sank my AI in Ste-Catherine Sound

Yes, Elm, I can understand some boats may have molding problems which make the front hatch prone to leak. That said, people, myself included, jump to the conclusion that the front hatch is leaking.

René has recently posted on his blog that he is taping his rear hatch cover shut--presumably to prevent leaking. To this point, he has not said his front hatch is leaking.

On one of our first camping trips about 3.5 yrs ago, a fellow with a new AI had gallons of water in his hull at the end of the first day. We had to tack into the headwinds all day. He was very upset and assumed it came in his front hatch. He then took a piece of plastic cloth, and, on the return trip, placed the plastic over the opening before closing the hatch. I didn't hear any more about whether his boat leaked on the return. I do know that he sold his AI after that first camp trip.

In my case, on the first day of that trip, I had some water in my hull. On the return trip, running before the wind fully loaded, my AI did a lot of diving. Assuming that the front hatch would be leaking, I expected the worst. When we landed, I was amazed to find almost no water in my boat. It was then, that I decided the front hatch was not leaking.

My argument that the front hatch is a good design, if you have not read it before, is (1) with the peaked hatch cover, the hatch sheds water, (2) the hatch has a moat with 2 drains to aid in shedding water, (3) there are 2 tube rubber seals to keep water out of the hatch opening. If the 2 rubber seals are working, why should the hatch leak?

As long as your hull is sound, the hatches are the source of leaks. My practical test is as follows. If your boat does not get water in the hull when you are running downwind with a lot of diving, your front hatch is not leaking. If you are tacking into headwinds, which lift your bow, and tend to submerge your stern, and you get water in your hull, it is likely coming in the stern hatch.

If the front hatch is leaking, I would look closely as to why the 2 rubber seals are not working. Because the tube rubber seals are so important to the front hatch, when my boat is not in use, I remove the front hatch cover to prevent compression and wear on those front seals. I've done that from day 1.

In the 2 cases I know of where the front hatch leaked, the cause was as follows: Case 1: a large, solid-frame fish net was put under the bungees. The hatch leaked. Case 2: I put a large amount of gear in the front hatch. I had to force the hatch cover down to secure the bungees. The hatch leaked. Those are the only 2 verifiable cases I know of, where the front hatch has leaked.

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

On my boat all the hatches leak a some point. The middle hatch is less likely to leak since it is less exposed but I'm sure it leaks too.

I got the tubing and connectors for the bilge pump. I'll install it soon.

_________________
Rene

http://miami2montreal.com
http://renepotvin.com

Nor do I to be honest. I've had water leaking in through these, especially apparent if the white tube comes away from the black end cap (and I've been seeing this happen more often with 2011 boats, I suspect as a side effect of greater tension in the up/down lines). One can expect a few litres of water to sneak in after a few hours in open water if this happens. I sorted this by removing all white tubes from their end caps and putting them back with some goop to keep them there. And when reinstalling, I smother the edges of the tubes with clear silicone, to make sure there are no small leaks around the edges where end cap meets hull plastic.

And Elm is correct - some forward hatches will leak. I tested this myself by placing a large open drybag underneath that hatch. Few hours at sea, bingo, some water ends up in the bag. Close inspection on these instances often reveals a split in the trim-loc sealing where it is clued down. Not a whole lot of water comes in in my experience, and because I often have fish in that front frybag, I'm actually happy for the water to get in. Doesn't go into hull, only into bag, and it helps keep fish cool.

Providing your gaskets are in good shape, a good way to get a neat seal on the 8" hatches is to use a bit of petroleum jelly grease.

_________________
Kayak Fishing Specialist: SLH
https://slhobie.com.au

G'day Josh, been a while since I said Hi!!! Dropped in to the site a few times, and it is still doing well by the looks, well done. Haven't seen much War on fish any-more though?

My front hatch seals are in ace condition, I find when it leaks most, it is in severe conditions or when I am loaded up with dive gear, where I believe the hull is flexing quite a bit. With the flex, I assume will also come a blow/vacuum/blow/vacuum effect, and with the amount of water I get (sorry, got) over my bow in these conditions, it was inevitable that it would suck water up under and then over the lip. With the hull in a flexed position, and again I am only assuming, there is a good chance the seal is not as good as it should be, possibly across the front and rear of the hatch because, the bungies are more across the middle area and not pulling down at the actual edges of the rear and front.

