Offset Thru-Hull Fitting

[A-37]

2001 Proline 20 Walk: The outer flange of my nylon thru-hull fitting broke off and I replaced the fitting. The old fitting has an offset barb. I thought the offset might be to facilitate hard to access hose clamps and enable attaching the fitting by running the bilge hose thru the hole and outside the hull. This would allow you to install the clamps then push the fitting through the hole. Wrong! The clamp screws prevent slipping on the big retaining nut. My question: Why the offset??

 

[Grub54891]

Picture please! I can't understand what the offset fitting would be.

 

[JoLin]

Wonder if you mean a fitting with a 45 deg. or 90 deg hose barb, rather than a straight one? You're right- they aren't there to facilitate placing the clamp. AFAIK there isn't a thru-hull n the market that'll let you install the hose clamp from the outside, then push it through. I've wished for it more than once.

The manufacturer used an offset barb either (1) because the hose would've kinked if run where it needed to go, or (2) because that was what was lying around when it came time to install that fitting.

My .02

 

[A-37]

No Title

The centerline of the barb is offset from the centerline of the barrel. All dimensions are exactly as the new one except that the new one is not offset. There's no hose routing nor inside hull clearance problems which would dictate an offset fitting. This is the bilge pump outflow fitting. The picture shows the old fitting with the flange broken off.

Some company should make a thru-hull fitting with the external flange having a male stub thread which screws into the fitting. That way, you can clamp the hose to the fitting out in the open, hold it in position, run the retaining nut to the hull, then screw in the flange. Easy.

As it is, I'm working through an aft seat hatch using a mirror and flashlight because the fitting is high out of sight. Try putting a socket on the clamp screw using a mirror! Did I mention that I'm right handed and I have to work left handed?

 

[smokeonthewater]

I suspect we're talking about a reduced size hose compared to the thru-hull portion.....

 

[JoLin]

The centerline of the barb is offset from the centerline of the barrel.

Huh. Never saw one of those before.

 

[smokeonthewater]

Whoops he posted while I was typing.

Soooooo that thru hull fitting is designed for use where clearance is an issue.... The reason it was used on YOUR boat tho is because that's what they had when they built it....... It was likely cheaper to order, inventory, and store, 100,000 offset fittings than 50,000 offset and 50,000 centered.

Since there was no downside to just buying and using the one style it made sense to just use them for everything.

 

[Grub54891]

Yeah,never saw that one. Just get a regular fitting,and wiggle yourself into the area,with all the tools in your toolbox,and go to it. Been there,done that. If there is a removable cushion,or panel in that area,you can remove it, drill a proper sized hole with a hole saw,access the fitting,and re-install cushion /panel. The hole will be covered with the panel.Just be sure to seal the edges of the hole with epoxy if wood backers are installed. Or fill the hole with a deck plate.I've even just drilled the hole and simply used a deck plate where it can be seen,still looks good that way.

 

[Yacht Dr.]

Only time Ive seen those is for cockpit drains ( clearance like smoke said ^^ ). Would love to see the flange that busted off. I dont think they were as beefy as a normal through hull fitting though. Again like Smoke said..its what they had on hand..or mebbe someone grabbed it off the wrong shelf.

 

[A-37]

Cockpit drain is the correct answer. I found them on a vendor's site. BTW, my replacement thru-hull for the bilge out-flow is installed and not leaking. Imagine that!