leaking seacock questions

[shawn382]

Yesterday, I put my '85 CD26 in the water for the season and after checking for any leaking from the newly greased Spartan seacocks (always done annually), I noticed a small amount of leaking coming from between the seacock base and the plywood underneath. With the close supervision of the well experienced yard owner, I gently tightened the seacock bolts and thus stopped the leak. I realize that I will have to eventually replace the wood and rebuild the thru-hull to its original integrity. My first question is.... will the tightening of the bolts hold off the leaking for this season or should I pull the boat now and rebuild everything before starting the season?

My second question is.... The yard owner suggested that in rebuilding the thru-hull, that I saturate the new plywood with an epoxy and this should prevent the leaking from penetrating the wood and causing the wood to rot from the wet-dry cycle. Has anyone done this and also what type of epoxy is recommended? Also, what type of sealant should I use between the hull and the wood and the wood and the seacock?

This is all new to me so any guidance/suggestions will be appreciated.

[barfwinkle]

Shawn

<a href="http://capedory.org/board/viewtopic.php ... rt=0">Here is a link to a thread </a> from a year or so ago on this subject. It is mainly about the backing plates!

As far as tightening up the thru hull bolts, I would be concerned that you may have "spun" the bolts thus breaking the seal they had! When you tighten these (at least when I do) I have someone outside the boat with a screw driver holding the bolts while I tighten from inside to prevent the bolts from turning and breaking the bonding seal.

As far as the backing plate information, the above mentined thread has a lot of ideas and suggestions.

Goof luck and fair winds

[John Ring]

<img width="540" src="http://www.yachttantalus.com/Tantalus%2 ... 20File.jpg">

Shawn,

If the leaking stopped, I think your bolts are ok for this season. Just keep an eye on them.

I suggest using GRP or a plastic, such as Starboard, for the backing plate. It will save you a lot of work, and will never rot out. I've been using Starboard for backing plates and it works fine.

For sealant, use 4200 Fast cure. Do NOT use 5200. Use the 4200 on the flange of the new thru-hull to seal between the flange and the hull. Use it on the threads of the thru-hull to seal between the thru-hull and the valve, and use it on the hose adapter threads to seal between the valve and the hose adapter. Be sure to reach in and put some on the deeper sections of the female threads too.

Do not use any sealant on the backing plate - it doesn't come in contact with water, so put it in dry. If water does leak past the seal areas mentioned above, you want to know about it (see it leaking out) rather than trap it under the backing plate or unde the valve.

Good Luck,

John Ring
CD28 #241 Tantalus

[John R.]

John,

Just a heads up regarding the use of "Starboard" or any other polymer sheet product with seacocks. These materials are not structural products and are not applicable to uses such as backing blocks. Every polymer manufacturer I have spoken with regarding uses of their polymer product has stated the product is not to be used in any structural application. In addition, typical sealants like polysulfides (4200 et al) will not bond to a polymer properly. There is no way a satisfactory seal can be made between a polymer backing block and a hull or a backing block and the valve body. The sealant will not bond to the polymer product. Having said all that you may still find it will be satisfactory and meet your needs as a seacock backing block in your boat but everyone should know that it is not engineered for that usage. FYI, every surveyor that I have ever discussed it with (about 5 of them) said they would flag it on a survey report if it was installed in lieu of traditional materials in a structural manner. For seacock backing blocks a fiberglass/epoxy matrix is hard to beat. Like many people I like polymer for a lot of uses and use it whenever I can but it has it's application limitations. I have seen it used in some powerboats on above waterline applications such as backing support for vents and things of that nature.

[Zeida Cecilia-Mendez]

FYI all... This is a very different way to replace the backing plates on my CD-33 seacocks. I used 3/4" marine plywood with three coats of epoxy and a final coat of varnish and squeezed lots of polysulfide to give it a solid seal with the hull.-Three years later, this is how they look. I used the Red Morey's grease to lubricate inside the barrel...[img]http://www.imagestation.com/picture/sra ... 017f8b.jpg[/img]
[img]http://www.imagestation.com/picture/sra ... 017f8e.jpg[/img]
[img]http://www.imagestation.com/picture/sra ... 017f95.jpg[/img]
[img]http://www.imagestation.com/picture/sra ... 017f85.jpg[/img]