Friday, December 31, 2010

Slaving away in the engine room

We haven’t done it for a couple of years now but for several years we spent the September long weekend on the Churchill River with our good friends Doug and Joanne.  Doug always referred to his role as “slaving away in the engine room” and the phrase has stuck in our vocabulary.

With all due respect to Doug, the engine room duties on a 16 foot Lund were relatively benign.  Occasionally he had to pull twice on the starting cord or maybe pump the primer bulb a few extra times after we switched tanks.  But he did a fine job and he did it with style as the picture above attests.  He’s already volunteered for engine room duty on Gray Hawk but I’m not sure he knows what he’s getting into.

In the last two days I’ve changed the fluids in both propulsion engines.  The genset in the middle of the picture above is still untouched but it’s next on my hit list.  I waited to do the fluid changes until some parts arrived from the east coast.  If you look closely in the picture you can see an engine oil filter sticking out on the port engine (the one on the right in the picture).  Somebody has changed the original canister and element filter to a spin-on type on both engines.  When they did that they mounted the filter on the starboard side in such a manner that it was rubbing against a raw water cooling hose.  That and some other leakage around the raw water lines made me think that I should just change all the raw water hoses so I was waiting for those parts to arrive before I tore into the engines.

When we attended the working boat show in November I got introduced to AWAB hose clamps.  They are obscenely expensive but I think they are actually a significantly better clamp than the regular old gear clamp.  They are certainly much heavier construction and the fact that the inner surface is completely smooth seems to me to make sense that they would clamp more evenly and securely.  And it’s only money, right?  So now every one of those hoses that is exposed to raw water has a clamp on it that costs in the neighbourhood of 4 bux per.  (I found a cheaper source than West Marine who want $5.94 per)

During the coolant change I discovered that the zincs on the oil coolers and the raw water cooler were pretty well completely consumed.  For those of you who don’t know, salt water boating depends in large part on zinc smelting.  I hope there is a good worldwide supply of zinc, there must be because it is relatively cheap.  There must be literally hundreds of thousands of tonnes of zinc lying on the ocean floor, if not more than that. 

The reason zinc is so important is something called the noble hierarchy of metals.  It’s a subject for a week long seminar which I am in no way qualified to teach but the five minute explanation follows.  When you immerse different metals in salt water they behave like a giant battery.  I don’t really understand what goes on inside a lead acid battery either but in layman terms electricity causes the lead to go into solution.  When it comes back out of solution it releases electrical energy which you can then use to start your car.  Similarly on a boat differences in electrical potential can cause your hull fittings to go into solution in the ocean.  This is bad.  Particularly so if its an important fitting like your prop shaft or your rudder or some underwater through hull that decides to dissolve.  And this is not some abstract problem.  There are abundant stories of hoses falling off the sides of hulls after the through hull dissolved because the owner did something stupid.

The metal part that gets dissolved is called the anode.  Some metals are much more susceptible to being dissolved.  Those metals are termed “less noble”.  Conversely some metals are much less likely to be harmed and they are termed “more noble”.  Zinc happens to be way down on the nobility pecking order. 

The reason zinc is so important on the boat is that galvanic nobility is like the schoolyard pecking order.  The biggest, toughest kid picks on the next toughest kid and so on down to you cowering in the corner waiting to be picked last for soccer.  Zinc is the kid in the corner and as long as the zinc is around all the other metals have somebody to pick on so they don’t get dissolved.  Which is why it is imperative that a boat in salt water have lots of zinc hanging on it.  

If you look back to the photos from the haulout you might be able to see the big zinc plates hanging underwater on the port side and on the transom.  In theory all of those plates are bonded with a low resistance path to all metal on the boat.  That means wires from every through hull to a common bonding strip as well as wires from the rudder shafts, prop shafts, engine blocks, etc etc.  In practice wires have resistance so nothing is perfect and you should have extra zinc wherever any metal touches salt water which is why the pencil zincs are located directly in the oil coolers and heat exchangers.  If you don’t have adequate protection in a heat exchanger for example the copper coils can get pinholes which would let salt water into the oil.  That would be really bad so we won’t go there.

Last night I phoned Gray Hawk’s two immediate previous owners.  George, the immediately preceding owner, is coming for a visit today but I think the owner prior to him will be more of a mechanical resource.  We must have talked for an hour last night and I’m not a phone talkative kind of guy.  He did a lot of work on the boat and he still is completely in love with it.  He has a 53 Defever now but he told me he would still prefer to have this one if his wife would let him.  Evidently she likes to entertain large crowds and I can see where more than about 6 people onboard Gray Hawk would get crowded fast.

Yesterday I ordered a second deck box from Costco.  We ordered the first one about a week ago and were absolutely delighted with it when it arrived.  They didn’t have one in the store so we weren’t 100% sure what we were getting but it is perfect for our intended use.  Originally we thought we would put it across the back of the aft deck but we like it so much that now that we think we want one on each side of the aft deck.  We’ve got so much in transit now that I’ve pretty well completely lost track of what is coming and from where. 

1 comment:

Anonymous said...

Hello Bobofthenorth,

Fellow DeFever owner and TrawlerForum member here.

I’ve read more than a few boat blogs over the years and I must say yours is among the best.

I really like your attitude. I really enjoyed the PayPal post.

I’m thinking of starting a thread at TF calling attention to your blog. If you rather I didn’t then say so.

I can be reached - mike At mvfullstep dot kom

Wishing you many years of cruising on your DeFever,

I post as - Mike - at TF.

Merritt Island, FL.
DeFever 40 PassageMaker by Jensen Marine