How dumb of an idea would this be?

M

mobocracy

Active Member
Jun 29, 2014
541
United States
Boat Info
310 Sundancer
Engines
350 Mag & Bravo III
(I hope this title was click bait enough...)

This summer I've had multiple weed obstructions on my generator raw water intake. The filter basket is empty and with the valve open there's barely a trickle of water. I take the boat out at planing speed for a bit, run the generator (which stays on, but with obviously less cooling water output), check the basket and find little in there.

I have one of those little cable-actuated grabbers that I can stick down past the strainer (but not far enough to get more than 6" from the through hull) and never pull anything out. I ginned up a fitting with a plastic elbow, some silicone putty and connect it to my shop vac hoping to blow out the obstruction with not much effect.

A week or so later? Like magic, the water flow with the generator on is back to normal, meaning whatever was stuck is now unstuck.

My "genius" idea? Putting a quick-release fitting from McMaster-Carr on the through-hull side of the hose that runs to the strainer. This would let me get right at the outside obstruction easily by just disconnecting the hose.

Is this a dumb idea? I'm kind of worried about persistent drip leaks from something like this. They the cam and groove style connectors look like they would seal pretty well, but the overall size looks too big. The sleeve-lock style looks like it would fit the space available better, but I'm not sure how well it would seal (though they seem rated for insane pressure).

I'm gonna have my haul out guy check it more closely for something that's really snagging growth or other more durable issues. The impeller I will do next spring, but I'm thinking the impeller probably isn't that bad as it has maybe 20 hours on it, installed spring 2019.
 
Is the top lid of your strainer not above the waterline? I'm probably not understanding the issue. I just pop the lid, and pull the strainer basket to clean things out.

oh wait, I think I get it. You're talking about the route from the strainer to the seacock?
 
Anything that adds to the through hull plumbing is a suspect idea.

All hardware added must be bronze. Brass will degrade as the Tin leaches out in salt water. You don’t boat in salt water? Then you still don’t use bronze because it becomes a time bomb for future owners.

strainers aren’t perfect, stuff gets past them and can accumulate, as can marine life like barnacles. I had to fish (pun intended) half a small fish out of my ac plumbing this summer that got past the strainer and plugged up one of the elbows. The back half of the fish was stuck in the sea cock.
 
bobeast said:
Is the top lid of your strainer not above the waterline? I'm probably not understanding the issue. I just pop the lid, and pull the strainer basket to clean things out.

oh wait, I think I get it. You're talking about the route from the strainer to the seacock?
Click to expand...

I'm talking about marine plant growth stuck in the inlet of the through-hull. It's definitely not in the 8" of hose I can reach from the strainer. When I've had weak water flow out the generator discharge it definitely hasn't been just because the strainer has been full of stuff -- it's been nearly empty. I can stand there with the top off the strainer and the seacock open and there's not the normal waterfall of water into the bilge.

Henry Boyd said:
Anything that adds to the through hull plumbing is a suspect idea.

All hardware added must be bronze. Brass will degrade as the Tin leaches out in salt water. You don’t boat in salt water? Then you still don’t use bronze because it becomes a time bomb for future owners.

strainers aren’t perfect, stuff gets past them and can accumulate, as can marine life like barnacles. I had to fish (pun intended) half a small fish out of my ac plumbing this summer that got past the strainer and plugged up one of the elbows. The back half of the fish was stuck in the sea cock.
Click to expand...

As I mentioned above, the obstruction has got to be at the through-hull because even with the seacock open and the top off the strainer I get way less than normal amounts of water. If there was an obstruction past the strainer I would be seeing normal levels of water flow out the strainer with the seacock open.

Plus it has this tendency of almost self-clearing after a week or two where open strainer water flow looks normal as does generator discharge. This would seem to exclude the idea of upstream (past strainer) obstruction or just a worn impeller. As just basic PM, I am going to replace the generator impeller next season as maybe there's some idea that a worn impeller does OK with a completely unimpeded water flow, but lacks the suction to ingest a hunk of weed into the strainer and gets it wedged in the through-hull.

I should have mentioned that I boat in fresh water, so the salt water issues (barnacles, brass corrosion) are less of a factor. That I boat in Minnesota with a stern drive means this boat will probably never be in salt water.

What I'm trying to weigh is the convenience of a quality quick-disconnect fitting vs. the wear and tear and headache of releasing the worm gear clamps and pulling the hose off the seacock hose barb so I can unclog the intake. I haven't done that this year because I'm just real sure the hose on there now craps out in the process. Even with new hose, I'm almost as suspect of yanking hose off hose barbs and then putting it back on as I am a quick-release fitting, plus it turns reaming out the intake into a much longer job than just disconnecting a fitting meant to be easily disconnected.

