Raw Water Washdown Pump and Intake Grill

H

hardee

New member
I have a raw water washdown pump on my 22 Cruiser. The intake is through a grill, brass, just starboard of center and inches forward of the transom. There is a brass valve just above the sole.

I am considering taking out the grill and more importantly, the through hull in the bottom of my boat. I will probably keep the pump on board, and use a flexible hose that could be put overboard if I need to use the pump, Which I have not used more that half a dozen times in 10 years.

I have a concern with removing the through hull and valve. There is a wire attached to the valve. It appears to be a ground wire. Would this be a likely place for a common ground for the entire boat system? If so, what would be the next best place for that?

I do have trim Lenco tabs, stainless, and electric. Would that be a usable connection or would the outboard be a better choice?

Harvey
SleepyC :moon

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The grill and the thruhull and the valve should be bronze, not brass. Brass will lose zinc and become worthless.

Why do you want to remove this system? If intact, and not corroded, it should last forever.

As to the "ground wire," where does it go? A proper setup should tie it to other metal fittings. You need these electrically grounded to protect them.

Do you know the history of the washdown pump system, or who installed it? If not, you might want someone competent to inspect the system before proceeding with bottom paint. Bottom paint should not be applied to the grill.
 
I have 2 hose connections in my splash well. 1 for the wash down hose and the second for the intake hose it's about 3 feet long with a screen on the end. The nice thing about it is the intake can be put in a 5 gallon bucket with fresh water for rinsing off the salt. I couldn't talk myself into drilling the through hull.
 
A raw water wash down is great thing for fishermen (especially if one ever fishes tuna). So for some people it adds value (something to consider for future resale). As mentioned above, it should be (and probably is) bronze. If you want to replace it, you might consider doing what I had done on my tomcat - my raw water wash down pickup is a piece of plastic pipe about 3/4". It has several holes drilled in the side of it (small diameter) and it's attached to the outside of the hull with a through hull well above the water line. The small diameter holes filter out larger bits of vegetation and the raw water pump itself has a screen at it's input. The common ground for the boat is probably attached to the engine housing/lower end. Attaching the bronze through hull to the rest of the system, allows the zincs of the system to protect the through hull.
 
You all are right, I'm sure, it is most likely Bronze. The valve on the inside has a bit of a gray-greenish patina (I think it is called.) I will be tracing that wire today.

Harvey
SleepyC :moon

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hardee":2ye6xbpu said:
You all are right, I'm sure, it is most likely Bronze. The valve on the inside has a bit of a gray-greenish patina (I think it is called.) I will be tracing that wire today.

Harvey
SleepyC :moon

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That is a "Bonding Wire terminal" on the through hull.
There is more than one theory on Bonding. On my 25 that through hull is under the cabin step mid boat, with no other metal around it for 8' or so. I chose to remove the bonding wire & the green crap has disappeared :wink: My boat spends 10 months a year in the salt water :mrgreen:
 
i just got through pulling Journey On's strainer plumbing apart, to flush the strainer out. It had a lot of crud/seaweed in there.

So the first question I have is: why wouldn't one paint the strainer with bottom paint? It's bronze, but it still gets covered with growth, unpainted inside where I can't paint. I also paint over the brass (let's hope it's bronze, but I don't think so) strip on the bow of the boat. No one seems to object to that. Been doing it for a decade and can see no deleterious effect, except plant growth when I haven't painted the bottom for awhile.

Next is the use of bronze versus brass. I'm not going to advocate the use of brass but several of the fittings in the plumbing are brass and they've held up well in the last decade. As a matter of fact the factory installed shutoff valve has a bronze body but brass internals and it looks great. That's what i read on the tag attached to the valve. The whole assembly is in salt water when the boat is in the water since the valve is open to allow the head to be pumped.

Boris
 
Boris,

My naive assumption on keeping antifouling paint off the bronze screen/thruhull innards is based on two principles:

Marine growth should not occur on bronze because the copper in it should prevent barnacles and similar from attaching there. Sediment, sand, etc., will catch there whether you paint it or not.

If the assembly is part of the electrical ground bonding system, I think you would not want any coating because it could interfere with current flow in/out of the boat's electrical ground, to/from surrounding seawater.

On that second one, I would have to check Gerr to verify it, but Gerr is buried in a box somewhere.
 
I have always painted the thru hulls, including the strainers--they will have growth--believe me--the copper in the bronze does not prevent this.

