Sizing Seacocks

[Spirit of Glenans]

I'm just about to embark on changing seacocks and I'm not sure how to ascertain their size, for ordering.
Should I be measuring the internal diameter or the external diameter, or perhaps the I.D. of the hose attached?

 

[lpdsn]

I'm just about to embark on changing seacocks and I'm not sure how to ascertain their size, for ordering.
Should I be measuring the internal diameter or the external diameter, or perhaps the I.D. of the hose attached?

ID of hose attached. Check the seacock carefully though, I've 1 1/4" fittings with hose connectors for 1 1/2" hose. Bought 1 1/4" hose connectors initially.

 

[BabaYaga]

I'm just about to embark on changing seacocks and I'm not sure how to ascertain their size, for ordering.
Should I be measuring the internal diameter or the external diameter, or perhaps the I.D. of the hose attached?

Assuming that by seacock you mean through hull fitting+ball valve+hose tail and that you want to change like for like, the bore/ID of the through hull will give the size in inches for that part plus the ball valve. As mentioned above the hose tail for a given valve size can vary at the hose end to suit the ID of the hose.
As an example, 1 1/4" through hull+ball valve might be fine in combination with a hose tail that has a 1 1/4" size thread and a 1 1/2" (38mm) OD for a toilet outlet hose.
So beware when ordering such a tail that there are two "sizes" to consider.

 

[Tranona]

The most common sizes are 3/4" for water intakes and sink/shower outlets and 1 1/2" for toilet outlets. Other possibility is 1" if you have a waste outlet using a macerator and possibly for a large (by yacht standards) engine.

If it is a reasonably modern boat highly unlikely to be any different.

 

[vyv_cox]

The most common sizes are 3/4" for water intakes and sink/shower outlets and 1 1/2" for toilet outlets. Other possibility is 1" if you have a waste outlet using a macerator and possibly for a large (by yacht standards) engine.

If it is a reasonably modern boat highly unlikely to be any different.

Just to add, these are the nominal bore sizes according to BSP fittings, which are universal. Nowadays the wall thickness is less making the actual bore somewhat bigger but the name remains the same.

 

[macd]

+1 to all othe above.
If you need it, Wki has a page detailing all BSP dimensions: https://en.wikipedia.org/wiki/British_Standard_Pipe

More easily, if you contact ASAP, they'll tell you precisely what skin fitting/ball valve/hose tail combinations you require. I assume you'll be using DZR?

 

[Spirit of Glenans]

+1 to all othe above.
If you need it, Wki has a page detailing all BSP dimensions: https://en.wikipedia.org/wiki/British_Standard_Pipe

More easily, if you contact ASAP, they'll tell you precisely what skin fitting/ball valve/hose tail combinations you require. I assume you'll be using DZR?

Thanks, Macd and the four previous posters. I have enough info now for my purposes.

 

[rogerthebodger]

Thanks, Macd and the four previous posters. I have enough info now for my purposes.

As a rule of thumb, measure the outside diameter in millimeters round up to the nearest millimeter then deduct 8mm to the result the this will give you the approximate nominal bore size. Convert to inches.

 

[bluerm166]

Before finalising take the opportunity to check what the engine installation requirements are from the manfrs.manual.Recent Yanmar and Beta models both require larger cooling and exhaust flow than did older engines.