In addition to ordering an impeller kit this winter I'm going to get 6' or so of hose so I have some pre-cut new lengths of hose. In the spring I'm gonna scrap the existing hose segment between seacock and strainer so I can really get at the seacock/through hull from the inside.

Overall this seems to be a bigger problem over the last couple of years. The lake has warmed real fast -- over 70 by Memorial Day, which just accelerates our marine plant growth. I avoid running the generator in any kind of shallow water to minimize weed ingestion, but the marine growth the past couple of years has been noticeably worse and it seems much harder to keep water flowing well through the generator cooling path.
 
Are you sure it's not a failing hose from the seacock to the strainer? Could be a flap of rubber moving around inside.
 
brewster16 said:
Just a thought....you might consider adding a bronze "clam shell" to the intake grate on the hull of your boat once it's hauled out: https://images-na.ssl-images-amazon.com/images/I/61a3bFlcAIL._AC_SL1000_.jpg
Click to expand...

Torn between the value of the added hydrodynamic pressure maybe blasting stuck stuff into the strainer basket where it can be dealt with and just more complex surface area where weeds can get stuck. My last boat was a Yamaha jet and it always amazed me how gunked up the intake grates could get.

What I'd really like to do but won't for various reasons is replace the through-hull and seacock with something triple the existing internal diameter. I feel like part of the issue is that while .75" is probably the right flow size for cooling the generator, it's also small enough to easily get plugged. If the through-hull to the strainer was 3" I might suck in more weeds to the basket, but I'd have a bigger basket and way less obstruction opportunity outside.

quality time said:
Are you sure it's not a failing hose from the seacock to the strainer? Could be a flap of rubber moving around inside.
Click to expand...

I guess I'll find out next spring. I'm gonna remove the existing hose and replace with new then, at least partly to be able to clean real well inside the seacock. My guess is it's not the hose as I seem to veer between high levels of obstruction and apparently normal, unrestricted flow.
 
This happens a lot in our area; a lot of grass and very shallow.
I usually go in the water and pull the exposed weed from the thru-hull then poke a long slender screw driver or my flex snake up into it and move the clog to the strainer. This work most of the time. When it doesn't work I go in through the strainer with a sink flex snake and push the clog out the thru-hull; things tend to get a bit wet in the bilge when it clears. One word of caution - do not have anything on the end of the flex snake that could hook and prevent you from pulling it back. You could imagine water flowing back through the strainer and not being able to close the valve or cap the strainer....
 
ttmott said:
This happens a lot in our area; a lot of grass and very shallow.
I usually go in the water and pull the exposed weed from the thru-hull then poke a long slender screw driver or my flex snake up into it and move the clog to the strainer. This work most of the time. When it doesn't work I go in through the strainer with a sink flex snake and push the clog out the thru-hull; things tend to get a bit wet in the bilge when it clears. One word of caution - do not have anything on the end of the flex snake that could hook and prevent you from pulling it back. You could imagine water flowing back through the strainer and not being able to close the valve or cap the strainer....
Click to expand...

Yeah, part of my whole motivation for adding a quick disconnect at the seacock/hose junction is that I'm not super comfy shoving reamers and what not down the hose from the strainer with some risk that I get something buggered up and can't close the seacock. I'd be much less worried if I was working more or less directly at the seacock where I could get at stuff and realistically close off the seacock, or at least keep the lid on the strainer.

Idea #2727346 for dealing with this problem is seeing if I can MacGyver a rubber plug that seals the intake from the inside of the seacock but can be connected to a compressed air line. I figure a #2 or #3 rubber stopper, a bit of brass tubing and an elbow connected to a compressed air fitting and I could blow it out.
 
I’ve just started using my generator more and with that I have had 4 instances in less than 100 hours of runtime of blocked hoses. In most cases the 90 degree joint into the strainer is jam packed and needs to be cleared, one time it was both the strainer and the 90 degree, and one time it was right at the through hull and was a large artificial lure, the soft part. About 6” long.
I added one of these now. So far so good, but I’m going on an 8 day cruise starting Saturday, so I’ll report back. It covers the intake without forcing water up the through hull.

FA823E4B-78BB-4252-9CBB-F236815A9E6F.jpeg
 
The top of the strainer basket is most likely above your water line - thus your not seeing a flow of water when you open the top of the strainer. Mine is like this as well - guessing by design.

When you have a problem, can you disconnect the hose from your thru hull and see what the flow looks like? Surprisingly it doesnt flow uncontrollably.

