• How To Make Your Own Backing Blocks for Seacocks

    A seacock needs some extra bulk between it and your hull mainly to absorb abuse from wrenching the valve handle, but also because once you add any adapters and a barb fitting, the hose can put some pretty serious side loads on your seacock flange. Here is one solution for the backer plates;

    When I'm doing any fiberglass work, I try to think ahead a bit by saving some of my scrap pieces of mat or cloth and cut them
    up small and kinda shred them up to be added to resin for a filler material. This mix also works well for casting fairly strong parts such as backer blocks. Here's the shredded 'glass...

    http://img.tapatalk.com/b80268c4-a6bd-2d2d.jpg

    Knowing the size I needed, I found a suitable mold...

    http://img.tapatalk.com/b80268c4-a6f4-98f0.jpg

    I'm adept in the art of re-using things, not necessicarily for a typical purpose either! I made sure to mix up a little extra resin each time I did a layup on my present project, and put it in my mold with a healthy portion of the shredded glass to make my backer plates, but typically something this size will take around 4-6oz of resin...

    http://img.tapatalk.com/b80268c4-ac3d-38a5.jpg

    They came out nice and flat on the bottom, but the tops needed a little work...

    http://img.tapatalk.com/b80268c4-ac8c-0c81.jpg

    I basically knocked down the sharp edges to keep from shredding my fingers...

    http://img.tapatalk.com/b80268c4-acc6-09d5.jpg

    I drilled an appropriate hole, then sanded the top flat and parallel as I could to the bottom on a belt sander...

    http://img.tapatalk.com/b80268c4-acfd-61b1.jpg

    And here is a relatively finished product with a seacocks sittin on it...

    http://img.tapatalk.com/b80268c4-ad47-b9be.jpg

    The bottom has a little divot from the raised portion of the bucket and that will make a perfect 'well' for sealant, the seacocks have a groove in them for the same reason. These should work out great, I'll snap more photos as I finish the process.

     

    This article was originally published in forum thread: How To Make Your Own Backing Blocks for Seacocks started by Cap'n Ray,
    To Join The Discussion and View the Original post Click Here.

     

    Comments 15 Comments
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      I took photos of the bottom of my second backer to show the recess I was talking about...



      The bottom of my 'mold' couldn't have been planned better. Here it is with the hole drilled and nearly ready for install...



      The two holes near the top are for the thru-bolts that secure the strainers outside the hull, I will also have to drill three more for the seacock flange, but their location will be determined after everything else is in place.
    1. JAT's Avatar
      JAT -
      That is pretty nifty how the bottom of the bucket produced that "indention" in the backing plate.... that coupled with the machined indention in the seacock itself....will help to produce a very good seal...around the threaded through-hull.

      Are going to mud in the backing plates with an epoxy slurry or use a sealant?
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Jat- Thanks for the compliments! I bedded them and the seacocks with 3M 5200 sealant. I wanted something that wasn't going to come undone, but would still provide some flex as the hull, thru-hulls, seacocks and associated hardware all flex, vibrate, move, expand and contract. I'm VERY comfortable with the install and have seen no signs of any leakage at all. She's been on the water since July of this year, and I make it a point to exercise the seacocks regularly while looking for any signs of leakage. I have NOT painted the bilge yet, I wanted to watch my repairs, backer blocks, thru-hulls etc for a while first. I will most likely do so early next season though as I want to try to wrap up all the major projects and settle into the maintenance stuff now. I don't know if I posted any final 'finished project' photos of the install, I'll go back and look and if I didn't- will get some up soon.
    1. Hendo78's Avatar
      Hendo78 -
      Quote Originally Posted by Cap'n Ray View Post
      Jat- Thanks for the compliments! I bedded them and the seacocks with 3M 5200 sealant. I wanted something that wasn't going to come undone, but would still provide some flex as the hull, thru-hulls, seacocks and associated hardware all flex, vibrate, move, expand and contract. I'm VERY comfortable with the install and have seen no signs of any leakage at all. She's been on the water since July of this year, and I make it a point to exercise the seacocks regularly while looking for any signs of leakage. I have NOT painted the bilge yet, I wanted to watch my repairs, backer blocks, thru-hulls etc for a while first. I will most likely do so early next season though as I want to try to wrap up all the major projects and settle into the maintenance stuff now. I don't know if I posted any final 'finished project' photos of the install, I'll go back and look and if I didn't- will get some up soon.
      Can't see any updated pics mate. Would live to see some tho :-)

      iPad Forum Runner
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      I'm planning to swing by the boat this evening- I'll try to snap a couple then. If not, it'll be Sunday or Monday- but I will get some up. Still dunno why I didn't put any up a LONG time ago! The last couple weeks before launch was pretty crazy though!
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Here's a picture of the starboard block and seacock installed- but before I put the flange screws in...Attachment 2280

      The wire in the picture is the factory bonding wire, it gets secured under one of the flange screws to bond the through-hull and seacock to the rest of the underwater metal.

