Max psi permitted on freshwater system in 400 Trawler

[Mermaid]

Hi. I want to upgrade the 3.5 GPM Jabsco pump (that has a 40 psi built-in pressure switch) to a 5 GPM with a 60 psi built-in pressure switch. The shower water pressure is abysmal.

Does anyone know what the max psi permitted on these systems in the 400 Trawler series? This is the first time I’ve had a boat with the plastic tubing for water lines. My previous boat was all copper, so psi was never an issue. I also want to install an AC-powered shallow well pump at some point (keeping the DC pump for redundancy). Knowing the max psi on these boats will help me set the pressure switch on that pump, too.

Thanks.

 

[O C Diver]

40 psi isn't a bad pressure. Before starting, I would check the pressure with a pressure gauge near the shower. First, you may have a faulty pressure switch on the pump giving you low pressure. There could be crap in the shower head reducing flow. There could be a filter in the line that needs to be changed.

Regarding the plumbing pressure rating, most boats were built to handle municipal water pressure from a dock hookup. The plastic tubing should be rated over 100 psi.

I switched my freshwater pump from 30 PSI to a 60 PSI pump with a separate adjustable pressure switch. I added a larger expansion tank and set the pump off at 50 on at 40 PSI.

Ted

 

[rslifkin]

The only times I've found my 40 psi freshwater system inadequate has been if a faucet strainer was getting clogged with crud or something. Otherwise, more pressure would just make it easier to go through water faster.

That said, 60 psi should be perfectly safe for the water lines, I'd expect.

On the shore water topic, a lot of boats have a pressure reducer in the inlet to protect the lines. Mine did from the factory, set somewhere around 35 psi.

 

[kchace]

60 PSI is fine for normal boat systems in decent condition.

 

[tadhana]

Take the shower head off and check the screen. There is probably a lot of calcium grains in the screen. Try a new shower head before you replace the pump. Most boat showers run at 40 psi perfectly well.

 

[FlyWright]

Take the shower head off and check the screen. There is probably a lot of calcium grains in the screen. Try a new shower head before you replace the pump. Most boat showers run at 40 psi perfectly well.

+1

 

[Comodave]

On a previous boat we had problems with low flow. After taking the strainer/aerator off i found it full of white chunks of stuff. Mine wasn’t calcium but rather the gel coating coming off the inside of the fiberglass water tanks. The debris also caused the electric head to constantly fill due to the chunks of debris stuck in the solenoid fill valve. The ultimate fix was to replace the fiberglass water tanks with plastic tanks. But I would check the shower faucet for debris before replacing the water pump. Do the easy things first. Also cheaper if that is the problem.

 

[caltexflanc]

I think the OP is doing the right thing trying to get facts about his specific boat. I think making broad presumptions, as many here have, is dangerous,

FYI, most boats have a pressure regulator on the shore water circuit, so that their plumbing is not subject to city water pressure.

I do agree that 40-ish psi is typically just fine. The OEM put a pump of that spec in the boat for a reason. We had both a shallow well pump and DC pump on our old Hatteras. Really liked that set up. Make sure you have check valves on the outputs of each and you can leave them both on, a trick I learned from Razz Marine.

Our plumbing was designed and maintained to handle much higher pressures, but after living with it for awhile, lowered the big pump's pressure to 50, the DC remained at 42.

Having a pressure gauge plumbed into the main really helped.

 

[Giggitoni]

Pressure and volume are two different but somewhat related parameters. High water pressure can cut steel plate if the volume is reduced to a fine stream. However, that volume will take a long time to fill a pail! Keep your fingers out of the way. IOW, clean the shower head. As others said above, make sure no volume restrictions exist. 35-40 psi is more than enough pressure in our average boat systems.

