Clogged thru-hulls

[Rodd]

Maine-

I have not had my boat out hauled for several years now. Now that I am on the hard, I noticed that the few thru hulls that have external strainers built into them are very clogged. By that I mean that the small holes in the strainers are clogged with paint and debris. I was wondering, do you think if I drilled out the holes using a drill bit of the proper size that this would be a good way to clean them out so water could flow freely again. I have not had any issues with overheating, but I would like to get all these holes in the strainers cleared.

Thanks!

Rodd Leeds

 

[philwsailz]

Look like these?

http://www.pbase.com/mainecruising/external_strainers

The link is to Maine Sail's website showing different images of clogged thru-hulls.

I am trying to determine what to do on my boat when I put it back in the water. My lake is infested with Zebra mussels so I am trying to either change to a mushroom with a raw-water strainer, or a clamsheel that has a quick-release cover..... A buddy and I just hauled his pontoon for the season and I was shocked to see how quickly the little mussels can fill a casting cavity on an outboard transom bracket. 'Don't want that in my external strainer!!!!!!!

 

[Rodd]

hi Phil-
Yes! I've seen those photos before! They are indeed what mine look like. Question is how best to clean out the holes for next season.

Rodd

 

[CalebD]

Rodd,
I've also got an external strainer like that on my T27'.
This spring I cleaned mine up and found the 3 or 4 screws that hold it to my hull. Once the screws were removed I was able to remove the strainer from the hull and clean it thoroughly from both sides as well as clear away any barnacles that had made a home further up my through hull. This also allowed me to slap some fresh anti-fouling paint where it was badly needed.
I think that this is the best way of dealing with this kind of strainer, short of replacing it.
Do you also have an internal strainer? Something like this: http://www.defender.com/product.jsp?path=-1|311|314196&id=137564

 

[Rodd]

Caleb-

thanks for the input! yes that is the best way, but I believe my strainer is integral to the thru-hull, and I don't feel like removing and replacing the whole thing!! This is a 3/4 inch thru hull used for my engine raw water intake, and yes, I have a large Perko raw water strainer right near the seacock. I have not had issues with overheating, so I just want to clean this puppy up!

Rodd

 

[philwsailz]

While at IBEX this year, I got the opportunity to stop and visit with John Cly at Groco. I explained my situation and he took the time to show me some neat new(?) external strainers that would open and close extremely easily. I saw these as a great option for me in order to "dive" the murky home lake waters to inspect and clean out the external strainer without removing screws. I need to get his CD catalog into the computer to see if I can find it. I have not seen it online anywhere, hence my assumption it is new.

Still not sure if I want one of these, or a simple mushroom.... Debating options and relative ease of maintenance. I do not have grass to deal with, just these stupid mussels.....

 

[Stu Jackson]

Phil, I've read Maine Sail's excellent writeup. Seems to me one has two choices:

1. An "easier-to-open" external strainer

2. None at all

The downside of the external strainers is well covered in MS's writeup. It always seemed to me that smaller holes, even if completely clear, would reduce flow and be easier to clog with whatever is down there.

The advantage of no strainer is that you can clear it out more easily, even compared to one that hinges.

The best solution I've heard of is to plumb your raw water intake into a T, so that you can literally rod out the thru hull, with a simple dowel, if it gets clogged.

 

[Maine Sail]

While at IBEX this year, I got the opportunity to stop and visit with John Cly at Groco. I explained my situation and he took the time to show me some neat new(?) external strainers that would open and close extremely easily. I saw these as a great option for me in order to "dive" the murky home lake waters to inspect and clean out the external strainer without removing screws. I need to get his CD catalog into the computer to see if I can find it. I have not seen it online anywhere, hence my assumption it is new.

They are not all that new...

However we had one of the weediest summers I can remember and I had no clogs in my intake. Everything made it to the internal strainer. My 1" intake with smooth sweeps worked flawlessly. We were cleaning the internal strainer two+ times per week... It was a bad summer.

What I do like about no external strainer, even if "opening", is the ability to never need to go into the water to clear it. I can ream it out from inside the boat, something you simply can't do when eel grass or muscles take up residence in no-mans-land behind the strainer.....

If you want an intake to work well and be safe. I've found...

Oversize the intake to a min of 1"
Use only smooth sweeping ells NOT 90's (if they are needed at all)
Use a LARGE basket strainer 1" +
Keep the intake hose long enough to reach above the static waterline when removed from strainer.
Keep a reamer on-board in case you plug it.

If you plug it:

Stop boat
Close seacock
Remove hose from strainer
Fetch reamer
Hold hose above static waterline
Insert reamer into hose
Push down forcing weeds back into ocean, then pull out of hose
Close seacock
Reconnect hose
Open seacock

Takes about 2 minutes if properly set up...

 

[philwsailz]

Phil, I've read Maine Sail's excellent writeup. Seems to me one has two choices:

1. An "easier-to-open" external strainer

2. None at all

The downside of the external strainers is well covered in MS's writeup. It always seemed to me that smaller holes, even if completely clear, would reduce flow and be easier to clog with whatever is down there.

The advantage of no strainer is that you can clear it out more easily, even compared to one that hinges.

The best solution I've heard of is to plumb your raw water intake into a T, so that you can literally rod out the thru hull, with a simple dowel, if it gets clogged.

Brilliant!

They are not all that new...

However we had one of the weediest summers I can remember and I had no clogs in my intake. Everything made it to the internal strainer. My 1" intake with smooth sweeps worked flawlessly. We were cleaning the internal strainer two+ times per week... It was a bad summer.

What I do like about no external strainer, even if "opening", is the ability to never need to go into the water to clear it. I can ream it out from inside the boat, something you simply can't do when eel grass or muscles take up residence in no-mans-land behind the strainer.....

If you want an intake to work well and be safe. I've found...

Oversize the intake to a min of 1"
Use only smooth sweeping ells NOT 90's (if they are needed at all)
Use a LARGE basket strainer 1" +
Keep the intake hose long enough to reach above the static waterline when removed from strainer.
Keep a reamer on-board in case you plug it.

If you plug it:

Stop boat
Close seacock
Remove hose from strainer
Fetch reamer
Hold hose above static waterline
Insert reamer into hose
Push down forcing weeds back into ocean, then pull out of hose
Close seacock
Reconnect hose
Open seacock

Takes about 2 minutes if properly set up...

Between the two of you a not so obvious, but elegantly simple solution is in my mind. Thank you SO MUCH.

Plain smooth mushroom thru-hull and flanged seacock it is....

 

[Chris Patterson]

I had the same "strainer" type thru hull, and when I attempted to clean it with a drill bit, it crumbled. Not a problem. I disliked that thing anyway, and like Maine said more or less, there are a lot of things that I would rather do than go under a boat. Cleaning the rest of the screen out was a snap.
So, large inboard strainer, and a piece of throttle cable for a snake.
Plus, I, like you, thought the whole contraption looked kind of restricting anyway.