Thursday, March 14, 2024

While I wait

With the injection pump at Diesels Fuel Injection Services for a rebuild (should be completed next week) and the weather still a bit too cold to work on the boat itself, I decided to tackle rebuilding the propeller. With previous boats I've owned, I've only had 2 blade fixed props, but Velorum came with a MaxProp classic which is a 3 blade automatic feathering prop.  I've seen them before on other boats at the yard, but never really paid attention or gave them a second look.  I'm not convinced that a slowish cruising boat needs a feathering prop but I'm sure I will appreciate the additional power a 3 blade will deliver and not be concerned with the drag that a fixed 3 blade would have on performance.

Anyway, the prop was in a box in several pieces and covered in grease and barnacles, so I wanted to clean it up to assess if it needed to be serviced.  I started by degreasing all the parts and doing a rough scrub to get as much old marine growth off as I could.  

After the first round, it really didn't look any better than when I started except there was less grease. 'Less' is the keyword here because even the industrial strength grease remover I was using didn't seem to do much other than spread it around.  Close to a roll of paper towels and more degreaser finally proved effective and I was finally able to handle the parts without my hands turning black.  

Next, I tried a brass wire brush to get the rest of the barnacles off and finally resorted to a wire wheel, but it still looked pretty sad.  After a little online research, I picked up a gallon of vinager and soaked all the parts in a bucket overnight.  That seemed to loosen up the remaining barnacle 'roots' and I was finally down to a mottled brownish bronze finish. 

I felt like I was finally making some progress (albeit slow). My wife suggested I use Bartenders Helper to get it shined up.  Apparently, it's a powdered form of oxalic acid with some sort of abrasive in it.  Once again, I'll admit my wife is brilliant, that stuff works great.  Just shake some on the part and scrub it with a wet sponge and it works wonders. After a few rounds of that stuff, it looked great (at least the pieces did).  

Now it was time to put it all back together and hope all the pieces were there.  I found that PYI Inc is the distributor and service center for MaxProp in addition to the very popular PSS dripless shaft seal (I'll be installing that once the engine is back in the boat).  They have a great site and even though the MaxProp Classic (the model I own) is discontinued, PYI still services them and sells parts.  I contacted the service department and they got back to me with all the info I needed along with a detailed pdf on assembly.  They even took the time to run Velorum (displacement), along with engine size, and transmission gear ratio to give me a recommended pitch setting for the prop.  

Putting it back together was pretty straightforward given how precise everything needs to be in order to have a smooth, balanced, and powerful propeller.  It's really a lovely piece of kit and the engineering is downright elegant. It's simplicity is deceiving, it really has a difficult job in a very unforgiving environment.  Once I got it back together for a test fit (once it goes back on the boat it will be stuffed with grease like a turkey), it looked amazing and operated smoothly.  I was told by support that it should have a tiny amount of play, but more than an 1/8" and I should think about a rebuild.  Fortunately, everything checked out and it's in remarkably good condition.  I don't know the history of this prop, but it should last me for some time as long as I keep the internals greased every year and don't back it over a rock :)


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