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Old Nov 30, 2010, 03:38 PM
Square-rigger
meatbomber's Avatar
Klatovy, Czech Republic
Joined Mar 2004
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Just a question, with the original Battery how much seatime did you get before there was a worry about running it flat ?
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Old Nov 30, 2010, 03:42 PM
Paratrooper
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Eubank Kentucky
Joined Nov 2007
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I was getting about 2 hours on days the winds were not too high but less than an hour on heavy wind days. I admit I have sailed this ship in some rough weather and I suspect that the tug on the braces and sheets was a higher drain to the battery, plus I have an additional servo for the cross over jibs and the gun servo.

This is going to increase range considerably.
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Old Dec 01, 2010, 05:52 AM
1915 Schooner Mariette
delaneyp's Avatar
Sydney, NSW, Australia
Joined Feb 2008
243 Posts
Hi Ray, it would be greatly appreciated if you could let us know what capacity your old single & new dual battery setups were/are (AH or mAH, etc).

The reason that I am interested is because my Mariette is a fore & aft schooner, the winches will be fighting some big direct loads most of the time (unlike a square rigger where there is some balance across the braces).

At the moment, I have 4 batteries installed :

- 2 x 2200 mAH 11.1V (3s) LiPo's diode-combined in parallel for the twin motors
- 1 x 2200 mAH 7.2V (2s) LiPo for the 2 x RMG sailwinches
- 1 x 2200 mAH 7.2V (2s) LiPo (with 6V regulator) for the Rx / rudder servo / jib servo.

From the sound of your experience, I might be better to go for more capacity on the sail winch battery ?

PS : Thanks for your posts / pics / vids - they keep my enthusiasm going !

I have finally finished planking the deck (644 individual pieces of 4mm x 1mm limewood), and am now working on the deckhouses).

Kind Regards,

Peter D.
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Old Dec 01, 2010, 10:06 AM
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DanL's Avatar
United States, MN, Brainerd
Joined Oct 2004
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Battery capacity

Peter,
The Mariette is absolutely beautiful.
Some thoughts on batteries for her:
Ray had one 7AH, 6V SLA (sealed lead acid). Syren has the same.
Syren has 12sq ft of sail and has been out as long as 4hrs on a single battery charge. High, shifting winds and frequent tacking -or attempts to tack ; ) - cut that time down. I'm guessing that Ray has almost 20 sq ft of sail, and his operating rigging has, by design choice, less mechanical advantage than mine. So his max run time on one 7AH battery is expected to be less.
He now has two 7AH in parallel - a total of 14AH. That should roughly double Surprise' sailing time.
The model Mariette, by estimation from the 8,000sq ft prototype sail area at your 1/18 scale, has approx. 25 sq ft of sail. That's a lot! I don't know the gearing in the RMG's or your operating mechanics, but if the gear ratio is high enough the reduction ratio will help hold the winch position (if it is just a drum winch winding the sheets directly) without the motors constantly working to do so. Still, I think you will need something in at least the range of 10AH or better.
Since the Mariette is big enough, why not use big, cheap lead acid batteries, low in the hull (rather than having batts mounted on the bottom of the hatch), for the AH capacity that you need - perhaps a single 10AH SLA. Or two smaller SLA's so they can be laid low in the hull. You likely can use the ballast weight. I'd rather use battery weight as inside-hull ballast than anything else. SLA's are cheap per AH, waterproof, low maintenance, safe and have a long life. One 7AH SLA weighs about 1.3kg (2.9lb) -a pretty small percentage of the total ballast requirement.
Hope this proves helpful (and I hope it's all somewhat correct....)
Cheers,
Dan
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Last edited by DanL; Dec 01, 2010 at 10:12 AM.
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Old Dec 01, 2010, 04:40 PM
Paratrooper
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Eubank Kentucky
Joined Nov 2007
873 Posts
G'day Peter--Dan has given you a whole lot more information than I actually have mental capital to possess. He is right that my rigging is closer to the kit configuration for the braces with some modifications as I learned what was involved in actually making this thing sail. My braces are connected to the yards at 5" from the mast while Dan's is connected as per the prototype at the end of the yards. All the forces on my rigging is obviously higher for the servo winches but with the additional battery power I think I can stay out longer. I will see how she does the next time we can get on the water.

Meanwhile I am trying to learn how to run this new 9 channel radio and when I get the hang of that I plan to install the receiver and start programming.

