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Raw Water Strainer

  • March 05, 2012 3:08 PM
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    Message # 848532
    Anonymous member
    Before I reinstall my engine, I'm considering the possibility of moving my raw water strainer and would appreciate some input. The photo is not very good, but seems to be one of the few I can find that was shows the strainer before I removed engine for cleanup and the strainer for rebuild.




    My first concern was that the strainer is mounted directly to the Groco seacock at a 90 degree angle. There was a bronze fitting on the discharge side, either for clean-out or for fresh-water flushing. (This really didn't make much sense to me, as it would seem that a clean-out would be in the intake side and a fresh water flush could simply be done via the through-hull fitting.) Either way, it would seem that this setup would add a great deal of leverage and stress to the bronze seacock. 

    Connected to a clean-out was a hose that ran under the engine, making a 180 degree turn before going into the raw water pump. While the hose didn't appear to be unduly crimped in spit of the 180 degree bend (plus the additional length of hose), it still seems as though this would be likely to reduce the volume of the throughput.

    Although the boat is a 1975 model, the engine is a 1987 Perkins. While I don't know that much of the history of the boat, it's evident by the engine pan modifications that it was a replacement for a smaller engine, presumably a Volvo MD2B. I make the further assumption that the Starboard side of the compartment was a more convenient location for the strainer for that engine.

    There was previously a smaller raw water strainer on the Port side, apparently used for an old refrigerator compressor, mounted in the engine compartment. This had a hose attached, suitable for a fresh water tank (certainly not suitable for a below-waterline application) which was simply plugged with wooden bung. Of course the seacock was at least closed. I removed this seacock and filled the hole with an epoxy patch.

    Now, I'm thinking I might move the larger seacock for the engine raw water intake to the Port side, remove the strainer from the seacock, make a solid mount somewhere, and feed the water pump without the loop under the engine and 180 degree bend.

    It will mean drilling the previous hole back into the Port side and then patching the one on the Starboard side. This seems like a logical decision to me (albeit a pain in the butt to do), but I would appreciate some input. Am I being over-reactive to the potential for damage, due to the strainer's direct 90 degree mount to the seacock? Am I overly concerned about the reduced water flow caused by the length of hose and its 180 degree bend?

    Am I missing anything? Any feedback will be appreciated.

    Jack

    Last modified: December 14, 2015 3:47 PM | Anonymous member
  • March 05, 2012 3:22 PM
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    Reply # 848552 on 848532
    Anonymous
    Jack, 

    You know me, I've just got to run my mouth.  ;) 

    I'd move the strainer but being on the port or starboard side is up to you.  Personally I'd not go through all the trouble of changing a seacock position unless it was time to actually change the seacock.  However...

    I would get that strainer off of its mount directly to the seacock.  I like strainers that are easily accessible and that are fault tolerant.  What do I mean by fault tolerant?  If you broke the handle on your seacock (say because it froze up) and then needed to get into the filter, you'd be SOL without sinking your boat.  If it is mounted above the water line you could still do it if you needed to.  

    Here is how we mounted our old groco: 

    Good luck! 
    Tate
  • March 05, 2012 3:54 PM
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    Reply # 848585 on 848532
    Anonymous member
    That's about where I thought about mounting the strainer, Tate, but perhaps a little further forward. Where did you find the mounting bracket? I think mine is somewhat different and may need to make something from scratch, but it would be nice to find something ready-made.

    From you photos, it appears that you have down-sized the fittings and hoses from 1" on the intake size to about 1/2" (possibly 3/4") on the outlet side of the strainer. Is this correct? If so, what was your reason for that? I would think this would substantially decrease the flow.

    Jack
  • March 05, 2012 4:00 PM
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    Reply # 848589 on 848585
    Anonymous

    Jack, 

    I got the mounting bracket from Groco.  We just called them up and they shipped us everything we asked for to refurb.  Great service and very reasonable pricing.  Was nice.  I'd call them up and see if they have a mounting option for your model. 

