Water tank issues

HopCar said:

Marty will you join the two tanks so you can fill and draw from them at the same time?

Possum had two 25 gallon water tanks, one port and one Starboard. I ran a hose under the engine connecting them. The fill and draw fittings were both in the port tank but I had no trouble filling and emptying both.

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That might get to complicated for me to plumb . I may try to fill from one fill with a y-valve and draw from separate lines with a valve for each . I’m not sure yet and also not sure if I want to drain from bottom or pull from top. Just getting the right tank or tanks is about to whoop me.
I’m overthinking it as always.If this works out I will install two next year on my starboard side. I sure hope Ronco will sell me direct .

It would be pretty easy to connect them but you’d probably need at least six inches between them.

Don’t forget both tanks will need to be vented.

This is the inside of my old port side water tank. There is about a 2” radius type stringer running through the center of the old water tank area. We have a total of four of these stringers 2 port and 2 starboard running along the inside of the hull under the aft deck and into engine room. I’m assuming these are for strengthening the hull. I posted just to show yet another challenge in trying to nest hard water tanks in the area, but I’m getting closer.

I have bought tanks from Ronco directly before. As to the supports in the hull, can you add some filler in between the supports to make it flush for the tanks to sit on? How high do they stick up from the hull? Maybe cut some wood to that same thickness and glass some more inbetween the supports. Then lay a thin piece of plywood on top of them to provide support for the tank. If the area is too curved for regular plywood then get some “wiggle wood”. It is plywood that the grain runs in the same direction so it will literally roll up into a drum. I have some in my garage if you want to come pick it up... I use it to make curved molds for fiberglass.

Thanks Comodave. I think the last mock up I made is going to work . It’s Ronco’s model B348 and I’m planning on two side by side.
I’ve been talking with Ronco and yes they are very helpful. They think my mock up is pretty close to their tank. I still haven’t pulled the trigger to order the tanks but after this weekend I should be ready. I want to make dang sure they’re gonna work , 25% restocking plus all the freight is scary . The tanks will probably set up about 1-1/2” away from the hull so I’ll have fill with something. I’ve got some of that bendable plywood also and I was thinking of doing just what you suggested. Whatever I do it will probably be out of wood . I’m not to good with fiberglass.

Greetings,
Mr. PM. I would advise against wood in any form as a filler. Perhaps strips of rigid foam? Easy to carve and if used in thin sheets, quite bendable.

My reasoning is IF there is ever any ingress of water into that area, there will be a rot potential no matter how well you think you've sealed a wood spacer. Glue the foam down with appropriate adhesive and you've essentially got a "flat" curved surface.


https://www.finehomebuilding.com/2012/01/24/buyers-guide-to-insulation-rigid-foam

RT Firefly said:

Greetings,
Mr. PM. I would advise against wood in any form as a filler. Perhaps strips of rigid foam? Easy to carve and if used in thin sheets, quite bendable.

My reasoning is IF there is ever any ingress of water into that area, there will be a rot potential no matter how well you think you've sealed a wood spacer. Glue the foam down with appropriate adhesive and you've essentially got a "flat" curved surface.


https://www.finehomebuilding.com/2012/01/24/buyers-guide-to-insulation-rigid-foam

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Thanks RT, that sounds like a good idea. Do you think the blueboard type insulation board used on houses would be good enough? I don't guess it would absorb water or deteriorate?
Sorry I see now it was included in your link ,I just didn't read far enough.

Greetings,
Mr. PM. I guess pretty well the only thing you might have to consider is the compress-ability of whatever foam you use. A 25 gallon tank will weigh in the neighborhood of 200 lbs or so (+ the weight of the tank). Even distributed over a larger area, you don't want the foam to compress to the point of creating a pressure point along that 1/2 round stiffener.


I would also incorporate some, even a minimal amount of, ventilation (IF possible) around the tank. Even small bits of stagnant water will smell after a while.

I would epoxy coat the wood and plywood.

Comodave said:

I would epoxy coat the wood and plywood.

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Thanks , I’m sure whatever I decide to use it will outlast me.

