Underwater fittings and hoses

coopec

coopec

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I know underwater nylon skin fittings are not recommended and I (now) know nylon ball valves are not recommended for underwater but what about hoses?

I am about o fit a hose that is reasonably flexible unlike others that have several layers of canvas(?) reinforcing and I'm wondering whether I am doing the right thing.
 
coopec said:
I know underwater nylon skin fittings are not recommended and I (now) know nylon ball valves are not recommended for underwater but what about hoses?

I am about o fit a hose that is reasonably flexible unlike others that have several layers of canvas(?) reinforcing and I'm wondering whether I am doing the right thing.
Click to expand...

Clive you will find that most reinforced hoses I know are not nylon but PVC. The only nylon hose I have ever user was in pneumatic pipe work and it is very stiff and kinks very easy.

Nylon hose
nylon-hose-250x250.jpg

PVC hose
http://www.tufflinehose.net/pvc-suction-hose.htm
 
if by "nylon" you mean such fittings as Marelon (Glass Reinforced DuPont Zytel) or the NZ Trudesign through-hulls and valves, then they have been proven safe over many many years. The garbage about fire melting them is rubbish: any fire big enough to melt the through-hulls has done monstrous damage to the hull already.

Your question about hose needs more info. Is it suction (e.g. engine intake) or delivery (e.g. cockpit drain). Some hoses will need wire re-inforcement, others just the criss-cross terylene thread is OK. So many types of hose for different uses.


For any flexible hose you need to ensure that the hose cannot collapse at the point of maximum bend and restrict flow. This is not easy, especially when e.g. hot water is the content.

Canvas re-inforcing ? A pic will be useful please.
 
sarabande said:
if by "nylon" you mean such fittings as Marelon (Glass Reinforced DuPont Zytel) or the NZ Trudesign through-hulls and valves, then they have been proven safe over many many years. The garbage about fire melting them is rubbish: any fire big enough to melt the through-hulls has done monstrous damage to the hull already.

Your question about hose needs more info. Is it suction (e.g. engine intake) or delivery (e.g. cockpit drain). Some hoses will need wire re-inforcement, others just the criss-cross terylene thread is OK. So many types of hose for different uses.


For any flexible hose you need to ensure that the hose cannot collapse at the point of maximum bend and restrict flow. This is not easy, especially when e.g. hot water is the content.
Click to expand...

+1 to all that.
I wouldn't use a plastic skin fittings underwater unless it had good provenance, such as Trudesign or Forespar (Marelon). It's doubtful that unbranded fittings are nylon, anyway. (I'm equally suspicious of many 'bronze' fittings.)
 
sarabande said:
i

Your question about hose needs more info. Is it suction (e.g. engine intake) or delivery (e.g. cockpit drain). Some hoses will need wire re-inforcement, others just the criss-cross terylene thread is OK. So many types of hose for different uses.

For any flexible hose you need to ensure that the hose cannot collapse at the point of maximum bend and restrict flow. This is not easy, especially when e.g. hot water is the content.

Canvas re-inforcing ? A pic will be useful please.
Click to expand...

The hose is radiator hose and I would have no worries putting it on a car engine so you will gather it is not too flexible. It is 32mm diam. between the skin fitting and the raw water strainer so it is a suction hose and will be straight.
I'm using rubber hose on the toilet inlet but of course suction would not be a problem there.

I am going to the trouble of installing top quality skin fittings and ball valves but the switch to rubber hose which seems to be a weak link. I can't give you a pic as I would have to climb up into the yacht and it is blowing a gale here but this is what my hose looks like.

http://www.ebay.com.au/itm/STRAIGHT...-HOSE-1-25-32MM-X-1-METER-SHL32-/251320456394
 
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coopec said:
The hose is radiator hose and I would have no worries putting it on a car engine so you will gather it is not too flexible. It is 32mm diam. between the skin fitting and the raw water strainer so it is a suction hose and will be straight.
I'm using rubber hose on the toilet inlet but of course suction would not be a problem there.
Click to expand...

Both the cooling water intake and the toilet flush water intake are subject to suction and require hose with a spiral steel reinforcement.
 
macd said:
+1 to all that.
I wouldn't use a plastic skin fittings underwater unless it had good provenance, such as Trudesign or Forespar (Marelon). It's doubtful that unbranded fittings are nylon, anyway. (I'm equally suspicious of many 'bronze' fittings.)
Click to expand...

"Plastic" is a generic term so it can cover many things.
I had planned to use this PVC Ball valve on my skin fitting but the guy at "Wilsons Chandlery" said the insurance companies would have a problem with that so I'm using it on my fresh water tanks now. 'This is the fitting and how much faith would you guys have in that?
https://www.whitworths.com.au/main_itemdetail.asp?cat=133&item=78436&intAbsolutePage=1
 
coopec said:
"Plastic" is a generic term so it can cover many things.
I had planned to use this PVC Ball valve on my skin fitting but the guy at "Wilsons Chandlery" said the insurance companies would have a problem with that so I'm using it on my fresh water tanks now. 'This is the fitting and how much faith would you guys have in that?
https://www.whitworths.com.au/main_itemdetail.asp?cat=133&item=78436&intAbsolutePage=1
Click to expand...

Plastic may be a generic term, but nylon, the word you used, certainly isn't.

