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Old 16-03-2019, 12:31   #1
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TRUDESIGN - Beaware

Hi,

I just realised a huge mistake I made when replacing all my thruhulls/seacocks/Ball valves on my Hallberg Rassy 42.

After many hours of googling I decided to go with this new komposit trudesign. However, now after everything is bought and installed I reliased that they in fact only have three different kind of ID on the ball valves, 3/4", 1 1/4" and 2" which means that all the 1" and 1 1/2 I bought and installed are more or less in vain since the narrovest point in the the flow will be the narrow place in the valve (i.e. my cockpit selfdrains that is 1 1/2 inch scupper, hose and thruhull are just waste since there will be a 2 inch long narrow point in the "so called" 1 1/2 inch ball valve that will only be 1 1/4 inch in its ID.)

Just wanted to give a warning so none else repeats my misstake and waste money and time down the drain....

Should have gone with groco.
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Old 16-03-2019, 12:56   #2
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Re: TRUDESIGN - Beaware

“Good judgment comes from experience, and experience comes from bad judgment.”

...not that you showed bad judgement...it just reminded me of that quote. Thanks for the head's up and sharing your experience.

Pat
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Old 16-03-2019, 14:13   #3
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Re: TRUDESIGN - Beaware

A short 2” section that is only slightly narrower than the hose will not make a significant difference in the flow rate.

More important is how the diameter changes inside. Is it a step or taper? A step might catch debris and be more prone to clogging. Do you know if this is a problem? If not, I would not be too concerned.
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Old 16-03-2019, 17:35   #4
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Re: TRUDESIGN - Beaware

If this flow restriction was not prominently advertised it would seem to be a case of false advertising. Who would knowingly purchase a 1 1/2” seacock which was actually a 1 1/4”? This is just wrong. The flow rate is dictated by the minimum diameter, regardless of the duration of the minimum diameter.
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Old 16-03-2019, 18:32   #5
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Re: TRUDESIGN - Beaware

If it's not a full flow valve, that is normal. Any fitting that accepts 1 1/2" hose is going to be smaller than 1 1/2" inside diameter.
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Old 16-03-2019, 18:46   #6
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Re: TRUDESIGN - Beaware

It’s pretty clear from the drawings on their web site that they use the same valve for 1-1/4” and 1-1//2” pipe thread size.

Franky I don’t see the problem.
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Old 16-03-2019, 19:01   #7
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Re: TRUDESIGN - Beaware

Quote:
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A short 2” section that is only slightly narrower than the hose will not make a significant difference in the flow rate.
Bernoulli disagrees.
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Old 16-03-2019, 19:47   #8
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Re: TRUDESIGN - Beaware

For most boat systems the ID of a hose barb/hose tail already reduces the flow diameter (since it fits inside the hose). If the valve port bore is as large as the barb ID then the modest additional length at that diameter is generally not hugely significant. If the valve port is the only restriction then it's a different story.

As a general (very broad) rule a full-port ball valve has about 3x the flow capacity of a reduced-port ball valve of the same size for the same pressure drop. In Imperial systems commonly denoted as Cv; the flow in GPM that causes a pressure drop of 1 psi. For a 1" full-port valve typical values are around 100, for a 1" reduced-port typical values are around 30-35, so the restriction can make a significant difference in flow capacity.
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Old 17-03-2019, 07:22   #9
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Re: TRUDESIGN - Beaware

But there is a hose of some length. So flow is not proportional to the pressure drop across the valve. When taking the hose and all other fittings a diameter change from 1.5” to 1.25” for a 2” length cannot make a significant difference in flow rate. Maybe if the hose is less than a foot it will matter but what thru-hull is equipped with a really short hose.