There is "naval" Brass. ( 60 percent copper, .75 percent tin and 39.2 percent zinc.) This may be salt water resistant. But one issue is keeping the boat in the water all of the time, vs the occasional trip--with brass.


The bonding is another issue--and there are two sides to that. There is enough surface which is not painted so that conductivity is not an issue. I tend to not bond the thru hulls.

After you remove the fittings, how are you gong to "plug" the hole? This will include some glass work inside and outside of the boat. The new glass should be tapered in on at least 6:1 bevel both inside and outside. You will have to provide a core for the center--could be wood, could be glass/fiber. Consider the strength of secondary bonds of various materials.
 
Harvey you do tend to post questions just when I need the answers most! Thanks for that.
I have just removed the same type of through hull as yours. Thankfully the core, even though it only had 5200 or something similar as a sealant, was bone dry. My through hull was for a long removed marine head and is located in the area below the entry door step. I've ground the outside glass back around the 1 inch hole at my best guess of about a 12 to one, I'll do the inside probably a fair bit less as the space is somewhat limited in the step area. I will use probably 4 layers of glass on the outside and maybe 2 or 3 on the inside. I had planned to use 1/2 plywood to replace the core part.
My main concern is getting the cloth to stay in place during the overhead work on the outside of the hull.
I haven't worked with epoxy and cloth in an over head situation before so would appreciate any suggestions people may have.

I may have to wait a bit before completing this as it still is dropping well below 10 c (50F) at night here. I really don't want to add the complications of having to heat
the hull in order to get the epoxy to cure.

Again thanks for posting your questions Harvey!

Cheers
Ron
 
Just a thought on the ground as opposed to bonding. It's a chassis ground meant to dump stray high frequency voltage into ground. That kind of frequency will treat the bottom paint as a capacitor and go right through it. So if your green wire comes from your VHF or MFA or any other electronics, allow it to be attached to something in proximity to water. I lay it along the bottom inside of the hull though I've used those bronze grounding plates when I've had SSB.

One interesting fact is that high frequency current travels only on the outside of a conductor. That's why they use flat strips of copper for the ultimate ground plane. I use common stranded wire.

Bonding is a different subject in which I'm not well versed. Nor can I give advice on how to fiberglass. And Judy demmands the flush head, so I can't get rid of the thru hull.

Boris
 
Thanks to all for the great responses.

Ron, glad I could help, and thanks for sharing your experience. My boat is the same year so I'm hoping it will be about the same result. My through hull is in the aft sump, right next to the transom, and aft under the splash well. Not going to be room for a very large "grind out" but I might be able to get out from the hole about an inch. Don't expect to find coring there in the sump basin.

Working "up" under the bottom where the work is hanging in your face is not going to be easy. I wonder if it would be easier to tape of the bottom of the repair, and then fill it in from the top. That wouldn't work for putting glass fabric, mat or tape over the taper ground edges to the hole though. I was thinking I could get this done with the boat on the trailer but the FG guy would rather have the boat in his shope and up on blocking stands.

Harvey
SleepyC :moon

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Some folks cover the entire bottom of large boats working upside down with glass cloth and epoxy.

I have done a lot of this working on boats with osmosis. Mix fairly small batches of resin fairly "hot"--(but use the proper ratio--not like MEKP with polyester resins. The concentric circles of glass cloth will stick fine overhead. (small circles first) The type of grinding Ron did should be fine and his schedule sounds good.

Harvey--I would try and go out more than an inch--and definitely glass on the bottom. Just above is where folks occasionally get in trouble. reports have been that there is a reduced amount of core in this area--so you will find out when you take out the thru hull. I personally would use a round dowel rod rather than laminated plywood. Do the bottom glass first, then push the round core replacement in from above, with plenty of epoxy around it. That should cinch sealing the hull. Be sure and clean the edges of the hole well; get rid of any other sealants.
 
Harvey, to reinforce what Dr Bob said about working overhead with epoxy and glass: I have never worked large areas. Most have been a few square inches, with maybe one as large as 12 x 12 inches, but working overhead is straightforward, largely because epoxy resin is relatively viscous, and thickens as it cures, allowing successive layers of glass to go on in one continuous operation.

Very important to work with small batches of resin and get them out of the pot and onto the work area ASAP.

