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Old 10-02-2021, 12:48 PM   #1
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Deck pooling

Hi All, I have been away from the forum for some time so pardon me if I have forgotten proper protocol. I sold my beloved 1986 GB 36CL recently andI am in the process of purchasing a lovely 1998 GB 42CL that has enjoyed covered moorage and excellent maintenance it’s whole life. I have noticed that in its current berth the bow protrudes from the slip about a foot and this rain water does come in an onto the decks in certain weather. Although water and fuel tanks are full water pools on the port side midship (under the galley window). Have others had this issue? Is it a situation for added ballast? Other thought? Thanks for your input. John
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Old 10-02-2021, 03:08 PM   #2
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I would start with a level or measure the waterline at each corner of the transom to maybe the cap rail. I would want to know if the boat is level side to side before doing anything. After that if the boat is out of level, put some temporary weight along the side to get it into level, and see if that solves the pooling water problem.

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Old 10-02-2021, 04:33 PM   #3
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Welcome aboard. Does it have teak decks or fiberglass?
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Old 10-07-2021, 08:42 PM   #4
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John
What is the tankage arangement. I have a 49 classic and it has three tanks if the forward one is empty vs full it does change the trim which would cause the water to move aft towards the drains. Adding some lead ballast could also help to change the trim. I corrected a list of about 1 to 2 degrees by rearranging the batteries from starboard to port. You need to take a careful look at heavy components and where they are placed in the boat. Full vs empty water tanks, fuel tanks and batteries. I filled the fuel tanks today adding about 3000 lbs and the stern went down a little and the bow came up about 1.5 inches. Lots to look and evaluate. I would empty the forward water tank if you have one for the winter months an easy fix. We met in the Auxiliary years ago.
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Old 10-08-2021, 06:32 AM   #5
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it may be the deck sagging if the boat is level . if there is not a bulk head to support the deck . the inside edge can sag under the weight of the house structure .
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Old 10-20-2021, 12:36 PM   #6
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I had a 1979 GB CL with the same problem, on both sides. I have heard of other GB 42s having it as well.

I fixed mine by putting in drains to the side. I drilled a hole at about a 45º angle (if I recall correctly) from the inside corner where the deck meets the gunwale to the outside of the hull, at the corner where it meets the rub-rail. I then added a sealent (probably Sikaflex 291) inside the drilled hole and pressed in a copper pipe (maybe half an inch OD) into the hole.

I plugged the leading end of the copper tubing so the sealant would not enter it as I pushed into place.

The pipe was slightly proud of the hull so the water would not run down the side of the hull.
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Old 10-20-2021, 01:28 PM   #7
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GB 42s (likely 36 as well) have a single deck drain at each aft corner.
Fuel tanks are in the ER, water tanks are in the lazarette.
With all tanks full, the deck drains are above the lowest point along the side deck. Not by much, just enough to be annoying.
Leaving fuel tanks 1/2 full and keeping water tanks full corrects the angle.
Some have added water tanks, so don't have this issue. Some may have altered storage of heavy items to correct this.
(Try keeping a supply of beer and wine in the laz instead of in the midships lockers.)
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Old 10-20-2021, 01:46 PM   #8
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Quote:
Originally Posted by Xlantic View Post
I had a 1979 GB CL with the same problem, on both sides. I have heard of other GB 42s having it as well.

I fixed mine by putting in drains to the side. I drilled a hole at about a 45º angle (if I recall correctly) from the inside corner where the deck meets the gunwale to the outside of the hull, at the corner where it meets the rub-rail. I then added a sealent (probably Sikaflex 291) inside the drilled hole and pressed in a copper pipe (maybe half an inch OD) into the hole.

I plugged the leading end of the copper tubing so the sealant would not enter it as I pushed into place.

The pipe was slightly proud of the hull so the water would not run down the side of the hull.
Xlantic: would you take pic and provide dimensions of the drilled hole and size and length of pipe?
I have same issue with mine.
Thanks
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Old 10-20-2021, 02:36 PM   #9
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Quote:
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Xlantic: would you take pic and provide dimensions of the drilled hole and size and length of pipe?
I have same issue with mine.
Thanks
Sorry, I did this on my previous boat around 10 years ago. I enclose a diagram of what it looks like, in cross section.

I just used some copper pipe I had or bought. I think it was around half an inch OD or, possibly, bigger. (If its is too small it gets clogged mores easily but you don't want to have to drill too big a hole either.)

You need to get the angle as close as possible so the exit point is where you want it. Hole diameter needs to be only slightly larger than the copper tube OD. once you drill the hole you can "dry fit" the tubing to see how long to make it.

Make sure the tube extends an eight or a quarter of an inch beyond the hull so water doesn't drain down the side of the hull and stains it.
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drain.jpg  
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Old 10-20-2021, 04:36 PM   #10
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I did something similar to Xlantic, but used PVC plumbing pipe. Chose one that has an outside diameter for which there is a commonly available hole saw. Something like 1.25 inch will have a 1 inch inside diameter. You aren't looking to drain the deck in case of taking on a wave, only getting a pesky puddle to drain. Get the angle right (and get over the terror of drilling a hole in your deck and hull). Drill the hole. Dry fit the pipe and get the deck end to match the contour of the deck (outside isn't as important). Sand the exterior for good adhesion. Goop the whole area up with epoxy thickened with cabosil. Insert the pipe and clean up the area. White PVC and epoxy with cabosil should match close enough that it won't be noticeable.

Here is a picture of a PVC drain from outside the hull.
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Splash_well_drain_2.sized.jpg  
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Old 10-21-2021, 07:02 AM   #11
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Quote:
Originally Posted by Obx View Post
Xlantic: would you take pic and provide dimensions of the drilled hole and size and length of pipe?
I have same issue with mine.
Thanks
I found some old pictures showing the drains, circled in red:
Attached Thumbnails
gutter.jpg   port.jpg   stbd.jpg  
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Old 10-21-2021, 07:47 AM   #12
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FWIW our 36 Classic has 2 aft deck drains and also 2 more about 6' forward from the stern. They appear to be factory however they are not in the correct location regardless of fuel and water tank levels. We also get pooling. I think that Gilberto has the right idea. When our boat is back in the water I will locate the exact location of the pooling and give it a go.
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Old 10-24-2021, 08:55 PM   #13
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Hi there,

We have double pooling! We have a GB EU52-23 with a top deck, and the top deck drainage should work it's way to the aft drains, but pools in the middle of the length of the top, creating a mess where the water flows over the top and on to the deck below.

The water pools at the deck below and doesn't drain correctly because the pooling is forward of the drain hole.

This solution previously provided does give me some ideas to alleviate the pooling on the bottom deck.

Does anyone have any thought to how to mitigate the pooling on the top deck - short of drilling a hole and installing a PVC type downspout that exits the water 6" or so over the side? The low spot changes by a foot or two, depending on how much fuel and water I'm carrying - but I can deal with that.

Thanks much,

Jim
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