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[Martin-S]

So Ive established that my model needs some more weight in her for stability, so here is the question.
Do I position the ballast (lead in this case) on the centre line as low as possible or below the waterline where the hull sides curve underneath to the underside of the hull in other words the chine area.
My bath test has proved inconclusive in terms of the dampening effect but its clearly more stable with the ballast in either position.


Thanks in advance for your knowledge.

[roycv]

Hi, when using ballast for stability then as low as possible. 
BUT also it depends on fore and aft balance as well.  If you put the ballast at the bow and the rest at the stern you get a more even running boat.  Think of the boat as a dumbell!
With planing if you want the bow to rise then there should not be too much weight there.  To keep her at the waterline move equal(ish) weights in each direction.  Do not forget that most boats have a Vee entry to the water but change to a U section as you get to the stern, so a given weight has a different effect on waterline.

I suggest you make her look right in the bath and then see how she behaves at speed.
Good luck
Roy

[Neil]

I DON'T put permanent sticks of lead into my models any more and havent done so for many years after a fellow modeller gave me a tip.
now a days I have multiple "bags" of lead ballast, made fropm lead shot available on ebay.

I bought a few kilo of it off ebay and put bags together using sandwich bags in weights of 1kl, 0.5 kl and 0.25 kl, and then wrap these in a couple of layers of carpet tape. Then either using the bath or if larger , the lake I take the boat and bags to the water and distribute them around the hull at the lowest points.

Once I have the hull sitting right, I take each bag out in turn, and number it, and the place in the hull where that bag has come from. Then I take a strip of INDUSTRIAL velcro and stick one side to the bag and one to the hull in the correct possition.

Easier to lift a boat in and out of the water minus ballast than heavy with a few kilo's of it.

 Believe me it works, and the bags being subtle and bendy being loosly bagged, NOT tightly they will also bend around obsticles like motors and prop shafts.

[John W E]

hi there,


The general rule of thumb that everyone seems to abide by is to place the ballast as low as possible in the hull and on the centre line.  There will always be exceptions to this rule though - e.g. when you have an obstacle in the centre line; such as motors and batteries.  Therefore the ballast must be arranged either side of these obstacles.   In extreme cases the weight sometimes can be fastened on the exterior of the hull when there isn't enough space inside the hull.  Bearing in mind - what I personally have found with paddle driven vessels - and not using feathering paddles - the vessel tends to dig in and pull to one side when turning or even going in a straight line.  You can, if you are not over careful, exaggerate this effect by over ballasting the hull.


john