Through hull clean out.......

Benny17441 · May 23, 2012

Not sure of the frequent need or the advantage of doing that just to clean the strainer. It may be just as simple to remove the hose and work through there. In the past we have used compressed air successfully to remove debris that has blocked the intake. For safety I would install the valve to the thru-hull and then the fitting which brings us back to why have the fitting at all.

alexco38 · May 23, 2012

What you described requires the boat out of the water.
GROCO Bronze Perforated Hull Strainers with Clean-Out Door would work. It's available at West Marine.

If you want to "blow" out the strainer while the boat is on water, you can use compress air or city water hose as Benny suggested.

Steve Dion · May 23, 2012

Woodster:

Do you have issues with weeds/grass in your area? If not it may be easier to have a regular through hull and just clean the strainer periodically.

seadaddler · May 23, 2012

Ditto

What was already said and the value first in case any other thing needs doing and just another tip about using the clam shell on the out side which I have on my boat and rather not have it only it is a PTA to clean inside of it builds up and really hard if not almost inpossible to clean.
Nick

alexco38 · May 23, 2012

Hi seadaddler,

Please kindly explain why the clam shell harder to clean. I have been thinking of it for some time. My neighbor got one and swear by it. BTW, he went through the ICW and the Carribeans.

I found that the non open clamp shell near impossible to clean as you can't reach inside even the boat is out of the water.

seadaddler · May 24, 2012

No Problem

I have the clam shell on my 2007 H-36 and have never had a problem and just me when it was on the hard I noticed deep inside some barnacles wer some very little and tuff cleaning it out but have from others it is good and bad but sorry just me over time with many years could restrict.
I can't remember who told me they rather not use them but like I said never had a problem I just worry years down the road keeping them clean.
Nick

Maine Sail · May 24, 2012

woodster said:
i am putting a through hull fitting on the outside of my bottom to receive sea water for cooling my 2GM20F...the one i am using is the type that has a scoop like bulge with slits in it for intake....i am going to use a flange type fitting inside the hull to attach it to....now on to how i am plumbing it ....i am going to use a bronze tee at the connection with a close bronze nipple at the valve so that the top end of the tee can be plugged with a bronze plug.....there are two options in doing this....one is to put the tee on the flange first then add the valve coming out the side of the tee and plugging the top ....

second is to put the valve on first then tee on top of that(valve) with the hose coming out the side with hose barb and a pipe plug at the top...

both ways will work in order to be able to remove the plug in order to take a wire and clean out the outside strainer but is it better to have the valve first at the flange rather that last on the side of the tee...

regards

woody

Woody,

Scoop style strainers are generally designed and intended for power boats. Round, non-directional strainers are intended for sailboats. An improperly installed "scoop" strainer can cause hydrolocking of a marine engine of it "scoops" or faces forward. Facing aft they can create unwanted vacuum and air in the intake which can lead to shorter impeller life.

This on top of the fact that when, not if, they need to be cleaned out it will be a royal PITA!!

I stopped using external strainers after having to dive for well over an hour in sub 60 degree water temps to clean out a slotted strainer that had become clogged with eel grass.

I know there are those that claim "never had one clog" but the pictures I have prove otherwise.. There are enough photos here to show this is NOT an isolated or rare occurrence.

Without an external strainer a dowel can be reamed through the thru-hull to clear clogs. As long as the inlet hose is long enough to extend above the static waterline you can easily close the seacock, pull the hose off the strainer end and while holding it above the waterline send a dowel down it to clear a clog. Far safer than entering the water with a coat hanger to try and clear an external weed catcher....

If you feel you must have one this is the type I prefer.

If you have to dive this one can be opened. Round strainers are also MUCH less susceptible to sucking up eel grass than a slotted strainer... I much prefer to catch the weeds in my internal strainer basket than externally..

My general rules of thumb for engine raw water intakes is this. MINIMUM thru-hull and seacock of 1" to a 1" strainer or larger.....

arf145 · May 24, 2012

Seems to me it is best to let junk get to a place that is convenient to clear it out--in this case a sea strainer in the boat. This is similar to the issue in diesel fuel systems where wire mesh on the fuel intake clogs, creating a mysterious problem, where if the crud had been left to travel to the filters all would have been fine.

Trust your filters/strainers and keep them where you can get at them.

Jim Seamans · May 24, 2012

During haul out this year, I found a baby 1/2" crab inside the external strainer. Have no idea how long it had been in there but took a hook and needle nose pliers to remove the pieces...