hitec sail winch

<center>Hey !

Was that an intentional mis-spelling or what???

[:-propeller]

Should that have been low-“TECH” or low-“TACK” ?</center>

I need to know, as I have been using the yellow colored stuff, and if that isn’t cutting edge - I have to modify my materials list! [:D][:D]

Dick,

It is “Tack”.

You are clearly way behind the curve on masking tape!!! The blue stuff has lower stickiness coefficient leading to a much lower gumminess factor upon removal. It is the only way to go in this day and age. The beige stuff is no good! Throw it out!

  • Will
    (On the trailing edge of leading edge technology)

Will Gorgen

Ha!!!..another proof!
Dick…the Middle Age is over! (grin [;)])…i did know that one

Laurent

_/ if it isn’t broken, don’t fix it! _

http://wismerhell.esmartdesign.com/index.htm

Craps - [:-banghead]

and I suppose rubber cement and duct tape are the next things out! Dang - just when I find something good it gets replaced.

Wonder what I’m going to do with all those great new, unused buggy whips ? [:-headache]

Masts!!!

Thanks
Don
Vancouver Island

Hey Don -

[;)][;)]

A truckload and a half is being shipped your way tomorrow. Please simply sign for the shipment and pay the driver ! I’m sure you will be able to put them to good use. Ummmm - they ARE braided rawhide, but good luck anyway. A wise buying choice! Probably will need something to prevent them from bending too far.

Enjoy !

And don’t try to hide on the delivery driver. He has been advised you really <u>ARE</u> at home - just [:-eyebrows] hiding !

hi guys sorry it has taken so long to get back to you. thanks a heap for all the information and all the ideas btw the blue 3m low stick tape is good but the line is not as sharp as it could be if you want a sharp line there us a black plasticky tape a lot like electrical tape but in a low stick the only problem is that you can strech it and its hard to get a straight line.
you can get gears for the hhitec hs725bb i have one on order should have it by tomrow with any sort of luck .
lester your wonders nevier sease to amaze me thanks for all the imformation its a pitty that all the maths went way over my head i world ask for an explaniation but i dont think i would be any better for it keel weight is 1.265kg(just measured on my trusty digital scales
keel length is 800mm
arm lenght is 80mm
cant angle is actualy around 35degreesbout does not have enough beam to alow me any more bu ah well there is always next time well after i have got my 1 meter going( there is way too many ts2’s down hear for it to be healthy need to show em a thing or 2 about hull design and that fat is not fast.)
so if i have any idea on maths
keel length/arm length
800/80=10
and than answer* weight of lead
10*1.265=12.65kilogram-centimetres
so if im right??
my 12.65kilogram-centimetres is less than hitecs load rating off 14.5 kilogram-centimetres
so in theroy my winch should not have blone its self to pices. note the in theroy part.:stuck_out_tongue:
now that is all said and done why did my winch die??
and will putting a 2 to 1 pully system work??

Never hold your farts in.
They travel up your spine, into your brain,
and that’s where sh*+y ideas come from.

<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by michaelb

keel weight is 1.265kg (just measured on my trusty digital scales), keel length is 800mm, arm lenght is 80mm, cant angle is actualy around 35degrees

… so if i have any idea on maths …<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
Ah. OK… Here we go, and there is an exam at the end (smile).

Your lever ratio of 10 (lever arm 80, keel 800) makes the 1.265 kg bulb look like 12.65 kg to the winch working with the lever. So you are asking your winch to move an apparent 12.65 kg.

To start, let’s work with an effective cant angle of 90, for the times when the boat is blown horizonal and you still want to cant the keel out. Next, let’s take the stall torque of your HB 725 of around 14.5 kg-cm, and decide that we are only going to ask this winch to deliver around 25% of this rating. If you drive it any harder, you have less margin for friction losses, less speed when canting, and so on. So we want to work something out that has the winch driving with around 4 kg-cm of torque.

The question becomes, what kind of arm do you need to move 12.65 kg with 4 kg-cm of torque? Answer, 12.65 / 4 = 31.625 mm. If you put a drum on your winch and ask it to cant the keel with a line attached to the top of the keel lever arm, your drum needs to have a radius of around 32 mm. That’s a rather large drum.

