Installing Holding Tank: HOW!?

Apex

.
Jun 19, 2013
1,197
C&C 30 Elk Rapids
Taking advice on installing a new bow holding tank. I have the fittings, new tank (Ronco) etc. following Peggy's advice. I also built a shelf for the tank to sit on (it's in a new location) It occurred to me that I want to create more security for the tank. It fits well in it's location, with both sides of the tank bottom sitting level on the hull surface. After some initial fitting and grinding in prep for tabbing to the hull, I decided that the edges of the base would not create a hard point, as it sits low in the bow of the boat, so something to further spread the load wasn't needed. Currently the base is a simple flat "plate:". The original thought was to simply strap it in place and build a lip at the base to keep it from sliding. It can't slide forward, the bow of the boat prevents that.

Perhaps 1" sides all around? Completely encase? Any dampening media (non-slip mat?) underneath.
I could pre-secure the tank to the base with some drywall screws? (j/k)

Overthinking what should be simple, but I don't want to crawl under the v-berth once this is done once.

Thanks for your input.
 
Dec 2, 1997
8,710
- - LIttle Rock
I'd use picture frame molding or quarter round all the way around the bottom of the tank--or just on the sides that could slide. You can use screws or something like Gorilla Glue to secure the framing.

--Peggie
 
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Jan 11, 2014
11,324
Sabre 362 113 Fair Haven, NY
The attached photos shows how Sabre installed the holding tank in the my Sabre 30. It may be overkill, but that's how Sabre is about building boats. :)
The bulkheads Sabre installed help to stiffen the bow as well as restrain the holding tank. The hoses are state of the art 1981 hoses. :holding nose emoji:

The photo only shows half of the install. There is a longitudinal frame that sits on the bulkheads. this frame provides support for the V-Berth. I'm not sure what's under the tank as I did not remove the tank when I re-plumbed it. The upgrade is documented here:


PC170022.jpegPC170023.jpeg
 
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Apex

.
Jun 19, 2013
1,197
C&C 30 Elk Rapids
Peggie: I am building my own fiberglass with foam core. So far, so good! So I can build in the edges or retaining features as needed.

DLochner: Thanks. Perhaps building up a box around the edges would be most secure, no straps needed then. But that becomes very challenging, as there is NO TOP ACCESS. On the O'Day 28, the v-berth is part of the floor pan. I had to cut a huuuge hole in the forward bulkhead to create access. Talk about a pucker moment... It looks like Sabre tabbed a slot into the hull, and the divider boards then drop in, or is the plywood directly tabbed to the hull?
 
Jan 11, 2014
11,324
Sabre 362 113 Fair Haven, NY
The plywood bulkhead is tabbed to the hull. Sabres are mostly stick built, so bulkheads, knees, and floors are tabbed to the hull. O'Days are built with a fiberglass pan that sits in side the hull. For your install you might be able to use both methods, tab some supports and restraints to the hull or the pan.
 
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Jan 7, 2011
4,727
Oday 322 East Chicago, IN
My Hunter 280 had a bow water tank (plastic). Hunter used some sort of foam (like spray foam) under and around the tank. And a plywood cover over it (to make the platform for the V-berth).

My O’Day 322 has 30 gallon tanks under each settee (also plastic). They are just sitting on the hull, wedged in a bit and a single wood brace across the top to keep it from flying around if the boat rolled.

Greg
 
Dec 2, 1997
8,710
- - LIttle Rock
In your first post you said:
I have the fittings, new tank (Ronco) etc. following Peggy's advice.
In your next post you said:
I am building my own fiberglass with foam core. So far, so good! So I can build in the edges or retaining features as needed.
A fiberglass tank would add a lot more weight to the bow than a PE tank, which can affect the boat's trim. Ronco's standard wall thickness is 3/8", which is strong enough to support the weight of the contents (8.33 lbs/gal) without the need to support on all sides, so there's no real advantage to fiberglass--which, btw, would need gelcoat or other sealant on the interior walls or it'll soak up tank contents. And if you build in the retaining features, I don't think it could ever be removed.

So although you might save a few $$ by building a tankinstead of buying one, you don't gain anything else and may wish you hadn't.

That's my $.02 worth anyway...

--Peggie

Oh...if you're building because Ronco doesn't have a tank that'll fit the space, there are other spaces...or, Triple M Plastics in Maine Triple 'M' Plastics » Custom Fabrication makes TOP quality custom tanks A bit more expensive than rotomolded PE, but everyone who's gotten a tank from them raves about 'em.
 
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Apex

.
Jun 19, 2013
1,197
C&C 30 Elk Rapids
...... And if you build in the retaining features, I don't think it could ever be removed.
Good point Peggie, I am keeping that in mind also.

The tank is a bow shaped tank from Ronco, #184, and fits PERFECT, well other than having to cut a huge hole in the interior pan to slide it forward into the bow area.

I ended up building a 1" tall ridge on the aft end of the fiberglass trapezoid base I built to support the bottom of the PE tank. With the fittings installed, I don't think I have much more room than that, and still be able to remove with fittings installed. After test fitting, the tank could potentially slide forward/up a couple of inches so a 1" tall flange in front is in order as well. I will tab the support base to the hull, and will likely strap the tank to this base to prevent any unwanted movement.
 
Dec 2, 1997
8,710
- - LIttle Rock
I'll be glad to help you spec the best sizes and locations for the fittings...that would be easier if we can TALK instead of type. If you'd like my help, send me a PM and I'll reply with my phone number.

--Peggie
 

Apex

.
Jun 19, 2013
1,197
C&C 30 Elk Rapids
I'll be glad to help you spec the best sizes and locations for the fittings...that would be easier if we can TALK instead of type. If you'd like my help, send me a PM and I'll reply with my phone number.

--Peggie
Thanks Peggie, we talked about the fittings, and from my copy of your book, I ordered the tank with the appropriate fittings and locations. All top fittings, they shipped with the pick-up tube pre-cut at an angle, and ready to install. I have the plan in place as well for the new 1" vent line, up from the old 1/2". Tonight is more glassing of the shelf. Hopefully it warms up enough to tab to the hull, snow overnight, and high of 33°F today?