Inlet Suction Hoses for Raw Water Pump

[Eggbert]

I’m not happy with my current inlet hose for sea water to the raw water pump. You can see from the (badly sketched) picture below what I’m dealing with.



Carver put the seacock just slightly to port from center and the pump is a little further to starboard from center. It used a molded hose (which I can’t identify) from the seacock to position “X” where the was a bronze coupler and from there to the water pump was a corrugated rubber hose that made the 180 degree bend. It kinked easily although I never seemed to have any overheating. The molded hose had seen better days as well, so I decided to replace them.

I got two hoses that fit from an auto-parts store but they are radiator hoses, probably upper ones as there is no coiled wire inside to prevent collapsing. I doubt they would collapse under normal use, but when I flushed the system with fresh water from my garden hose, it couldn’t keep up above an idle and I saw the seacock hose collapse. I also used a PCV coupler as the bronze one wouldn’t fit. I’m not sure why that was as everything seemed to be 1, ¼” hose. I don’t trust the PVC as it may degrade due to temperature extremes when the boat is stored for the winter.

Looking at the sketch, points “A” to “B” is in the horizontal plane and from “C” to “D” is in the vertical plane. “X” is where the coupler is.

Is there suction hose available that is flexible to make all these bends? Is there a 1, ¼” 180 barbed bronze U-tube to make the 180 degree bend? Should I replace the straight barbed fitting on the seacock with a 90 degree barbed fitting? Basically, I am open to any suggestions that doesn’t involve moving the seacock.

Any thoughts? Thank-you.

[bud37]

I think you have answered your own question.......bronze thread to barb 90 from the thru hull ( quite normal ) then marine wire reinforced suction hose and a barbed 180. The marine suction hose will bend to a fairly tight radius by the way.....may just need to be a bit longer.....maybe install a sea strainer while you are in there......see I can spend your money quite easily.....

[Eggbert]

It does seem more obvious now that I wrote it and you answered it. Isn't hindsight great... not to mention a fresh look from someone else! LOL. Thank-you!

I suppose the biggest problem if I go that route will be to identify a 1, 1/4" bronze 180. God bless Google. I'd probably wrap it in something to keep it from banging the inside of the hull where it would lay under the engine.

[Viper]

I'm not following the "180". You need an elbow at the seacock that is a male pipe thread to thread into the seacock with a 1-1/4" barb at the other end for the hose. The hose should be one piece from the seacock to the raw water pump. As mentioned, adding a strainer at this time would be ideal.

[Eggbert]

Qr Bbpost I'm not following the "180". You need an elbow at the seacock that is a male pipe thread to thread into the seacock with a 1-1/4" barb at the other end for the hose. The hose should be one piece from the seacock to the raw water pump. As mentioned, adding a strainer at this time would be ideal.

The 180 is for the left end of the sketch and the thought is that tough suction hose isn't flexible enough to do that without either kinking or putting undo pressure on the raw water pump nipple. But as you say a single hose would be the most reliable solution.

It turns out these 180 degree U-tubes are called "return bends" however bronze ones seem to be a custom order from suppliers who manufacture to a MIL-Spec (i.e. atrociously expensive). So far I have not found SS ones in 1-1/4" size. I don't trust plastic, or copper for that matter.

I can make one up out of bronze 90 degree fittings, a joining nipple and two barbed ends, but lots of joints isn't great, plus it would be heavy and if it flails around, something could go wrong.

I really don't' know, but at the seacock end I wonder if they use a straight nipple and that molded hose so that it puts some of the system above the waterline. As long as it didn't siphon (which is unlikely as the height difference is not much more than the thickness of the hull) a break in the system wouldn't cause the boat to sink. A 90 degree elbow there might not be "as safe". However, I'm not really that worried about using a 90. I'm more concerned with all the joints and the weight of the 180.

When I first posted about this, I was sort of fixated on finding the correct molded hoses as I thought Carver would have positioned the seacock to work with existing available hoses. Failing that, I was looking for extremely flexible suction hose, being more concerned with the aft 180 bend without much thought to the seacock bend. A 90 would solve the latter and it could be all one hose if it were flexible enough.

[mjk1040]

I question the addition of sea strainers in the raw water supply to the engines? There must have been a reason Carver and the engine manufactures never installed them when the boats were built? I have owned 2 different Carver models with Crusaders and no in line strainers on the raw water engine supply. I have also looked at several other Carver models and no sea strainers on the engine raw water supply. As for the raw water supply hose a longer piece with a larger sweep may be the install answer. Also has any one tried warming the inlet wired hose and putting a 180 sweep in it?

[bud37]

So here is a thought that may help you.....go to your local marina or whoever sells the marine suction hose and try to bend a piece ....you already will know what radius you need to make ....draw that on paper and bend new hose to match that to see what happens.....you may only need the 90 at the thru hull....

[Eggbert]

Qr Bbpost So here is a thought that may help you.....go to your local marina or whoever sells the marine suction hose and try to bend a piece ....you already will know what radius you need to make ....draw that on paper and bend new hose to match that to see what happens.....you may only need the 90 at the thru hull....

Ahh... and that's the rub and partly why I posted. At this point I only have catalogs to look through. They invariably say "flexible" but I think that basically means they are not rigid. Most of the local marine supply places are small and have limited inventory. Nevertheless, I think that is my next step.

So if I could find hose that is reasonably flexible but would yet want to straighten to the point that undo pressure was put on the water-pump nipple, I could strap it as long as it didn't strain the hose past its min. bend radius (see below). Plus the idea of heating it to help it maintain the bend is worth trying. Basically I have the distance between engine mounting stringers to make the bend.



ps: Interestingly enough, I have a 2017 catalog that lists 1-1/4" suction hose anywhere from $5.60 a foot (cheap enough... I only need to buy 6 feet or so) to a whopping $856.25 for a 50 foot roll ($17.13 per foot)! There is also clear PVC suction hose @ only $2.10 a foot, but I don't think I'd trust it. It might hold a bend better if heated though.... nah... still wouldn't trust it.

[Midnightsun]

I would definitely consider PVC hose. I have a bit of experience with it since my aquariums and pool all use this and have installed all of it myself. The pool plumbing sits outside all year long with extreme heat to extreme cold. Never heard of one rupturing or leaking. Looks and feels very similar to holding tank hose. Definitely 10x stronger and more resistant than radiator hose. No way can this type of hose collapse. Definitely durable and relatively cheap. https://www.amazon.com/TekTube-UltraFlex-Schedule-Flexible-Pipe/dp/B01N80U62T

[Eggbert]

Now that's quite interesting and it sure looks more robust than the clear stuff I was looking at. Quite frankly, I was worried about cold temperatures such as when the boat is stored during winter, but you do reassure me.

Looking up the manufacturer, I see it has a 4" min. bend radius for 1-1/4" hose. So that's 8" between bends. Add double the OD, which is 1.54 x 2 I get a total of approx. 11" I'm quite sure my stringers are farther apart than that, but I do need to measure them.

Ref: http://www.maxflex.co.kr/board/bbs/boar ... _id=100034

I must try to identify my other choices and see if I can find bend radius data. But as Bud37 mentioned, there's nothing like getting a piece in my hands at a marine supplier, or boatyard.