[Sentoa] Heat exchanger

Tue Sep 15 15:10:22 EDT 2009

Bob, 

Many thanks. I think there has been an increase in the erosion rate of my main zinc since an older sailboat moved to a slip across the main dock. Looks like I need a new tool. Will use your note as justification if the admiral asks me to explain the expenditure. 

Following that thread, a few weeks ago while browsing a tool retailer's shelves I found a tool for removing hoses that have "set" in place. Looks like a screw driver with two 90 degree bends, the one closest to the end also slightly bent off the line of the main shaft, say 10 degrees. Made removal of the heat exchanger much much easier. I paid $1.99 for it and it's now my best friend. 

J 
----- Original Message ----- 
From: bevins2kellie at aol.com 
To: sentoa at lists.samurai.com 
Sent: Tuesday, September 15, 2009 10:28:40 AM (GMT-0800) Auto-Detected 
Subject: Re: [Sentoa] Heat exchanger 

A quick check for stray current is to place a clamp on ampmeter around your power cord. The correct reading is 0.0. 
i.e. the current coming in thru your power cord is also returning out the neutral. If you read anything but 0.0 then not all current coming in thru the shore power is returning thru the shore power neutral. The stray current is returning thru your hardware and not the wire. This stray current will quickly eat your zincs. 

Also check the vessels moored near you....one of them could have a leak and the current from their vessel may be returning thru your boat. 

Bob 
Sidekick 32-009 
Anacortes, Wa 

-----Original Message----- 
From: tugs4me at comcast.net 
To: South East Nordic Tugs Owners' Association (SENTOA) <sentoa at lists.samurai.com> 
Sent: Mon, Sep 14, 2009 6:26 pm 
Subject: [Sentoa] Heat exchanger 

Fellow tuggers, 

This is a "heads up" and a request for information relating to heat exchanger experiences. Saturday morning in pre-departure check before leaving with several other tugs for Half Moon Bay, I found salt crystals on the tool chest and damp towels and boxes in my "junk box" in the engine room on the starboard side equipment deck just forward of the house battery bank. In addition the bilge had about 1 1/2 inches of water though I try to keep it dry as a bone. About a week ago I had about an hour run to the fuel dock and all seemed well when I returned but I did not check the engine room or bilge after I tied up. 

Just before departure time I started the main diesel, lifted the hatch and saw a 1/8" inch stream of (salt) water arcing across the engine room. With assistance of Cal Robie ( EMIKO) I went into the engine room and Cal restarted the main which immediately exhibited a "fountain" near the aft end of the heat exchanger just below the elbow leading to the exhaust elbow. ( I carry a number of hose clamps up to about 10" diameter on the assumtion that a couple hose clamps and duct tape will provide an emergency patch on a hose but this perforation was directly below the elbow, thereby precluding that potential temporary repair had I needed it to get home.) I checked the zinc and found about 60% remaining. So, instead of a nice trip down the coast I had an opportunity to enjoy draining the coolant as well as draining the aftercooler to replace those zincs, upper about 70% left, the lower about 30%, then removing the heat exchanger and finally cleaning u p salt water residue and sponging 3-4 gallons of salt water from the bilge. 

Will meet with Chuck's Marine in the morning to have him inspect the heat exchanger to see if it can be repaired and to determine if it failed due to a defect or electrolysis. Meanwhile, I mixed a major gin and tonic and contacted the Cummins distributor for price and availability of a new Part #4020101. Price is $1,101 but not in stock locally or at the factory. A little bing search found it available at inetmarine.com for $591.54 plus shipping and handling. (I asked what it cost to just ship it and not handle it.) They have it built by Seakamp Engineering in Bellingham, WA and I was assured it will be fabricated and shipped within about 2-3 days. I did order the racing model upgrade so SFBANTA members you are forewarned, soon there will be a new Alpha male on the Bay. 

Here's the puzzle. I give myself an A- to B+ overall on zinc anode maintenance. About 2 1/2 years ago I had to replace one of the Marine Air reverse cycle units due to a failure the tech said could have been caused by electrolysis. There are no replaceable zincs on the A/C units. I'm suspecting a "stray current" issue and will start serious work to determine if that is my problem. Would welcome any comments or advice from anyone who may have experienced a similar problem. When I say "any" advice, I will not be receptive to any response including words such as idiot, dummy, meathead, etc. You get the picture. A preface of Your Excellence will guarantee my favorable acceptance and review. 

James Moore 
RILEY 37085 -2003 model. 

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