Fix for Leaky 8" Twist-n-Seal Hatches

I know there are other posts on this topic but I wanted one that doesn't debate if there is a problem with the O ring design and instead contains solutions forum readers have tried that work and don't work with specifics. I have a pair of first generation Outfitters that have both leaked excessively in rougher water since new while hardly leaking a drop on calm lakes and waterways. By excessive I mean a quart or more per hour. I was able to identify the source of the leaks early on by taping strips of paper towels in various places and confirming water was seeping past the hatches (especially the rear position crotch hatch and the stern hatch) but did not know why. Just figured "they all do that" and so we drained them anytime we beached.

Other posts identified/confirmed the root cause of the leaks as the O rings "rolling" so that rather than a corner surface facing out, a flat surface faces out and does not stick out as far, forming a poor seal.

For reference on proper O Ring positioning please see US Patent US8453589B2 Hatch With Cover for Boats filed by Hobie Cat Company.
http://www.google.com/patents/US8453589

CORRECT O RING POSITIONING



LEAKY O RING POSITIONING



As others have reported, correcting the positionng usually only works until the next time the hatch is closed and, in fact, these photos were taken a few seconds apart. I reseated the O ring properly, took the first picture, closed the hatch, opened the hatch and took the second picture.

Possible solutions using Hobie O rings:

1. Glue. I have 6 new O rings but want them to seal properly. I am looking for a decent waterproof glue such as E6000 or Goop that will adhere rubber to plastic. I recall at least one poster used glue and would like more details.

2. Grease. Several posters used various grease-like substances to improve the seal. Per Matt's recommendation, use only silicon based lubricant as petroleum based greases can damage the O Ring material or cause stretching. (See links A5, B1.)

3. Teflon Pipe Thread Tape. At least one forum user has had success with white Teflon piping tape to reduce leaks. (See link A1.)

Other solutions:

1. Different O Rings. One poster found an alternate O ring with circular cross section that worked and the following link provides sources and part number for a replacement (non OEM) O Ring with round cross section. (See Link B5)

What else have you done that did or didn't work?

Interesting posts in these forums related to hatch issues:
A1 Leaking Twist-n-Seal Hatch and Teflon Tape http://www.hobiecat.com/forums/viewtopic.php?f=11&t=43211
A2 alternate twist n seal hatch gasket https://www.hobiecat.com/forums/viewtopic.php?f=11&t=48057&p=213289
A3 Old Problem but not Solved, Leaking T&S Hatches https://www.hobiecat.com/forums/viewtopic.php?f=75&t=32772
A4 TnS Cover O Ring https://www.hobiecat.com/forums/viewtopic.php?f=71&t=20898
A5 Which Silicone Grease? https://www.hobiecat.com/forums/viewtopic.php?f=75&t=11630

Other interesting links regarding hatch issues:
B1: Leaking Hobie Adventure caused by Twist-n-Seal Hatch? http://www.northwestkayakanglers.com/index.php?topic=6384.0
B2: Hobie Twist & Stow Hatch Leaking http://www.kfdu.com.au/forum/viewtopic.php?f=7&t=42297
B3: Hobie Hatch Questions http://www.norcalkayakanglers.com/index.php?topic=18846.0
B4: Hobie Hatches, Poor Sealing http://www.vyak.net/forum/viewtopic.php?f=11&t=14710
B5: Hobie Hatch O-Ring Replacements http://www.northwestkayakanglers.com/index.php?topic=13269.0


Peter

Are your pics mixed up Peter?
I've always made sure the O ring was positioned as in your lower pic.
Roadrunner in this post https://www.hobiecat.com/forums/viewtop ... 7&p=213289 provided the following pic with the correct position highlighted in green and incorrect in red.

Interesting... I based my understanding of the "correct" O Ring positioning on:

1. The 6 brand new O Rings I just received lay that way naturally right out of the bag. I figured they would not manufacture them twisted inside out for the installer to know to correct.

2. My quick forum search did not hit the thread you referenced but instead found this one which has detailed pictures showing the same good/bad orientation as I used: viewtopic.php?f=44&t=12020

[edit] 3. US Patent US8453589B2 (http://www.google.com/patents/US8453589) filed by Hobie Cat Company confirms correct positioning. [/edit]

I guess we'll need Matt and the engineers to tell us which is correct!

