Upgrade to a 30-gallon Holding tank possible on a Mk II?

[Seascape]

Hello All!
We purchased a 2007 Mk II last winter, and are enjoying it immensely.
We would like to upgrade the 18 gallon holding tank, to the 30 gallon tank that was standard on the earlier models.
Catalina Direct sells the replacement tank (F8016) for the earlier models, but they have no idea if it will fit in a Mk II.
The compartment access under the cushion appears to be just large enough, but it's impossible to tell for certain if the larger tank will fit, until the existing 18-gallon tank is removed, and the macerator pump, and thru hull are relocated aft. I would hate to tear it all apart, only to find it's not going to work!
Have any of you Mk II owners tried doing this upgrade already? 
Bob Sherman
Catalina 34 Mk II "Seascape"
San Diego, CA
519-847-1122

[Dave Spencer]

Hi Bob,
Welcome to the forum. 
I've attached a link to a lengthy thread about increasing the size of the holding tank in MkII boats.  It's s slog to get through all the posts but it looks to be doable.  There are lots of great questions and answers / back and forth / try this, measure that etc. in the post. 

https://c34.org/bbs/index.php/topic,6593.msg43332.html#msg43332

Although the post is fairly old, it should still be relevant.  I know one of the owners (Dolphina) has since sold his C-34 and now has a new C-42 in a slip a few down from me.  I think he still checks this board out periodically and may be able to offer further advice. 

[Admiral_Swellson]

Pardon me for asking a possibly dumb question, but if you're in the Pacific ocean, why do you need a larger holding tank?

[Ron Hill]

Bob : The 30gal stock#B179 holding tank dimensions I have are:

Top -35 1/2"x 16 1/2"x 21 1/4"
Depth - 7" to 13 1/4"

Ask Catalina direct for a diagram as I can't describe the other measurements!!    Catalina tank # 60170

Sorry about that    - A thought

[Steve McGill]

Bob,

Ronco-plastics.com makes our tanks. CD resells them. At the Ronco site it will have the dimensions for the B179 tank or for 400 others. Additionally they will make it for you with all inlet, outlet or vent ports where you want them.

Good luck,

Steve

[patrice]

Hi,
I bought mine direct from Ronco when I changed our holding tank.
Gave them the original model no.  And gave them location of holes reqiired.
Exellent service.

[Ron Hill]

Bob : I'll be surprised if you can fit a 30 gal tank into the same space that the Catalina factory installed an 18 gal. tank!!   

Make yourself a cardboard cut out of the 30gal tank and see if it fits?!? 

A thought

[patrice]

Hi,

Why not take some empty cardboard box, tape.
On Ronco web site, they  give tank dimensions.
Make a full size mokeup and try to make sure you can get the tank in  place.