External Sea Strainer for Engine

[dclagett]

This is the first full year we have had our RT25SC and we launched the boat in April. It has stayed in the water throughout the boating season. So far I have needed to have a diver twice go down and clean the barnacles from the sea strainer to unblock the strainer due to high engine temperature. I recently went to a marina that has significant spinach looking algae on the sea bed. We were the only boat out of eight from our club that had our external sea strainer clogged with the algae. It appears to me that this external strainer may be inadequate for the boat.

My question is has anyone out there had similar problems with their RT and if so what did you do to solve the problem. I have keep boats on the Chesapeake Bay, where I keep my RT, for years without this type of issue. I use Micron CSC on the hull and so far this season, as in past seasons, I have had no barnacles. I normally don't paint the metals, however this year I was talked into painting them with Pettet Barnacle Barrier.

Thanks in advance for help with this problem.

 

[knotflying]

My boat is a 2011. This is the first year I had and issue with growth blocking the external grill. However, I was able to clean it myself outfitted with a snorkel and mask and a good scraper. I think the real answer is, use the boat more. 😀

 

[Brian B]

Every body of water can be different regarding sea growth.
I have used the Petit Barnacle Barrier with good results but I would find some barnacle up inside the strainer where the paint doesn't reach. I have used cold galvanizing paint with very poor results (never again).
I recently hauled the boat and for the first time I applied this paint from TotalBoat. https://www.jamestowndistributors.com/u ... ling+Paint
I bought the quart so I can brush it on and get up inside the strainers, no over spray to worry about. The boat will be going to FL Jan - April so I'll see how it does.

 

[pickles]

Hi

I was plagued by this issue in 2016, at one point I thought I detected the beginning of gills behind my ears, so often I was in the water 😀 unblocking the hull grate. Beginning of this year I replaced the existing grate with a bigger one...probably has about 4 times the surface area, also has a screen that you can remove and clean. This whole season I have not entered the water once (albeit once when I fell off the swim platform, and that was undoubtedly due to a couple of glasses of wine)

Pickles

 

[dclagett]

Knottflying - I used the boat on average 3 hours a week, still the barnacles kept coming. Also the algae I picked up clogged the external strainer to the point that the hoses from the transmission cooler to the water pump were sucked flat at rpm above 1300. All the boats I have had the internal sea strainer caught algae etc not the external one. I am going to look at Pickles approach, I just don’t think the current configuration is adequate for my environment.

Brian - let me know how that paint workes. It seems like Pettit Barnacle Barrier attracts the barnacles in my area.

Pickles - could you let me know the manufacture and model for the external strainer you use to replace the factory installed one.

Thank you all for your replies.

 

[pickles]

Hi

I replaced the strainer with this one:-

RETANGULAR SCOOP STRAINER - BUC 2349SP

All the best
Pickles

 

[dclagett]

Pickles,

Thanks, I will look into this type.

Richard

 

[knotflying]

I can see this working to avoid barnacle buildup inside the existing scoop, but It seems to me that it will be more susceptible to getting clogged with growth etc. since the holes seem so small.

 

[NorthernFocus]

Every body of water can be different regarding sea growth...

Every location IS different. And brackish water is far worse than either pure fresh or salt water. Marinas in the same estuary will have dramatically different growth rates depending on how far they are up river.

I can see this working to avoid barnacle buildup inside the existing scoop, but It seems to me that it will be more susceptible to getting clogged with growth etc. since the holes seem so small.

I had similar thoughts but we can theorize all we want. There's direct evidence from one source that is the opposite. But regarding plugging by barnacles, the strainer configuration isn't highly relevant if the barnacles are growing inside the inlet to the seacock(a typical problem).

Since we trailer marine growth isn't a concern. Our biggest issue is plugging the intake with floating eel grass. The subject strainer looks like it would surely perform better in that regard. Likely the opposite in areas where "angel hair" type algae is more common.

 

[CAPTCRUNCH]

Here's a long-held-but-untried idea that Rube Goldberg might approve of. Replace the 90-degree elbow on the seacock with a tee that has a plug at the upper end and the hose/nipple on the side outlet. As needed, remove the plug, open the seacock, and use an appropriately sized dowel or broomstick to ream/tamp out the thru-hull.

 

[pickles]

Hi

I changed to this design based on barnacle growth and weed. Mainly weed however as that was my problem last year. I boat in Connecticut and the grass weed was always the issue that had me grabbing for my facemask and snorkel. The larger surface area of this design makes the possibility of a small amount of weed clogging the screen less likely. Add to that the removable screen that I can remove at the end of each season and clean the grate and intake, seems to have resolved my issues.