I also believe the rear 8" hatch and rudder lines are the main culprits for water ingress. After replacing the original Hobie seals that fit around the 8" hatches and also the so called strength ring that fits under it on the inside to a stiffer material, it did reduce the amount of water I was getting. The rudder lines, I also fitted extra O rings form some dive regulators that also helped for a while, but towards the end of the AI's use seemed to be becoming infective again. Possibly because the line cuts into them, I am unsure as I have not tried to remove them for a look, no need to now!

You don't have to be an engineer to figure out that the suction that occurs when the boat flexes in conjunction with the the fact that the hatches are located under the water line are not " winning conditions "

I may go to the kayak convention.

_________________
Rene

http://miami2montreal.com
http://renepotvin.com

Now Hobies are living breathing beasts!

Not sure I buy the flexing/breathing argument. Maybe to a degree, but these boats are pretty stiff. The argument should apply to all AIs. It still comes down to the rubber seal not holding on some boats.

Josh's point that the bow hatch seals come unglued longitudinally is true and can be a source of leaking. Superglue/Krazy Glue works great to re-attach the rubber seal to the black plastic support. Each rubber ring seal can also come unglued (if it is glued at all) where the 2 ends meet. I seal the "ends" connection with some goop.

If the rudder lines/openings are leaking, that can definitely be a serious problem since they are frequently underwater with a heavily loaded boat. We had that problem with a TI on a recent trip when 1 of the black rudder-line guide(s) came out of the opening. The boat took on a large amount of water, so much that the stern was basically under water after 1.5 hrs of sailing. It may have been that once the stern got low enough, then the T-n-S hatch began to leak also. The 1-man crew was using the rear seat.

Of course, no water will make its way into the hull if the opening is not under water. For an AI, the bow hatch is about 1" or more above the water line compared to the rear hatch, and the lower rudder lines are closest to the water line.

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

Are our boats made of the same stuff? Mine is, I believe, polyethylene (PE) and I can flex it with the push of a hand, and by changing/opposing forces over the length of the hull (pushing up at the bow/stern & down in the middle (cockpit area), it definitely flexes. Even on a cold day when the PE appears to be stiffer.

I believe that breathing hulls, siphon, suck and indeed vacuum pump, and these three traits are the main reason for all the water. I do not believe the quantities of water people are experiancing, come from water just trickling in through gaps, cracks, small holes and poor seals.

I think there are two main contributing factors to it; Flex & Squeeze

(1) Flex. If you bend a long tube, the area inside that tube through the middle changes and becomes smaller. To the point, it kinks and closes the tube off. An SOT kayak is, in essence, a long tube that is pinched and sealed at each end, and the longer the kayak, the easier it is to flex. Sure they have scuppers and in Hobies case, the Mirage drive well, but if there is enough force applied, they to will bend, Kink and reduce internal area where ever it is possible.

(2) Squeeze. Every 10 meters that you submerge an item below sea level, the atmosphere pressure doubles. You only have to put a lose fitting glove on your hand and seal it around the wrist with tape, put it 300mm (1') below the sea level line and you will experience squeeze.

If we were talking about a Hobie Sport or a short kayak similar in length, then I would support your opinion, however we are taking about the much longer narrower Adventure and also Tandem Adventure hulls. While they sit in flat water and are fully & just as important, supported equally, then again I support your opinion. But once you add waves and more to the point, substantial waves and even more so, loads added to the bow (front hatch bulk head) and stern (rear storage well) the equation is exacerbated dramatically and the hulls will flex.

While the cockpit area of a kayak is supported on the crest of a wave the bow and stern do not have the same level of support, the kayak will bend down at the ends. Then as the wave and kayak change positions the kayak will begin to flex back through the fully supported stage as it falls off the wave and end in a flexed up at the ends state as the bow and stern begin to submerge and the cockpit area becomes less supported.

Its when the kayak bow and stern are in this submerged state, the kayak starts to also experience squeeze and the hull exhales even more air. If you are in conditions rough enough to cause substantial bow submarine characteristics, then your hull will experience even more squeeze and increased deformation occurs through the bow area.

