Did You Test The Vent?

Did You Test The Vent?

The thought never crossed my mind......Here's my story...Live and learn....

I shaped a stringerless longboard out of 1.5# EPS foam. The crew at the Low Tech Lab helped me vacuum bag wood skins on the bottom and deck. Wood tail block / stripes / glass on fin.....Awesome board. There's photos on the Low Tech Lab thread...Last Saturday I surfed Terramar with Surf4fins. Board worked great. When I got home I set the board down in the front yard and forgot about it. I normally do not leave my surfboards out in the sun. I have all kinds of storage space...But the board is vented and we needed to glass Surf4fins' gun and a New guy named Trevor was coming over to fix a snapped board.................................Bla Bla Blah....

About one hour in direct sun. 80 degrees F...Major delam / bubble...yeah...the whole nose concave delamed...WTF....I just had to stay mellow....set it aside...think about it for a while......

Today...One week later , I put the board out in the sun...80 F....my plan at this point was to just delam the whole thing...

and then repair it...and then send an e-mail to Brian over at GreenLight......Well....maybe...just maybe...maybe.. I screwed up the install...

And I said to myself...out loud..."Did you test the Vent?"........NO.

 ...Well....I put some water on the vent...no bubbles. I went inside and grabbed another board with the same style vent...Less than 60 seconds in the sun and the water bubbled. Then I got the 12'6" SUP...it has 2 mini leash plug vents from Greenlight......water bubbled..vent worked.....Lesson learned.

Test your vents......

I hate to say I'm wrong or that I screwed up but at this point I think my vent install on the delam board was my fault. Too much resin around the plug....ect ect ect......

Test Your Vents!!!!   Live and learn.....





I had a related problem installing a gore-tex vent.  Fortunately I caught it in time.  I installed the vent, then I didn't mask or tape it off while wetsanding my gloss coat.  The resin slurry got in there, and completely plugged the fabric.  No more vent. 

When I first discovered the vent wasn't working, I blamed the vent .  Then I got to thinking about what I did.  Duh!

Ray, that’s a good tip.  What did you use under the veneer that failed, and what density is the foam?

Brian Syzmansky build a lot of SUP’s, he has had the gortex vents fail, feels that the micro grains of salt dissolevd in the seawater condense out and fill the membrane

Which vents would you recommend?

Weird - my concern with Gore-Tex vents is based on stories I've heard that ocean water soaks in, dries up, leaving expanding salt crystals in the fabric that spread the membrane open eventually causing water leaks...  exactly the opposite of the problem that happened to Ray.

Gore-Tex membranes are manufactured to different specs and some types are more breathable than others. 

I know that the ones from PeteC work fine but it is important to follow the instructions.  After installing you have to unscrew the cap, drill a hole (two holes - one to either side of stringer?)  through the body of the vent and replace the cap.

I've also read that some manufacturers recommend fresh water rinses and annual cap replacement.


Ok....some interesting comments....After reading this thread I took the board outside and sprayed the hose on the vent. Nothing new happened. No bubbles. The board has been surfed about 10 times and the vent never rinsed out. I bet the instructions tell you to rinse the vent.....I have lots of surfboards so it's not like I lost my ultimate stick....I was doing a  test with 2 longboards the same length and template with different rocker and rails.So I guess that test is over for now.......

The blank was from the White Hot close out sale. Not 100% sure what density but an educated guess is 1.5#. It came to me as 2 halves that I glued together with Gorilla Glue. The skins were vac bagged directly to the foam with Resin Research and no glass.

My theory is.....

1) The Gorilla Glue expanded and filled up all the voids in the foam where the two halves were glued together. The heated board wants to outgass but the expanding gas inside the surfboard cannot make it to the vent because the pores are clogged.

2) The resin from the skins made it down into the foam a little clogging some pores. The last step of the the vent install is to fill the hole with resin. Maybe the resin soaking into the foam went past the epoxy putty and did a little exotherm melting the foam around the plug. And I just poured on more resin making things worse.........

