Providing Tank Removal Access

Discussion in 'Fiberglass and Composite Boat Building' started by SeaJay, Jun 20, 2010.

  1. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    Suggestions please. So far, in the design and build of my 46’ motorsailer, I’ve been able to provide lift our access to all of my tanks…except one. It is located under the cockpit sole. I could just build the sole so with a “soft patch” that could be cut out later if necessary, but that doesn’t seem like a very elegant solution. The need to get at this tank again is probably close to zero, but I just don’t like the idea of glassing it in if there is a better way.

    One alternative is to build a “box hatch” over the tank, but I’d prefer something flush. Would anyone have some ideas of how to go about this? There would be no need for hinges, or quick access…the top would essentially be permanently “bolted” in place, but with effort, could be removed if the tank needed to be replace sometime in the future. Obviously, keeping it leak free is the trick.



    Sea Jay
  2. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    "The need to get at this tank again is probably close to zero"...

    If it ain't broke, don't fix it. Why cause yourself needless aggravation? We can provide that for you.:p
  3. Lurvio
    Joined: Jul 2009
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    Lurvio Mad scientist

    I see this as a question: Is it easier to make the hatch than to repair the sole panel once it's cut open (if/when you need to get to the tank).

    Just my two cents.

  4. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    I'm a bit like SJ here in that I hate to bury anything in such a way that I can't get to it later.

    What I'd be tempted to do here is to build the cockpit sole with an opening to access the tank, but have the cover for this opening bolted down flush with the rest of the sole. A lip fastened to the underside of the sole, extending an inch or two into the cutout, should do the trick. Then, tapped holes (if metal) or T-nuts (if wood) can be installed in the lip to receive flush-head bolts for the cover (use enough bolts that it won't flex at all- our local car ferry has such access ports in its steel deck, and I think they're bolted every six inches or so, several dozen bolts for each cover). The cover could be bedded with something like Dolphinite or one of the low-strength, low-modulus miracle sealants, keeping it watertight until the boat's third owner feels the need to open it up.
  5. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    What's the tank for? How big is it? Does it have to go there?

    Marshmat has the right idea, a permanent semi-permanent cover that can be removed in an hour more or less without having to compromise any structure or do any repair other than replace a permanent semi permanent sealant.
  6. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member


    Your suggestion is along the line of what I was thinking about. The suggestion about Dolphinite is a good idea. I was thinking about a rubber gasket but I don't think I'd get the seal I need (at least after a period of time).


    "Why cause yourself needless aggravation?"...good question! but you know how it goes...just as I say, "oh well, I'll never need to get back in there again", and then glass the tank in for all eternity, the next week I'll discover that I didn't tighten down a fitting and I'll be cussing myself for months. Of course if I do put the access plate in I'll never need it. You know how these things work. Maybe I should think of it as an insurance policy.;)


    I think Matt's suggestion is pretty simple to implement. Although in theory the patch wouldn't be that much work, it would likely happen some point down the road when I (or a subsequent owner) wouldn't have all of the tools and materials at hand. I could see that what might be a day's project in my current shop could end up being a real headache down the road. But the question you posed is indeed the issue.
  7. apex1

    apex1 Guest

    For engine replacement on our larger boats we build a hatch framing in the saloon sole (to handle the loads from interrupted frames), then tightly insert a hatch (without hinges), which continues the frames pattern underneath. On top the common saloon floor (teak deck) is layed.
    In case of engine replacement one would have to lay a new teak deck, but thats all. (apart from lifting the cabin roof)

    Quite close to Matts method.

  8. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    Thanks Richard, we are on the same page.



  9. apex1

    apex1 Guest

    I forgot to mention that Sikaflex will be probably the sealant for your requirement.

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