While your stern is below water and begins to rise, there is less squeeze, also the area through the middle of the hull, begins to once again expand and your kayak will start to breath in. It only takes a tiny amount of suck for siphon to begin at that level, and if the vacuum is great enough through that period of time that the stern is submersed, it turns into a vacuum pump through the rudder tubes and any other hole that is covered by water.

If the bow is in a submarine state experiencing squeeze and possibly deformed, the chance of maintaining a good seal, no matter how good a condition your seal is around the front hatch, it is drastically reduced. And again with a vacuum inside the hull trying to equalise. if water is blocking the path of air, it's going to suck the water.

As far as I know, the larger the area to maintain a seal. the harder it is to maintain that seal. Those front hatch seals are big, and considering how much PE flexes over a small area, and both bodies are made from PE, the chance of keeping a complete seal, is flawed to begin with.

As already explained, I know for sure I get water in the front hatch and I know for certain, my seal is in good condition.
I have removed every screw, bolt, seal, tube etc and added more seals goop etc and remade and strengthened any area that I thought possible for water ingress, yet I still got a lot of water inside my hull.

I have both vacuum and pressure tested my hull using soapy water, several times. One day when again testing, I realised how much flex there actually was and how it breathed by blowing soapy bubbles when it did flex and having experienced squeeze with my surface dry-suit every time I walk in the water, I started to think about what actually happened out on the water. It's the only real reason I have been able to find and made sense for the quantity of water I experience in rough conditions and when loaded up.

Give me a better explanation than I have seen on any of the other forums and on here, as to why I experience the water I do, and I will listen. But I a damned certain it ain't from just trickles and drips and I cannot find any cracks and neither could my local dealer.

All good points, Elm. Your comments would be apply to all AIs. Yet, some AIs apparently leak in the bow hatch and others apparently don't. That implies some AIs have a solid front hatch seal, while others do not.

We are all guided by our experience. My experience is largely limited to my boat and my wife's boat. I don't ask others how much their hull is leaking. My anedotal story about a TI taking on a lot of water was based on the comments the owner made. That day (1 of 4 days), he took on a lot of water which he attributed to a small opening in the hull at the rudder lines. The other 4 boats present did not have problems.

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

I am a strong believer in a front bulkhead located behind the mast. When I first bought my TI I had a water problem. I could not tell where the water was coming from. Once the bulkhead was installed I had a front and rear leaks that I could troubleshoot. The front turned out to be leaking front hatch bungee plugs. During production they cut the threads and the tap cut through the side of the cup in two locations. In the EC my front hatch was holding a vacuum when I stopped for the night. Hatch was down tight and heard a sucking sound when I tried to lift it. Inside was bone dry. My aft part of the boat had some water that drops in when I open the hatch underway. The new rudder comes with new tubes and improved plugs.

Rene,

let us know what you think about the Charleston Kayak Festival...

_________________
Paul
DogsLife
2011 Adventure Island


http://dogslifeadventures.blogspot.com/

Good point, Paul. Clearly, the hatch seal is not the only place the bow may leak.

Sounds like you put in a serious bulkhead. Great way to isolate your leaks. How did you put the bulkhead in--what materials? What adhesive did you use?

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

Sorry, I could not attend the festival. I thought it was in Charleston. It was half an hour drive away. I don't have a car and the winds were blowing too hard to even consider going by water (well not until I can find a way to make the boat dry).

_________________
Rene

http://miami2montreal.com
http://renepotvin.com

The solution to the flex and contract breathing might be to pipe up a vent much higher than any water would ever reach that would let air in and out . Maybe as part of the rear mainsheet attachment point that was raised above our heads via some crossbars and braces etc .

DogsLife, vacuum sealed hull, now that does sound dry!!!

I to would also like to hear how you have fitted a bulk head. It would not let me put rods in hull, as I do, any more, but sounds great.

I would recommend Rene's blog http://miami2montreal.com/ blog on Charleston--great pictures and good text.

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

I dont know the materials involved, but petro jelly may not be compatable with the O-rings and may cause excessive swelling.. In diving, Silicone grease is quite often used with success.

Does anyone know the O-ring gasket material ?

_________________
Alan W.

Papaya AI2 to replace my well worn V1
TheTwins - His/Hers 2007 Papaya Hobie Adventure Island's (v1.00.01)
.. and a Hobie Outback SUV