 

[johnma]

Is the pressure bad at all of your faucets or just the shower. Our 390 has a shower head with an on/off/adjuster on the shower head. The adjuster wasn't all the way opened when we first picked up the boat. When I took the first shower i only got a trickle.
Also every so often one or more faucets start slowing down. Removing the aerator at the end of the faucet and cleaning the crap out of the screen solves the problem.
John

 

[Mermaid]

Thanks everyone. This Mainship 400 is new to me - just brought her home (Miami) from Key West on Sunday. This Mainship is a big step down from the 58’ Hatteras (four staterooms/four heads) I had and I am beginning to outfit her with some of the redundancy and better creature comforts I had on the bigger boat. I didn’t want to blow out the plastic water pipes. I’m very knowledgeable about the more robust systems on the Hatteras to which I am accustomed, but don’t want to over-do something here that this boat might not be able to handle. I got the water situation in the shower squared away for now. There was a large chunk of old gasket in the path of the water coming out of the faucet. There was no mineral build-up or melting gelcoat (tanks are poly). Between removing that, replacing the shower head with a Waterpick Power Spray head, and connecting to dockside water (yes, I know there is a regulator in the connection on the stern), I can finally wash my long hair well. It’s a pretty darn good flow now.

I do have some tinkering to do with the water pump set up. Mainship failed on that. There are no hose loops on each side of the pump to account for the vibration. Even Mainship’s Operator’s Manual shows the erroneous setup. The piping between that and the accumulator was too rigid and wore the o-rings. I fiddled around with that for a while getting that to stop leaking for now. I’ll get some new o-rings. Tonight, I just turned them around and snapped it all back together. That Jabsco pump with “snap-in” fittings seems a little cheap to me. Three of the locking clips (2 on the pump and 1 on the accumulator) just fell out. I suppose that was because the natural vibration had nowhere to relieve itself. My Hatteras roots make me want to do better in that department.

That said, I am enjoying the boat. It’s nice to have something a lot more simple for now - something I don’t have to work on all the time. I think I rebuilt every system in that Hatteras over the 13 or 14 years I had her, even the inside guts of one of the holding tanks. Eeewwww.

Ang

 

[Lou_tribal]

Pressure and volume are two different but somewhat related parameters. High water pressure can cut steel plate if the volume is reduced to a fine stream. However, that volume will take a long time to fill a pail! Keep your fingers out of the way. IOW, clean the shower head. As others said above, make sure no volume restrictions exist. 35-40 psi is more than enough pressure in our average boat systems.

I think you are mixing volume, area and flow rate.
You can cut a steel plate on a greater area than a needle if you can reach the same pressure over that area (the pressure that will break steel), pressure being a measure of a force over an area. The rationale behind cutting steel over a needle area is that you want to cut the steel plate not waste it.
Similarly, time needed to fill a bucket is a matter of flow rate, what is a volume through an area by unit of time, so you can quickly fill a bucket with a needle size of water flow, just that the flow needs to be quicker.

L

 

[Dougcole]

I do have some tinkering to do with the water pump set up. Mainship failed on that. There are no hose loops on each side of the pump to account for the vibration. Even Mainship’s Operator’s Manual shows the erroneous setup. The piping between that and the accumulator was too rigid and wore the o-rings. I fiddled around with that for a while getting that to stop leaking for now. I’ll get some new o-rings. Tonight, I just turned them around and snapped it all back together. That Jabsco pump with “snap-in” fittings seems a little cheap to me. Three of the locking clips (2 on the pump and 1 on the accumulator) just fell out. I suppose that was because the natural vibration had nowhere to relieve itself. My Hatteras roots make me want to do better in that department.


Yes, my 400 has the same setup. I just replaced those three O rings last week as all three of them were leaking. It stopped the leak, but I'm not a huge fan of Jabsco's push and clip hose connections. They are super easy to use, but honestly, how often do you install a pump? This is the first time I have messed with it since we bought the boat in 2013. I guess that says something about its durability, but I think screw in connectors with hose barbs and clamps would be more secure.


Also, when I was working on the pump one of the clips popped out and shot across the ER. I eventually found it, but its loss would have made the pump inoperable, and I doubt that a replacement for that little thing is easy to find.

 

[Alaskan Sea-Duction]

Good advice here. Welcome to TF Ang......

 

[kchace]

Also, when I was working on the pump one of the clips popped out and shot across the ER. I eventually found it, but its loss would have made the pump inoperable, and I doubt that a replacement for that little thing is easy to find.

2 Years ago I put in a new (very beefy) Jabsco pump for anchor wash down. I am definitely no fan of those clips, but they DO work and will not pop out if pushed in all the way. The downside is they break easily. I do end up releasing one each fall as part of winterizing that system - so its worked out ok for me.

It turns out replacements are easy to find and I definitely bought some as soon as I saw how "thin" they look. 2 for $8

Ken