Mariner 3297 replacing/reconfiguring black & fresh water tanks

[KipW]

Hi All, I'm curious if anyone has attempted or has experience replacing the tanks in a 32' 1988 mariner. Right now the boat I believe is configured with a 15 gallon black holding tank below the galley floor. This spot is rather space limited, I measured the current tank at roughly 27.5"x14.5"x10.5" which seems to be a 15 gallon tank. According to the manual, I have (2) 35 gallon (I assume they're the same size) tanks totally 70 gallons below the floor in the salon. The 15 gallon tank I believe will be easy to taken out, not sure about the (2) other tanks but I'm assuming they can be slid around to get out, there's a big opening in the floor.

Here's my thoughts, the 15 gallon waste tank fills pretty fast from my raritan crown toilet and we're often at a marina so we don't really need 70 gallons of fresh water capacity (use the shore hose hookup). So I'm thinking replace those two 35 gallon tanks with roughly the same size, maybe a hair larger if I can, tanks since they are fairly old. That would then give me 35 gallons black & 35 gallons fresh. All new hoses as well, I think especially the waste ones have been leaching odors.

Is this crazy? Any other ideas for how to configure this? I'd likely be just abandoning the space where the current 15 gallon tank is. I'm losing half my water capacity but it's way easier to fill a water tank than it is to pump out a head.

[km1125]

When you get around to looking at the new tanks, check out what greatlakesskipper has. I bought a couple that were intended for a Regal to put in my Carver and it costed less for two tanks and shipping then just buying one tank from somewhere else! I was pleasantly surprised!

15 gal sounds woefully small for a blackwater tank! I would be looking at larger sizes too!

Don't know that model so I can't offer any specific advice there.

[Alanna Mo Cree]

Are all of the tanks on centerline? If the two 35 gallon tanks will be port and starboard, you might have to consider if that will induce a list to the freshwater side. I'd assume you will often have close to 35 gallons in the freshwater side and hopefully close to 0 on the blackwater side. That's 300-350 pounds difference to that one side. It might not be enough to make a difference. You can have a couple people stand over where the freshwater tank will be to see the effects before making the switch.

[KipW]

QR_BBPOST When you get around to looking at the new tanks, check out what greatlakesskipper has. I bought a couple that were intended for a Regal to put in my Carver and it costed less for two tanks and shipping then just buying one tank from somewhere else! I was pleasantly surprised!

15 gal sounds woefully small for a blackwater tank! I would be looking at larger sizes too!

Don't know that model so I can't offer any specific advice there.

Thanks for the tip! I'll keep an eye on their inventory once I get tank sizes figured out.

QR_BBPOST Are all of the tanks on centerline? If the two 35 gallon tanks will be port and starboard, you might have to consider if that will induce a list to the freshwater side. I'd assume you will often have close to 35 gallons in the freshwater side and hopefully close to 0 on the blackwater side. That's 300-350 pounds difference to that one side. It might not be enough to make a difference. You can have a couple people stand over where the freshwater tank will be to see the effects before making the switch.

That's a good point, I believe one of the 35 gallon tanks is roughly at centerline, maybe slightly to port with the other one next to it but all on the starboard side (I'll need to confirm). That said, we've had 4 adults around the table on the port side and I've never noticed much listing so it probably doesn't a difference.

[bud37]

QR_BBPOST That said, we've had 4 adults around the table on the port side and I've never noticed much listing so it probably doesn't a difference.

It quite possible you wouldn't notice a list from inside , but if you went and stood on the dock behind the boat there would be more of a chance to observe the level. Not saying there will be but that is how I would decide.