Seawater Strainers

[gcarter]

Since wev'e had a couple of overheating problems mentioned lately where strainers were also mentioned, I thought I would post what I'm doing. Disclaimer; this is my way to do this, not necessarily the way anyone else would do it.
To refresh everyones memory, I've removed the Alpha pump impellor while maintaining the water passage through the driveshaft case. Any water picked up by the foot dumps back into the surrounding water. A driveshower is also used (NOT a Simrek!) :wavey: :rlol: I went CHEAP !!! :hyper:
I used a Stainless Marine through transom seawater pickup on the starboard side followed by a SST ball valve for positive shutoff. The water then goes to the port side (so I can service the starter) to the 1" Perko strainer. If you notice, there are two swingcheck valves on either side of a tee before the strainer. This allows the use of a transom mounted flush hose. Do you get it?
Well, once through the strainer, the water travels forward to the engine crankshaft mounted Johnson seawater pump (I think GEOO used one of these, but he put his strainer and coolers AFTER the pump, just personal preferance)
Then exiting the seawater pump the water travels back to the starboard side to the power steering cooler (hidden by the engine mount), across again to the port side and the BBC oil cooler, yes it's a small block Vortec, and yes I said oil cooler. Why not? Better safe than sorry.
Coming out of the forward end of the oil cooler,(no hose yet) the water goes to the sea water inlet of the engine heat exchanger (San Juan full system) and exits through the Stainless Marine risers.
Questions and differing opinions gladly accepted :wavey:

[MOP]

George you having run this by me on the tele and now to see it, it looks better than excellent! Hell of a lot prettier than I would do. What I would add is to include it into the engines bonding system and add zinc, having mixed but reasonably friendly metal you still have a bit of a battery. The Teflon tape may not have cut through on some connections leaving them floating, do a continuity test. The strainer is the best in the Biz and can be modified to accept a fairly decent sized zinc, cut the strainers pull and bend L's that will allow you to drill and tap the cap for an anode. I have installed many of these systems and they do require additional zinc, S/S, brass and aluminum can get real flaky when in such close proximity. The majority of the electrolysis occurs during operation as the electrolyte is constantly being changed.

Phil

I can hear the phone ringing!!!!

[Donzigo]

I saw this arrangement myself. George, you are a flawless technician.

The work is really nice.l

[Cuda]

Looks great George. Will you come over and install one for me? :)

[Cuda]

Btw, if you got the Donzigo seal of approval, you know it's right! If you ever get a chance to see his work, you will realize you are two peas in a pod. Deb and I were talking about that the day you were here. :)

[gcarter]

Looks great George. Will you come over and install one for me? :)
I'd consider it for your windshield!!! :rlol:

[Cuda]

I'd consider it for your windshield!!! :rlol:


Errnnttt! Wrong answer. But thank you for playing "What's my Part". We have some fine parting gifts for you back stage. :)

[gcarter]

G,
I understand the check valve on the hose from the raw water pickup, but the one on the other side throws me. I sort of figure it is to prevent water from the pickup from going up that flush hose with the pressure from running . However, air trapped in the hose will accomplish that also.

Looking at the system, IMO, it is uneccessary. The water is under vacuum from the pump, so both check valve's will swing open if you leave the cap off the flush attachmen. In that case, it will still suck air and overheat.



A beautiful installation though! I have looked at the Perko's myself, but was thinking of using the 1.25" on mine since my feed hoses are that size. The SSM pickup uses 1" hose??

The other Scott

Oh so easily confused :confused::confused:
The SSM pickup is 1" without any other choices, so that determines the inlet size. All my assumptions about this pickup and checkvalves are based on the belief that, while under way, there will be positive pressure in the suction line and strainer (I may be wrong, but I don't think so). So the two swingchecks are back to back, so water can be fed to the strainer from either direction. If I'm right about the positive water pressure, then I'm not relying on a 1/2" garden hose to keep the boat from sinking.
The Johnson pump is really 1", but supposedly pumps about 35 GPM although I've not seen a curve on it. As I'm sure you know, these pumps are used on litterally thousands of ski boats with SBC's, BBC's, and Ford inboards. It takes about 10 minutes to rebuild one.
I'm using a 1 1/4" discharge ell because everything downstream is 1 1/4", i.e. coolers and heat exchanger inlet. The 1 1/4" hose has 56% more area than 1", so the coolers should do a good job due to lower velocity.
I would like to hear from someone with some actual experience as to whether there is positive pressure in the pump suction line while underway.

