Raw Water Intake RT25SC

[dclagett]

Since we purchased our RT we have been plagued with clogging of the raw water hull strainer by green leafy algae causing the engine to overheat. We do our boating on the Chesapeake Bay out of Cambridge, MD on the Choptank River. The slotted hull strainer provided by the RT factory seems to be a magnetic for this algae. In addition there is no way to cleanout the factory hull strainer without removing the boat from the water and disassembly of the raw water intake components.

We decided to modify the engine raw water intake by using a hull strainer typically found on the Chesapeake Bay. Also in removing the factory parts we found that the factory hull strainer was 1" ID while the engine plumbing was 1.25" ID. The new raw water intake uses a Groco APHS-1250-3 hull strainer with cleanout access door and an 1.25" ID thru hull. In addition, inside the boat, we replaced the 90 deg elbow on top of the ball valve that directs the raw water plumbing into the internal sea strainer with a "T" fitting. This "T" fitting allows for cleanout of the hull strainer from within in boat and a side benefit provides an easy connection to do fresh water flushing and winterization of the engine.

See pictures in our album.

 

[BB marine]

Nice job,I like the screen on the thru hull. Are the holes in the thru hull screen smaller then the strainer screen holes? My next project is to either replace the strainer ( which I don't want to) or find a finer screen to install in it. I feel like my reverse gear cooler is my sea strainer. It is easy to clean but my concern is how much is passing thru the reverse gear cooler and clogging up the after cooler and exchanger? After cooler and heat exchanger are harder to inspect. It looks like your system should help considerably.

 

[dclagett]

Brian,

Thanks. I think the holes in the screen a a bit smaller, they are 0.188 “ dia. That series of Groco hull strainers the screens are replaceable and also come in 0.077” and 0.125” dia. I was going to see how this works and may change to a smaller screen size if I still have problems.

Dick

 

[nzfisher]

As a temporary fix are expanding rubber fittings that can be crammed in the in flow that you can use water pressure to drive stuff out through the hull fitting. Have had to do this occasionally with mystery clogs, (probably plastic bags), with an occasional over heat issue. So far so good. The device is cheap and easy to store. It helps to have a second pair of hands operating the seacock of course.

 

[dclagett]

I have used a big shop vac to blow out the the hull strainer, however it was not very effective. The green leafy algae is the main problem I have to deal with and it really clogs the slotted hull strainer. The boat was just put in the water this week and I have not had a chance to run with the new configuration. I will provide my experience with it after I get a couple months of operation.

 

[dclagett]

Yesterday I picked up the boat and tested the new raw water configuration. I was pleasantly surprised to find that the engine temperature ran a solid 7 to 9 degrees lower than the factory configuration. My temperature at cruise is now 178/180 degrees instead of 187 degrees with the old configuration. I assume this is due to increased water flow through the raw water system with the larger thru hull & hull strainer. This hopefully will provide additional margin in the event of growth, clogs, etc. Also, I did not notice any boat performance/handling differences with the larger hull strainer.

Now, TBD is how well the new configuration will eliminate the algae ingestion problem that has plagued my boat on the Chesapeake.