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Water pressure and wood


DrWatson

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Two different questions, actually.

 

1. For those of you with pressure water systems on your boat, at about what pressure do they run?

 

2. Can anyone point me to a good resource on the mechanical properties of NZ native timbers? things like monin hardness/janka scale, rupture strength, density etc etc.

 

Cheers,

 

R

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I think my water system is pressurised to about 60psi - will check the pump next time abaord. I bought it in Sailor's Corner a couple of years ago after the last one packed up. Seem to recall I increased it from 40psi to 60psi and did wonder whether my system would withstand it - but figured I'd soon find out and hey, it's not gonna sink the boat if one of my pipes weeped.But so far seems to be ok.

 

The upside of the extra pressure is nice strong hot showers.

 

The downside is that female visitors aboard have also discovered this fact.

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Water pressure is normally 35 to 45PSI. I know of one as low as 20PSI. You don't want to get too high as it only ends up in water being wasted. A combination of Pressure and Pump volume is important. A pump that can move only say 1ltr/min for an example but have a static pressure of 45PSI would start with a big flow as you open the tap and die quickly to a trickle. The greater the volume, the more water can be pumped at a pressure. My system has a pump pressure of 35PSI and 17ltr/min. Showers are awesome. Water use is high.

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So, AC, how much water do do you use taking the average shower, and for a lady? Serious question.

 

 

But i guess it's a trade off, if your pump can pump at 17L per min but only at 20 psi, you're still going to use a lot of water.

Yea, I still guess that on a cruising boat with 490L of water, showers will still use the supply quite quickly.

 

I'm thinking about a system using a reservoir (not total stores) under pressure. ie pump water into tank until headspace air pressure = pump cutoff. Then have the flow determined more by the tap setting than by the flow rate of the pump - well, for the first bit at least until the pressure in the reservoir drops too low, but that can be countered to some degree by having a greater headspace.

 

Thanks also, for the wood links and info.

 

Cheers

R

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Look into the new VSD (variable speed drive) water pumps. No need for an accumulator, the pump only turns as fast as it needs to supply the system so no cycling and it's nice and quiet.

As for wood, I'm trying to remember the website for Oz that had every damn thing you wanted to know about their wood. From memory it was a govt site so maybe NZ would have the equivalent. Try http://www.masterbuilder.org.nz/ they can probably give some good info.

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There is ne problem with those VSD pumps. The Price. Plus I have had two of their Macerators and never had one auto switch off yet. The first one eventually had the seals fail and motor destroyed. Was replaced under warranty. the replacement did the same thing at the same point in time. Gave up and got one of those Suction diaphragm pumps.

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DW, I wish I could remember the brand of my pump, will check it out and let you know next time. It's great. Although AC does also have an accumulator you can run this pump without one - Fusion installed exactly the same as me a few weeks prior with no accumulator and it works fine. We are both chuffed with the efficiency, pressure, quietness etc. Wasn't expensive either. So I wouldn't bother with your complicated sounding setup, just try direct pump first.

 

Water usage. I don't know exactly how much the ladies use but it depends on the circumstances. If it's a regular on board then they know the routine is to use the shower for initial wetting and rinse off but stop for the lather up. And they know I can hear the damn pump running and that I will start growling if they over do it. Worst case scenario I'll flick the pump master switch off. :D

 

I only carry about 300L water so fine for a long weekend including 2-3 economical showers.

 

If it's not a regular but a newbie visitor and it's a short trip and I can't bothered to explain the whole water rationing thing then they obviously chomp through a bit more.

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If it's a regular on board then they know the routine is to use the shower for initial wetting and rinse off but stop for the lather up.

 

Isn't that how you always shower anyway? Unless, of course, you are having a high pressure shower massage. :think:

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If it's a regular on board then they know the routine is to use the shower for initial wetting and rinse off but stop for the lather up.

 

Isn't that how you always shower anyway? Unless, of course, you are having a high pressure shower massage. :think:

 

Not at home in a rain-soaked country like NZ, no.

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We had 5 people aboard and used all the 2000lts of water we had aboard in 7 days. A few years ago 4 of us brought the same boat across the Tasman slowly and had well over 1/2 fill tanks on arrival.

 

The difference? The tazzie trip was 4 blokes, last Xmas we had 1 bloke and 4 females, 3 being teenage girls, aboard.

 

It has good high pressure pumps but they can turn real bad if the wrong crew uses them.

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What about a two pump system with a simple cross-over feed, so you can select which one drives the water system depending on how is in the shower. 20psi vs 50psi?

 

The marine equivalent of the two keys you get with high performance cars, one for the owner, the other for the wife/husband/son/valet attendant.

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We have an egg timer. No batteries - just the old fashioned "wind up" toy type thingie (to be technical). :roll:

 

Yep, it's shaped like an egg and you twist the top half around over the bottom half to set a time - say 1 minute, 1 minute 30 seconds etc.

When the times up a LOUD bell goes off.

 

So we tell the (female) crew how long they have. We explain what happens if they exceed said time. We suggest they prioritise their cleaning mission.

 

When buzzer goes off, the skipper leaps nimbly into the "control area" and turns off the switch that says "water pump".

 

Skipper retreats to cockpit, turns stereo up so as to "avoid" noises of distress from (female) crew.

 

The sound of another can opening can be heard. Skipper happy. Very happy. :thumbup:

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We have inexpensive pressure pump (not sure of spec) with no accumulator and engine heated cylinder - works fine. 300 litres last a week with short showers most days for four people.

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We have inexpensive pressure pump (not sure of spec) with no accumulator and engine heated cylinder - works fine. 300 litres last a week with short showers most days for four people.

 

 

Wow! That seems quite impressive.

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