Thanks for your comments!               Stingray

Why didn’t you put a layer of cloth under the veneer, that way you get such good adhesion with the cloth between the foam, and the veneer?  I suspect the failure is in part do to the means of construction.  80 degrees isn’t that hot.  


Why didn't you put a layer of cloth under the veneer, that way you get such good adhesion with the cloth between the foam, and the veneer?  I suspect the failure is in part do to the means of construction.  80 degrees isn't that hot.  


Low volume Low Tech Lab. I did one with 2oz under bamboo. I did 2 or 3 with 4oz under wood. Beechwood and Rosewood. Surf4Fins has done a few with 2 oz under......I have to work out all the bugs and try different things........I fix a lot of things for other people...I plan to use cloth in the future....,..why no bubbles on the vent when wet????    regardless of construction....   I'm backyard...sometimes the lack of volume slows us down on the troubleshooting......I'd like to hear more Mr. GhettoRat......

...but really.....imagine if I was a first time guy...freaking out...oh my God my masterpiece is dead!...ha ha......

I paddled around the Auga Hedonia Lagoon yesterday on my new 12'6" SUP ....I have all kinds of wierd aches and pains in all kinds of wierd places....the vents worked....I checked them when I got home.......Ray

The petec gortex vents are the best in my opinion, and post drilling them as in the instruction diagram that is provided is important.  The bubbles appear to be on both sides which can be because of the post drilling after setting was improperly done.  Now that may factor in but I believe the biggest mistake was the blank being not sealed correctly so the resin wept into the interstices because of the cure time of the epoxy.  Even without the vent the board should have been Ok at that temp.  Next time seal the blank with an epoxy filler slurry, and sand when dry, then use a fiber to bond in between, and that should be enough, so that the vent only acts as an insurance policy.  How are you regulating your vacuum, and how do you measure, and how much are you pulling?  The fiber acts to mechanically bond the substrates as the fibers get down into the pores, or interstices, and with a 1.5lb eps the weight addition will provide sustained momentum.  Mass X speed = momentum.

Ghettorat the great...........I get it........thank you.....and the offer to buy you lunch is real.......you're right as always....

The insurance was the vent..... the vent did not work.....bad lam,bad install whatever.....I'm not blaming the vent or the vent maker.......Feel free to throw out more big words......the lam failed...the vent failed....

now...do you want a free lunch or not....I'm in North County...,,,,


Hi stingray

I learn from a wood mold boat builder that you must use colloidal silica in epoxy resin when you glue wood (without fiber between) to be sure that resin stay in glue join and not travel in wood (and foam for use).I have some delam problem with balsa skin evcen with fiebre between, so now, as ghettorat said, i do both: seal wood and foam with epoxy/silica and add fiberglass laminate, all in same process. i do some test panel before, impossible to separate without destruct foam.

I see a Score with a vent that not work, board look like a ballon, funny when it’s not your board LOL.

Sorry for my frenglish

A customer or ours made this video of his low tech method of testing Greenlight’s Vented Leash Plugs.


Correct installation is key. If you get resin in the gortex membrane than it’s just another leash plug.

Here’s the new VXV install video





I'm suspecting the wood to foam was the failure, and not so much the vent... I never use any vents. No vent in my 16 ft man machine.   Plenty of dings, plenty of water bubbling out...no delam though.  Never had any delam yet on any of the  Timberflex designs? I think the deck should always have an under wood glass lam of 4 oz, then a top layer of either 4 or 6 oz....maybe under 6 oz if weight isn't the issue.   If only a 4 oz then the wood sometimes cracks depending on the type of wood.  The beach wood is really tough, the mahogany not so tough.

The only time I do a straight wood to foam connection is on the bottom.  But then I wet that out pretty good, and I leave the foam scratched up pretty good too. 

When we all doing lunch. I love tacos..........