Link doesn't seem to work...but oddly enough did in the quote. Yes, a cheap PVC ball valve

If you'd said the ball valve was PVC in your other thread, you might have received more pertinent answers than you did.
 
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macd said:
Plastic may be a generic term, but nylon, the word you used, certainly isn't.

Link doesn't seem to work...but oddly enough did in the quote. Yes, a cheap PVC ball valve

If you'd said the ball valve was PVC in your other thread, you might have received more pertinent answers than you did.
Click to expand...

I don't know why the link won''t work. I just googled PVC Ball Valve and got picture of the type I have.
How good are these?
https://www.google.com.au/#q=pvc+ball+valve
 
pvb said:
Both the cooling water intake and the toilet flush water intake are subject to suction and require hose with a spiral steel reinforcement.
Click to expand...

I'm a bit reluctant to use steel reinforcement near sea water. Now you say it must be reinforced to avoid collapsing I did a bit more research and came across this.

"Raw water hoses
Intake hoses ingest “raw” or outside water to cool the engine, flush the toilet, feed the AC and supply fresh water for the fish in the bait tank. Use only hose recommended for “below waterline” connections with a hard spiral that prevents kinking and collapsing under suction should the screen of the intake become clogged. We recommend two-ply pickup hose with heavy-wall rubber and helix reinforcements or extra heavy-duty smooth vinyl hose with a hard PVC helix for non-heat sensitive applications. Series 135 Heavy Duty Water Hose (polyester yarn spiral reinforced), pressure resistant to 800psi"
I wonder if this link works?
http://www.westmarine.com/WestAdvisor/Selecting-Marine-Hoses
 
pvb said:
The steel spiral is sealed within the hose wall and isn't exposed to seawater.
Click to expand...

Yes and it probably is SS anyway.

Just as well I asked because I was going to do the wrong thing. Thanks guys for sorting that one out.

I'll stick with the quite heavy walled rubber tube for the toilet as it would probably destroy the toilet pump before that collapsed.

Clive
 
macd said:
Plastic may be a generic term, but nylon, the word you used, certainly isn't.

Link doesn't seem to work...but oddly enough did in the quote. Yes, a cheap PVC ball valve

If you'd said the ball valve was PVC in your other thread, you might have received more pertinent answers than you did.
Click to expand...

When I used the word "plastic" I meant it in a general way to include PVC, nylon, polyethylene etc.

"1. a synthetic material made from a wide range of organic polymers such as polyethylene, PVC, nylon, etc., that can be moulded into shape while soft, and then set into a rigid or slightly elastic form
 
The PVC ball valve is a standard valve used in irrigation systems and is on for non critical controls. I had one supplied with my bore hole pump to control the flow but would never use one for a seacock.

For suction you do not need steel reinforced but you do need reinforced hose like this which has a hardish plastic spiral reinforcing.

pvc-medium-duty-suction-hose-1396999.jpg


http://www.tufflinehose.net/pvc-medium-duty-suction-hose.htm

IMGP2569_zps0fd4bf98.jpg


IMGP2570_zps564b8f22.jpg


IMGP2573_zps7807de94.jpg


The white is special sanitary hose the yellow id the same as the green as above.

The clear smaller hose is braided reinforced PVC.

The red fittings are nylon BTW the yellow hose is PVC.
 
Roger

That spiral reinforced hose looks good.

Next Thursday I'm doing a trip to Perth and want to pick up some economically priced elbows for my cockpit drains although I'd prefer they were straight thru hoses. Those red elbows: what are they? My drains are 37mm so I'll try to get some irrigation fittings (but they won't be red)

I was on a 35ft launch (newish) and when we left the boat at it's pen (berth) the skipper didn't close the ball valves on the underwater skin fittings. I'd like to see that they are "free" to turn apart from anything else?

Clive
 
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coopec said:
Roger

That spiral reinforced hose looks good.

Next Thursday I'm doing a trip to Perth and want to pick up some economically priced elbows for my cockpit drains although I'd prefer they were straight thru hoses. Those red elbows: what are they? My drains are 37mm so I'll try to get some irrigation fittings (but they won't be red)

I was on a 35ft launch (newish) and when we left the boat at it's pen (berth) the skipper didn't close the ball valves on the underwater skin fittings. I'd like to see that they are "free" to turn apart from anything else?

Clive
Click to expand...

We get the nylon pipe fittings in various colours from different suppliers and I can get then from my local DIY chain or a specified irrigation equipment supplier, builders merchant or agricultural supplier .

Look here

insert-fittings.jpg


http://www.incledon-ipi.co.za/Documents/NYLON INSERT FITTINGS.pdf

http://www.irrigation4africa.co.za/...tings-and-microjet-price-list-march-2016.html
 
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Well I'll go to Bunnings and get some irrigation fittings but I'm sure they'll be black (I've never seen red ones in Australia)
Thanks
 
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coopec said:
Yes and it probably is SS anyway.

Just as well I asked because I was going to do the wrong thing. Thanks guys for sorting that one out.

I'll stick with the quite heavy walled rubber tube for the toilet as it would probably destroy the toilet pump before that collapsed.

Clive
Click to expand...

A bit like "plastic", "rubber" tube can be all sorts of things. For toilet hoses you need sanitary grade butyl rubber, sold specifically for this job. Otherwise you will almost certainly bet smells as many other types of hose are slightly porous.

Your PVC valves are only suitable for internal water systems provided (like any other hoses you use in the water system) they are food grade.
 
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