Sea water strainer

[alancollins]

I want to replace the strainer on my Volvo tamd41p engine with one with a clear lid, eg Vetus. Can anyone advise what size strainer I need? Apart from pipe diameter I am also unsure about water flow, as there is no information from Volvo as to the capacity of their standard strainer which I have at present.

 

[Plum]

I want to replace the strainer on my Volvo tamd41p engine with one with a clear lid, eg Vetus. Can anyone advise what size strainer I need? Apart from pipe diameter I am also unsure about water flow, as there is no information from Volvo as to the capacity of their standard strainer which I have at present.

I have the same engine and replaced the existing lid with a clear perspex diy one. This meant i had no problems with capacity, mountings or hoses. I fitted a 10mm stainless stud in the centre and made a 6mm thick square of perspex with a hole in the middle, a 2mm thick rubber gasket and an o-ring under the central nut. Workes perfectly and i get a more reliable airtight lid seal than with the original black one.

Www.solocoastalsailing.co.uk

 

[alancollins]

Thanks Plum. An interesting suggestion.

 

[praggers]

There's a very good reason why the sea water strainer is commonly encountered as a 6" to 10" tall, vertical bronze cylinder fitted with a stainless steel mesh filter, the whole thing screwed onto the top of a sea cock, deep in the bowels of the boat. Such a strainer's outlet is taken from the side of the cylinder close to its bottom end, which some find counter-intuitive, until one considers the purpose of the strainer and the effect of bobbing around on the uneven surface of a body of water. The strainer described has a twofold purpose (1) to prevent debris getting into the engine cooling pump which could cause very expensive damage and (2) to maintain a steady supply of engine cooling water even when the sea state is rough. This latter is achieved because the boat's designers will have arranged for the top of the strainer to coincide with the nominal sea level in calm conditions. When big waves are encountered, the skin fitting of the sea cock itself could momentarily come out of the water, in which eventuality the water already in the strainer 'column' acts as a short term reservoir, minimising the risk of the pump's impeller encountering 'dry patches' that can cause premature wear.
There's now a fashion of convenience to mount strainers remotely from the sea cock; typically on a bulkhead. That's all very well, providing the impeller pump can cope with the additional workload of the extra 'head', but I'd be inclined to fit a non-return valve in the pipe run from sea cock to strainer which would go some way to mimic the advantage of a short term reservoir.

 

[Bandit]

I have had Vetus sea strainers with clear screw on lids on three boats and they work very well.

The Vetus seastrainer is not made to be mounted straight off the valve on the skin fitting screwed on to the valve, this is probably below water level and if a leak developed this could be serious.

Mine have all been mounted with the inlet next to the keel then a section of clear armorin hose ( hose with galvanised steel wire in it to stop it collapsing under suction) with the filter cap sightly above water level at rest but below the top of the engine and in view of the engine floor hatch.
The Vetus sea strainer is made to be mounted to a vertical surface.
You want to be able to open and clear the seastrainer without closing the inlet.
You need to be able to see the lid of the seastrainer to see if there is air being sucked in through a loose connection or the lid and to see when the seaswater is being pulled through and clearing the air to give a clear water column
I have never had non return valves and would not want them.
They have all primed very well.

You can buy a tool from Vetus with a cross cut out of it to fit on the lid to open it if it gets stiff, buy it or make one out of plywood. when you fit the strainer lightly vaseline therubber seal on the lid hand tighten but do not over tighten or you can split the plastic lid ( which will suck air).

 

[matt_lake]

You can buy a tool from Vetus with a cross cut out of it to fit on the lid to open it if it gets stiff, buy it or make one out of plywood. when you fit the strainer lightly vaseline therubber seal on the lid hand tighten but do not over tighten or you can split the plastic lid ( which will suck air).

The tool in question isn't by Vetus but we see them around. The problem is people are tempted to use the tool to put the lid on, at which point it's wound on so tight you are in danger of breaking it next time you try to remove it. If the o ring under the lid is clean, an occasional spray of silicone means you should only have to use light finger pressure to ensure a good seal.

 

[aquapower]

The tool in question isn't by Vetus but we see them around. The problem is people are tempted to use the tool to put the lid on, at which point it's wound on so tight you are in danger of breaking it next time you try to remove it. If the o ring under the lid is clean, an occasional spray of silicone means you should only have to use light finger pressure to ensure a good seal.

This is it, I have one and used many of times to prevent breaking lid

www.vetus-shop.com/filter-lid-remov....html?osCsid=3233d39ac39205e57228f5b8092bf884