NOTES OF AN ELECTRIC SAILOR: Harbor Test 2013 Part One

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Back in early June I had just splashed BIANKA but, had to wait for the boatyard to step the mast. Since I had nothing else pressing on board I thought I would take the opportunity to do some testing of the electric propulsion system both without and with the mast installed. So that's what I did. I made several runs between two buoys in the harbor that were 450 yards apart. I did a similar test back in the fall of 2011. Though I conducted these tests with a cleaner bottom since the boat had recently been splashed.

The mast on my 30 foot Nonsuch weighs about 300 lbs which is pretty heavy compared to a lot of other boats the same size. So I was curious to see what effect the mast weight might have on the boats performance. Like the test I did in 2011 I made two passes between the buoys. One going east and then turning around and making another pass going west. They were made at various current draws from the 48 volt battery bank of 10, 20, 30, 40 and 50 amps. The two passes were averaged to take into account any tidal current pluses and minus to the speed.
Here is the graph comparing the speed both with and without the mast on board:

As you can see there is a slight difference at the low end and upper end of the speed data. But, only about a  quarter of a knot or so. The sweet spot seems to be right around 3 to 4 knot range where both graphs are pretty close. Out of curosity I took the data from the Harbor Test of fall 2011 and added it to the above graph's data:

What's interesting to note is that the 2011 test data was taken at the end of the season just before I pulled the boat for the winter. The hull and prop had not been cleaned for probably a month or more:

So that growth seemed to have had some effect on that test data. 

WHAT WORKS: Plastic bag on the prop.

That's The Bag I'm In -Fred Neil

Once again I was away from the BIANKA for an extended period of time. One month or so. I wanted to avoid the marine growth on the prop the boat experienced earlier this summer as you can see below:

So this time I decided to do an experiment of something I had heard about from other sailors. Before I left the boat I covered the prop with a plastic bag. One of those that you get when you buy something in supermarkets etc... I tied it around the prop and came back a month later and it looked like this:

I dove under the boat just using my snorkel and quickly removed the bag from the prop:



I must say it worked pretty good  in keeping the prop clean of the major marine growth and only had a barnacle or two on the blades:

So if you are going to away for an extended time covering the prop with a plastic bag does work pretty good in keeping marine growth off the prop.

PROP TALK

As I mentioned I was away from the boat for over a month thanks to some freelance work that came my way. It will certainly help pay some of the boat expenses. Unfortunately, it was in the wicked city of Washington DC two hundred and fifty miles away from the boat and so I was not able check on the boat. I was expecting the worse and hoping for the best when I finally returned. I was hoping that I would not greeted by a sail cover full of bird poo like I was last fall after being away for three weeks. I had deliberately kept the lines securing the boom a little loose hoping that it's movement would discourage the birds from landing there for long. This plan seemed to work or maybe I was just lucky.

The other area of the boat I expected to have to clean was the prop. Unfortunately, this had met my expectations for a mess. I don't paint my prop with any anti fouling coating as I try to keep metallic interactions to a minimum. I also don't mind diving down below to clean the prop with a paint scrapper on occasion. As you can see in this video below the sponges and barnacles can grow pretty rapidly on a prop that has not turned in over a month. Even a small blackfish seems to like hanging out there. Interesting that the two zinc are relatively clean:



After seeing the job that awaited me I decided to see if I could minimize the cleaning and scrapping I would need to do by using the torque of my electric propulsion system to knock off what marine growth I could. Turning the prop with an EP system for this function is a lot easier than with a diesel engine. One of the nice benefits of electric propulsion is there is no need to warm an EP system up. You just turn the key and run the  throttle back and forth for under a minute. It's not really healthy to turn fire up a diesel and  turn it on and off for such a short time. Electric Propulsion does not care if you just need it for a short burst of power to clear the prop. The video below shows how  my little forward and reverse propulsion routine cleaned away a lot of the marine growth:



I still had to dive down and clean some of the barnacles of with my handy dandy five in one paint scrapper tool. The video below shows what it looked like after a quick cleaning:



Much better but, I found the blade on my scraper blade was a little wobbly due to rust finally having it's way. So it looks like it's time to replace it with a new one.

Perhaps one made from stainless steel next time. So it won't rust out and I can scrap the prop blades with a little more force next time.