Vent or Hole?

6

66sunfish

New Member
In the center of the cockpit just under the standard mainsheet hook. Is there supposed to be a hole in the verticle wall up high?
I seem to get about 2 cups of water out of a drainplug someone added to the stern of my 71 fish. So I pumped some air in the drain plug hole and checked for leaks. That is the only place I found air coming out. I taped it an my hull expanded so I shut the blower off. After at least 10 minutes I pulled the hose from the drain plug and air rushed out. So air pressure remained in for quite a long time.
Now before I found that hole, air pressure remained in the hull for awhile even with the hole untaped. So I don't doubt I have another leak somewhere to account for the water.
My real question is If I do have a very minimal leak that hole in the cockpit would act like a vent letting water in. If the hole wasn't there water might not come in significantly.
 
If the hole wasn't there the first time or two you left the boat out in the sun it would have leaks. You need to vent the hull to stop expansion/contraction from the air in the hull getting heated/cooled.
As for a leak it's very possible. Just a hairline crack can allow a cup or so of water into the hull during an afternoons sail. Remember the hull flexes and even a tiny crack can flex open/closed while sailing. Allow moisture into the hull.
It takes a soapy solution, just like with a tire with a tiny hole, to find those minute crack/gaps and look for bubbles. And we're talking maybe taking a few seconds to get just one little bubble from any really small leak.
 
The hole under the rim of the cockpit tub is a vent hole. It's to equalize pressure in the hull with the atmospheric pressure outside.
 
The two most common spots for leaks on the older hulls are at the back bottom side of the dagger board trunk. The blade wears through after some years. Also around the splash rail where it attaches to the deck. Also if left out in the weather and the bailer plugs up I've seen water get in through the vent hole.
Good Luck
 
66,

Wind Line Sails (http://www.windline.net/index.html) has instructions on finding any leaks that you may have along with instructions for many other repairs. As you noted, it doesn't take much air pressure to make the hull expand, you only need 3 to 4 psi to find any leak. Take your time, do any repairs correctly and you will be rewarded with many more years of sailing your Sunfish.
 
HI,
Sunfish, up until 1968, came without vent hole. The problem was that if you went to unscrew your deck drainplug, air would rush out and possibly the deck plug if not properly fastened with the chain could fly and hit you in the eye.
The earlier ones that have them were either added by their owners or a local dealer.
Check the stern hull plug that was added after the fact and make sure that the leak is not coming in there. Use silicone sealer around this drain and your cockpit bailer.
Also check mast well by blowing air into hull and filling step with water.
Good luck
Herb
 
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