Exhaust port corrosion

[Hydraulicjump]

Mike Rizzo (former RT27 owner) turned me on to this potential problem, and since it reared its ugly head, I thought I would post it for some of you to address.

On our 2015 R29CB we have the RT standard exhaust port that many have commented on, particularly about the flaccid rubber flapper. But that is not the part to pay attention to. Mike (one of our most savvy members) pointed out the potential for corrosion (rust) on our stainless steel exhaust ports. Mine was not bonded, meaning not connected to the web of green wires that link all the things that might undergo galvanic or dissimilar metal corrosion. After Mike said I should check this, I did, and there were streaks of rust in the lazarette running down from every bolt holding the exhaust port in place. Well, that won’t do.

I had the boat hauled two weeks ago at CSR Marine in Ballard, Seattle, and while they were sanding and painting the bottom and buffing that fast-fading blue hull, I asked them to check on the exhaust port and replace if necessary.

Oh, it was necessary alright. They handed me the old exhaust port today while I handed them a very large check that was demonstrably in flames (why leave this money to your kids?) to retrieve my boat. The walls of the port had corroded until you could see pinpricks of daylight through it, which is pretty impressive given how thick it was. Who knows, if I had ignored this for a few years, I might have found my boat sunk in its slip (the old friend from grad school who helped me move through the Ballard Locks told precisely this story about his sailboat, albeit with an unhappy ending involving insurance).

So this is my heads up to those of you who have diesels and regularly stick your heads into the lazarette. If the bolts are streaking rust (not just the usual crusty stuff), get this checked out next time you haul the boat. And absolutely connect a bolt on that exhaust port to your bonding system (Andrew Custis’ advice from RT).

And remember the sage advice I learned from the Nordic Tug next to me in Elliott Bay Marina: “A boat is a series of problems yet to be revealed.” Even our well-built Ranger Tugs.

Jeff

(In Seattle now, instead of California, enjoying the most beautiful weather in all of the US. Go on, look it up!)

 

[SparklePlenty]

This past April I had the same issue rearing its ugly head on my 2016 Ranger Tug 25SC, only discovered because I was hauled out for bottom paint. One screw on the exhaust flange had completely disintegrated. On further inspection, screws in the exhaust port were disintintegrating. The exhaust port was not bonded. Later, less than $20.00 for new ss parts and green bonding wire, and $512.50 for labor, all is well.

 

[Dale777]

HydraulicJump,

I had the same crevice corrosion problem and lack of bonding on my R31S. See this link:

viewtopic.php?f=5&t=10474&hilit=+exhaust

"On my 2014 R31S, I had a seepage of sea water at the D4-300 exhaust port through the hull. I first noticed it due to a streak of rust colored stain coming from the bottom of the exhaust port along the inside of the hull. That stain was always wet, even after I wiped it dry a number of times over several days/weeks.

At the 2017 Ranger Tugs Rendezvous in Florida, the factory technician thought the screws on the flange on the outside of the hull needed to be tightened. That that did not help. Next, where the exhaust hose clamps to the exhaust port, I then replaced the lesser quality SS clamps with high quality T-bolt SS hose clamps - hoping that would stop the seepage. T-bolt hose clamps permit extreme tightening without damaging the hose. No luck!

It appeared that the exhaust port was seeping sea water due to crevice corrosion on the stainless steel exhaust port. There was no bonding wire to this exhaust port even though it is always partially submerged in sea water.

So, while the boat was out of the water for Florida hurricane season storage, I had the entire exhaust port through-hull assembly replaced with a new one. At the same time, I had a bonding wire attached to that port and to the nearby generator exhaust port, with both connected back to the common bonding at the stern.

After over 3-1/2 months in sea water since the repair, there is no sign of any seepage. I suggest that everyone periodically examine that area for any leak or seepage. Also, you might consider bonding that assembly if it is not already done."

 

[Hydraulicjump]

Dale,

Well, I wish I had remembered this. Glad we both surfaced this for other RT owners. Bond that exhaust port!

Jeff

 

[GaylesFaerie]

After inspecting my boat now that it is out of the water, I just discovered some corrosion on the exhaust port on my 2012 R27, which I understand from other Tugnuts (this thread in particular), said hardware is not bonded to prevent such corrosion. There is also corrosion on the threads of the two bolts that hold the flap in place.

https://share.icloud.com/photos/0OAk7RT ... VPdh7PjcNg

I read that there are bolts holding the fitting in place that can be used as bonding points to the rest of the boat, but on inspection of the fitting from inside the battery compartment I don't see any screws or bolts to receive a bonding wire. It looks like my fitting uses a single large (4" ?) nut to fasten the fitting to the boat.

https://share.icloud.com/photos/0ugNxXO ... Bl-A39YXEg

My question is how might I bond that fitting? I'm thinking of cleaning the threads, then wrap copper wire around the threaded portion of the fitting a couple of times and fasten that tightly in place on the threads using a hose clamp and finally attach the end of the copper wire using a floating fastener (nut and bolt) to a green bonding wire routed to the bonding bus bar.

There is no water intrusion occurring around the fitting and I think a bit of 4200 or Life Caulk will plug that external hole well enough to get more years out of the fitting provided I bond it well.

All comments welcome. Gary

 

[knotflying]

Your setup will not cause a catastrophic failure like the 29's. It would take quite a bit of corrosion to deteriorate the entire unit. On the 29's there are thru bolts holding the unit to the hull and once they get compromised the only thing holding things together is the caulk. I never had a corrosion issue on my R-27. Perhaps my persistent washing and waxing helped. If I were to use a bonding method I would fasten a stainless clamp around the threads not covered by the exhaust hose and then attach a bonding wire to the strap sticking out of the clamp. I would drill a hole through the strap and then use a screw with washers with a ring terminal fastened to the wire. I would then spray everything with corrosion block or apply some dialectic grease to the connection.

 

[BB marine]

You actually have a better exhaust through hull exhaust port compared to the through bolted exhaust port . I don't think you are going to have a water leak with that set up. I would still want that through hull protected by bonding. My solution would be to have a small stainless plate tab welded to a hose clamp. Before welding the tab, drill and and use a 10/32 tap so a 10/32 machine screw can be theaded to the plate to hold the bonding wire. Clean the OD of the threaded through hull fitting so a clean contact can be achieved. The area that you will tighten the hose clamp should have a thin layer of anti corrosive grease applied, then clamp the hose clamp tight. Attach the bonding wire to the welded tab. Apply a small amount of grease at this location too. With a VOA meter set at lowest ohm setting touch the red lead to the boats bonding buss strip and the black lead to the exhaust though hull ( do not touch the hose clamp with lead). You should see under 1 ohm. If you do the through hull is bonded correctly. Now check from the exhaust though hull fitting to another accessible bonded component, Rudder, swim tab support, sea strainer...... The reading should be under 1 ohm.

This would be a good time to check all accessible components bonded.

 

[GaylesFaerie]

Thank you both for your solutions that confirm I was heading in the right compass direction. Your suggestions now give me a true rhumb line for a fix. I have questions on grease though. I have di-electric grease (non-conductive), a conductive grease, and also silicone grease. Would all 3 quality as anti-corrosion grease? Does it make sense to also put conductive grease between the hose clamp and the exhaust port threads?

Thanks again and much appreciated. One has to love this website, and more so, the people who habit it and give so freely of their time and detailed knowledge. Gary

 

[dbsea]

I wondered about this on my 2016 C30-CB, after a warning during the haulout from my surveyor that he had seen this issue on other Cutwaters / RT's. I just looked through my photos from the survey and thankfully mine has been bonded to the electrical system, either by Cutwater or one of the previous owners. Also zero signs of rust on any bolts! phew...

 

[knotflying]

Thank you both for your solutions that confirm I was heading in the right compass direction. Your suggestions now give me a true rhumb line for a fix. I have questions on grease though. I have di-electric grease (non-conductive), a conductive grease, and also silicone grease. Would all 3 quality as anti-corrosion grease? Does it make sense to also put conductive grease between the hose clamp and the exhaust port threads?

Thanks again and much appreciated. One has to love this website, and more so, the people who habit it and give so freely of their time and detailed knowledge. Gary

I prefer corrosion block. O would clean the exhaust fitting as best as possible and apply some corrosion block and then the clamp and then apply once everything is connected.

 

[GaylesFaerie]

The weather warmed up and I finally got the exhaust fitting bonded. Here are a few pics of the approach I took that may help others faced with the same task. Had to remove the batteries to get some elbow room and lighting. Wire brushed the threads on the fitting as best I could, cleaned up all the debris, drilled a hole in the hose clamp end, applied a small amount of conductive grease around the fitting and on the surface of the hose clamp, fastened the clamp, fastened 8 AWG Ancor wire to the clamp and routed it to the bonding bus, and finally sprayed the clamp and wire fitting down with T-9. The Ohm test per BB's advice gave me a good tone and showed 0.1 Ohms with the red lead on the bonding bus and the black lead on the large exhaust fitting nut.

Cleaned fitting:
https://share.icloud.com/photos/0d0MwOA ... mJuqubM_9Q

Drilled clamp:
https://share.icloud.com/photos/001udIY ... wu-JyqK6Fw

Clamp fastened:
https://share.icloud.com/photos/0d654R7 ... 0cV0dpOsMQ

Bonding wire fastened:
https://share.icloud.com/photos/0f8ndBM ... dux-cCUD4A

On the outside of the fitting where I found the corrosion, I simply taped off a section exposing about a 2 cm x 1 cm rectangle containing the small hole on the flat surface of the fitting and filled it with 4200.

Thanks again everyone. Gary

 

[bluestreak]

We had the same problem on our 2016 R-27 classic.
Exhaust port material was almost nonexistent from corrosion.
Boat is in Anacortes, WA