How to find the proper holding tank for my boat?

[SSBN506]

I am looking to install a holding tank in my 1977 challenger 7.4 sailboat (about 25 ft). I have a few books on doing it but there is one question I have not found an answer for. How do I find one that will fit in my boat? Do any suppliers keep records of what tank shapes will work in what boat brands? My boat a challenger and had about 800 made in Canada so it is a bit more obscure than say a Hunter. I don’t know what size I should buy and in and what shape. I would like to put it in the bottom part of the v-berth or on one side of the v-berth.


Do any of you know of a good company that has experience helping someone figure out the best tank for their boat? I live in a remote location so I can’t take it to a full serves marina because there aren’t any, but I don’t mind doing the work myself.

Thanks for your help

[smackdaddy]

I just bought a Todd holding tank for my C27 (from SailNet actually - just click the link to the left to see them). It's been great. Fortunately, I had the old one to compare.

From what I could find in my research, there's not a lot of info (apart from owner's manuals, etc.) on tank size specifics per boat.

Can you just measure the area in which you want the tank? From that, you can have one custom made in any shape you want (which is pretty expensive) - or you can buy a standard "box" tank which is far cheaper - and put it in the space with bracing to make sure it doesn't jump around and spew.

[JimsCAL]

Some thoughts based on my exeperience doing this 15 years ago. Figure out the largest off-the-shelf rigid plastic tank you can fit in. Consider where you will run the hoses and consider the space needed to make bends, etc. You may have to cut away and then re-install some of the vee berth to get the tank in. I did.

[newpbs]

It might be worth considering a composting head. They are self contained and installation would be much simplier.

I'm getting close to replacing my existing head and a composter might work for me. I'd gain space from my curent tank. My current holding capacity is often not enough. The composters boast a good capacity because they are waterless.

Paul

[SSBN506]

Thanks for the advice. Can you get per made ones in a V shape to contour to the shape of the v-berth? If you can figuring out if it has the proper couture i assume could be tricky.

I have a friend who has a composting head in his trawler. Very interesting but from what I have seen quite large.

[Architeuthis]

I faced this problem when Ezell would not supply a replacement tank with different fittings or size. Even when you have the manufacturer you can end up in the same position.

If I was to do it again I think I might go for that composter but room is an issue. Check measurements to see if you can fit one in place.

Designing your own tanks seem to be the only way to get the most out of limited space.


I would suggest designing each side by itself. It is possible to bend the metal to make the tank but that takes more skill than just cutting out 6 odd pieces and welding them together.

Always keep in mind that the company making your tank is not likely to have highly skilled engineers and machinists on staff and if they do they are not likely to build your tank, remember you wanted affordable.

Consider opening the V berth. The projects that cut the whole section out looked like the best to me. Then when the tank fails or you have to work on something you can open the whole thing up just by removing about a 100 bolts, LOL. I still like that set up the best.

I have seen some very complex items made by just cutting cardboard.

By that I mean they took some stiff cardboard and cut it down to fit a side. Then they tape all the sides together, while in place. That became the model. That model was used to create prints and was taken to the machine shop so they could see the product in 3D and have something to compare during construction.

I prefer drawings but think the models are best. I'm pretty sure the last tank I had made was built properly because I gave them a similar tank so they could see what the final product should look like.

I've tried to have stuff built without a model and in one case got back $15G worth of nice looking but not fitting product. Hard to understand with several sheets of autocad prints sitting in their office. Turns out they didn't use the prints, instead they build everything with a little pocket size notebook. When looking at the two pages used in the notebook it was easy to see that they transposed a few numbers and since the notebook was God and the prints never looked at the errors just built on to each other all week, grrr. When someone supplies thousands of dollars worth of prints use them!!! ok ok l know let it go, LOL.

It is much easier to just fit an off the shelf tank and not think of the wasted space.

[mitiempo]

For a holding tank you want plastic or fiberglass if making your own. Metal holding tanks are a disaster waiting to happen with the corrosive qualities of human effluent. Here's a link to an Ontario plastics company that makes custom tanks and tells you how to size them.
Ontario Plastic Fabricators: How To...

[btrayfors]

SSBN506,

Ronco Plastics in California makes hundreds of very high quality but very reasonably-priced tanks, including holding tanks.

They have an extensive catalog available online, and can make custom and semi-custom tanks. I bought one for my boat several years ago. It was painless.

Marine Tanks - Ronco Plastics

Bill

[arf145]

I can second the use of Ronco. I just purchased one from them last month and am in the process of installing. The quality is excellent--much tougher than I expected--and they'll put the fittings whereever you want.

I'd check their excellent catalog for as close a fit as you can get.

[Architeuthis]

Plastic is the way to go. I went metal because all the plastic quotes were way more expensive and I could get a metal tank made locally in a few days. Companies like Ezell coat the inside of their metal tanks but most don't. As a result they can fail after just a few years, though some do seem to last for decades. Those I suspect have been coated inside and the owners just forgot or didn't know.