It would be great if I could get Ronco to modify these two stock tanks. If they could cut out a section in the bottom and weld in a 1/2 round tube a little larger for clearance of the stiffener these two tanks might nest almost perfect. It doesn’t hurt to ask .

I just called and they said they cannot. It would require a new tank mold.

"I just called and they said they cannot. It would require a new tank mold."


There are other tank mfg sources that might have a better fitting tank.

FF said:

"I just called and they said they cannot. It would require a new tank mold."


There are other tank mfg sources that might have a better fitting tank.

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Might need to do that . That 1/2 round stiffener is the bugger bear right now.

Marty, do I understand that the new tanks will end up sitting on the half round stiffener? If so could you build a low platform over the stiffener for the tanks to sit on?

You could also set the tank in place above the hull support and then shoot expanding foam under the tank for support. Several issues with this approach. You might trap any water that drains through this area. Also would make removing the tanks more difficult if needed in the future. But you could wrap the bottom of the tanks in plastic before foaming to allow future removal. I did foam in a holding tank in a previous boat and it worked great.

Playing around in the shop today because it’s too cold for me at the boat . I think this is pretty close to what I’ll be dealing with to straddle the stiffner . I do need to practice my fiberglass skills and what better place than below deck . I’ve been looking at gridded foam core, epoxy and fiberglass for platform. Lots of options.
Thanks everyone for all the input . Tomorrow is supposed to be warmer here maybe I’ll get a little further along . I’m slow these days . I hate it but that’s just how it is .

Pack.. Why not get a piece of Pipe (PVC) the same size and bandsaw cut it in half. Epoxy and fiberglass it in on either side of the stringer to make a base for the tank. As many as your comfortable with to fill in and make a base. Maybe a piece of plywood or starboard under the tank straddling the supports if you think it needs it. Those tanks are pretty tough.

Solly said:

Pack.. Why not get a piece of Pipe (PVC) the same size and bandsaw cut it in half. Epoxy and fiberglass it in on either side of the stringer to make a base for the tank. As many as your comfortable with to fill in and make a base. Maybe a piece of plywood or starboard under the tank straddling the supports if you think it needs it. Those tanks are pretty tough.

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Thanks Solly that’s s good idea . The tank mfg claims it needs full support on all sides. I’ve thought about starboard also but not the pvc pipe. Do you think starboard would make the bend of the tank? Maybe three frames out of 3/4 starboard and then bend a piece of 1/4” starboard and screw to frames ?

Pack Mule
How about just cutting rings off PVC pipe as spacers to support a piece of plywood?
You should be able to use a belt sander w coarse grit to contour the rings where needed to fit the curve.
Dry fit masking tape rings in place if necessary to test fit then epoxy bottom side of plywood.
Weight it till epoxy sets up.
Remove & add more epoxy to bottom if necessary and top side to seal it.
You might even be able to use the old luan tank mock-ups that didn't work?

Bacchus said:

Pack Mule
How about just cutting rings off PVC pipe as spacers to support a piece of plywood?
You should be able to use a belt sander w coarse grit to contour the rings where needed to fit the curve.
Dry fit masking tape rings in place if necessary to test fit then epoxy bottom side of plywood.
Weight it till epoxy sets up.
Remove & add more epoxy to bottom if necessary and top side to seal it.
You might even be able to use the old luan tank mock-ups that didn't work?

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Thanks Bacchus another great idea. So many great ideas here. Thanks guys , I love this forum.

Pack Mule,

Here's another couple approaches - forget the off the shelf rotomold tanks. The reason you see those odd shapes as that at some point in the past, a boat builder or RV builder has commissioned the molds for that shape to suit their installation need. You could likely find something "that will work", but you can do better.

With your fabrication skills , it appears you could either:

- Make a mold, and build a custom fit fiberglass tank. Working with glass is not all that hard, and you would maximize your water storage that way, plus be able to make the entire installation to your liking, AND be able to modify or fix it yourself if it ever has a problem.

