quick seacock question

[JH_B28]

Hi guys,

I'm currently removing all my raw water intakes to replace with flanged seacocks. My current setup consists of apollo ball valves attached to bronze thru-hulls for the engines, genset, a/c, head intake and head discharge. I'm a bit confused with the size & measurements of my current valves. The ball valves for the engine intakes read 1-1/4", which i believe is the I.D, but the intake hoses are 1-1/2" I.D. Same happens with the genset, ball valve is 1/2" and the hose is 3/4".

I'm buying all my parts from Lewis marine and now i'm not sure what size seacocks and adapters to get. I was thinking on the FBV full flow series for the engine intakes but don't know if it has to be 1-1/4" with a 1-1/4 thread to 1-1/2" hose adapter or just a 1-1/2".

My engines are 4lh-ste's, so i think some of you guys are running the set up i'm looking for. Any input will be very well appreciated.


Im looking for a setup very similar to what i believe Capt. Pat used on hancock's b31. Maybe he can chime in with some details on what size seacocks and 90 deg. adapters were used.
Here's the pic of capt.Pat's install


Thanks!!!

[CaptPatrick]

George,

The "standard" valves are always smaller than the hose size. For a match to the hose size, (1 1/2" hose 1 1/2" ball valve), you need to order/specify "full flow" valves...

[JH_B28]

oohh, now I understand the "full flow" concept. Thanks for clearing that up Capt. Pat.

'ppreciate it!


-George

[JH_B28]

ok just to be clearER... i need to buy the 1-1/4" full flow flanged seacock along with the 90 degree full flow pipe to hose fitting, which converts the 1-1/4" Npt thread to 1-1/2" hose I.D.

Correct?


-George

[mike ohlstein]

1.5" full flow valves are what is called for.

[JH_B28]

Ok. got it!

Thanks Mike

[CaptPatrick]

What ever size hose goes to the engine, (main or generator), is the size of the full flow ball valve that you'll need.

In the case of your main engines, the 1 1/2" I.D. hose going to the raw water pump, dictates you'll need 1 1/2" full flow valves and 1 1/2" through hull fittings. The flanged full flow valves come with a properly sized through hull port. If you're going with external strainers, which you should, over size the strainers to at least the next size up. See: http://bertram31.com/proj/tips/strainers.htm" onclick="window.open(this.href);return false;

[JH_B28]

Ok! 1.5" full flow it is! I already have Groco internal strainers and are still in good shape. When I change them out i'll go with the external strainers you suggested.

Thanks again Capt!

[IRGuy]

Be sure to install the external strainers correctly.. I don't have them on my boat and I will leave it to others more knowledgeable than me to advise you on this, but be sure not to use any kind of external scoops to aid the water flow. I have read about boats with scoops on their generator raw water inlet where while running the boat with the generator shut down caused the scoop to catch water and force it up into the engine, hydrolocking it. I suppose scoops on the engine raw water inlets could do the same thing when running on only one of the engines.

[JH_B28]

Frank,

Thanks for the advise on the ext. strainers, i'll be sure to let a pro install them. As for the scoop strainers, I have one for the a/c intake because the pump is not self-priming. Also have them for the engines raw water inlets, but since I always run both engines I dnt think it would be a problem (i hope). I'll have to double check that..

Best regards,

-G

[Rawleigh]

I still don't see how you can hydrolock a motor unless water gets in the intake or exhaust. I won't get in from the cooling system unless there is a breach somewhere. Someone educate me on how this can happen.

[JH_B28]

Good point Rawleigh. If water is rushed up by a scoop strainer, it should circulate through the cooling system as it would normally do when it is in operation. The only way for hydro-lock to occur is if there's a breach where water can get in to the combustion chamber. (my opinion) I'll let the pros chime in on this.


best regards,

-G

[Navatech]

As for the scoop strainers, I have one for the a/c intake because the pump is not self-priming

As long as the pump is below the water line (where it should be) you shouldn't have a problem with priming.

[Navatech]

Someone educate me on how this can happen.

First, this can only happen with water cooled exhausts. Second, it depends on the design of the exhaust. Many boats don't have enough rise downstream of the mixer. If the system partially depends on the exhaust gasses for pushing the water in the right direction (as opposed to naturally flow downhill) water could top the elbow and stream into to exhaust side of the engine. From there it's a short trip into one or more cylinders...

[Rawleigh]

Makes sense. Thanks.

[JH_B28]

As long as the pump is below the water line (where it should be) you shouldn't have a problem with priming.

I believe the pump is just at the water line. I'll have to check on that. Thanks!