The main concern with flow is for a bilge pump discharge. The losses associated with overcoming the head loss of the anti-siphon loop and hose friction will overwhelm a tiny short restriction like these valves.
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Old 17-03-2019, 07:22   #10
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Re: TRUDESIGN - Beaware

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Bernoulli disagrees.
Isn’t he dead?
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Old 17-03-2019, 07:38   #11
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Re: TRUDESIGN - Beaware

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...
The main concern with flow is for a bilge pump discharge. The losses associated with overcoming the head loss of the anti-siphon loop and hose friction will overwhelm a tiny short restriction like these valves.
Depends on the bilge pump. A 1-inch reduced port ball valve introduces 1 PSI of loss all by itself at about 30 GPM (1800 GPH). Our insurance requires at least 1500 GPH from our bilge pumps, so getting pretty close to that figure. And most bilge pumps are rated for output at no more than 1-2 PSI total head loss.

A full-port design with a Cv of 100 introduces about 0.1 PSI (remember, head loss is a squared relationship) under the same conditions. The one place I'd really want a full-port design is the bilge pump - because they have very limited output head.
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Old 17-03-2019, 07:54   #12
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Re: TRUDESIGN - Beaware

Well, I would assume that there was a few mm difference on the inside but the difference between 38 mm (1 1 /2 inch) and 32 mm (1 1/4 inch) is quite big % wise when you calculate the area since this is not linear.

Once again, when you read the folder the information is clear but you dont see it on their products before you buy them hence my post to warn other to check it out before.

Anyway, worse thing has happend and this is not the end of the world BUT with this knowledge I will most likley make a third self-drain for the cockpit (a 2 inch). All other thruhulls affected I think this is kinda whatever and more falls under the category "slightly inconvinient".

Fair winds all
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Old 17-03-2019, 08:39   #13
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Re: TRUDESIGN - Beaware

It may be worth it to test the cockpit drain system. I’ve done that by covering the drains with rubber flaps. Put several gallons of water in the footwell then pull up the rubber flaps. Our 4 drains can remove about 80 gallons per minute through the gravity drains. I wish it were faster. There is no pump to drain our cockpit and it can literally hold a ton or two of water. You want that gone as quickly as possible so I understand the concern.
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Old 17-03-2019, 09:41   #14
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Re: TRUDESIGN - Beaware

Quote:
Originally Posted by Mr.Feeney View Post
Well, I would assume that there was a few mm difference on the inside but the difference between 38 mm (1 1 /2 inch) and 32 mm (1 1/4 inch) is quite big % wise when you calculate the area since this is not linear.



Once again, when you read the folder the information is clear but you dont see it on their products before you buy them hence my post to warn other to check it out before.



Anyway, worse thing has happend and this is not the end of the world BUT with this knowledge I will most likley make a third self-drain for the cockpit (a 2 inch). All other thruhulls affected I think this is kinda whatever and more falls under the category "slightly inconvinient".



Fair winds all


Isn’t the hose barb on 1 1/2” hose going to restrict the diameter as much or more than the 1.27” of the valve?
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Old 17-03-2019, 10:56   #15
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Re: TRUDESIGN - Beaware

Quote:
Originally Posted by Mr.Feeney View Post
Hi,

I just realised a huge mistake I made when replacing all my thruhulls/seacocks/Ball valves on my Hallberg Rassy 42.

After many hours of googling I decided to go with this new komposit trudesign. However, now after everything is bought and installed I reliased that they in fact only have three different kind of ID on the ball valves, 3/4", 1 1/4" and 2" which means that all the 1" and 1 1/2 I bought and installed are more or less in vain since the narrovest point in the the flow will be the narrow place in the valve (i.e. my cockpit selfdrains that is 1 1/2 inch scupper, hose and thruhull are just waste since there will be a 2 inch long narrow point in the "so called" 1 1/2 inch ball valve that will only be 1 1/4 inch in its ID.)

Just wanted to give a warning so none else repeats my misstake and waste money and time down the drain....

Should have gone with groco.
With your scupper designed for 1 1/2" hose it is already smaller as it goes into the hose. I don't see an issue.
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