    We sized from 1 1/4" on the seacock side to 3/4" on the engine side of the strainer.  The reason was that I had the hose/fittings/seacock for the 1 1/4" from our old engine which required a bigger hose.  The engine we installed (Beta38) only required a 3/4" and the fitting on the pump was for the 3/4" size.  So we just sized it down at the strainer.  It does indeed decrease flow but it is correctly sized to the engine.  I guess you could say that from the seacock to the strainer we are actually oversized. 

    Tate
  • March 05, 2012 4:12 PM
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    Reply # 848608 on 848532
    Anonymous member
    I thought that might be the case... I couldn't recall what engine you installed. (It sure is pretty!) Thanks.
  • March 06, 2012 4:07 AM
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    Reply # 849027 on 848532
    Deleted user
    Jack,

    Take a hard look at the existing strainer.  My old groco looked okay but soon blew out the drain plug on the bottom.  A new 3/4" Groco ARG strainer is about a $100.  I have the full engine room liner.  My strainer is mounted on the stbd side below the molded battery tray.  Easily accessible through the door to the main cabin.
  • March 19, 2012 8:48 PM
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    Reply # 863647 on 848532
    Deleted user
    I just replaced the Raw Water Strainer (RWS) on my vessel (it's a 43 ft WS with a Yanmar 54hp).  The RWS was integral to the seacock and thruhull which presented an interesting problem when the RWS strainer failed.  Luckily the seacock was good but due to being an integral piece it was not a simple plumbing problem.  I had to get a piece machined to fit the thru-hull/seacock casting otherwise I would have had to haulout and replace the thru-hull and seacock.

    My point is change out the old parts it isn't worth it to do all that work and then have a failure down the road or you can do what I just did and have a part machined to fit.    I am still planning a haulout to change it but now I can do it at my convenience rather than under duress and can paint the bottom and organize other work at the same time.
  • March 19, 2012 11:20 PM
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    Reply # 863770 on 848532
    Deleted user
    Glorious's strainer is on a riser about a foot tall and mounted on the house battery box.  Right next to the altenator.  Every time I open that strainer, rap a knuckle and drop a tool, I promise to move it. In your photo, that broken fitting and hose that ran under the engine may have been an emergency bilge pump.  If the vessel takes on water the sea cock would be closed, the hose valve opened and the engine would suck water out of the bilge.  If the hose ended under the engine maybe stuffing box concern?  The bilge is the low spot though.
  • March 20, 2012 9:59 PM
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    Reply # 864697 on 848532
    Anonymous member
    I'm afraid that nothing in the engine room looks much like the first photo any longer... that was a couple of weeks ago!

    I rebuilt the existing strainer, but removed it from the seacock. Although it came out in great shape, I decided to replace it with a larger one and move it to the bulkhead. In the first photo, the glob of wires that came out of the back of the bulkhead to the original electrical panel have all been removed. That cabinet with the old panel was open at the back and exposed to the heat fumes from the engine. Not too good. So the panel was removed, the cabinet was sealed all the way across, and all wiring was moved into the cabinet.

    The entire cabinet behind the Nav station is now in the process of being rewired, with every wire in the boat having been removed and replaced with proper boat wire, heat shrink, etc. There will no longer be any wires in the engine room that are not part of the engine and/or battery banks, and these are all properly bundled and insulated.

    The raw water strainer was moved to the position where the old, open electrical panel existed. As such, it is just above water line (should the glass ever crack) and it is very simple to clean the strainer from within the cabin, leaning into the engine room.

    Gerald: The "broken fitting and hose that ran under the engine" was not broken at all. This WAS the hose that ran from the strainer to the water pump. It only looks broken in the photo because it had a T-connecter, with a plug at one end.

    Note: The temporarily strapped coil of wires in the top photo (right side) are bonding wires that will be run to the engine when I stick it back in next week.

    Thanks for everyone's input.

    Jack





    Last modified: December 14, 2015 3:50 PM | Anonymous member
  • March 20, 2012 10:40 PM
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    Reply # 864706 on 848532
    Deleted user
    Nice Jack good job.