- Find a local welder who will weld your job together, and save money by cutting the pieces yourself. Doing the cutting yourself lets you ensure the size and fitting placement will work best for your boat. You could end up with a custom fit stainless steel tank that will last decades.

Pack Mule said:

Thanks Solly that’s s good idea . The tank mfg claims it needs full support on all sides. I’ve thought about starboard also but not the pvc pipe. Do you think starboard would make the bend of the tank? Maybe three frames out of 3/4 starboard and then bend a piece of 1/4” starboard and screw to frames ?

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I don't think I've ever seen a tank with full support on all sides !! Maybe a built in one. They really should put baffles inside but that would make the price out of sight.

I'd go for good support underneath and something to keep it from sliding around and call it good. I was thinking of the PVC when I saw the half round stringer and thought it wouldn't rot. Also I'd want to see how slippery the starboard is with the tank sitting on it.

I put another water tank ( 40 gal.) in that sits on a plywood base with a ratcheting strap to hold it in place. Seems to work. Doesn't slide and the tank walls seem to be strong enough to resist the water sloshing around.

I think it’s time to STOP back up and regroup. The more I mess with this “off the shelf” tank I can see it doesn’t make sense. Compared to my old tank area this tank is just not going to set low enough for me. This is what I think the profile of the tank is and it’s only the bottom half, there is another 7” or so of tank above this. You can see how far it’s going to be from the bottom of my original tank area and it’s almost to the old top then I have to add 7” to that.
William already has enough of a snappy roll and I’m afraid it will just get worse adding the extra weight higher up, Y’all hang with here. I don’t want to loose my motivation.

The profiles available of off the self tanks just are not working. Now I’m considering having a stainless steel tank custom made. I made a template of the forward end of the tank today. I’ll make an aft end template tomorrow, there is a little difference in the two ends. This will be the port tank . If I get it right the starboard tank should be a mirror image. .

New tank mock up for custom build out of stainless steel. If the tank will be supported on all sides will 16 gauge stainless steel be sufficient?

Marty, I’m not an expert but my guess it is strong enough to hold it's shape but can you weld it? I think metal that thin is usually spot welded and your going to need a continuous bead weld. I may be wrong but I’d ask the welder.

I love your wood work. I’m Mr. Two By and Ply, the Crappy Woodwork Guy. I have business cards that say so.

HopCar said:

Marty, I’m not an expert but my guess it is strong enough to hold it's shape but can you weld it? I think metal that thin is usually spot welded and your going to need a continuous bead weld. I may be wrong but I’d ask the welder.

I love your wood work. I’m Mr. Two By and Ply, the Crappy Woodwork Guy. I have business cards that say so.

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Parks, I’m planning on using the guy that built my davits. He’s a young farmer that does body work and builds custom cars for fun. He’ll probably bend whatever he can and then weld the rest and maybe weld some small angle over the welds. He custom fits turbos in tight areas with with sections of thin stainless pipe cut in all kinds of angles to get the curves he needs,tack welds it together and then welds it solid after he’s satisfied with the fit.

I think I would go with 1/8". 16 gauge is only 1/16". 0.125 vs 0.065. Stronger and a little easier to weld. Still probably need to skip weld it and fill in.
I think my aluminum fuel tank is .125 and it's 200 gallon.

I'd also make it sized to fill the space. Can't have to much water ! If your worried about the roll put some baffles in it too.

Solly said:

I think I would go with 1/8". 16 gauge is only 1/16". 0.125 vs 0.065. Stronger and a little easier to weld. Still probably need to skip weld it and fill in.
I think my aluminum fuel tank is .125 and it's 200 gallon.

I'd also make it sized to fill the space. Can't have to much water ! If your worried about the roll put some baffles in it too.

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Thanks , If we I build it out 1/8” I’ll have to take out the side of the old tank so I can slide it into place instead of dropping it in , but I could do that. 1/8” would probably weigh about a 100 lbs or more .

Looking at your pics again it seems you have support to the front, back, bottom and 1 side. If you could fab support on the 1 side ( inside ) left you could go with a flexible tank.
Maybe reconsider that now that you have the access and open space...