S/V Hello World's Travel Log

max prop

(This post is chock full of boat nerdery. If that's not your thing, feel free to move on. It won't hurt my feelings. No really, I'm fine. There's just something in my eye, that's all. I'm fine. I'M FINE.)

Like all things Italian, the Max Prop is beautiful, complicated and a real pain in the ass. Unlike a fixed propeller which is a monolithic hunk of bronze, the max prop feathers it's blades while sailing to reduce drag and when under motor re-aligns the blades depending on whether you are in forward or reverse to give you the optimal bite in the water. This is accomplished via some engineering witchcraft of intermeshing gears and parts. Re-assembling a max prop is like re-assembling a transmission. From the space shuttle.

Fortunately, the good folks at PYI - who distribute Max Props - are located up in Lynnwood just north of us so I hauled the pieces of my prop up there in a bucket. I spent a half an hour talking with Fred who seems to genuinely enjoy educating people about this bit of equipment. The main reason for my visit was a part called the central cone gear that looked a bit worn, causing some play in the prop blades. Fred confirmed that it was a bit sketchy and went off to the bin of central cone gears he has laying around. After a few minutes, he resurfaced at the top of the bin with a slightly less used cone gear, plugged it back in to the prop and Bob's yer uncle! Good as new. Well, almost. It'll probably need some re-conditioning in the upcoming years but nothing we need to get really worried about. His total charge: nada. These guys at PYI are nothing short of wicked cool. I'm very impressed after this visit.

Here's some tips Fred gave me that I'll pass on to y'all. I know you're all wondering what you're going to do with your max prop. Don't worry, I gotcha covered.

1. When pulling the Max Prop off the prop shaft, before you do anything else, feather the blades and then draw a straight line on the outside of the prop from the forward end up onto the body of the prop itself (say, near the bolts holding the two outer body halves in place). This will tell you what the prop is currently aligned to. You need to know this alignment when you re-install the prop. Skipping this step sucks. Ask me how I know.

2. When pulling the hub off the prop shaft, expect to use alot of force. Our Max Prop was previously installed by Zeus, God of Thunder and Lightning and Really Really Tight Prop Installs. I have a tendency to be mechanically insensitive (my motto: Why Use a Scalpel When I Got Me This Here Backhoe?!) so I bought a gorilla of a gear puller to get this thing off and even I started to get concerned with the amount of force I was using to remove it. After tossing all common sense aside and throwing some anger into the gear puller, the max prop hub came off in an explosion of bronze and tools. Which leads us to tip #3:

3. Loosen the nut on the end of the prop shaft but don't back it all the way off. Apparently, when these things come off they have a bit of energy stored up. Keeping the nut on the prop will prevent the explosion you'll otherwise create in tip #2.

4. When re-installing the prop, slide the hub on the shaft without the key. Mark a line on the shaft how far up the shaft the prop went. Pull it off, put the key in place and re-install the hub. If the hub doesn't slide up to the line you drew, you need to file down the key until it does.

5. A little bit of my advice. Write down the X-mark and Y-mark letters in your maintenance log. Somewhere, down the line you're going to want to remove and re-install and having these settings handy is key to get back to your original pitch.

In the feathered position, ready for sailing.

In the forward position, ready for motoring.

In the reverse position, ready for motoring backwards.

No comments: