Replacing propeller shaft cooling hose barb Beneteau 305

[Salty Tradewinds]

Hey Folks,

Like a lot of you, my propeller shaft hose barb broke off, leading to a small hole in the bottom of my boat which is mercifully plugged. However replacing the hose barb looks tricky while the boat is in the water but since I can't pull the boat for at least a month I thought I might give it a try. I've been researching how to repair when I saw several suggestions of using fiberglass to build up the area around the shaft and putting in a new hose barb. One suggestion was to glass a nut in place so that the hose barb becomes a user serviceable part. Being a hands on kind of guy I like this idea.

My approach is to keep the broken brass that is through the fitting now, glass a nut on top of it, then screw a new hose barb in place with a rubber washer to seal between it and the existing bronze hole. This should allow the same water volume to the bearings and should be strong as the nut will be glassed in, and has the added benefit of being completely removable should it not hold water well. I would be no worse off, and I would just get the boat pulled.

So my question is what advice would you have in doing this? I know to avoid brass so I am using a stainless hose barb. I will be taking care to really glass the nut in well, and will likely use locktite to make sure the barb is in the nut as solidly as I can make it. Other than minding for leaks is there any reason to believe this won't work?

 

[BrianRobin]

Well, that barb is likely NPT, is the nut also the same?

 

[Salty Tradewinds]

Hi Brian, The nut is Brass, but I can replace that with stainless if that matters. The barb will be a stainless steel one that I have ordered. I figured the nut is less important as it will be encased in glass and theoretically won't interact with salt water if I do it right.

 

[BrianRobin]

Sorry, I was asking if it was the same thread.

 

[Salty Tradewinds]

Oh, yes. Same thread. 1/2 inch

 

[BigEasy]

Should work fine if you can keep the surfaces dry while doing the glass work. Instead of locktite, I would wrap the npt threads on the nipple with Teflon tape and put some 3M 4200 on it. Should seal it and allow for removal to service in future.

 

[DougM]

Looking at your photos, the new barb appears to be NPT threaded and the nut appears to be straight thread. If that is the case you are going to either have to find a straight threaded hose barb, or a pipe threaded nut. Otherwise its unlikely that you will be able to get a good seal.

 

[BrianRobin]

Looking at your photos, the new barb appears to be NPT threaded and the nut appears to be straight thread. If that is the case you are going to either have to find a straight threaded hose barb, or a pipe threaded nut. Otherwise its unlikely that you will be able to get a good seal.

That's what I was thinking as well!

 

[Gunni]

So my question is what advice would you have in doing this?

Do it the factory way. Install the threaded nipple into the fiberglass shaft log and reinforce it with silica thickened epoxy. Gluing a nut to the shaft makes the security of the connection entirely dependent upon that glued connection. Dubious.

 

[Salty Tradewinds]

Just to be clear the nut fits fine with the threaded barb. So the fit is good. And I am not talking about gluing the nut to the shaft log but fiberglassing it in. Effectively it just makes the barb a removable and replaceable part without pulling the boat. As long as the nut is completely glassed in and waterproof I think this is actually better than what was there before.

 

[BrianRobin]

Just to be clear the nut fits fine with the threaded barb. So the fit is good. And I am not talking about gluing the nut to the shaft log but fiberglassing it in. Effectively it just makes the barb a removable and replaceable part without pulling the boat. As long as the nut is completely glassed in and waterproof I think this is actually better than what was there before.

Out of curiosity,where did you ever find a nut with the same thread?( I may a have a future use, thanks)

 

[Gunni]

A nut will be subject to the same corrosion that took your original hose barb, but now you will have to cut away glass to get it off. That fiberglass shaft log tube has relatively thin wall and can be damaged if you get too froggy with a grinder.

 

[Salty Tradewinds]

I had it on hand. It has a flange on the bottom as well so it is easy to build up the glass around it. No idea where it came from.

 

[Salty Tradewinds]

A nut will be subject to the same corrosion that took your original hose barb, but now you will have to cut away glass to get it off. That fiberglass shaft log tube has relatively thin wall and can be damaged if you get too froggy with a grinder.

I agree that the brass Nut will be subject to corrosion. It's unlikely that I can isolate the water to just the channel with rubber washers and silicon tape. I will look for a stainless steel equivalent.

 

[cymeyer]

I had it on hand. It has a flange on the bottom as well so it is easy to build up the glass around it. No idea where it came from.

Hey Salty Tradewinds,
We put a dripless coupling on our boat 15 years ago and don't mess with any of what you show any longer.
Ever think about that?

 

[Mechone]

I would not use the nut, I would build the area up with west epoxy and 404 high density filler. I would then drill and tap the with a 1/4 BSP not NPT. BSP are straight threads not tapered like your ball valves on your thru hulls.You can buy tap for 3.00 off ebay ss 1/4 BSP 12mm barb off ebay. If you want it even stronger you can also purchase a 1/4 BSP thread insert kit . Now threads and Barb are s/s and replaceable. You can also buy NPS national pipe straight.
I did a similar repair on my rudder ,I now have a removable drain plug to ensure no water in rudder after hull out

 

[Salty Tradewinds]

No, but I like that idea. I inherited this boat a year and a half ago so I am very much in learning mode.

 

[Salty Tradewinds]

I would not use the nut, I would build the area up with west epoxy and 404 high density filler. I would then drill and tap the with a 1/4 BSP not NPT. BSP are straight threads not tapered like your ball valves on your thru hulls.You can buy tap for 3.00 off ebay ss 1/4 BSP 12mm barb off ebay. If you want it even stronger you can also purchase a 1/4 BSP thread insert kit . Now threads and Barb are s/s and replaceable. You can also buy NPS national pipe straight.
I did a similar repair on my rudder ,I now have a removable drain plug to ensure no water in rudder after hull out

OK, I found a bronze barb on ebay so that referral was great. Hope it's BSP, but I won't know until it shows up. Looking for the tap now.

 

[BigEasy]

This was recently discussed/debated. Check out "Hose barb 1/2 npt male to 3/8" in the archives, posted by BlueNose.
No definite consensus on this issue; everyone seems to have their own opinion. IMHO there is no perfect solution. Keep in mind that any refit will require your labor and $$, and you need to refit in a manor that will allow for maintenance in the future. Lots of guys advise a dripless seal; however, there is the initial cost, your time to uncouple the shaft and install. The bellows and nipples on these dripless seals should be replaced periodically also...they are not maintenance free.
Probably the best solution that I have read about is building up the stern tube thickness with a few wraps of roving tape & epoxy, retapping to diameter of your choice, and installing a new 316 SS nipple or perhaps marelon nipple and calling it a day. Even with my OEM setup, I was able to unscrew the nipple, inspect, and reinstall without incident. With the additional layups added to the tube diameter, you should be able to remove and replace the nipple periodically fairly easily. The above photos are images of a new Beneteau oem fitting for reference

 

[Bob S]

I've read a lot about this issue and was curious at what point and/or how do these fail? Does it just pop off or is it bumped to break it? I tried pulling the hose off the barb with no success and didn't want to compromise the fitting. My 2003 has spent half it's life on the hard so the systems are in good shape. The problem on the 393 is it's under the aft birth and it's not in an easy area to get into so I leave the through hull open.