Peter

It does not really matter which one is the right position of the o-ring.
It changes every time when you open/close the hatch.
Also depending how recently you greased the o-ring and what grease you used.

The grease also attracts sand and dirt and that also effects o-ring movements.
But if you don't grease both the o-ring and the twisting lock mechanism, the hatch will not work at all.

Only reason I have not adressed this problem is the fact that the big front hatch leaking was a much bigger problem and had to be fixed first.

Also don't like the small amount water that gets in EVERY time you open the "tvist and seal"-hatch.

The leaking front hatch is a PROBLEM.
The leaking "tvist and seal"-hatches are ANNOYING.

br thomas

Only use a dry silicone spray lube on the O-Ring and Cylinder... Easy close and open... No sand stuck to it.

Never use a petroleum grease on the O-Ring... that will ruin the O-Ring material.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Matt: Can you please answer the question as to which of the two photos in the first post of this forum thread show the O Rings as they should be when we have the hatches open? There are two forum threads (other than this one) with contradictory yet seemingly authoritative opinions from non-Hobie-employee posters. It would be good to know which is correct and I will edit the first post if needed. I would still like to experiment with using a marine glue between the O Ring and hatch but would want to be sure to glue it in the correct position.

Peter

It is my understanding that the O-Ring seals in any position. Non-issue according to the designer.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

That seems a bit dismissive Matt. "The designer" custom engineered an O ring with a modified triangular cross section rather than using an off-the-shelf one with a round cross section. Clearly there was a specific way it was intended to go. I just want my hatches (on two Outfitters) to stop leaking which they have done since new.

Peter

For morning fun while drinking my tea I went and looked up some patents.

The pictures in the first post of this thread are correct as to proper and improper positioning of the O Ring. For reference please see US Patent US8453589B2 (http://www.google.com/patents/US8453589) filed by Hobie Cat Company and specifically:

"said hatch cover having an annular sealing ring of generally triangular cross-section with the point of the triangle abutting an inner surface of the hatch to form a water tight seal."

"The known internal o-ring seals are very water resistant but are typically dependent on accurate alignment between the lid and base of the hatch. Imperfections in plastic molding make close concentric alignment of the lid and hatch base not practical. Some areas of the lid are always closer to the base and the opposite side is always further away which makes common round o-rings not functional. According to this invention, a unique square-bottom with triangle-top rubber ring has been developed which easily deforms in the areas where the lid is too close to the base and yet still seals in the areas where the gap is larger."

Actually quite clever... Unless the O Ring reorients itself. And when it does, as can be seen in my photos, the effective hatch diameter of the outer O Ring surface is reduced and the contact surface area increased, possibly reducing the ability to seal properly and making the hatch "sticky", harder to open and close. Both of these complaints can be found in this and other forums.

The engineer in me says the triangular base of the O Ring cross section needs a slight notch in the middle and the hatch lid channel needs a corresponding slight protrusion in the middle. This should prevent the O Ring from rolling within the channel. Think tongue and groove. Or maybe the O Ring channel on the lid just needs to be slightly narrower to hold the O Ring tighter and prevent rolling. That would probably fix it.

I have 6 new Hobie O Rings to install and may give glue a try on one or two of them just to see how they hold up. I should add that the leaking becomes a big problem only when we use our Outfitters in open ocean conditions with sails up and wind and waves. Lots of water over the hatches.

Peace,

Peter

Thanks for that interesting info Peter.
All this time I've been orienting the O-Ring the wrong way. Not that it matters much as I haven't really had a problem with leakage from the round hatch.
Different story with the bow hatch though.

In other words, the hatch only leaks when you really need it not to leak.

The hatch in front of the seat on my 2013 Revolution has been difficult to close for quite a while, and the O-ring looks like it's twisted. I didn't realize that the ring has an asymmetrical cross section until I read this thread. The O-ring is pretty flabby and easy to remove from its groove, so I took it out and put it back in with the triangular side facing out. Then I lubricated it with a silicon lubricant, as Matt Miller suggested. The lubricant makes it easier to close the hatch, but the first time I closed the hatch, the ring twisted again. I think this is a lousy design. The ring fits too loosely in its grove to prevent it from twisting, and the triangular side of the ring puts enough leverage on the ring to consistently twist the ring out of its desired alignment the first time I close the hatch. I'd prefer to have a round ring. Does anybody know where I can buy a round ring with the appropriate dimensions?

