Friday, January 27, 2023

Revolutionary Propeller Design


 

I have talked about propellers and propeller design before, here and here.  In fact I proposed a new propeller design with a circular rim, but this revolutionary design  takes it a huge step further.  

Called a 'toroidal propeller', this design claims to eliminate tip vortices, consequently delivering a 20% increase in efficiency, and a huge decrease in noise.  Tho the article seems to be more focused on the application of the design to drone propellers (because drones and quadracopters are new, hip, and cool), it does mention marine applications.

And speaking of marine applications, when you are below decks and a boat passes by, you are certain to hear him - his prop makes a lot of noise in the water, and it is conveyed to your hull where you hear it.  Submarines have spent fortunes trying to eliminate prop noise because this noise carries a long way in the water and frustrates stealthy operation.  Expect these props to be refitted to all current and new submarines.

For now, if you want one for your boat, expect to pay approximately 10X the cost of a conventional prop, but this cost should come down significantly over the next few years, as the design gets adopted widely.


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Wednesday, July 13, 2022

Bullet-proof? Not hardly

 

Not even finger-proof

Well, now I have the answer.  

Remember way back, when I discussed Lexan vs. Plexiglass and postulated that polycarbonate (trade name: Lexan) would lose its properties when exposed to the sun over time? 

Well here is one of my polycarbonate storm windows, after 6 years exposure only in the winter, on the sunny side of Eolian in her slip.  I literally put my finger thru it when gently lifting it out of the slot today.  It is as fragile as a dry, dead leaf.  So much for 'bullet proof'!  And further, please look closely and note how the polycarbonate has crazed and browned up nicely where the port gasket did not protect it from the sun.

If you are changing/installing ports or hatches on your boat, specify acrylic (trade name: Plexiglass) instead of polycarbonate!  This is most important on hatches, where the possibility of someone standing on the hatch makes the choice of material a safety issue.

(One of the benefits of owning the same boat over a long time is the ability to do longitudinal studies like this.)


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Thursday, June 16, 2022

Back on the Dock

Well, here we are back on the dock in Anacortes.

The  last few days were great.  The forcasted blow did indeed come, but in Blind Bay, where the anchor loves the bottom and with 100' of 3/8" chain out in 25' of water, we were more than secure and slept soundly.

There were no more sunset moments from Blind Bay (view to the west is obscured by the protecting ramparts of the island), but it was wonderfully quiet.  Most of the boats in the bay were doing what we were doing... peacefully spending days in the Islands at anchor.  A few left and a few came in, but the balance stayed at about 10  transient boats - far below the ridiculous total of 51 boats at the height of the COVID Canadian border closure.

I puttered around working on the inevitable boat problems, an overhead light that had quit working, water pump that seemed to be continuously inhaling air, etc.  But mostly we read books on our Kindles.

And a joy...  with my phone acting as a hotspot, we were able to stream videos from Roku at anchor, so that took care of the evenings, in spades.  What a luxury!

So this afternoon we are back at the dock in Anacortes, cleaning up the boat and restocking it for the next adventure... Jane just arrived with a huge batch of groceries for that next outing - I need to go help her get them aboard and stowed... and then to make the bed...


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Sunday, June 12, 2022

Finally!

This has been the coldest, wettest spring in decades here in the PNW.  There has been absolutely no incentive to go out and sit in the cold rain.

Until now.

We are finally (!) off the dock, anchored out in the San Juan Islands in our favorite anchorage: Blind Bay.  But lest you think the rains had stopped... no.  One of our days out here (day 3) was spent at anchor, listening to the rain pelt down on the deck... for 24 straight, relentless hours.  But that day was bookended by two wonderful sunny days (2, and 4), so it was OK...  we stayed below and read, and cooked.  Speaking of cooking...  over the years our time on the water has been favored with increasingly great meals!  I'm glad our onboard scale has a dead battery.

On day 4, we hoisted anchor...  but wait.  There's a story there too.  Part of our prep for leaving the dock is to run the anchor windlass, to make sure the relay contacts or commutator haven't corroded up over the winter.  We've had to hoist the anchor (66 lb Bruce, 300' 3/8" chain) by hand, once.  And we intend for that to never happen again, thus the test run.  Now, our windlass has a counter on it that shows how many feet of chain have been let out.  When I tested it, I just lifted the chain off the wildcat, meaning that the counter showed chain overboard even tho there wasn't any.  And I forgot to reset the counter at the end of the test.  So, when Jane put the anchor down in Blind Bay the first time, she was baffled by the counter reading.  She was pretty sure that she had put down more than 100', but the counter only showed 25'.  So we put down more, just to be safe.  Hoisting and flaking all that chain into the chain locker was quite the chore...  hopefully that will be one of those lessons that will stick.

Experience is the best teacher,
but she gives the lesson after the test.

So, continuing with day 4, we hoisted anchor and went to Parks Bay on the south side of Shaw Island.  We call this bay "Sunset Bay" for obvious reasons:

We spent two idyllic days in Parks Bay, but the holding there isn't as ideal as it is in Blind Bay, being that it shoals steeply going to the back of the harbor, and to add to the fun, there are a number of abandoned pilings on the bottom in part of the ideal anchorage.  Meaning that Parks Bay is a great place to visit, but not one in which to weather a blow.

So, this morning we hoisted anchor again (just the intended amount...) and moved back to Blind Bay in anticipation of tonight's blow.  Rain and wind (16-22 kt) are expected tonight, and Blind Bay's gently sloping hard mud bottom is ideal holding for our Bruce.

We'll check in again later.

 


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