3.75 O.D. hose's corresponding I.D.??

[Bob Pullen HC-33 1981]

We're going to pull the hose connecting our cockpit scupper to thru-hull.
I'm trying to figure out the I.D. of said hose, being that I can only (easily) measure its O.D. = 3.75" or 9.5cm.
It looks like regular black rubber (radiator) hose...no distinguishable writting, and I don't want to pull it off until I get back from heading to the neighboring town which has a hardware store, for fear of not being able to get it back on.
I have a plug for the thru hull, but it rains a lot and I can't leave it in, as that will send all rain into hull, bilge, etc.
Does anyone know or have suggested sizing? Seanorita is a 1981 Hunter 33.
Many thanks
Bob Pullen
S/V Seanorita
Yucatan

 

[Ross]

Can you get access to measure the wall thickness?

 

[Bob Pullen HC-33 1981]

Ross,
I'm aiming to not pull the hose before I have a replacement onboard, so an accurate measurement of the wall thickness will not be easy.
The only replacement I can get is far from here, so I am trying to see if anyone knows if that is a common measurement, and would therefore tell me the corresponding I.D. without having to pull the hose. From the amount showing below and above the hose clamps it seems very close to a .25" hose wall. Maybe I will try either 10cm or 4.25" i.d. hose, or anything they have just slightly bigger and smaller.
I'm basically at the mercy of the local hdwr store either way, so just keeping my fingers crossed.
Bob

 

[Ross]

Bob, Redo you math! The O.D. is 3.75 with a 1/4 wall the I.D. would be closer to 3.25.

 

[Ron20324]

Can't you measure the hose barb that it is on?

 

[Bob Pullen HC-33 1981]

In answer to both: Yes, I added instead of subtracting -- 3.25" seems like the target.
Ron: In order to measure the barb to which it is attached I wiould have to take the hose off. I am trying to prevent this until I return with some replacement hose.