[gcarter]

I saw this arrangement myself. George, you are a flawless technician.

The work is really nice.l
Thank you Richard. :wavey:

[gcarter]

I follow the logic.

On my TRS setup I use weatherhead hose to the flush atachment vs garden hose. However, if I leave the cap off the atachment and run the boat, I do not get water out the cap @ any speed, but I do run hotter because it sucks air through the cap. I am using a BBC Merc seawater pump, and a stock Merc transom mount water pickup..

when flushing, when i first hook up the hose to the flusher, it flows out the pickup (backflushes it ;) ) till I start the engine. Then the pumps vacuum takes over.

Having seen swing checks fail, I am a bit leery of them, thus the questions..
Scott, your TRS like my Alpha, has the pickup on the sides of the leg. That's fundamentally different from the SSM pickup which is like the pitot tube on your speedometer, and should be delivering substantial amounts of water. If it's more than 35 GPM, you experience rising pressure. I think this is why GEOO has a relief valve in his system.
If I understand your point though, I don't need the inlet check valve? Hmmmmmm...thats interesting.
Pros;
Inlet check will keep water in the pump, so it can't run dry.
While flushing, all water goes to pump. :yes:

Cons;
Inlet check may fail if not maintained properly (not good). :eek!:

I'm inviting any or all to comment.

[GEOO]

George,
Nice Plumbing!!! WOW...
You can get to your strainer to clean it... no fair. I think I need a tool box to reach the Strainer??
FYI, my plumbing 2004, thru-hull P/U to Sea Strainer to oilcooler/steering cooler to Pump to Pressure Release Valve to Engine..etc.. ( No check valves or shut offs, :frown: can't reach them anyway)
The feed line to the pump may or may not have positive pressure. It depends on the pick-up and speed of the boat. At one time I had my P/U, scoop to much water and it blew out my intake gasket. Now I have the pick-up cut down and a Merc.pressure release valve between the pump and engine.
This year when I add the strainer I notice two things. One it takes too long for the pump to get primed,(after Trailering) 30sec-45sec. I'm not happy with this, working on a way to bleed out the air or prime the pump/line. Second the water flow at slow speeds is much less then without the strainer. I think the extra 90 degree turns, bends and hose length cut down the water supply at slow speeds. Everything stays cool, I just noticed a lot less water being dumped out the back.

[gcarter]

George, maybe a check valve screwed directly to your inlet would solve your priming problem.
BTW, do you know the Merc P/N for the relief valve? Better safe than sorry. :confused:
Not that I think I would have as much pressure as you could generate, but if I leave in the inlet check valve and I'm hose flushing, I wouldn't overpressure the pump before starting or idleing.
Thanks;

[gcarter]

This is an interesting thread, and I'm learning a lot from all the input.
Does the lip of your Merc pickup you're useing extend below the transom? The SSM does extend below the transom about 1/2" high X 1 1/2" wide, what I would like to know is if this would act as a scoop and deliver an appreciable amount of water at cruise speed?
Please understand, I'm working on theory here, I have no personal experience with these pickups, so I don't want to dismiss something I may be missing.
I think a loop would work fine for GEOO, but the hose is so very stiff, it might be quite large. A loop could be fabricated from copper pipe, i.e. household plumbing, that would be more compact, but it would still be larger than a check valve.

[ALLAN BROWN]

Bum dope! I looked up your order, George, and you bought a 1" NPT pickup. 1" NPT = 1 1/4" hose size. Small piece of info.... Formula for ram pressure (Speedometer pitot pressure). V squared X .0147= psi. V is speed in statute mph, Thus, water pressure at 30 mph = 13.23 psi. 100 mph = 147 psi., 200 mph = 588 psi. Holy chit! Same could hold true for cooling water pickup. Hmmm........

[gcarter]

Thanks BROWNIE, you're one of the voices I was hoping to hear from. This is excellent information.
Pitot pressure is exactly what I was thinking of. Unless there's something I'm overlooking, it should be very similar.