Model Boat Mayhem

Dry Dock / Shipyard: Builds & Questions => Yachts and Sail => Topic started by: LarryW on February 22, 2011, 12:54:29 PM

Title: n z trowALMA
Post by: LarryW on February 22, 2011, 12:54:29 PM
hi all. started to build new Zealand  river trow , from a plan by ktd designs of NZ.
  it is a footy sail boat also can be seen in san Fransisco bay called ALMA,.....
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 if build goes i will build a 2 footy model , but still looking for data      cheers Larry
Title: Re: n z trowALMA
Post by: Roadrunner on February 22, 2011, 01:12:28 PM
Very nice, where did you obtain the plans from? I'm very interested as a project as its quite different from the standard footies out there.
Title: Re: n z trowALMA
Post by: LarryW on February 22, 2011, 01:40:22 PM
HI ROAD RUNNER plan is on modelboats. hobby -  or google KEIL KRAFT MODEL BOATS, lots of down load plans on there..........LARRY'....
Title: Re: n z trowALMA
Post by: Greggy1964 on February 22, 2011, 01:45:23 PM
Hello Larry,

I love it!  :-) :-))

I love unconventional models, especially sailing ones.

Look forward to seeing her finished and sailing O0

Lots of photos please  :-)
Title: Re: n z trowALMA
Post by: roycv on February 22, 2011, 01:55:06 PM
Hi Larry W not having much luck getting this site, can you be a little more precise please?
I expect it is just me but I have been all over the place.
regards Roy
Title: Re: n z trowALMA
Post by: Netleyned on February 22, 2011, 02:05:00 PM

Dodgy Geezers Site Roy

Title: Re: n z trowALMA
Post by: LarryW on February 22, 2011, 02:11:15 PM
Title: Re: n z trowALMA
Post by: LarryW on February 22, 2011, 02:14:36 PM
THANK YOU NED  must learn how insert web sites............LARRY :-))
Title: Re: n z trowALMA
Post by: roycv on February 23, 2011, 06:13:14 PM
Thanks Ned it looks very nice.
regards Roy
Title: Re: n z trowALMA
Post by: LarryW on February 28, 2011, 02:44:28 PM
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HI ALL here are some pics of ALMA RIVER BOAT footy size next step is getting the controls right ,
  this is the bit i am not good at, {:-{ but still enjoying the build bit :-)) ......cheers LARRY.
 PS ,ALMA IS ON THE DECK OF A 6..8 Yacht hull not yet identified {:-{....
Title: Re: n z trowALMA
Post by: Netleyned on February 28, 2011, 03:00:45 PM
Looking Good Larry

What servos are you using ?

I've printed the plan out poster style and cobbled them together.
Lots of tiny bits to make when I get the chance to start!


PS Aint that an 'A' Class?
Title: Re:NZ trow ALMA
Post by: LarryW on February 28, 2011, 03:20:14 PM
hi ned, 2 no spektrum didital micro dsp 75........ when i no what goes where.
 a bit confused when looking at plan {:-{...... but i will get there to me sial bits is a black artr  {-)   LARRY..
Title: regarding servos
Post by: Brooks on April 30, 2011, 05:54:17 PM
The Alma plans mention shock loads on the servos. I use Hitech 82mg, (micro, metal-gear) servos on my boats. No stripped teeth yet :-). Nylon gears will strip, been there done that.

I have 2 schooners (not Alma). You will find it easier to tack and wear if the mainsail is on a separate servo, rather than controlling it simultaneously with the foresail+jib, as shown on the plans. The big advantage of a multimasted ship is the ability to use the sails as "air rudder." For schooners, in particular, if the sails are fighting the rudder, then the sails will win. One schooner modeler (on another site) who controlled all his sails on one servo (per plans, different design) quit sailing. He kept ramming into the stone wall surrounding the park's pond. Turns are just very slow if performed under rudder only, he found. He's thinking of redesign of his sheeting scheme.

Differential sheeting, that is, controlling the sheets of the sails fore of the CLR (center of lateral resistance) separately from the sails aft of the CLR, is the key. To bear off, slack the mainsheet: the sails fore of the CLR will automatically turn the bow away from the wind. To head up, slack the foresail and jibs: the mainsail will automatically make the hull turn into the wind. Tacks and wears are much easier to complete with differential sheeting. I use differential sheeting on all my boats.

There seems to be plenty of room to add a 3rd servo below decks on the Alma, one nice advantage of the scow-type hull.

Sail arm servos have proved sufficient on all my sailboats: Pamir, 4 masted barque; Aldebaran, fore&main topsail schooner; BottleBaltimore (foretopsail schooner); Sandbagger (gaff sloop). I've not had to go to the expense of winch servos. Winches are nice, but are more sensitive to slack&snarls. John Dowd has mastered the winch technique for schooners, though; his Bluenose is magnificent :-).
Title: Re: n z trowALMA
Post by: Brooks on May 04, 2011, 09:05:04 AM
btw, when I was referring to "winch" servos in the above post, I meant the kind with a drum that reels-in and pays-out line. I forgot that some modelers use the "winch" term for servos that run a gear array (for more power) but still use a sail arm attached to the array. You won't need anything like that with your Alma, a simple arm on a standard servo will do the job.

If you use standard aircraft servos, you'll only get a little less than 90deg of total arm swing. Planning the length of the arm, and the attachment point of the sheet to the sail's boom, then becomes important: ideally, you'd want the boom to be controllable from centerline of boat out to 90deg to the centerline. This will require you to attach the sheet to the boom closer to the gooseneck than the real ship's attachment point. Most of my ships do fine with that setup. The sandbagger, with it's large mainsail, can overpower the HS-82mg, making it impossible to haul in the sheet if the wind is strong. In that case, do as real ships do, namely head up a bit to relieve the wind strain on the mainsail, then work the servo to take-in slack in the sheet.

I didn't mean to scare you off from RC-ing your schooner's sheets by over-complicating the matter. I think it is easier to sail with separate sail servos for the 2 categories of sails: fore of the CLR and aft of the CLR. It's still possible to have fun with a schooner with only one sail servo, though. It just takes more micro seamanship skill to maneuver with one sail servo (and more luck). As long as you have a pond where you can get to all sides for retrieval (if you are unlucky, can't tack, and end up on the shore....been there done that :-)  you can proceed with one sail servo. My bias is to replicate real ship sailing practice, so I emphasize maneuverability in my builds, and de-emphasize scale detail; but it's your hobby, so you can emphasize anything you want. My hat's off to Jimmy James, he seems to be able to emphasize both, Well Done Mr. James.