No problem, you can now rig up a 2:1 purchase – wire a pulley block to your keel lever arm, and have the winch wind the line that runs through the block. Ignoring friction losses, your drum radius can now be 16 mm. That’s better, 'cos of course a 32 mm dia drum is a pretty standard size.

Final reality check, let’s calculate the length of line that the winch must wind, and the number of drum turns needed, to cant the keel 35 degrees with a 2:1 purchase and a 32 mm dia drum.

We asume you’ve positioned the winch so that it can reel in the keel lever arm fairly directly. The distance the keel lever arm travels when rotated 35 degrees is given by

Travel = 2 * lever radius * sin (angle / 2)
= 2 * 80 * sin (17.5)
= 48.1

We have a 2:1 purchase, so we are going to run around 96 mm of line.

A 32 mm dia drum will take 96 / (pi * dia) = 96 / (3.14 * 32) = 0.96 turns – call it 1 turn. Great. One turn cants the keel 35 degrees port, one turn cants it starboard.

Lester Gilbert
http://www.iomclass.org/
http://www.onemetre.net/

Just found the water bottle test pic;

I felt it was worth doing, saved on hassel later…

Luff 'em & leave 'em.

oh good that privet education is finaly coming good my maths was right:)lester thank you a whole lot idd buy you a beer but the thousands of km between us kind of makes it hard:) now all i have to wait for is my new gear set to come in so i can go for a sail

Never hold your farts in.
They travel up your spine, into your brain,
and that’s where sh*+y ideas come from.

Hey Lester,

I think you are overly complicating the matter. here is how I did my calculations:

Heeling moment is just that - a moment. You have the keel bulb mass at a distance from the point of canting and you must react that moment to hold it in place.

In this situation, you have 1.265 kg of mass and a moment arm of 800mm. If we assume that in the worst case we need to hold it in position when the keel is horizontal (through a combination of heeling and cant), then you get a moment of 1.012 kg-m of torqu at the pivot.

Now if we are going to react that torque by a force at the end of an 80mm lever arm, then you get a Force at the end of the lever arm of 12.65 kg.

If you apply the force with a string tied to the end of the lever arm, then the force through that string needs to be 12.65 kg. If you use a pulley system to gain a 2:1 mechanical advantage, then the string tension needed is 6.325 kg. If that string (or block and tackle system) pulls at an angle, you need to do the approprate trig to determine the force in the torque direction (perpendicular to the lever arm) from a string pulling at some angle.

Now you have the force in the string. Getting that force from your servo depends on the drum size. If you have 6.325 kg of force and you have a 2cm drum RADIUS, then you need 12.65 kg-cm of servo torque. But if your drum were smaller (say 1.6cm radius or a 32mm diameter) then you need 10.12 kg-cm of servo torque. The smaller the drum diameter, the less servo torque you need.

The drum diameter should be set by the canting requirement. From your travel calculations, it looks like you have more than enough travel on the drum with a 32mm diameter drum. If you go with a smaller drum so that you use the entire travel of the winch to get just the cant angle you want, then you will find that the servo torque required to move the ballast is lower…

The biggest thing you need to consider to get these calculations right is the geometry of the block and tackle system relative to the lever arm. This is an easy thing to calculate with a little trigonometry and will most likely not remain constant as the keel cants as the angle will likely change. Sounds like spreadsheet time to me!!!

If anyone is interested, I can email the spreadsheet I used to determine how my mast canting mechanism would work. It calculates the forces and moments at each joint of the system at various degrees of cant and various degrees of heel. I tried posting it here, but aparently the system does not allow Excel files to be inserted into a forum message… Send me an email if you want to see my spreadsheet. I’ll also give you some instructions on how to use it…

  • Will

Will Gorgen

I found a link to a servo that you guys may interested in:

http://www.servocity.com/html/power_gearbox_servos.html

Rcher,

Those are sweet and along the same lines as what I put together. I used this gearbox:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXSL79&P=ML

with a Hitec 725 servo. It took a bit of harnaging to attach everything together, but it works pretty well now that it is done. I’ll try to snap a picture or two to post here…

  • Will

Will Gorgen