Sunday, January 31, 2010

Rube Goldberg Prop Puller Version 2.1 a Success!

Isabella - Galapagos - Ecuador

Yesterday Bill and I hit the water early with version 1.0 that had been fabricated Friday afternoon. We were just loading things up when our first breakage occurred. We had borrowed a 3/4" drive breaker bar, 3/4" to 1/2" adapter, and 15/16" socket with 1/2" drive from Dave on Soggy Paws as the adjustable wrench was going to strip the head of our jacking bolt. Unfortunately, the 1/2" nipple of the adapter broke clean off. It looks like it may have had some cracks before as there was some corrosion in there, but it still gives you an idea of the load we are creating with our 5' long lever arm. We got out of the water and headed ashore to look for alternatives at the hardware store.

We bought ourselves a 1/2" drive breaker bar and got back to the boat and into the water (this time donning wetsuits as we were getting pretty chilled after 30 minutes or so). The new breaker bar held fine, but I noticed some weird popping coming from the bolt. It turned out we were galling the threads. Galling is basically caused when two hard metals have too much friction between them and you end up rolling up little bits of metal in the thread. To say the least it ruins the thread of at lease one part and made getting the damaged bolt out quite difficul. We did have a spare bolt, but the nutthread was too damaged to reuse...back to shore for another late afternoon welder run.

By 5:30 we had our Rube Goldberg Propeller Puller V 2.0 in hand with a larger diameter nut and bolt welded to the plate. We found a 1-1/4" socket to fit the new 3/4" bolt and we were ready to go for this morning. We got started at about 9:30 this morning having used High Molybdenum Grease (used in rigging terminals to prevent galling due to its very high bearing strength). About 30 minutes later we had sheared the 3/4" diameter jacking bolt. We realized that the bolt may have been slightly annealed, weakening it as it was used to align the bolt during welding of the nut, so we headed back ashore to get the broken bolt removed so we could try our spare. While there we also picked up a similar propeller puller that the welder's partner had in his tool bin. It had a slightly larger diameter jacking bolt, but otherwise was fairly similar. Still, we wanted to give our unit a try as we will have it in our tool kit in the future, so we hooked up version 2.1 with a new, non-annealed jacking screw and about 10 minutes later we heard a large pop as the prop finally broke free of the tapered shaft.

We screwed in the jacking screw as far as we could to start to pull the prop off the rest of the way which could now be done with just the short breaker bar. A future revision to the tool will be to thread the remainder of the jacking screw to make removal a bit easier. To get the prop the rest of the way off, I pulled tugged and tapped with a hammer to work it off the shaft while Bill made sure we didn't loose the key. We had tied it to the boat, but I didn't want it to hit the bottom, or swing wildly, so I held onto the prop and sank like a stone with the 40ish lb prop in my hands. I waited on the bottom while Bill pulled off his gear and climbed aboard to pull the prop up onto the transom. We then took a break for lunch and a bit of celebration.

After lunch we started the process of trying to dismantle the propeller to inspect the bearings. This unfortunately hasn't progressed well. There are grease caps that screw into the blades and cover the nut and locking screw that hold the blades to the hub. These are proving VERY difficult to remove so after trying some more Rube Goldberg contraptions we called it a day and plan to call Brunton in England in the morning (Monday) to get some advise. Then we will likely head back to Pachi's (welder) to borrow a large vise and make up a better spanner for the the cap pin holes.

So we are not out of the woods yet, but we still accomplished something few cruisers ever will, which is removing your propeller in the water on a VERY remote island.

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