Fresh Water Pumps DD vs BD

[natew]

Anyone have any info on the differences in water pumps out there? Specifically the piston belt driven water pumps vs the direct drive pumps? My boat currently is fitted with these for fresh water as well as shower draining and a few other things. One of them failed a while ago so I replaced it with a direct drive type pump and tossed it, now another one has failed and am considering replaced it with another direct drive but just noticed that these belt driven pumps are about $400 each vs the direct drive pumps at about $100 each.

Why the price difference? Should I buy a service kit for the dead one that I have? Or replace it?

I am personally leaning towards the direct drive pumps because they are cheaper and I am not a fan of belt driven technology. It seems inefficent, old, and prone to failure of the belt leaving you hunting for an odd sized replacement belt that you will likely never find. And even if the DD one's are less reliable I can replace it 4 times for the price of the BD one.

So does anyone have any real compelling reasons to go with the more expensive pumps?

[CaptTom]

I also had two of the belt-driven piston pumps on board, and I suspect there was at least one more originally, because I found quite an assortment of belts in the PO's parts drawers.

I've seen them before, always in older boats. I thought it was just a case of technology moving forward. I replaced one old piston shower pump with a more modern sump. The other still works, but I plan to do the same when that one finally dies. My reasoning for going with the newer bilge pump style sump is that it's simple, reliable and the pump and parts are all widely available.

I'd also be curious if there's any advantage to the old-style belt-driven piston pumps.

[Jim Cate]

I've never seen a piston water pump on a boat, so I'm curious about these. Could you give us the mfg. and model numbers, please?

The old standard water pumps were indeed belt driven, but were diaphragm pumps. These were very long lived and when the rubber bits failed they were easy to repair. The one on our previous boat was still working at age of 30 years. Had had one diaphragm and two pressure switch replacement in that time, still on original belt.

I don't know what replacement part prices are like now, but likely less than replacing with "modern" pumps... but then, your piston pumps are a different thing... maybe.

Cheers,

Jim

[natew]

They look basically like those. I don't have a model number off hand but I think they are all made by jabsco.

[Jim Cate]

Originally Posted by natew

They look basically like those. I don't have a model number off hand but I think they are all made by jabsco.

Natew, that is, as I sorta thought, not a piston pump but rather a diaphragm pump.

My comments from my previous post stand.

Good luck with your decision.

Jim