90 deg elbows in raw water intake

[pasty63]

While re-installing everything in our engine room, I'm trying to figure out how to mount the strainers and raw water hose in a more organized fashion. The raw water intakes are in the center on either side of the keel, with the pumps mounted on the front port side of each engine, about 4 feet forward of the intakes. The transmission coolers are on the aft of each engine, mounted to the top of the transmissions. Raw water was pulled through the transmission coolers on the way to the pumps. I'd like to put 90 deg bronze elbows in the hose at a few points (after the strainers) in order to allow some uniformity in the placement of the hose and strainers. Without the elbows, the hose runs are awkward because the 2 ply reinforced 1 1/4" rubber doesn't bend well in such a small space. Would the elbows cause a flow issue after the strainers? My thought is that it doesn't matter after the system is primed. Is there a better material for this application than bronze?

Originally Posted by pasty63

Would the elbows cause a flow issue after the strainers? My thought is that it doesn't matter after the system is primed. Is there a better material for this application than bronze?

All bends cause resistance of course. But as long as you don´t reduce the inner diameter it should be neglectable.

If your boat isn´t Al. yes bronce is your material of choice.

Regards
Richard

[wardd]

can you make them a 270 degree loop?

[pasty63]

Thanks for the input! It's a GRP hull.

bryan
Lake Stevens, WA

[FAST FRED]

Sometimes 2 - 45 deg elbows or "street Ells" will ease the turn with lots less resistance.

FF

[CDK]

If you use the bronze water scoops with a number of narrow slits instead of one hole, I do not see the need for strainers in the raw water circuit.
Their shape is such that with increasing speed there is positive pressure at the pump's intake.

[Bglad]

Originally Posted by pasty63

While re-installing everything in our engine room, I'm trying to figure out how to mount the strainers and raw water hose in a more organized fashion. The raw water intakes are in the center on either side of the keel, with the pumps mounted on the front port side of each engine, about 4 feet forward of the intakes. The transmission coolers are on the aft of each engine, mounted to the top of the transmissions. Raw water was pulled through the transmission coolers on the way to the pumps. I'd like to put 90 deg bronze elbows in the hose at a few points (after the strainers) in order to allow some uniformity in the placement of the hose and strainers. Without the elbows, the hose runs are awkward because the 2 ply reinforced 1 1/4" rubber doesn't bend well in such a small space. Would the elbows cause a flow issue after the strainers? My thought is that it doesn't matter after the system is primed. Is there a better material for this application than bronze?

Check page 4 of this catalog for an example of an outboard mounted strainer. I have seen these used in place of an internal strainer which would cut down on a lot of bits and pieces in your engine room leaving you more space and quite a bit less to maintain. May also solve your hose routing issues. Would require a haul-out to install.

I am sure others may wish to way in on their own preference regarding outboard versus inboard strainers. Here in NE Florida bottoms get scrubbed by a diver once a month between haul-outs including the external strainers. They don't seem to pose a problem.

[wardd]

what happens if the external strainer clogs?

[CDK]

The temp gauge moves to the red part of the scale and urges you to jump in the water armed with a wire brush.

[wardd]

I think I'd stick with a strainer you can clean without swimming with the sharks

Forgot to mention, that you have to install zinc´s when you go bronce! Otherwise your engine will slowly disappear.

And have the strainer inside and serviceable, the entire commercial fleet does it that way!

Regards
Richard

[pasty63]

The boat's on the hard, so I can install any configuration. The pick ups are currently the "strainer" type with bars over the opening. The strainers are inboard with glass cylinders - just cleaned and refitted these with new gaskets. We have a lot of junk in the water here - even with the barred inlets we get plastic bags in the strainers from time to time.

[Bglad]

Originally Posted by apex1

Forgot to mention, that you have to install zinc´s when you go bronce! Otherwise your engine will slowly disappear.

And have the strainer inside and serviceable, the entire commercial fleet does it that way!

Regards
Richard

The commercial fleet I was familiar with in the Florida Keys commonly used the external strainers without problems. You have an external strainer/scoop either way so you could get clogged up using one or the other causing you to see red and maybe have to go overboard I am betting the little holes in the external strainer would be less likely to let stuff in than the tines on the clam shell types. If I was starting from scratch or just didn't want to deal with the basket inside I would use the external strainer only.

Originally Posted by Bglad

If I was starting from scratch or just didn't want to deal with the basket inside I would use the external strainer only.

Seems you have not read the post above yours!

[Bglad]

Originally Posted by apex1

Seems you have not read the post above yours!

I did read it and I suspect a barred inlet will let things in that won't go through the exterior strainer. If it will go through the exterior strainer it will likely go through the engine just like things that will fit through the basket strainer because the holes in the exterior strainer are about the same size. The advice of others on this forum is well taken and respected by me. I am just offering the benefit of my own experience. If in the OPs shoes I would check around my area and stick with what others are using successfully because my experience may not work in the OPs area. My own shoes prefer less stuff to maintain, watch turn green, gaskets go bad, stainless clamps corrrode off, etc