Adapting hose size on thru-hull fittings

[mitiempo]

Originally Posted by eheffa

Most Bronze through hull valves have a female NPT thread. (I'm betting that if the OD is ⅞", you need a ¾" MPT male fitting to mate with the ball valve fitting.

Can you not find a Bronze ¾" NPT male thread to fit and then use NPT adapters to downsize to the ½" barb fitting you need? These are readily available at our local marine store.

-evan

Spartan standard through hulls have barbs that are part of the fitting - not removeable.

Trudesign makes Marelon reducers 25mm to 13mm
https://trudesignplastics-com.s3.ama...223ea79b74.pdf

[mitiempo]

Originally Posted by NorthCoastJoe

I would run 7/8" hose the whole run then use a reducer at the hand pump. Thus keeping the reducer above the water line. Then it would not matter very much what material you use for the reducer just check it once in awhile.

Spartan does not make a 7/8" barbed seacock. It is either 3/4" or 1"

https://www.spartanmarine.com/all-pr...artan-seacocks

7/8 is an odd size that isn't produced by any through hull manufacturer as far as I know.

[Cheechako]

Adapt with a fitting on the faucet, above the waterline, not the seacock. Use brass double barb or Grey PVC (Grey PVC tends to run large, so their 3/4 is likely closer to 7/8 actual.
7/8" is odd, but that's the way the marine industry seems to be. "Let's make the fitting a size that's not what we say it is!"
It sounds to me like you need 3/4" Non wire wound hose to get onto the 7/8 nipple. There is 7/8" hose available though. Trident I think. I have used automotive heater hose for such a thing before. It's tough as heck and handles heat for 20 years but may not be available in 7/8.
A bronze 3/4 nipple (cut the thread off one end) works for 7/8 hose.

[Nicholson58]

Originally Posted by Atcowboy

Positive it is a barbed thru hull.

Can you link to any examples of such a barbed reducer?

Thanks,
AT

Search on Google, barbed hose fittings amazon

Many pages of links. Add Groco or Marlon to the search criteria.

Do not use yellow brass as it has too high a zinc content.

Another good source. Banjo fittings

https://www.usplastic.com/catalog/de...AaApkTEALw_wcB

[pcmm]

Originally Posted by Atcowboy

I have an unused 3/4" or 1" spartan marine seacock (measures about 7/8" OD) that I would like to repurpose as a saltwater intake for the galley sink, which would be 1/2" hose.

I cannot seem to find parts in brass or marelon to make the adaptation. I'm considering making a PVC adapter for the task. Is there a 'proper' way to do this?

I wish I could just go to the thru-hull for the raw-water intake for the engine, which is the right size and so very close to the sink. Don Casey's book "suggests" against this for risk of cavitation. Any experience with this? I would think this would only be a problem if the intake were blocked, making back-through-the-pump the "easy" way to get some fluid (whether water or air) through the impeller. In that situation, the problem (for the engine) exists if the seacock is dedicated or not.

Thanks,
AT

you just need one of these

https://www.westmarine.com/buy/seafi...03?recordNum=7

and one of these

https://www.westmarine.com/buy/groco...3?recordNum=13

easy.

[mitiempo]

Originally Posted by pcmm

you just need one of these

https://www.westmarine.com/buy/seafi...03?recordNum=7

and one of these

https://www.westmarine.com/buy/groco...3?recordNum=13

easy.

And how would you fit the above onto the seacock he has as shown below?

And as I posted earlier they make them in 3/4" and 1".
7/8" doesn't exist.

[pcmm]

Originally Posted by mitiempo

And how would you fit the above onto the seacock he has as shown below?

And as I posted earlier they make them in 3/4" and 1".
7/8" doesn't exist.

That would be difficult He didn't mention that he had integral hose barbs. Never seen that before in a seacock.

[Differentroads]

Exactly what I did on my saltwater intake 3/4'' hose to 1/2'' through a Vetus plastic reducer above the waterline. I avoid extra joints below the waterline because of the risk of hoseclip failure on, so the reducer matetial is irrelevant. That said, I have distirted the shape of a lightweight reducer by tightening up too hard, so the OP's caution is sensible.

And good point about the reducer needing support. Also the hose either side reasonably close to the reducer.