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BigB

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Thanks a LOT!! Sounds like a plan..

I'm gonna price out the wood and glass..

Small Problem - don't wood only come in 4x8 sheets?? I need it to be 9 feet, and I can't have any seams..

[ July 04, 2001: Message edited by: BigB ]
 

BigB

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Do I have to use plywood, or can I use another hardwood?? I found 5x9 sheets.. That will work.. They offer it in Oak, and all kinds of others..

I don't know what "Marine Grade" means...
 

MarkS

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by BigB:
<STRONG>Do I have to use plywood, or can I use another hardwood?? I found 5x9 sheets.. That will work.. They offer it in Oak, and all kinds of others..
</STRONG><HR></BLOCKQUOTE>

In one word, no! Plywood is MANY times stronger than a sheet of the same wood. The reason is due to it's construction. It is a laminate. What makes it so strong is that the grains from each piece of laminate run perpendicular to each other. A regular sheel of wood would bow terribly and crack under the pressure.

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by BigB:
<STRONG>
I don't know what "Marine Grade" means...</STRONG><HR></BLOCKQUOTE>

I am trying to find this out too. From what I understand, it is glued together with a marine glue and sealed against salt water.

Mark

[ July 04, 2001: Message edited by: MarkS ]
 

BigB

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Awesome.. Then that is what I am going to do..

Marine Grade 3/4" Thick Plywood.. May even go to 1" thick for the hell of it..

That Brings me to another question...

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BigB

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Well - I was wrong.. The local lumber yard only sells 4'x10' sheets of marine plywood..

I just have to decide on thickness, and the small details...

I appreciate all of your help.. This is WAY cool!!
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Jase

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by BigB:
[QB]

As for the size issue - 400 to 500 gallons is plenty for what I'm going to do.. When it gets too big, I can bring it to the Birch Aquarium.. /QB]<HR></BLOCKQUOTE>

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rottndog

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Hi, Don't know if anyone is still interested in this thread and I'm not an engineer but had a few thoughts to add.
1) The stress on a tank containing 600 gallons is FAR greater than that on a tank of around 200 gallons, which is what the other wooden tanks mention were. My point being that unless the 3/4" plywood is grossly overly sufficient for those tanks it might not be strong enough for your proposed tank.
2) I wouldn't use 4" screws ever 4" as someone mentioned (for joining the end panels). It would be extremely difficult to keep the screws straight enough to make sure they did not come out one side or the other of the panel they are going into lenghtwise. (They'll go through the end piece perpendicular, therefore only the thickness of the wood, but will have to pass over three inches into the next piece, hopefully staying withing the 3/4" thickness of that piece.) My suggestion, much shorter screws would hold just as well and not puncture through either surface of the second piece of wood. I would think 1 1/2" - 2" screws would be fine.
3) A combination of outside bracing, preferably metal angle iron (could be aluminum, but in angle iron shape) and using fiberglass roving and epoxy, just like a boat hull, would make the tank plenty stron enough (if done well) and would get over the problem of joints. Another possibility to add strength would be to make the stand out of cement (possibly on top of an I-beam stand) but mold the cement so that it comes up around the base of the three sides of the tank which are not glass. It would only need to come up, or the tank be recessed into it, a few inches to add tremendous rigidity to the shape of the tank.
4) MANY public aquariums have large tanks made of fiberglass. I think most are cored with plywood, not so much for the strenght of the plywood but to have a form over which to lay the fiberglass roving. I think that would be well worth looking into since you know people at scripps and they undoubtably know people at other places, such as the National Aquarium in Baltimore. Cement isn't such a bad option either, for the whole tank, it's relatively cheap and this won't be a quick deal no matter how you do it.
5) I think the point one of the earlier posters was making about sizing the tank to the sharks was that sharks really should have lots of room to turn around in and that a tank a little more square is probably in their best interest and yours. From what I understand sharks are quiet prone to bacterially infections and bumping into the tank could be a good intro to an infection.
6) Why not keep smaller sharks (than tigers) like bamboo sharks or cat sharks which you could keep thier whole life in a tank such as you're thinking of? Not being critical their, just think it would be neat to grow old with a shark.
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Hope this works out for you, I definately think it's doable. I think the biggest issue is just being sure of the necessary material thicknesses/wieghts to be sure of adequate strenght. I don't think it's undoable by any stretch!
Mark
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dbman

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by rottndog:
<STRONG>Hi, Don't know if anyone is still interested in this thread and I'm not an engineer but had a few thoughts to add.
1) The stress on a tank containing 600 gallons is FAR greater than that on a tank of around 200 gallons, which is what the other wooden tanks mention were. My point being that unless the 3/4" plywood is grossly overly sufficient for those tanks it might not be strong enough for your proposed tank.
2) I wouldn't use 4" screws ever 4" as someone mentioned (for joining the end panels). It would be extremely difficult to keep the screws straight enough to make sure they did not come out one side or the other of the panel they are going into lenghtwise. (They'll go through the end piece perpendicular, therefore only the thickness of the wood, but will have to pass over three inches into the next piece, hopefully staying withing the 3/4" thickness of that piece.) My suggestion, much shorter screws would hold just as well and not puncture through either surface of the second piece of wood. I would think 1 1/2" - 2" screws would be fine.
</STRONG><HR></BLOCKQUOTE>

Valid points, to a degree. However, the only important dimension is the depth when it comes to interior pressure. If the 600G is the same depth as the 200G, the same wood, same glass, everything is fine. Make it significantly deeper and you might have some problems and need to go 1" or maybe a 1.5" laminate or something.

Regarding the screws... if you're trying to screw into the ends of plywood you really need to pre-drill the holes; this makes it much much easier to drive a screw in a straight line. But 4" screws is probably excessive no matter what.
 

Moti Mo

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Hi guys, no advice here. I just wanted to say thankyou to everyone who posted for being so polite. There were a lot of points of disagreement in this thread, and never a mean word said. I've only been on this site a few weeks or so, and I've seen so many petty squabbles and flamewars that I thought about not coming back, after all this site is for people who are just looking for some advice or reassurance. Anyway, way to go!!!
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