|||
Current Website Support
You are Not Registered
Go AD FREE & get your membership medal
BRONZE
Less Ads
SILVER
GOLD
Ad Free
Β£2.50
Β£4.50
Β£6.50
Subscribe
Go AD FREE & get your membership medal
BRONZE
Less Ads
SILVER
GOLD
Ad Free
Valid 12 Months
Β£25
Β£45
Β£65
Donate
You Will Be Helping Towards:

  • Domain Fees
  • Security Certificates
  • iOS & Android App Fees
  • Website Hosting
  • Fast Servers
  • Data Backups
  • Upkeep & Maintenance
  • Administration Costs

    Without your support the website wouldn't be what it is today.

    Please consider donating towards these fees to help keep us afloat.

    Read more

    All donations are securely managed through PayPal. Amounts donated are not published online.

    Many thanks for your kind support
  • Join Us On Social Media!
    Download The App!

    Login to Remove Ads
    Model Boats Website
    Model Boats Website
    Home
    Forum
    Build Blogs
    Media Gallery
    Boat Clubs & Lakes
    Events
    Boat Harbour
    How-To Articles
    Plans & Docs
    Useful Links
    6

















    Followers
    How to Determine Ballast required?
    by Ron πŸ‡¨πŸ‡¦ ( Rear Admiral)
    πŸ“£










    Click To
    Follow
    14 Posts 13 Replies 5 Photos 22 Likes
    ( Newest Posts Shown First )
    Ron
    Rear Admiral
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¨πŸ‡¦ Canada
    Online: 11 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    This helps, thanks.
    1
    roycv
    Midshipman
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 10 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi, looking at your hull I see that the rudder is at a considerable angle. I have an Americas Cup yacht also with this sort of angle of rudder stock.

    You must keep the yacht as upright as possible to retain control as when the wind heels you over to 30 degrees or so the rudder is no longer any good for direction.

    It is now almost flat with waterflow and acts like the elevator on the tail of an aircraft. So it is trying to drive the yacht up or down and not left or right.

    The way round this is to have removeable sails like staysails to reduce wind pressure on the sails and allow the hull to sail more upright.
    Its a real bummer and my Endeavour only goes out in light winds.
    Roy
    2
    roycv
    Midshipman
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 10 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hello dave976 you are looking at the heeling moment in a static condition. In a well designed hull especially an apple cross section as the wind increases which heels the hull over the 'in wedge' of the hull increases.

    This means that the yacht is trying to rise so the whole weight of the yacht will try and right the hull and this gives more stability.

    I have an old Norderney Graupner sailing fishing boat and this has internal ballast and a very small 'drop' keel it is now fixed and contains a small amount of lead but no separate weight.

    It heels over in a light wind but as the speed of the wind increases it only heels a litttle more. It is noticeable that she could do with a larger keel area, but she works OK and stays looking scale because of it.
    Roy
    2
    ToraDog
    Lieutenant
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡ΊπŸ‡Έ United States
    Online: 11 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Ron,
    I think that she sails very nicely. I would make one point. I think that you mentioned abeing able to sail in a fairly high wind speed. Remeber scale.
    I build in 1/48th and as such natural condition sometimes work to my advantage. That said, real wind speeds can be deceptive. Scale them correctly and you find yourself trying to sale in a hurricane.
    2
    dave976
    Lieutenant
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 12 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi Ron
    Nice looking model. The on water pics indicate that your ballast provides the right waterline so adding more may not be a possibility. On our club schooners the fore mast is usually canted forward with the rear mast vertical to the hull. This will affect the metapoint so we use this method to fine tune the model depending on the conditions.
    I suspect you will need to increase the keel depth by an inch or two, as others have indicated, to allow the weight to be lower in the water. The model does appear to be quite tender even in light winds and a lower keel weight will solve this problem. I test my yachts in the water by pushing sideways on the top of the mast and if there is only slight resistance 9easily pushed with your little finger) I adjust accordingly. I don't have an actual measurement but if you have ever used a brolly on a windy day you will know how strong the wind can be.
    I wish our lake was as clear as yours.
    dave976
    2
    roycv
    Midshipman
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 10 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi all, if you read my bit on finding the CLR and wonder why, the nearest analogy I can think of is this.

    Someone is sitting in a swivel chair on wheels, feet off the ground and you want to push the chair with a broom handle. There is just one place where the chair will go forward all the rest will spin the chair one way or the other.

    Does that make the point?
    Roy
    1
    roycv
    Midshipman
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 10 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi Ron in addition to my last post I think your sails are not balanced correctly. As the wind increases the hull should heel over more but stay on the same course.
    I note you say 1.6 lbs wind force it is just 1 lb in the U.K. Have you got any snow in your wind?😁😁
    Roy
    1
    roycv
    Midshipman
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¬πŸ‡§ United Kingdom
    Online: 10 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi, you need a little more information derived from the sail dimensions you mention.
    You need to know the combined area of the sails and where this area is centred. This is called the centre of area! OK so far? Look it up if in doubt it is simple.

    This point is measured down to the waterline and the measurement noted, I use inches!

    Now put the yacht in the water and on a windless day or better still in the bath and see if you can find the point on the hull where you can push the hull sideways and it does not fall off to left or right but keeps going sideways. I stick some decorators tape on the side of the hull and mark with a pencil. This is very easy do not despair, we are nearly there!

    I use pounds as well! With the wind blowing at 20 mph it exerts a force of 1 pound on 1 square foot of sail!

    Allow for this as the most you will be sailing in. Reduce the sail area from square inches to square feet and note this number.

    Multiply the square foot area by the distance straight down from the centre of effort to the waterline. This number is the key to the weight of the keel.

    Supposing the numbers are 12 inches and 4 square feet then this comes to 48. If you place the weight 10 inches down you will need 4.8 pounds in weight for the keel. Another option might be the weight at 8 inches down from the waterline and this needs 6 pounds of weight.

    Now with this information you can improve the sailing of your yacht. Measure the waterline length and note the centre of lateral resistance (where you poked with your finger).

    The centre of effort of the combined sail are shound be 4% or 1/25 of the waterline length ahead of the finger poke spot.

    The above will give you a sweet sailing boat that tacks like a dream.

    For keel area water is 800 times more dense than air so use the minimum keel area to stop the yacht going sideways while tacking.
    If you have a long keel hull then if building perhaps extend the lines down a bit but that is another story!

    Persevere and it will work!
    Roy
    .
    2
    pressonreguardless
    Commander
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡ΊπŸ‡Έ United States
    Online: 9 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    Hi Ron
    I'm no expert but I would think a deeper keel moved a little more forward.
    I would not reduce sail area, unless under sail in heavy wind, as you would with a full-sized vessel.
    Hope it helps.
    Trev
    Ron
    Rear Admiral
    πŸ“ How to Determine Ballast required?
    Flag
    Country: πŸ‡¨πŸ‡¦ Canada
    Online: 11 hours ago
    😊 View Profile
    πŸ’¬ Send PM
    2 Short videos the second was s very calm morning and I am sailing into the breeze.
    2
    Show 4 More Posts



    About This Website
    Terms of Service
    Privacy Policy
    Cookies used in this website are gluten free, wheat free and dairy free. By using this website you agree to our use of cookies. More Info