cover it with electrical tape to make it look better).

Thanks fusioneng for taking the time to write such an informative post

I can't find the load information for the AL/TI Dolly anywhere, but page 15 of the parts catalogue states the dolly is "Much stronger and easier to load and use than plug-in carts for larger, heavier models". The strongest plug-in cart is the HOBIE TRAX “2-30” rated to 242 lbs followed by the HEAVY DUTY rated at 225 lbs

http://cdn.hobiecat.com/digital_assets/ ... 130906.pdf

The TRAX 2-30 has 30cm PU Beach Wheel rated at 121 lbs each (hence max load of 242 lbs and the AI/TI Dolly has 42cm PU Beach Wheels rated at 176 lbs giving a theoretical upper limit of 352 lbs for the Dolly.

http://www.wheeleez.com/beach-wheels-polyurethane.php

The Tandem Island fully rigged weighs 190 lbs and carrying an additional 50 lbs of gear on the AI/TI Dolly shouldn't be a issue since Hobie's own literature state the Dolly is much stronger than the plug in carts designed to carry up to 242 lbs. When I bought the Dolly, I did inform the Hobie Dealer I intended to transport camping gear for Island Hopping with it and was never informed it only had a 200lb capacity like some of the reply's are inferring.

Snakebite:
I don't doubt that Hobie will stand behind their product and will fix or replace your dolly, because that what they do. And it is likely while the replacement is being shipped to you they will have no problem with you continuing to use the old one as best you can (that's just the way they operate, they want to keep you on the water and happy if at all possible). I'm also pretty sure that quietly they will review their design, and in a year or two, the next generation dolly will be magically stronger (I have seen this from them time and time again), kind of a rolling product improvement program as they improve and perfect the designs of their products over time.
Obviously what you have is not working as shown in the photos, I was just trying to outline some extremely simple solutions that will fix your immediate problem (the axle bending), (shouldn't take more than an 30 minutes to make any of the fixes I outlined, doing the work yourself). Then when you get your replacement dolly, just duplicate the same changes (even re-use the same parts if you need to). I'm in exactly the same situation, I know I overload my TI from time to time and accept the consequences when I do. Actually to increase the load capacity of my trax II tires (not the 2-30 tires you have, (the smaller ones)) I filled them about half full of as substance called Slime, which is a green liquid goo substance that you squirt into the tire (it's a tire sealant for bicycles). I had problems with sea shells slicing and puncturing my tires, and constantly had to refill the tires with air. The self healing slime seemed to help in all those respects (but it makes the tires considerably heavier), on my scupper cart (which I hardly ever use) I typically use the foam hard tires which seem to roll a lot easier through everything except really soft dry sand.

We have the softest finest white beach sand in the world here in Florida, and I've had to drag my TI almost a half mile across many times (the sand here has the consistency of granulated sugar). Even using all the tricks I know I have to break the boat down completely (remove the motor, all the gear, and the AMA's) to get it across the beach to the water.
Just tryin to help.
Bob

Snakebite:

I have the same dolly as you and it is well used. Mine also developed cracks in the same location as yours. I simply filled in behind each crack with epoxy (I used G-Flex but any structural epoxy will likely be OK). I also filled in behind all similar locations regardless of the presence of a crack or not. Before strengthening the dolly with epoxy I scuffed the surface until the surface gloss where the epoxy would sit was gone. I applied the epoxy in several thin layers resulting in a quite thick patch when done. You cannot see the epoxy as it is visible from the bottom only.

It has been about a year and a half since I did this and no new cracks have shown up and the existing cracks did not reappear.

I cannot let you know what Hobie did for me in this regard, I did not contact them about the cracks my dolly developed. The repair I made was simple, quick and, at least to this point, was effective.

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Martin Hochberg
Tandem Island 2012
Pro Angler 2015

Gday, sorry to see the edge cracking. Please contact Dan @ the watershed to file a warranty claim. I also agree with Tony Scott, work with the dealer and Hobie Aus to fix the problem.
Just a question, how much gear is on board (weight) including rods, reels, cooler full of NZ snapper perhaps? Cheers

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Steve Fields
Hobie Cat Australasia
Huskisson NSW Australia
http://www.hobiecat.com.au

Unless there is well over 50 pounds of ice in that cooler, I would agree with snakebites observations. By the look of that axel, it is under-engineered and his comments are well-placed. He did us a service by posting them here.

If this is the $500 beach cart we're referring to, then it still needs tweaking.

hence the question on weight. As you know, we improve all the time. Could be NZ snapper!!!!

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Steve Fields
Hobie Cat Australasia
Huskisson NSW Australia
http://www.hobiecat.com.au

Nohuhu:
I agree 100% the design is lacking, I'm sure Hobie will fix it eventually, but that doesn't help him here and now, that's why I tried to suggest a couple simple improvements (tweaks) that he can easily do himself to get by in the mean time. We all know big wheels turn slowly ( no pun intended), and in my experience Hobie listens to us on the forum and continously improves their products like no company I have ever experienced.
Bob

Amen Bob. Is there anyway to sleeve aluminum inside this model? Or use a flatbar underneath? That pretty much would do it.

Another issue is that the weight seems to be loaded towards the center of the long span. Spreading it closer to the wheels would help.

Anyone have a picture of the underside of one of these sukkas?

I had similar problems with my cart within weeks of it's delivery. It was promptly replaced by Hobie and I have not had that problem with the replacement. I do not load my cart to the degree that Snakebite does but I feel that a $500 cart should be able to carry the weight he describes.

However, I do have my problems using the cart. I have not found a way to easily get the TI on the cart. I lift the front end of the kayak with one hand and holding the yellow handle, slide the cart under. All goes well until the yellow handle moves under the hull. Then as I try to pull the kayak further onto the cart the cart starts to roll, preventing me from centering the kayak on the cart. I have tried attaching rope to the cart and pulling the cart under the TI (as shown by someone who built their own cart), but then I have trouble with the kayak moving. I only use the cart once or twice a year because I keep my TI on my boat lift, but I would like the beach launch to go smoother. When I launch in the spring, I plan to try blocking the wheels. Anyone else have any ideas?