She'll be right mate!
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Old Dec 02, 2010, 06:06 AM
1915 Schooner Mariette
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Sydney, NSW, Australia
Joined Feb 2008
243 Posts
Dan & Ray, thanks for the quick & detailed replies. It sure looks like I am way underpowered for the 2 x RMG winches with only a 2.2 AH battery ! Extra batteries in parallel (located low in the hull beneath the existing hatch-mounted ones are a certainty) - I have 1.5kg of removable lead there, so it should be an easy fix. I am a bit inclined to stay with LiPo's as they are dirt cheap from Hobby King, & I have standardised on them for my planes (the devil you know, etc) !

The RMG's are hugely powerful - stall torque of 416 oz-in ! That's about 26lb of pull on the sheets with my drum setup. The stall current of the winches is 18A each - so if both winches were stalled, I'd get about 4 minutes of run time - not good !!

So the next step will be to find out just how much torque will be required of the winches as the wind speed increases & the heel angle increases. I have built a spreadsheet model that basically plots the wind speed against heel angle (based on righting moments of the hull CG & the bulb fin CG vs the wind force/speed acting on the centre of effort of the projected sail plan as the heel angle changes). I should be able to adapt this model to give me estimates of the sheeting forces (& hence winch torque) so that I can make an approximate guess at the current draw at max torque (hopefully a lot less than stall current !). If I de-rate this by 1/2 to account for periods less onerous reaching & running, I should be able to get some sort of reasonable guess at the average current draw - & hence be able to estimate a battery capacity vs run-time config.

All I can do then is to connect one of those nice little power meters (from Hobby King) between the battery & the load, then take the boat out for a 1/2 hour run in brisk winds. The meter will give me the total mAH draw, & the peak Amp draw, & I can then figure out a realistic balance between battery capacity & run time.

Thanks again for the heads-up on this issue - without this, I would have ended up motoring back to base after less than half an hour's sailing !

Kind Regards,

Peter D.
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Old Dec 03, 2010, 04:35 AM
1915 Schooner Mariette
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Sydney, NSW, Australia
Joined Feb 2008
243 Posts
Guys, FWIW, I modified the spreadsheet model (which basically plots wind speed against angle of heel) to give me sheeting forces => winch shaft torque => current draw.

If we assume that I won't go sailing in winds greater than 20kph (heel angle 35deg), then the total current draw predicted is 6.2A. The model is very basic & assumes the worst - flat plate instead of real sails for the drag coefficient, hull stationary, wind at 90deg to the sails. If I discount for these artificial conditions, my guess is that the current draw should be under 5A to hold a constant close-hauled tack in 20kph wind at 35deg heel.

In reality, we'll be probably sailing no more than half the time into the wind, with the rest of the time reaching & running. So it might be fair to assume an overall average current draw of, say, 3A. So a 3000 mAH LiPo should give me around an hour's sailing. I'll start there, & do a few half hour "typical" voyages, then see how many mAH's are needed to top up the batteries each voyage. If it looks a bit risky, I can simply add more/bigger batteries.

This is fun (or something), but it does keep the old brain active !!

Kind Regards,

Peter D.
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Old Dec 03, 2010, 07:30 AM
Paratrooper
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Eubank Kentucky
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G'day Peter--you and Dan are way beyond my mental capital when it comes to this engineering.

I did not design or invent the parachute--I just stood up, hooked up, stood in the door, and went out over the DZ 187 times. I still do not know precisely why a parachute works, I just know they do. Same for this ship of mine, when I started running out of power I just took the inventors suggestion and added another battery.
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Old Dec 03, 2010, 04:32 PM
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United States, MN, Brainerd
Joined Oct 2004
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Peter,
Interesting calculations - beyond me....
And Ray, quit kidding - your sharper than shinola....
When I first sailed, with original kit rigging, etc, I got blasted by some gusts and actually burned out servos (two or three times). I contacted the servo tech support (really excellent at ServoCity.com) and they said a two amp max was probably the safe limit on the servos. I fused each servo at two amps and have never blown a fuse -or servo - since. I have an overall fuse for all the sail servos, and blew that at three and at four amps. I now use a five amp overall fuse and that has not blown. (This is all now with custom rigging). Typically sail with winds under 15mph, but the gusts can ctually put Syren on her side.
Anyway, with 12 total sq ft of sail, and maybe half that on a windy day, a strong wind will blow a 4A fuse. With your sailplan and total area, I would guess that a lot more than 3-4A will be pulled. But all guesswork on my part, and I have no idea of the efficiency orpower rqmnts of the RMG's.
Your experience and info will be enlightening for all of us.
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Old Dec 04, 2010, 07:01 AM
1915 Schooner Mariette
delaneyp's Avatar
Sydney, NSW, Australia
Joined Feb 2008
243 Posts
Ray, don't undersell yourself - anyone who can build a ship as detailed and beautiful as Surprise (and get it to actually sail) is an engineer in my books !

