Bearospace Sloop EMMA - Page 6 - RC Groups
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Jan 31, 2018, 09:43 AM
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Looking forward to seeing your video on your Emma winch system. Are there two types of winch servo pulleys, one that transfers the line from one groove to the next groove on the pulley and one that is more or less a continuous line that wraps around a single groove on the pulley? When using a sail arm, if you run the line threw a pulley on the sail arm and tie off one end to somewhere near where the other end of the line goes threw the deck and connects to the sail, does that double the line pull distance for the servo? I've seen where some people do use a pulley on the sail arm.
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Feb 01, 2018, 05:14 PM
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I found a couple of good web sites that explain some of the pro's and con's of sail arms vs winch setups. I believe that what I was referring to with the pulley on the sail arm is a "double purchase" setup that will almost double the amount of line pull length . Good websites https://www.theamya.org/hints/sailservo.php http://ec12.org/disc/viewtopic.php?f=2&t=1528
Feb 02, 2018, 02:41 AM
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robcrusoe's Avatar
Stephen

Your sites are good, explains a lot.

However you don't get twice the sheet travel for free. The effective power of the winch is reduced by 50%, but only noticeably under load.

In light airs it will look great, but when pushing hard through mounting seas and strengthening wind, very slow boom movement.

When my Maxine is fully operational I'll do a video of the two boats operating their respective winches. Bit hard to do on the water but on a stand I'll use weights to show what I'm on about.

In the standard Emma the arm winch is located centrally which is normal. But if you want a really long arm that will move unimpeded as much as possible, you could mount the arm servo right over to one side with the arm going almost to the other side. with the battery on the other side lateral balance should be reasonable.

But I wouldn't recommend anyone spending too much time on winch design, the standard Emma setup works really well as it is.

One of the main reasons for making a second Emma is to be able to test what happens with fully available boom travel. Up to now the standard rig seems to be achieving most of what is needed.
Have a look at this test sailing video I made yesterday in stronger conditions, in particular constant wavelets and occasional strong gusts.

The video is just edited to the better bits, not intended as a spiffy production. It also show show much water c an come over the bow.

Anna crusoe 2 (4 min 2 sec)
Last edited by robcrusoe; Feb 02, 2018 at 02:49 AM.
Feb 02, 2018, 03:48 PM
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another double ender


Looks half Emma, half Irene
Feb 02, 2018, 04:58 PM
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Zbip57's Avatar
Quote:
Originally Posted by g'n's
Looks half Emma, half Irene
This one even more.

Pinky Schooner (4 min 24 sec)
Feb 14, 2018, 03:16 AM
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robcrusoe's Avatar

Does an Emma ever get water over, or in her?


If you sail in weather like we had today. Yes, and yes.

To give you some idea of how and why..

Anna in the wet stuff (3 min 28 sec)
Feb 14, 2018, 03:23 AM
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robcrusoe's Avatar

And did the others see her


Not many got up close, that's for sure.

Rc sloop Anna with the hammer down (4 min 43 sec)


Wind was generally 20 - 30 knots with a few even harder gusts.. Other boats found it either impossible to sail or, difficult.

Overall she took on about one cup of water in 3 hours sailing. How? I don't really know but it was to be expected not a problem so long as it gets dried right out afterwards. You can see how the deck cops a lot. The waves very pretty big for our lake. See if you can spot her "planing".

Will she take even heavier conditions.? . Possibly.
Feb 14, 2018, 03:26 AM
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robcrusoe's Avatar

Study of an Emma moving through water.


I film is slow motion for this, it lets you see just how the two main elements interact with each other.

This is just a minute's duration of selected clips..

Anna SloMo (1 min 13 sec)
Feb 14, 2018, 08:02 AM
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Nice !! She took the waves very well for that kind of wind and waves. Do you have the deck on your Emma glued down or removable?
Feb 14, 2018, 03:52 PM
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robcrusoe's Avatar
All 3 decks are screwed down to 14 pine blocks around the perimeter. These must be stainless steel (or brass, if you can find any of a suitable size) but don't need to be very big.
I chose this method for my first boat, the Molly b, as I just couldn't bear the thought that as soon as the glue dried, and I test sailed it, I'd find I'd done something terribly wrong (happens) or more likely, eventual maintenance on waterproofing or the winch system. Truthfully, I can't see any of that becoming necessary, but it is just comforting to know the deck can come off.
But, no matter how close a fit ALL the way around you make the deck section (mine have improved with practice) it is very likely that in wet conditions, like yesterday, considerable water will get in. I must confess that in my boats I have thought the drain holes in the bulkheads unnecessary. Turns out they would indeed be helpful to have the water ingress collect at the lowest point, the bilge area? So, I employ a large plastic syringe with a length of plastic tuber attach and simply suck it up. Then the boat is left in the sunny breeze fort a few hours to be totally dried out. I intend to put those drain holes into the sloop Maxine as she is still under construction.
However, it is necessary to employ some sort of sealant in that seam between the deck and the hull. First, I lay masking tape along the deck edge and vertically on the hull surface where the two meets. then, using my fingers, squeeze acrylic based gap sealer in (take so very little and only needs a skin, really) then when it cures enough, wipe a damp rag Over it to smooth it flat (you find it slightly recessed, but that's OK0. then simply remove the masking tape which has kept the sealant off the paintwork.
Should you need to remove the decking it would only require a careful run around of a thin blade to enable you to carefully pry the deck off. That is also why you only want to use the minimum of sealant; gap filler is a surprisingly good adhesive if used in a heavy application. I know as I set up an experiment early on where I used two pieces of scrap ply, lain a thick bead of whatever compound I was testing for bulkhead fixing, left cure for a week and then tested each to destruction. The good stuff, like Sikaflex liquid nails tore the top ply away under destructive testing. But the gap filler also did an amazing job, if not quite so "attached".
Sorry for the lengthy reply, everything is relative, though.


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