      I'll have to take some new photos to show the final result.
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Oh, and before someone with a really keen sense of direction and eye for detail (Tim) chimes in, the notation 'fore' in the photo IS on the aft 'end' of the block, what you can't see is the arrow above the lettering that points foreword (mostly covered by the seacock flange). Starb. is also printed on the block at the forward edge- I had to custom fit each of them as they wouldn't clear the stringer.
    1. TimG's Avatar
      TimG -
      lol, very nice pics sir
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Thanks Tim! about 95% of the photos I've posted have been taken with my iPhone- 10 years ago I would have never imagined we'd be able to get useful pictures with our phones... Much less 'good' ones!!
    1. Mitch's Avatar
      Mitch -
      Great information! I am a first time boat owner and just bought a 36 foot 1988 Carver Mariner that sat for 7 years. To say that I have become obsessed with learning about boats is an understatement. We just bought the boat in September and I have learned a tremendous amount through the internet and great people sharing information. I am now taking my projects to the next level.

      We only had the boat in the water for about a 6 weeks before the season ended. Before the boat came out of the water, I noticed a small trickle of water from around the intake for the air conditioning. Even being new to boating, I figured that water coming into a boat through an opening that was supposed to be sealed was probably not a good thing. Initially I wasn't sure if I should tackle such a crucial repair and considered just letting it go since it was minimal, but I read an article that stated "if water is coming in, no matter what the rate, that it is not just going to stop and it will probably get worse." After reading this I decided to move forward. With the boat out of the water for the winter (Chicago) I decided to make this my major winter project.

      After doing some research, I learned that all thru-hull seacocks should have backing plates. None of mine had backing plates. (Air conditioning, head, generator, or engines.) I took the A/C thru-hull loose and started configuring my reassembly. (My seacocks aren't flanged either, so I bought a flanged adapter.) (TimG had a great thread that gave me some tremendous insight.)

      There were 2 issues that I had to resolve. The first is that my strainer and thru-hull are one piece, and are attached to the hull with 4 machine screws. Drilling holes through the backing plate will allow for the attachment, but what about interference with the flange? Having the strainer attached to the thru-hull means that you have to tighten the assembly by screwing on the flange, not by screwing the thru-hull (as you can do with thru-hulls that don't have strainers). My work-around for this was going to be to use wood screws that would simply penetrate the backing plate, thus not interfering with the flange. What are your thoughts on this?

      My second issue is that I have seen most people put the screws to secure the flange facing upward through the backing plate. They attach the flange to the backing plate using those screws and then screw the thru-hull into place. Again, with the strainer attached to the thru-hull you must screw the flange to tighten the assembly, so you can't just sit the flange onto the screws and then lighten by screwing in the thru-hull (again, as you can do with thru-hulls that don't have strainers attached). My work-around for this would be to use wood screws again to screw down the flange into the backing plate. What are your thoughts on this?

      One final issue. I was going to use plywood coated in wood waterproofing sealant (used for fences). I would like to either use epoxy to coat the wood or make the backing plates that you have shown. Everyone keeps mentioning epoxy, but they don't give any specifics as to what type of epoxy or where you might find it. I am new to this and am not sure exactly what to look for. What type of epoxy are you using and am I correct in scrapping my idea about plywood backing?

      Sorry for being so lengthy! I want to make sure I get this right. Thanks in advance for any input that you or anyone else might have!
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Your first issue matches what was on the Carver I restored- the 'strainer' outside the boat is part of the through hull assembly which includes a threaded 'pipe' through to the inside. On my boat there were bolts all the way through with nuts in the inside- that held the strainers in the right orientation (my backing blocks got oversized holes drilled from the back 1/2 way through to clear the bolts) while new threaded seacocks with flanges were screwed down over the top sandwiching the hull and backing block between the strainer and seacock. I placed the backing blocks against the hull with a generous application of 3M 5200 sealant around the through hull, on the through-bolts, between the hull and seacock flange, and around the inside of the backing block. Once tightened down, the through hull was MUCH more stable than original, and a few bronze wood screws (added after my last photos were taken) coated with 5200 held the seacocks from turning at all.

      I would use polyester resin and fiberglass to make your backing blocks. Much more forgiving (and cheaper) than epoxy, while being essentially impervious to water and at least as strong as the original hull material if not stronger. You can purchase satisfactory fiberglass and poly resin products for the backing blocks (NOT FOR ANY HULL REPAIRS) at most auto parts stores, Walmart and the like.

      Hope this helps, post questions if you have any!
    1. Mitch's Avatar
      Mitch -
      Thanks! Are you able to remove the finished product from the bucket without having to cut it out? If so, do you need to coat the bucket first to allow removal?
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      If you wax the inside of the bucket with regular automotive wax, it'll usually just pop right out, I think I made several with the same bucket. Depending on how "fast" you mix the poly, it could get hot enough to distort the bucket and ruin it though. Best to find something disposable just to be safe.
    1. Mitch's Avatar
      Mitch -
      My first attempt at making a backing plate using your recipe. Will let you know how it turns out!

      Attachment 3582
      Attachment 3583
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Looks like you're off to an excellent start!
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