MacGregorSailors.com

Has anyone tried putting a Plastimo flexible water tank under the rear berth on a 26M? How about the port side under the galley?

Under the rear berth there appears to be about 6 inches of heighth available and plenty of width and length. The location would be excellent from a stability viewpoint. This is our second 26, the first one was an X and this one is a new model M.

Darrell

50 liter plastimo fits fine under the berth just behind the battery. You could fit the 100 liter if you wanted but it seems to be a lot of extra weight to be carrying around when day sailing. I carry collapsable jerry cans when cruising. I've run the filler hose to the rear corner of the starboard seats (04 model) - couldn't be bothered fiddling around running it to the exterior. By securing it midships using the tie points you get up to 50kg extra ballast at the lowest part of the boat.

Cheers,

AJ

I have my 32Gal plastimo tank in the far forward port locker across from the head. It seems to work good there. I was worried about putting it under the galley (on a 04 M) because I already have too much junk on the starboard side and wanted to even out the load.

Rich

Correct me if I'm wrong, but aren't the Plastimo tanks about a foot thick when filled to their rated capacity? Wouldn't you want one rated at least 50%, and maybe as much as 100%, greater than the water you'd want to carry given the 6" height limitation?

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Moe

To carry Moe's thought one further - also, if putting a soft tank in a space where it can't fill all the way up, monitor it carefully when filling!!

I have the 35 gallon Plastimo up under the V-berth and I got busy gabbing one day while it was filling ... luckily there was almost no pressure on the dock that day ... when I remembered and rushed below it had expanded upwards and lifted the covers and cushions out of place. Nothing was damaged, but I have a feeling that if the bladder had been under part of the liner somewhere, and there had been more than a trickle of water pressure, it may have cracked fiberglas...

- AndyS

P.S. I really HATE the tank up under the V-berth. If I had 3 adults in the cockpit all the time, it would be no problem, but with just me in the boat to counterbalance it, the weight up in the nose pushes the bow down a bit. If I want to motor fast in more than 2' waves, I need to empty that tank up in the bow or else I take a heck of a lot of spray

If you guys post some success with putting tanks under the aft berth, I'll probably make a similar mod to my water system. I've been kind of hoping someone would start manufacturing a flatter tank that would fit under the aft berth better.

- AndyS

Andy, won't trimming the motor up lift the bow enough?

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Moe

Andy26M wrote: P.S. I really HATE the tank up under the V-berth. If I had 3 adults in the cockpit all the time, it would be no problem, but with just me in the boat to counterbalance it, the weight up in the nose pushes the bow down a bit. If I want to motor fast in more than 2' waves, I need to empty that tank up in the bow or else I take a heck of a lot of spray

Rule-of-thumb is that major ballast should be centered to whatever extent possible. My dealer used this logic when I asked for my extra battery to go near the Vberth - instead, it's right next to the 26X factory battery. Water tanks are even more appropriate for a generally centered location, adjacent to (or aft of) the mast compression post. Ideal locations for water ... under the dinette or portside bench.

The tank bulges slightly when full, not enough to lift the mattresses. I only have about a 250mm (12inch) 'head' to the filler point, pressure in the tank when filled is not that high. It is under the central fibreglass liner that supports my hefty bulk (+ crew at times!) so should have no problem dealing with the forces generated by a full tank.

Cheers,

AJ

Thanks for the comments and thoughts. I've ordered a 26 gal tank and will post a note after experimenting a bit.

Is it possible that from a static stability viewpoint additional weight is best applied towards the rear? And, when considering dynamic stability, is additional weight best applied at the center?

Darrell

dgsl,

How'd the 26 gallon tank work out?

Can you fill it up? Does it fill the space between the ballast "tunnels"?

Could you use a bigger tank?

What would you recommend?

How do you suggest running the inlet and outlet hoses? How did you setup the inlet?

Depends how you use your boat. Mostly we day sail. I went for a 25 litre plastic bottle. Its mounted inside the cabin but at same level as the cockpit floor (26M). At this height, I can get water to run to the sink and to the stern of the boat (for motor wash out) under gravity. The 25 litre is filled from an external deck filler. I went for the smaller tank so I could use fresh water each time out and dump whats not used by opening the tap down in the motor well. If I need more water, I can always carry extra bottles under the forward V berth and top up my 25 litre as required. That way, I don't carry more weight than I need routinely and I don't get concerned about stale water in my tank.

Craig

Andy26M wrote:P.S. I really HATE the tank up under the V-berth. If I had 3 adults in the cockpit all the time, it would be no problem, but with just me in the boat to counterbalance it, the weight up in the nose pushes the bow down a bit. If I want to motor fast in more than 2' waves, I need to empty that tank up in the bow or else I take a heck of a lot of spray - AndyS

There are two benefits to center placement of major ballast that justify its rule-of-thumb status.

• 1. Weight in the ends of the boat, either fore or aft, imparts a hobby-horse behavior as the boat is lifted end-to-end by the seas.
  
  2. When "variable" weights like water tanks are End-biased, the handling of the boat varies more drastically with tank status, while center-mounted tanks simply change the depth of a level waterline - as does the Mac's water ballast tank.

But Andy's lament is notable. The first 'motoring proviso" offered by my dealer was that, "Water ballast offers extra stability for a large crew in heavy Bay conditions, but it's a very wet ride." He warned that we'd be much drier and use less fuel (and probably be happier) motoring in Bay chop with empty ballast, as long as it's only two aboard.

Tony's Smart Rails Pic from Mods Page


Without a dodger (still on my wish list), unless you add Smart Rails like Tony did, you'll need to empty BOTH ballast AND water tanks to dry-out the Mac's ride in rough conditions. Just one opinion, but I'd never place water tanks sternwise, just to dry-out the ride. I think the compromised crew capacity is too great a penalty, and I think it would impair sailing balance, too.

I (still) don't have a pressure-water system, but for the 26X, I think the ideal would be twin smaller side tanks (~12 g?) , one under port bench, the other under dinette flooring, outside the ballast rails.