If your thru hull is a simple round one, without any intake grates - if you need to clear an obstruction - one option is: Disconnect existing hose, install short section of new straight hose, route it straight up above the waterline. Then open up the seacock. Use a wooden dowel or the like to run inside the tube, through the seacock, and finally through the thru hull. Found this process described on a different thread here.
 
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Todd320 said:
I’ve just started using my generator more and with that I have had 4 instances in less than 100 hours of runtime of blocked hoses. In most cases the 90 degree joint into the strainer is jam packed and needs to be cleared, one time it was both the strainer and the 90 degree, and one time it was right at the through hull and was a large artificial lure, the soft part. About 6” long.
I added one of these now. So far so good, but I’m going on an 8 day cruise starting Saturday, so I’ll report back. It covers the intake without forcing water up the through hull.

View attachment 91979
Click to expand...

So do you have a place where you can get under the boat and monkey with this in the water? Or is the idea that its just so much bigger than the intake opening that it'd take a giant bag or something to completely obstruct it, plus it keeps out the weeds and whatever else? It also looks like if you got up on planing speed pretty much nothing would stay stuck to it.

Half my challenge is there's no place shallow enough where I could get under the boat to clear external obstructions that's not totally gross and likely to get me tangling with a snapping turtle or swimmer's itch. I'd have to dive in a deeper anchorage, and I'm too old and too...comfortable...to be doing that.

I'm lucky in that I have no 90 degree elbows in my genny raw water path. The hose segment from seacock to strainer is a curve.
 
Todd320 said:
I’ve just started using my generator more and with that I have had 4 instances in less than 100 hours of runtime of blocked hoses. In most cases the 90 degree joint into the strainer is jam packed and needs to be cleared, one time it was both the strainer and the 90 degree, and one time it was right at the through hull and was a large artificial lure, the soft part. About 6” long.
I added one of these now. So far so good, but I’m going on an 8 day cruise starting Saturday, so I’ll report back. It covers the intake without forcing water up the through hull.

View attachment 91979
Click to expand...

Hello Todd,
How did you attach it?
 
markrsimon said:
The top of the strainer basket is most likely above your water line - thus your not seeing a flow of water when you open the top of the strainer. Mine is like this as well - guessing by design.

When you have a problem, can you disconnect the hose from your thru hull and see what the flow looks like? Surprisingly it doesnt flow uncontrollably.

If your thru hull is a simple round one, without any intake grates - if you need to clear an obstruction - one option is: Disconnect existing hose, install short section of new straight hose, route it straight up above the waterline. Then open up the seacock. Use a wooden dowel or the like to run inside the tube, through the seacock, and finally through the thru hull. Found this process described on a different thread here.
Click to expand...

Mine is far enough below the water line that I get a lot of water with the strainer top off. I actually use this "feature" from time to time to flush out the water in the bilge by replacing it with new lake water and running the bilge pump. It's enough water that screwing the strainer cap back on with the seacock open is kind of a challenge.

My desire for a quick disconnect is to enable what you're talking about, minus having to release hose clamps, pull off hoses, and fish down another hose.
 
The issue with a QD is finding something that meets the requirements for below the waterline plumbing.
Maybe consider a bronze Tee and close nipple screwed into the valve with a plug on top and the hose bib / hose to the strainer off the side of the Tee. The plug could be unscrewed and that would be a straight shot through the valve and thru-hull.
 
Last edited:
mobocracy said:
So do you have a place where you can get under the boat and monkey with this in the water? Or is the idea that its just so much bigger than the intake opening that it'd take a giant bag or something to completely obstruct it, plus it keeps out the weeds and whatever else? It also looks like if you got up on planing speed pretty much nothing would stay stuck to it.

Half my challenge is there's no place shallow enough where I could get under the boat to clear external obstructions that's not totally gross and likely to get me tangling with a snapping turtle or swimmer's itch. I'd have to dive in a deeper anchorage, and I'm too old and too...comfortable...to be doing that.

I'm lucky in that I have no 90 degree elbows in my genny raw water path. The hose segment from seacock to strainer is a curve.
Click to expand...
The latter. My theory is, if something blocks it, and the gen shuts down, the current should take the debris away. Then, I can start it up again. But it should prevent the issues I’ve had so far. Also, I have 4 intakes, and this is the only open one, the other 3 have the scoop grate, and those have never clogged up in the last 2 years.
 
I had this problem on our 2 week trip in July. Seacock/through hull got jammed up with sea weeds so I took the hose off and used my packing hook to fish it all out while in the water. When a mini 6 inch fountain of water started flowing from the seacock, I knew it was clear. Closed the sea cock after a couple of seconds of flow and re-attached the hose. The packing hook is a tool I have for removing the packing around my rudder shafts when changing. Looks like this and worked like a charm.

image.jpeg
 

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