Advice please - 1. Accumulator tank 2. Rudder

[jeanb]

1. We've in the process of replacing our 5L Xylem accumulator tank and would be very grateful for any tips. We have the fact sheet and hopefully understand the pressure required but we're not terribly technically-minded; e.g. do we just turn the water off, unscrew the old one and then screw the new one in?

2. The other day cruising the Coventry and BANG whoops something on the prop. We pulled over and investigated the weed hatch but nothing. Set off again and we've now got a wobble on the tiller. Long story short been right down the weed hatch three times and felt as much of the hull and rudder as possible, still nothing untoward but we now have a permanent shake on the tiller and swan neck. Does this mean a dry-docking? Any help on these two headaches would be appreciated. Thanks.

[dmr]

Was it a really big boat shaking bang? You might have bent the prop but its pretty hard to do that. Go down the weedhatch, rotate the prop, and carefully feel each blade for any obvious bending. Make sure there is absolutely nothing round the prop which is the more likely explanation.

 

................Dave

[dor]

Make sure you check the prop shaft as well as the blades.  Mike will be along shortly to tell you about his love of pipe fenders and why.

[Sea Dog]

A rough edge on a prop blade after clunking something hard can also cause these symptoms. Feel the blade edges (careful of slicing your fingers) and dress any issues out using a file until any burrs are removed and the blade is as smooth as you can get it down a weed hatch. I've done this successfully on a couple of occasions.

[Chewbacka]

3 hours ago, Sea Dog said:

A rough edge on a prop blade after clunking something hard can also cause these symptoms. Feel the blade edges (careful of slicing your fingers) and dress any issues out using a file until any burrs are removed and the blade is as smooth as you can get it down a weed hatch. I've done this successfully on a couple of occasions.

You are so right, I had a terrible buzzing noise over a very narrow Rev range and thought something loose on the engine was resonating.  It turned out to be a ding on one of the prop blades.

[jeanb]

Very grateful for replies thanks.

[dor]

2 hours ago, jeanb said:

Very grateful for replies thanks.

Thank you for your thanks.

 It really pisses me off when someone comes on here and asks a question, gets several helpful replies, but is never heard from again.

[rusty69]

10 hours ago, dor said:

Thank you for your thanks.

 It really pisses me off when someone comes on here and asks a question, gets several helpful replies, but is never heard from again.

Now all the OP needs is an answer to Q1. 

[alan_fincher]

34 minutes ago, rusty69 said:

Now all the OP needs is an answer to Q1. 

How easy it is to swap an accumulator over rather depends on exactly how "like for like" are the old one and the new one.

 

Often if they have a parallel threaded screw brass stob on the end, they are best connected with flexible tap connector, as used on sink taps.  This means the seal is easily made with a fibre washer, and no other tapes or sealants are required.

 

However a recently purchased expansion vessel we now have, actually came with a short length of 22mm copper pipe attacked, so in that case I was easily ale to connect solid pipe to it using an appropriate Speedfit push on connector.

 

In other words, it depends what you have.

 

Post pictures, and someone will advise

[Chewbacka]

36 minutes ago, rusty69 said:

Now all the OP needs is an answer to Q1. 

On my boat all I need do is turn off the pump, shut off the supply tank valve, open a hot and cold tap until all the system pressure is released, CLOSE the hot and cold taps and then put a towel under the accumulator tank connection then unscrew the old tank and screw on the new, I only loose about half a cup of water doing this.  It all depends on how easy it is for air to get in to let water out, so your boat may be different.

so slowly disconnect the tank and if more water comes out than you are happy with, screw it back up, and you will need to drain down.

[blackrose]

The pump should state two pressure switch specs: a cut in and a cut-out pressure.

 

The accumulator should be set to a few psi below the water pump's cut-in pressure. Set with the pump switched off and taps open to release the pressure in the system. You'll need a tyre pressure gauge (and a couple of towels!).

 

Eg. My pump has a cut-in pressure of 10psi and a cut out pressure of 25psi so my accumulator is set to about 7psi.

 

If you were setting the pressure of a hot water expansion tank on your pressurised domestic water system, then you'd follow the same procedure but set the tank to or slightly above the pump's cut out pressure.

Edited September 28, 2019 by blackrose

[Chewbacka]

20 minutes ago, blackrose said:

The pump should state two pressure switch specs: a cut in and a cut-out pressure.

 

The accumulator should be set to a few psi below the water pump's cut-in pressure. Set with the pump switched off and taps open to release the pressure in the system. You'll need a tyre pressure gauge (and a couple of towels!).

 

Eg. My pump has a cut-in pressure of 10psi and a cut out pressure of 25psi so my accumulator is set to about 7psi.

 

If you were setting the pressure of a hot water expansion tank on your pressurised domestic water system, then you'd follow the same procedure but set the tank to or slightly above the pump's cut out pressure.

Shouldn’t need any towels if the bladder inside the tank is ok.

added - and a tire pump if the tank pressure needs increasing.

Edited September 28, 2019 by Chewbacka

[jeanb]

Renewed thanks for all your help. We feel more confident about changing the tank.

[blackrose]

On 28/09/2019 at 10:54, Chewbacka said:

Shouldn’t need any towels if the bladder inside the tank is ok.

 

 

Not true, you'll usually get some residual water in the pipe flowing out over the floor. It's always best to have a towel handy even if you don't have to use it. It's not like that's difficult to organise after all.

Edited October 1, 2019 by blackrose