Hobie Forums
http://www.hobie.com/au/en/forums/

Breather Holes
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=1304		 Page 1 of 1
Author:  Johneltin [ Mon Oct 25, 2004 6:42 pm ]
Post subject:  Breather Holes
Can anyone tell me if/where there are breather-holes on the H16 hulls? When I remove the plugs there's quite a puff of air and it really builds up during the hot weather down here. J
Author:  drej [ Mon Oct 25, 2004 9:43 pm ]
Post subject: 
Yes there are. The hull vents out one of the (front, I believe) pylons on each hull. Normally the pylons are filled witha foam plug, to keep water from coming in. But there is a metal tube that is punched through the foam plug on one of the pylons. That tube serves as the breather hole for each hull. The "track" in the back of the pylon allows the air to escape.

If you are hearing a rush of air every time you open your drain plugs, it is likely that you aren't venting any more. Check the back of the pylons and make sure you don't have extra silicone jammed in the track. Clean it out as best you can. If you are really worried about it, you can remove the hull from the tramp frame and make sure the vent tube is intact and not clogged.

I had the same problem with one of my previous boats. Its not really a good thing, as the air, when it heats up puts pressure on the hulls. I contacted Hobie about it and they indicated that as long as you store the boat with the plugs out, it should be OK - however. The cooler water when you are sailing should help keep too much pressure from building.

On my previous boat, I had epoxied the frame together, so removing the hull was not an option. Ultimately, I installed deck ports (for a different reason). A small airleak through the threads of the ports gave me the same effect of the air vent tube and solved the pressure problem.
Author:  JaimeZX [ Tue Oct 26, 2004 9:10 am ]
Post subject: 
I have a really bizarre issue on my boat. I store it with the plugs out, and of course only put them in when sailing. After taking it out of the water again, when I remove the drain plugs the port hull puffs out air. Obviously it didn't pressurize due to the high heat of the water... ( :roll: ) so I'm kind of confused as to how this happens. I also usually get a few quarts of water out of each hull (only after flying a hull) so I wonder if it has to do with water getting in some how but air not getting out...? Dunno.

:o
Author:  drej [ Wed Nov 03, 2004 7:47 pm ]
Post subject: 
Hmmm. You would think that for water to get in, air would have to escape...unless...the water is going in under pressure - ie when you are going fast or if the hole is at the bottom of the keel (where there is a bit more water pressure - albeit not much more).

Can't you tell I used to be an engineer? I might have to pull out a slide rule on this. :) So, continuing with this hypothesis, the pressure forces the water into the hull through some opening, but then when the pressure is gone, the raised pressure inside the hull (created by adding water but not removing air) is still not strong enough to let air escape (don't ask me why...this is just a hypothesis). Soooo...when you open the plugs, the boat puffs out at you.

You say it happens when you are flying a hull, do you get water in when you don't fly a hull (ok, we know that could ONLY be on light air days :lol: )?

Seriously, though...how much water do you get out of each hull? How long would you be out on the water for this to happen?
Author:  JaimeZX [ Wed Nov 03, 2004 8:57 pm ]
Post subject: 
Well, I haven't exactly done a scientific study to see how long it takes on a heavy-air day to take on water. :roll: Nevertheless, you are correct that it only happens when I fly a hull. So I think it's coming in the top somewhere. I have one hull that doesn't "pressurize" that usually takes on maybe a half-gallon after 2 hours' sailing, and the other one that "pressurizes" takes on maybe a quart. Give or take.

I've sealed around the pylons so I'm thinking maybe it's coming in the seam between the deck and hulls? I've noticed that the silicone there is slowly peeling off, so perhaps that's the issue? Dunno. Maybe I'll mix up some epoxy and re-coat those edges it that way. Whatcha think?

Jim
Author:  Johneltin [ Thu Nov 04, 2004 5:22 am ]
Post subject:  Breather Holes
Thanks for the advice . John
Author:  mmiller [ Thu Nov 04, 2004 11:30 am ]
Post subject:  Sealing the edges...
If you have looked at new Hobie 16's within the last few years, you would see that we pour resin along the lip now instead of silicone. It works great. We do it with the hulls upside down. Surface tension allows you to create a bead all along the seam.
Author:  JaimeZX [ Thu Nov 04, 2004 3:39 pm ]
Post subject: 
Thanks, Matt. I'll look into doing this when I have some free time. :)

Jim
Author:  drej [ Thu Nov 04, 2004 4:36 pm ]
Post subject: 
The resin on the seam idea sounds like a nice permanent way to fix any leaks there. I am sure you know the vaccuum cleaner test to look for air leaks. That would give you a definite answer

The last time I was getting water in my hulls it was coming through my gudgeon screws...so if you haven't checked those, they could be a culprit as well - although I think you would get a more consistent leak there - flying hull or not.
Author:  mmiller [ Thu Nov 04, 2004 7:01 pm ]
Post subject:  Leaks
Be sure to try the leak detection routine at this link (in our FAQ section):

http://www.hobiecat.com/community/viewtopic.php?t=169

Take a look at the shroud anchors. Their holes sometimes pierce the hull.

Looking at your earlier post... If the boat is in cold water, and the decks are hot, once you take it out of the water I guess the air inside can warm up pretty quick and expand. That could explain a puff after being in cold water?
Author:  JaimeZX [ Thu Nov 04, 2004 9:20 pm ]
Post subject: 
I'd expect the air inside the hulls to *contract* not expand. The air in the hulls would be pretty warm prior to my sailing. Then when I put the plugs in and put the boat into the cold water, they should be creating lower pressure inside. I guess that could suck in some water from somewhere, but then it wouldn't explain a puff when I take the plugs out again. Dunno. :o
Author:  mmiller [ Fri Nov 05, 2004 10:41 am ]
Post subject:  Maybe
Maybe it is a one way leak... like a flap. The hull cools as you place it in the water and the air contracts. There would be negative pressure and it could "suck" water in while sailing. The pressure would equalize. The decks would be warm and when removing from the water the air inside would warm and expand? Creating the puff once you get around to removing the plugs. I think hulls can pump water in as you sail too. the side panels compressing under load and relaxing when not. Would be constantly changing pressure inside the hull.

I know that masts / comptips will pump water in. We have seen masts in a boatyard fill with water. A very small vent can allow humid air and moisture to move into the mast when the mast cools, the air inside contracts. The water condensates inside and when the mast heats the air is exhausted. On a humid day with clouds going overhead, you could get this action repeated hundreds of times a day. I think this is mostly becaure of the black masts we have. We have painted the mold part lines on comptips to prevent this. Seems that very small pores in the glass allowed air and moisture to pass through.
Page 1 of 1 All times are UTC - 8 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/