I have other items of waterproof equipment which have O-ring seals, like an SI-Tech "Glove Lock" dry glove ring system, and back in the olden days before digital cameras I had a Nikonos V waterproof camera which had several O-ring seals with round cross sections, in particular an O-ring seal on the rectangular door on the back of the camera. I've never had O-rings with a round cross section fail to seal properly. I think that Hobie should go back to using rings with a round cross section on its hatches. The rings with a triangular lip work very poorly.

pmmpete: The following link provides source and part number details for replacement round cross section O Rings. I have not tried these so provide only as reference as I had already purchased 6 new OEM O Rings. If anyone gives these a go, please report back.

http://www.northwestkayakanglers.com/in ... ic=13269.0

Peter

Once again... The hatch design engineer insists that the seal can twist without compromising the seal and actually is his intent it seems. The seal allows some off center placement of the lid to still seal. A round o-ring does not have the flexibility he desired for sealing in the cylinder.

This hatch is a HUGE improvement over the viking hatches we used for many years.

There is always some small amount of water that rests above the seal and can drop into the hull when it is opened.

I suspect other sources of leaks in most cases. I have always found my hatch to seal well and I am in and out of the surf... surfing, so taking large amounts of water over the bow and hatch.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

My rear 8inch hatch leaks too. But only after washing the kayak down with a hose after using it lols - I keep checking for water and finding none before hosing after a trip out - then hosing the hull off and having to use a towel in the hull afterwards from water ingress lols.

I ended up removing foam blocks temporarily from under the seat - and getting the wife to hose various parts of the yak. It was pouring in from the rear hatch, I didnt have a great view from the middle hatch with my head upside down but I assumed it was the seal from hull--->gasket---->8inch rear hatch

I put on waterproof sealant both sides of the flat rubber gasket that sits between the hull and 8inch hatch after checking the lids oring seal wasnt twisted etc.

After waterproofing and re-testing for water entry and it failing again - Im dead certain its the rubber oring on the hatch lid itself allowing water past in my case, the fact my 8 inch tackletray insert also filled with water after i deliberatly left it installed inside the hatch with its lid off confirms it too (If the lids oring didnt leak the hatch tackletray couldnt of got anywater in it - yet it got the vast majority of water in it which managed to get inside)

I did also re-confirm the source of the leak by using a syringe and only putting water around where the oring is supposed to stop entry as well - thats where its leaking 100% - my extra waterproofing elsewhere passed all tests fine that the lids oring failed, Im not sure if the hull-->gasket-->8inch hatch sealing was required at all or not to be honest it might of been properly sealed from the beginning - and its the lids oring all along

My lid oring seals were flat on the outside - Ive removed the lids oring and stuck some waterproofing sealant/glue in the groove - then spun mine around so that the manufacturing seam on the lids oring is glued to the groove (which is generally where seams go?...hidden?)

Now it will seal against the triangle point when closed - which was designed to "give" easier than the flat surface can to allow for different gaps from what i read somewhere, and having the triangles point outwards also allows for larger gaps I assume as the circumference is visibly bigger with the triangle point out

Hopefully this fixes mine, as with the flat surface out - mine has no hope in sealing as the seal "flat out" isnt physically fat enough to do the job on mine (mine didnt "drip" in - it "trickled" in which means a proper gap still existed with the "flat out" and its not even close to being a watertight seal - and it leaked into my tackletray which means its the lids seal itself failing badly it cant come from elsewhere)

If this doesnt fix it - Im nearly sure a normal but fatter "round" seal will do a better job - and will infact conform better than a flat surface thats not even making contact is capable of, so thats where Im headed next (it cant do any worse in my case to be honest - I dont think mine would leak much worse If I removed the seal altogether with how it was lol)

Be sure you lubricate with a dry silicone spray as well to help the O-ring slide in the cylinder.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)