How much pressure does a pressure washer need?

Kelpie

Kelpie

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The boat is spending the winter at a site without mains water.
If I sit a jerry car full of water up on the deck, and stick a hose in it, would that be enough head to run the washer off? Obviously I would need to keep an eye on it so that it didn't run dry.

(btw my pressure washer is a tiny little Halfords jobbie, not some high powered Karcher)
 
Some pressure washers have the ability to suck up water (to an extent) but this may not be true for what you have. Only one way to find out....

Or you could look at the instructions I suppose but are you a man or a mouse...
 
I would recommend something a bit larger than a jerry can. The small Halfords washer will use 5.6 litres per minute so a 20L jerry can will last about 3.5 minutes. If you start a syphon running in the feed pipe it should feed the washer.
 
Flow is the determinant. There is no need for a head of water, but a reasonable quantity is the requirement. I used to use a pressure washer on a farm that ran from a cubic meter cube alongside it. No head to speak of, but quite a bit of water to have a go at.
 
i would recomend less than 1800 psi, or no mure than 1600 psi if planning to clean a wood surface....more pressure will peal the surfaces off brick and damage wood.
 
The pressure washer has a pump in it. It should suck the water through. I'd suggest using a plastic bin as the reservoir as a jerry won't last long.
 
My petrol one has a bucket on a 6' hose that I fill to prime the pump, when the pipes are full I kick the bucket into the water and it lifts the water ok. It needs a small head to prime the pump, then it can cope on its own.
 
Georgio said:
Some pressure washers have the ability to suck up water (to an extent) but this may not be true for what you have. Only one way to find out....

Or you could look at the instructions I suppose but are you a man or a mouse...
Click to expand...

Mine sucks the feed hose flat if you turn off the tap whilst using it - ie it can suck up water.
 
A few years ago I had to deal with a boat having come out of the water when the main water supply at the crane berth was frozen. The yard then placed the boat in a location further from any tap than available hoses would reach. I pressure washed the hull by carrying water 25 L at a time and putting a siphon hose in the jerrycan to connect to the pressure washer. Worked fine although it did make me aware of the very large amount of water that goes through even a small pressure washer, very quickly. The head of water through the siphon, above the inlet of the pressure washer, was about 700mm at the start, reducing to maybe 100mm as the jerrycan emptied.
 
Why not put a cheapo bilge pump between the water supply reservoir and the water intake, this would obviate the need for a 'head' of pressure.?
 
As LS says its volume of water you need not so much a very high pressure.

I have small pressure water ( A cheapie, from Homebase IIIRC) Pressure is more than adequate but the area that can be cleaned in one pass is hopelessly small.

It's like scrubbing off with a tooth brush
 
Further to that once the water has left the nozzle it is not under pressure. It is at atmospheric pressure. It is the velocity and volume of the water that does the cleaning, and of course, the shape of the jet.
It is more correctly called high velocity water jetting rather than high pressure water jetting.
 
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I have a Karcher (not a big one) which needs a little bit if "head". Last clean-off at slipway with no water tap I stood a wheelie bit in my trailer with Karcher on the ground beside it. The head was enough and the washer did a good job of cleaning the boat (9m GRP).
Only problem was it took about four "refills" of the wheelie bin, which meant a road trip to a nearby workshop!
Good luck.
 
Robert Wilson said:
I have a Karcher (not a big one) which needs a little bit if "head". Last clean-off at slipway with no water tap I stood a wheelie bit in my trailer with Karcher on the ground beside it. The head was enough and the washer did a good job of cleaning the boat (9m GRP).
Only problem was it took about four "refills" of the wheelie bin, which meant a road trip to a nearby workshop!
Good luck.
Click to expand...

has anyone powerwashed with sea water?

how long would the washer last?

ahh... you could flush it i suppose..... would hi presure sea water be an issue with the wood/grp?

hmmm...
 
Have a small karcher, however it wont suck, so connect it to deck wash pipe.

The OP could connect to his on board sink tap as most water systems would be able to keep up, and asave the wheely bin problem.


Suppose you could use sea water, but wouldnt it foam,on leaving the nozzle, or hitting the target and loose effectiveness?
 
david_bagshaw said:
The OP could connect to his on board sink tap as most water systems would be able to keep up, and asave the wheely bin problem.
Click to expand...

Well, since my water system operates on a foot pump, I don't much fancy trying to keep up with a pressure washer!
(And, with this being winter in Scotland, the fresh water system is long since drained dry).

Looks like a trailer with a big water container in it is the way to go.

On the seawater idea- I was told that it was essential to wash down with fresh water before applying antifoul, presumably something to do with salt residues stopping the paint from adhering properly?
 
Lakesailor said:
How does that work when antifouling between tides?
Click to expand...

Been there, done that... I've always used jerry cans of fresh water to mop down the hull, then rags to dry it off, before applying new AF.

When I started off with boats it was always between-tides maintenance and AF... but I've now seen what a difference it makes when AF is applied at a more leisurely pace with the boat ashore for winter, i.e. the paint actually stays on and does its job!
 
Size Matters

"If I sit a jerry car full of water up on the deck, and stick a hose in it, would that be enough head to run the washer off"

Would that be BMW 1 Series or a large Merc?
 
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