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PostPosted: Wed Feb 10, 2010 5:08 am 
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Joined: Tue Jun 19, 2007 6:14 pm
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Location: South Florida
Matt,

Part of this question is curiosity; the other is, as usual, wondering if there is a better way. Question: why is the TnS O-ring hard-chined (for lack of a better term)? Why isn't the O-ring a simple O-ring w/ a round cross section?

The reason for the question is my continuing quest to keep my boat free of saltwater in the hull. I've made great strides, going from gallons in the hull after a 3-5 hr AI-camping sail, to a quart (liter) or less. However, to keep to this acceptable (to me) maximum water, I have to carefully clean my TnS hatch opening, and clean and reseat the O-ring before each day's sail. I suspect that most of the water gets in my hull through the TnS covers because the O-ring has twisted.

Those of you who get very little water in your hull, count your blessings. Those of you who think the large front hatch is at fault, you need to make sure the 2 seals on that hatch are working properly. A rat chewed an 8-inch section of one of my front hatch seals, and my front hatch still does not leak, even when the bow submarines. Those of you who camp need to be careful not to have so much gear in the bow, that you must force the front hatch down to close it. That action can compromise the seals because of the back (upward) pressure on the cover.

Those of you who think water in the hull is no problem are (1) not sailing in saltwater environment, (2) not carrying sensitive electronic gear, (3) do not realize that ordinary dry bags leak when their openings are submerged in water for more than a few minutes, or (4) are not doing camping trips carrying gear and equipment. Water in the hull may not be a problem for you.

Keith

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Last edited by Chekika on Wed Feb 10, 2010 7:19 am, edited 1 time in total.

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PostPosted: Wed Feb 10, 2010 5:33 am 
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Location: Perth, Australia
Hey Keith, if you have electronic equipment already in your hull i'm guissing you are probably running off a 12V battery, in which case have you ever considered putting in a little bilge pump. You can get one with an automatic switch, for well under 50 bucks Might be worthwhile for big trips.

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PostPosted: Wed Feb 10, 2010 6:04 am 
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No, no, Dave, I'm thinking of cameras mainly, even telescopes, and other smaller items like cell phones, digital recorders, and things like that. I don't have a 12-volt battery in my hull.

When I had a major problem w/ leakage I did consider a bilge pump. Now, I don't think that is necessary. You know, you can plug all the thru-holes into your hull, but if the hatch covers leak, you have a problem. I give a lot of attention to the O-ring of the TnS covers. On my 2 boats, that has to be where the water is coming in. Keeping the O-ring clean, lubed w/ silicone grease, and cleaning the hatch cover and sidewalls makes a major difference.

Of course, the less load you carry, the less those TnS hatch covers are under water. I understand the new tandem AI has a rear TnS cover which is slanted--this prevents water from setting on the horizontal hatch covers and draining into the boat. Last year, on this forum I suggested changing the shape of these TnS covers so they would drain. The Tandem AI rear hatch seems to be another case where Hobie listened. I believe the rear hatch is also the closest to the water level, so to slant it may make a big difference. Bravo, Hobie!

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


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 Post subject: Bilge pump...
PostPosted: Wed Feb 10, 2010 8:45 am 
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Joined: Fri Sep 19, 2008 4:07 pm
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Location: CLEARWATER, MN
I tend to frequently submarine going down wind on my favorite lake. I began to notice
more than acceptable amount of water in the hull. I bought the smallest, automatic
12vdc bilge pump I could find and glued it to the bottom with 3M 5200 marine adhesive (which has held to the roughened hull). I installed a small lead-gel battery, which fit perfectly in
my rear hatch gear bucket. I ran a flexible hose up to a 90-degree hull-fitting pointed
diagonally rearward on top of the stern deck. The bilge pump has a built-in one-way valve so no water has ever entered via the fitting.
Even at the end of the roughest day, the battery had never run completely down. I just hook
a small charger to it when I put the AI away.


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PostPosted: Wed Feb 10, 2010 9:20 am 
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Location: Oceanside, California
As I recall, the explanation from the engineer / designer of this hatch is that the round "o" rings would not seal well with the hatch lid even slightly off center. This one allows for some differences in tolerance of the hatch fit in the flange.

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PostPosted: Wed Feb 10, 2010 4:50 pm 
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Location: South Florida
Matt, do you know if a simple O-ring is available with a round cross section? My thinking, again, is that the twisted O-ring allows water in. After trying to keep that bevelled edge out, I've given up and will simply orient the ring with a flat surface making contact with the hatch opening.

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


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 Post subject: Re: Bilge pump...
PostPosted: Thu Feb 11, 2010 2:33 am 
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Joined: Sun Oct 11, 2009 5:57 am
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Location: Perth, Australia
TIDALWAVE wrote:
I tend to frequently submarine going down wind on my favorite lake. I began to notice
more than acceptable amount of water in the hull. I bought the smallest, automatic
12vdc bilge pump I could find and glued it to the bottom with 3M 5200 marine adhesive (which has held to the roughened hull). I installed a small lead-gel battery, which fit perfectly in
my rear hatch gear bucket. I ran a flexible hose up to a 90-degree hull-fitting pointed
diagonally rearward on top of the stern deck. The bilge pump has a built-in one-way valve so no water has ever entered via the fitting.
Even at the end of the roughest day, the battery had never run completely down. I just hook
a small charger to it when I put the AI away.



awesome! I havent had any trouble with water in my boat yet but wanna install one just because it sounds like fun!

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PostPosted: Thu Feb 11, 2010 9:43 am 
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Joined: Tue May 27, 2003 12:44 pm
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Location: Oceanside, California
We don't have a round one. According to our design engineer... he expects our wedge o ring to twist a bit which actually creates a better seal than a round one in this application.

Water does gather above the ring when the hatch is closed, so unless you dry or drain that off first... you will get a small amount in the hull when you open the hatch.

Of course, it is critical to keep o rings (of all kinds) free of grit etc. They have to be clean and lubricated to function properly.

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Hobie Cat USA


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 Post subject: Re: Bilge pump...
PostPosted: Thu Feb 11, 2010 7:06 pm 
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Joined: Mon May 04, 2009 5:02 am
Posts: 817
Location: Sydney - Parramatta
ChaosDave wrote:
TIDALWAVE wrote:
I tend to frequently submarine going down wind on my favorite lake. I began to notice
more than acceptable amount of water in the hull. I bought the smallest, automatic
12vdc bilge pump I could find and glued it to the bottom with 3M 5200 marine adhesive (which has held to the roughened hull). I installed a small lead-gel battery, which fit perfectly in
my rear hatch gear bucket. I ran a flexible hose up to a 90-degree hull-fitting pointed
diagonally rearward on top of the stern deck. The bilge pump has a built-in one-way valve so no water has ever entered via the fitting.
Even at the end of the roughest day, the battery had never run completely down. I just hook
a small charger to it when I put the AI away.



awesome! I havent had any trouble with water in my boat yet but wanna install one just because it sounds like fun!


I can relate to this. It's what keeps me poor..... :P

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