I usually brush or roll on a generous amount of resin, using normal hardener unless it is cold, in which case I switch to fast hardener. Then using gloved fingers, I smooth in place glass precut for the area where the resin is, and squeegee lightly from the center to the edges, leaving some excess outside the glass. You will be applying successive layers of glass to build up the center and feather out to the perimeter, which you can do as long as the resin remains thin enough to wet out each successive layer.

When the first batch is exhausted, mix up another small batch and repeat the process, lightly squeegeeing each layer as you go. Successive layers applied this way will form a monolithic patch with chemical bonding throughout. When the patch reaches the green stage, fill the weave with successive coats of resin. Clean off excessive buildup with a scraper (easier when it is green, not fully cured). When it is fully hardened, fair it all with a large sanding block, followed by use of a ROS, walking the grit down to whatever you like for smoothness.

This is easier to do than to describe. And it might be good to practice with a square of plywood using the resin and glass you choose, to fine tune your technique. When I have worked larger jobs, it was handy for a reliable assistant to mix the resin, allowing me to concentrate on the glass and resin application.
 
On the side of the through hull fitting/ball-valve, there is a black wire attached via a size 8 or 10 machine screw, and it looks to be bronze or brass. it has had some corrosion, and the threads are pretty much shot. I was able to back it out, but there is nothing there to grab to go back in and hold the wire in place.

The local hardware store has brass screws or Stainless. I am trying to find which is the most compatible. If I have the chart figured, a Stainless steel screw would have less galvanic corrosion than a brass one since it is closer to the bronze on the chart.

Or do I need to find the mfg of the through hull and get an OEM screw from them?

Harvey
SleepyC :moon

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Why not just leave this wire off? What is going to happen when you remove the thru hull?

If you must use a screw, SS would work--it is not as "conductive" as brass or bronze--but that is not going to be an issue.
 
hardee":2tkisrh8 said:
On the side of the through hull fitting/ball-valve, there is a black wire attached via a size 8 or 10 machine screw, and it looks to be bronze or brass. it has had some corrosion, and the threads are pretty much shot. I was able to back it out, but there is nothing there to grab to go back in and hold the wire in place.

The local hardware store has brass screws or Stainless. I am trying to find which is the most compatible. If I have the chart figured, a Stainless steel screw would have less galvanic corrosion than a brass one since it is closer to the bronze on the chart.

Or do I need to find the mfg of the through hull and get an OEM screw from them?

Harvey
SleepyC :moon

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It is possibly a GROCO BV-750 (for 3/4") Bronze & stainless & Saltwater = corrosion.
 
Harvey, where does the wire go? By itself, a bronze fitting is pretty stable and resistant against salt water corrosion. Dr. Bob's question is worth considering.

If you can size the screw and threads, call Englund Marine down here and explain your dilemma.503 325 4341. Open at 730 am. They have a limited stash of bronze hardware and fittings. Or, try the Port Townsend yellow pages.

I you can pull a P/N off the thing, EM or another marine supply can probably figure out where to get replacement parts.

I know what it's like shagging parts in the sticks.
 
Dave, Thanks for the help.

The screw size is "probably" a 10, and the threads are either 20 or 24. They are pretty wasted,and there are only 3 on about 1/4" of screw shaft. I will try and get a photo of the fitting, it is in this one, to the left of the white bilge pump.

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If this works it is from the WestMarine.com catalog.

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It doesn't say if it is a bronze screw or not but it has a "stainless handle, bonding screw and drain plug." so it very well might be on this device, but the one I have in hand does not. It is bronze, brass or copper colored.

The descriptions mention a "bonding attachment screw" leading me to think that wire (black) goes to a ground someplace. I have not been able to trace it. I loose it behind the port gas tank, as it runs behind and up into the wire bundles.

I will see if I can get the number off it tomorrow.

Thanks again Dave, much appreciated.

Harvey
SleepyC:moon

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Not sure I helped you much.

Chasing wires is frustrating. If it disappears there, then you need to pick it up elsewhere by testing for continuity.

You may be able to reassure yourself that it goes to "ground" by disconnecting the battery and then using an ohmmeter to see if you have connectivity to the black wire coming off your battery. Wait an hour or so after disconnecting both terminals of the battery to allow any capacitors to drain out. Then test for voltage FIRST between that wire end and the black wire that was connected to the battery. Should be zero. If it is not zero, do NOT attach the ohmmeter! You may fry the meter.

Other metallic items may be bonded, also. If you are curious, you can see if they have connectivity to that wire, also.

My knowledge in this area is limited. You might want to check my suggestions with a marine electrician.
 
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