Dan, the RMG Smartwinch is quite a beast - it will pull 18A at a stall torque of about 30 Kg-cm - but, it will only do this for a short time before automatically shutting down to prevent thermal damage. Moving the stick back resets the winch & off you go again !

You are quite right in pointing out that "knock-downs" result in the max current draw - my initial intent with the model was to just look at an overall average current draw for a typical sailing session, & 3A to 5A "average" looks realistic in 20kph winds.

Your comments about blown fuses & servos got me thinking about worst case knock-downs - the model predicts an 80deg heel angle at a wind speed of over 100kph, & this results in a total current draw of about 7A-8A for the worst-case mainsail winch. As this is under 50% of the max stall current, I am reasonably comfortable that we won't have a winch melt-down (specially considering the self-protection features of the winch).

Well, that's my theory - but at least its a starting point ! Reality may well prove to be a little different !

Kind Regards,

Peter D.
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Old Dec 26, 2010, 07:29 PM
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boynton beach florida usa
Joined Dec 2010
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Need Info for building a new ship

Hi, My name is Steve and I live in South Florida. I cannot begin to tell you how much I enjoy watching your videos. I am also a rail fan and I have built a large N gauge layout. I am about to tackle a half inch scale Frigate, and, I am going to try and scratch build it. There are several things that I would like to ask you about. Please get back to me. My e-mail address is:
Kayak56@aol.com

Thanks,
Steve
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Old Dec 26, 2010, 07:43 PM
Paratrooper
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Eubank Kentucky
Joined Nov 2007
873 Posts
Quote:
Originally Posted by PVT.DANCER View Post
Hi, My name is Steve and I live in South Florida.]

Thanks,
Steve
Steve--welcome aboard. Dan, Don, and I have built our ships using SC&H hulls that saved a lot of build time. I believe you can buy the hull and deck assembly separately but you need to contact Phillip to find out for sure.

Here are some links.

http://www.rcgroups.com/forums/showt...1201539&page=4
JL is working on a really large model at 1:12 scale.

http://www.rcgroups.com/forums/showt...857438&page=34
Jerry is working on several ships but Constallation is the main subject of his thread.

Dan L has a magnificent brig Syren with an SC&H hull and deck but most of the rest he has modified or built.

We're looking forward to seeing your work as you progress.
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Old Jan 30, 2011, 05:58 PM
Paratrooper
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Eubank Kentucky
Joined Nov 2007
873 Posts
Ships log 30 January 2011

We finally managed to get to the lake today and Surprise sailed wonderfully. We had not been to the lake since October so this trip out was very nice.

Temperature was in the late 40s and winds out of the North from 8-10 but late in the day the winds increased and got colder so I only managed to get a few photos in about 1 hour of sailing.

Tacking back to the launch area was a bit difficult as wearing gloves and trying to sail proved more difficult than it sounds.

I cannot tell if the additional weight of the 2nd battery in the hull has pushed the bow down much. I did find that with the sails trimmed well and some weather helm, the ship really made a wake, in fact with the sails set as shown in the photos, I could not keep up with her in the bass baby. Tacking often kept her close for photos but trying to take pictures and control the chase boat as well as trying to sail Surprise proved to be a hand full. I did not try to fire the guns, that will wait for warmer weather.

The photos are the same as all the others I take, but here they are for January 2011.

I took a few videos and I decided to put them together to make a quickflick. My efforts in tacking were frustrated by the need to try to sail and take the flick at the same time. Wind also getting up some during the manuver.

Surprise at sea 30 January 2011.mpg (1 min 31 sec)


Brooks, thank you for your comment. I appreciate it.
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Last edited by Paratrooper; Jan 30, 2011 at 08:41 PM. Reason: Add-a-flick
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Old Jan 30, 2011, 06:08 PM
Damp and Dizzy member
Brooks's Avatar
Bozeman, Montana, United States
Joined Aug 2003
3,410 Posts
That just looks so real, Para. If you removed the backgrounds, I'd be hard pressed to know it was a model. You have done a magnificent job.

I hear you with the juggling to get photos. I do that & I'm always standing on the shore, hoho.
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Old Jan 30, 2011, 08:56 PM
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United States, MN, Brainerd
Joined Oct 2004
2,399 Posts
Jealousy!!!!!

Darn you Ray!!!! The water will be hard here til April the way the winter is going!

Hey - looks as if you could have used more sail.....

As usual, really great pics and video. And seeing you sailing in scale gale force winds just points out your mastery of sailing your ship.

Trust me everybody - from Ray's vids you can see, and I've personally seen him sail often - he's an absolute master at sailing his square rigger. Should be promoted to Admiral....

Cheers, Ray. Looking forward to the coming season.
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