sea strainer

[bevis]

We have a 2015 R31 with a cummins generator. In 60 hours we have gone thru 4 impellers. The sea strainers on the washdown pump and the air conditioner are both 3/4 inch. The sea strainer on the generator is 5/8 inch. Is this the correct size sea strainer for the generator? My plan is to install a 3/4 inch for the generator. Please advise. Our email is shellislandfishcamp@embarqmail.com.

 

[nzfisher]

Geez. Just a guess the generator impeller has been run dry. It seems to me that the generator would overheat if it was getting some water as coolant rather than cause the impeller to fail. Is the generator running from a dry hose on startup? If the hose is not primed would this be enough to cause the failure? If a clear hose is available and you are going to replace it regardless it might help you trouble shoot the problem as you could see the fluid supply to the generator. Most impeller failures as described on this forum have been through blocked intakes rather than hose size. Hopefully you will get other advice.

 

[trailertrawlerkismet]

Before you install a larger sea strainer, which could, may, possibly cause too much water to flow and cause problems I'd suggest you check with the generator manufacturer or Ranger Tug.

Jim F

 

[Andrew Custis]

I agree that this is probably not a case of the wrong strainer size but a case of the generator running dry at startup. Many times I hear about boats going on lifts in Florida so if this is the case why don't you shut the seacock off before pulling it out so the water stays primed. I'm not sure if a check valve is allowed to be put on but might also be worthwhile to keep the impeller from running dry. That's my opinion!

Thank you,

 

[bevis]

it is not at start up it runs for 6 to 8 hours with no prolem then eats a impeller .is a 5/8 sea strainer common pratice

 

[Todd]

If you are not seeing blockage in the strainer than it is not your problem. A 5.8 strainer can handle a lot more water than needed for cooling a generator.

You need to determine haw the failure is occurring. if it fails at 6 hrs I suggest you remove the impeller at 3 and check it. You may be able to determin the problem by looking at the wear pattern. Perhaps the housing has a rough section that is tearing up the impellers.

 

[Swamalcatraz]

My sea strainer lid has a few hairline cracks that causes air to enter into the cooling system which makes eng run ten degrees above normal! Check your lids!

 

[Connerkip]

Are you running your generator, while running the boat at high speeds? Old salts tell me not to run the generator at any thing above trawler speed, as it will be starved for water, or take in air. Andrew tells me that I should be able to run my generator up to 14 knots. I believe the Thru hull pick up will ingest air at high speed. I had been having impeller failures. Also I make sure my strainer is full before turning on the generator.

 

[BB marine]

We don't have a generator so I can not say I experienced high speed issues with sucking air. I would suspect there would be though. The Cutwater hull is a vented hull designed to create uninterrupted flow of air across the surface of the bottom. This doesn't happen at slow speeds but (opinion) at higher speeds there would be the presents of air. I have made a practice of checking the marine air water strainer and bleeding it after a day of boating before turning the unit on. The strainer is mounted above the water line and has a tendency to air lock. My thoughts would be the water would be forced into the stainer while running but from my experience it does not. As long as you are aware of the issue it is not a problem. I think I would go with what old salts tell you.