I use the screw in vent type, nothing against gL

maybe greenlite can design a gortex vent that can have a replaceable insert

like an outer cup to be resined in the board then a threaded insert with the goretex and leash bar that threads into the cup.

this Idea is presented by Kenneth Anthony Moore on 8-21-11


The blank was sealed with spackle. The wood to foam without cloth was a test. Test failed. I've done skins with cloth under and I still get resin soaking up through the wood. And.... I am NOT flooding the thing with resin when appling the skin...just enough resin to get the job done. Not sure on the Vac pressure. I have several EPS boards without skins ,without delam issues. and i've been doing some hard core testing with those boards. This is all new to me. I have read about it.......Today I was out in the shop looking at the delam , making a repair plan. Nice So Cal summer day. 8 miles inland...not too hot inside the shop. Surfboard looked like Mrs Puff from SpongeBob. I drilled a small hole so the thing can vent until I have time to fix it. I'm going to remove the leash plug vent very carefully and try to test it....any suggestions on testing the vent after removal?

Took the 12'6" paddle board out to the lagoon and paddled around. Rinsed it off real good when I got home. Resinhead does not need a vent because his boards are so thrashed the dings do the venting...Ha Ha ha ha ha ha ha.......



A customer or ours made this video of his low tech method of testing Greenlight's Vented Leash Plugs.


Correct installation is key. If you get resin in the gortex membrane than it's just another leash plug.

Here's the new VXV install video





I watched the video. Install is correct. But I use a cordless drill.

I started this thread to make sure people test their vents. I like Brian from Greenlight and I sent him a PM so he was aware of the thread.....

Ok...I carefully removed the leash plug vent using a Rotozip tool. The foam under the plug is virgin. Never touched by resin or Gorilla Glue. The glue stringer is very very  clean. Damm I do nice work....I put the Vented leash plug in the vise and filled it up with water. I took a hair dryer and placed it One inch under the vent and turned it on high........no bubbles or other action.....This vent is a reject. In the future I will test vents before install.

If Ghettorat wants to do independent testing I will be more than happy to drop off the vent at Jim Phillip's shop...We need to protect your true identity....sir GR....

And then...I have this delam to deal with...F^%$  it....I cut the whole bottom skin off....and it was a quality job...all nay sayers can go pound sand......

Did you test the vent?.......................Stingray.............

It takes a very long time to build up salt crystals on the membrane, and it’s very difficult to get them to stick since Gore-Tex is actually woven teflon.  However, it is important to rinse the vent since the openings or ports on the body are pretty tiny.  Wax, sand, etc can plug them up.   Ambient temperature isn’t so much the issue with eps heat problems, it’s solar loading.  It doesn’t take much time to rapidly heat up a surface 40 degrees over ambient temp in direct sun in SoCal with low humidity.   Once you get over 115 degrees F in the foam, most membrane vents don’t have enough airflow to compensate fast enough.  Another issue is vent location.  The air exhausting from the vent is squeezed from the spaces between the beads as the beads themselves expand.  From the point where the heating is occurring (i.e. surface in the sun) to the vent is critical.  Until the escaping air reaches the vent, it encounters resistance to the flow based on the distance to the vent.  Same as electrical resistance, it is a function of cross-section vs. length; longer or narrower = more resistance.  Venting is really converting the heat energy from the sun into the work of moving the air through the core to the vent.  If a high resistance to the air movement in the core is encountered, the solar radiated surface MUST become hotter to overcome this resistance.  It doesn’t receive more energy from the sun, but it cannot transfer what’s already there fast enough so it gets hotter to maintain the energy balance.  So if the tail is in the sun and the vent is at the nose,  there’s going to be problems at the tail and visa versa.  Harbor Freight sells a non-contact laser thermometer for about $15, all you need to do is scan the surface temperatures to watch this happen.  

My son’s repair business has seen a number of delam’s recently from guys who leave boards in the sun on their boats for days, even with vents.  Once the glass is removed some have had the foam melted/collapsed over 1" deep.  So my analysis is that these delam’s occur when the foam shrinks or melts and an air pocket forms.  The air heats much faster than foam (just ask the hollow core guys) and then the bubble happens.  Even just a minimal separation between the blank and foam for whatever reason during glassing will create an air gap layer that will react during heating. So as ghetto says proper sealing and blank prep is really important.

Not trying to scare anybody, but you have to very anal about sealing and the quality of lamination.  Prefect glass jobs may never have problems if not left in the sun as resinhead says.