Saying that I am sure I will revisit this if there is a need in the future that I become one with the fishes 

Thanks
Pickles

 

[Snowbird]

I have had the same problem a number of times as we do a lot of crabbing where eel grass is present. I have used a c02 cartridge with some success. The best thing I have done is make a folding brush. I used 3/4" PVC pipe a stiff brush and a flag holder all available at home depot. The flag holder is adjustable to about any angle and fits in the storage compartment on our R 29. I simply unfold to the proper angle, put it over the side and I can feel the strainer a few strokes and we are done. It works really well. If you email me I will email back a picture. snsolsen@msn.com

 

[dclagett]

Thanks for all the additional comments.

Where I am coming from is that I have been boating on the Chesapeake since 1954 and have not had the level of clogged issues with the raw water system with any other boat I have owned. Even the diver that cleaned the barnacles from the exterior of the hull strainer (not the interior of the hull strainer) told me that the strainer size looked quite small for an engine raw water intake. I had the boat pulled yesterday and met with the yard forman today at the boat and did not see any barnacles inside the hull strainer. I talked to him about changing the raw water hull intake strainer and he thinks a larger format with a screen would help. Also we discussed debris getting into the transmission oil cooler and we both think that the multi-port sea strainer inside the engine compartment is not adequate for my operating environment. The holes in the strainer are too large and there is insufficient screen area. All of my larger boats has a screen that looked more like window screen on a cylinder which the only time it clogged was from sea nettles.

So over the winter it is time for a redesign of the raw water system to copy boats built on the East coast.

Thanks again.

 

[NorthernFocus]

I have had the same problem a number of times as we do a lot of crabbing where eel grass is present. I have used a c02 cartridge with some success. The best thing I have done is make a folding brush. I used 3/4" PVC pipe a stiff brush and a flag holder all available at home depot. The flag holder is adjustable to about any angle and fits in the storage compartment on our R 29. I simply unfold to the proper angle, put it over the side and I can feel the strainer a few strokes and we are done. It works really well. If you email me I will email back a picture. snsolsen@msn.com

That's a great idea. I've only had to clear mine once and did so with a deck brush from alongside in the dingy. I posted about the experience this past summer. At the time I realized it would have been a difficult task if I'd had to do it in anything but flat calm conditions. Sounds like you've solved that problem. Yes I'll email you for said photo. Thanks.

 

[dclagett]

I wanted to provide a follow up on improvements planned for the engine raw water system on my R25SC to increase raw water straining area, help minimize clogging, improve the ability for cleaning and reduce engine overheating. Last year, the first full year we owned our tug, was not the best season we had boating on the Chesapeake Bay. The season was plagued with multiple raw water clogs, multiple diver visits to try and clear the problem and multiple trips having to run very slow in order to not overheat the engine. We decided something needed to be modified to support our environment and how we use the boat.

I met with the boat yard (Campbell's Bachelor Point Oxford, MD) where the boat is stored during the winter months. Campbell's is a well respected maintenance facility on the Chesapeake Bay and also builds custom yachts from 31 to 42 feet. After reviewing several options we decided on the following:

1. Remove the existing finned thru-hull scoop and replace it with a flush thru-hull.

2. Install a Groco APHS Series perforated hull strainer with access door over top the flush thru-hull. This provides significantly more surface area than the finned scoop thru-hull for straining the raw water. It also allows for easy cleaning with the access door and removable perforated screen.

3. Remove the 90 deg elbow between the seacock and the internal sea strainer and replace it with a T-fitting, suggested by CAPTCRUNCH. This will allow cleaning the thru-hull and some of the external strainer from top sides. It also has an additional benefit to fresh water flush/winterize the engine, toilet and raw water wash down.

I hope this may be helpful for others that are experiencing clogging of their raw water system and engine overheating due to a high marine growth environment.

I will provide an update on these modification once I get some experience this comming season.

 

[Doc of the Bay]

A trick from Andrew & Livingston was to close the seacock and run the boat in reverse, fas, for a minute or so. It's freed my strainer a couple times - the other times I had to do a cold water, butt naked dive.

I'm going to ask DreamChaser for pics of his brush also.

John

 

[dclagett]

Update on progress to solve my raw water clogging problem.

The yard removed the external sea strainer/thru hull and plumbing to the internal sea strainer. No barnacles or clogs were found inside those parts, all clean. In addition the yard found that the external sea strainer/thru hull and plumbing to the internal sea strainer was 1" inside diameter. The raw water plumbing output from the internal sea strainer to the engine and on the engine is 1.25" inside diameter.

So we have decided to upgrade the input side of the internal sea strainer to match the engine plumbing of 1.25" inside diameter. That means a bigger hole in the boat. Also we decided to use a regulator seacock instead of the current configuration of a thru hull and ball valve.

Once the job is finished I will provide some pictures.