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My hulls are sealed
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=65770		 Page 1 of 1
Author:  rudi9999 [ Mon Nov 04, 2019 8:07 am ]
Post subject:  My hulls are sealed
My hulls (1996 boat) are tight. After sailing I hear air getting out of the drain plug hole while opening it.
My understanding is that the hulls shouldnt be so tight but there should be some ventilation through the pylons /corner castings.
What do you think should I do? I never dissasembled the boat, so I imagine removing the castings would be close to impossible?
Thank you!

p.s. I found this thread about the vent tubes
https://www.hobie.com/forums/viewtopic.php?f=20&t=41119
Author:  flatlander [ Mon Nov 04, 2019 10:51 am ]
Post subject:  Re: My hulls are sealed
My first 16 (1982) starboard hull was like that from the factory.
A poof of air when removing the plug, I never did anything about it.
We ended up negotiating the sale of that boat in 2006 to it's third owner and that hull still poofed air!
Author:  HobieMarty [ Mon Nov 04, 2019 12:09 pm ]
Post subject:  Re: My hulls are sealed
I would guess that it is better to have that poof of air than for the hull to be leaking.
Author:  srm [ Tue Nov 05, 2019 3:29 am ]
Post subject:  Re: My hulls are sealed
I wouldn’t worry about it. Most likely what is happening is that after the boat is taken out of the water, the air inside the hull is heating up and expanding more rapidly then it can escape through the relatively small vent hole. My guess is that if you let the boat sit for a little while, and the temperature equalize and then the pressure would also equalize through the vent.

sm
Author:  gharr8 [ Thu Jul 09, 2020 8:40 am ]
Post subject:  Re: My hulls are sealed
Can anyone tell me where there went holes are located? Are they located at the pylons?

Thanks
Author:  ASDASC [ Thu Jul 09, 2020 11:08 am ]
Post subject:  Re: My hulls are sealed
Yes, that are at the tops of the front pylons underneath the corner castings. It's a little small, but I am surprised that the air inside the hulls can warm up fast enough that the air wouldn't get out fast enough. Anything is possible. The one mentioned by Flatlander could have just been partially blocked from the factory.
Author:  speed633 [ Thu Jul 09, 2020 12:22 pm ]
Post subject:  Re: My hulls are sealed
The poof means your hulls are completely sealed. With even a small leak you wouldn't get this. With light colored hulls in northern climates this is less of an issue. The darker your hull and the further south you live the bigger the issue. When you leave your boat parked on a trailer in the sun the air pressure builds during the day and reduces at night. The stress on the hulls from this air pressure can be quite high.

- For example the force exerted on an 18" tall by 16' long rectangle is ~3500lbs per PSI.
- When the air temp rises from 72F to 120F you will see a 1.2 PSI increase in pressure in a constant volume system. (math based on PV=nRT where P=14.7, To=297, Tf=322)

This can break stuff, often it doesn't. I bought a white H18 in Michigan that had completely sealed hulls. It didn't have any issues. So, do you feel lucky? are your hulls white enough?
Author:  rattle 'n hum [ Fri Jul 10, 2020 6:03 am ]
Post subject:  Re: My hulls are sealed
Remove drain plugs when not sailing.
Author:  srm [ Fri Jul 10, 2020 10:18 am ]
Post subject:  Re: My hulls are sealed
speed633 wrote:
The poof means your hulls are completely sealed. With even a small leak you wouldn't get this.


I disagree. The poof could also mean that the hulls are vented but just haven’t equalized yet. I have noticed several times when opening the drain plug (particularly on a hot day, and shortly after hitting the beach) that I get a poof of air coming out followed by water. If the hulls were completely sealed, then there would not be any water getting in. So the only explanation (that I see) is that the hulls have a small leak that is enough to let water in over the course of several hours on the water, but not large enough to let the air pressure equalize quickly after a rapid temperature change.

In any case, I fully agree that plugs should be opened whenever the boat is not being used. Even if the vents are open, you still want as much air circulation inside the hulls as possible.

sm
Author:  Tim H16 [ Fri Jul 10, 2020 2:26 pm ]
Post subject:  Re: My hulls are sealed
After each sailing session, I back my trailer down to the water's edge (leaving the tires in the sand). Pull the bows up onto the rear rollers of the trailer and then attach the extended trailer winch's strap to the front crossbar. Next, I use the winch to start pulling the boat up and onto the trailer. When the boat is at a steep angle and the drain plugs are just out of the water, I open them. After any water in the hulls has drained out, I partially re-install the drain plugs (this allows the hulls to breathe, and nothing can crawl in them). Then I finish winching the boat all the way onto the Trailer.

Image

The next time I want to go sailing, I always make sure the drain plugs are fully closed, before I take the boat off of the trailer.
Author:  CaptObviousNC [ Fri Jul 10, 2020 7:38 pm ]
Post subject:  Re: My hulls are sealed
My port hull just drained about 2 gallons after a 1 hr sail, so I’d much rather have a poof of air! Found a hole...overdue for a bottom job...whenever I complain about maintenance I’m reminded that it’s a 35 year old boat without a motor and then start smiling again.
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