Hull/seacock mounted raw water strainer design

[syvictoria]

Hi. I fear another stupid question coming up...! Sorry...!

Is the wing nut held cap design of the 1" hull/seacock mounted raw water strainer considered by the panel to be better than the screw cap on the 3/4" version, and would installing a 1" strainer with a 3/4" seacock and 3/4" hose risk introducing any problems with flow and/or priming (all assuming that 3/4" is sufficient for cooling purposes)? Would the additional capacity of the larger strainer offer an advantage over the smaller?

https://www.asap-supplies.com/raw-water-intake-strainer-hull-mounted-402024
https://www.asap-supplies.com/raw-water-intake-strainer-hull-mounted-402025

An above waterline strainer isn't an option due to the location of the seacock (in keel). Thank you!

 

[Daydream believer]

Forgive me for asking but why does the position of the sea cock prevent the strainer being above the water line.
You place the seacock by the hull. A hose leads upwards to a plastic strainer then the hose leads to the engine.
If there is little room at bilge level then that is the last place one would want a strainer.
Try https://www.force4.co.uk/department...es-engine-room-equipment/water-strainers.html

 

[Tranona]

The above the water strainer is not reliant on the location of the seacock. The constraint (if any) is usually finding a place to mount it so you can remove the top easily. ideally it should be vertically above the seacock so that if the seacock is a simple ball valve on a skin fitting you can rod to clear obstructions if necessary.

Suggest you look in the Vetus catalogue for schematics of water and exhaust systems.

As Daydream believer says a below waterline strainer in a bilge is the worst of all worlds.

 

[syvictoria]

Hi. Sorry, I should have explained myself better. There isn't anywhere to install an above waterline strainer directly above the seacock. The nearest suitable location is some distance away and would involve a much longer (relatively) hose run and also extra bends. This doesn't seem a good idea to me, despite the obvious popularity of the modern plastic Vetus strainers.

 

[Praxinoscope]

Hi
I agree with tranona that the position of a Vetus style strainer isn’t really dictated by the position of the seacock, however on my last boat my cooling water system consisted of, water scoop/strainer, ball valve seacock, and an ASAP bronze Seaflow strainer, all in the bilge Which was just to one side of the crankshaft pulley of the engine, easily reached and quickly viewable to make it easy to check that it was closed before leaving the boat. The Seaflow strainer has easily replaced filter elements. The system worked perfectly for the 18 years that I had the boat, and as far as I know is still providing the new owner good service.

 

[Tranona]

Hi. Sorry, I should have explained myself better. There isn't anywhere to install an above waterline strainer directly above the seacock. The nearest suitable location is some distance away and would involve a much longer (relatively) hose run and also extra bends. This doesn't seem a good idea to me, despite the obvious popularity of the modern plastic Vetus strainers.

That is not a problem. As I said it is a bonus if you can mount it above the intake. However on many boats this is simply not possible but you will still get the benefits of being able to see it and access it without shutting off the water and crawling in the bilge.

On my boat (and thousands of others fitted with saildrives) the intake is on the opposite side of the engine from the pump, well aft on the saildrive housing. The intake pipe runs under the engine, up to the strainer and down to the water pump. Well over 2m of pipe to the strainer and 3 changes in direction. Works perfectly.

 

[Daydream believer]

That is not a problem. As I said it is a bonus if you can mount it above the intake. However on many boats this is simply not possible but you will still get the benefits of being able to see it and access it without shutting off the water and crawling in the bilge.

On my boat (and thousands of others fitted with saildrives) the intake is on the opposite side of the engine from the pump, well aft on the saildrive housing. The intake pipe runs under the engine, up to the strainer and down to the water pump. Well over 2m of pipe to the strainer and 3 changes in direction. Works perfectly.

That describes my system & I have a different maufacturer's boat

 

[syvictoria]

Thanks for the replies. Our bilge and strainer are actually extremely accessible being directly under a small hatch in the saloon floor, and so I'm still not really convinced about changing to the Vetus type with it's associated potential air leak problems. I personally like the idea of having no risk of blockages in the hose, added to which (and as mentioned before) it is a scant 1m straight run to the engine raw water inlet from the bilge and probably about 3.5m to go to the rear of the engine and back again to use the only available space that can be utilised for a Vetus type (and where it would also arguably be less accessible and difficult to see into without the aid of a torch and removing part of the companionway steps). But, I do value the wisdom of the panel and we are giving the matter further consideration.

 

[Plum]

Hi. I fear another stupid question coming up...! Sorry...!

Is the wing nut held cap design of the 1" hull/seacock mounted raw water strainer considered by the panel to be better than the screw cap on the 3/4" version, and would installing a 1" strainer with a 3/4" seacock and 3/4" hose risk introducing any problems with flow and/or priming (all assuming that 3/4" is sufficient for cooling purposes)? Would the additional capacity of the larger strainer offer an advantage over the smaller?

https://www.asap-supplies.com/raw-water-intake-strainer-hull-mounted-402024
https://www.asap-supplies.com/raw-water-intake-strainer-hull-mounted-402025

An above waterline strainer isn't an option due to the location of the seacock (in keel). Thank you!

Either of your proposed strainer designs would be good although i would go for the design with the two wing nuts. With the screw on cap if it should ever become stiff when trying to remove it there is more chance of you rotating and disturbing the seacock and skinfitting below. I see no problem in fitting a 1 inch strainer to 3/4 inch seacock and hose, might give you a little more time/volume before it blocks with stuff.

www.solocoastalsailing.co.uk

 

[rogerthebodger]

I have been thinking of fitting a 110 pvc coupling like this on to the outside of . seacock/strainer that is below waterline so that a piece of PVC pipe can be slipped over the strainer and to reach above the waterline to restrict the inflow of water into the boat when you need to rod through an open seacock to clear a blockage from inside.