Model Boat Mayhem
Mess Deck: General Section => Beginners start here...! => Topic started by: Brock on February 24, 2008, 08:34:46 pm
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Help...I have a model Tug "brocklebank" which i did a bath test today.Apart from a very slight list when the superstructure was added and i corrected this with lead weights the boat seems to sit evenly in the water.However when the superstructure is added the boat seems to lean over when pushed very easily.It seems to sit evenly in the water with the screw covered and the top of the rudder is just level with waterlevel.The load markings on the bow go from 1-10 and the waterlevel is 0n 4-5.
As a newcomer i would welcome any advice on how deep they should sit and do they have a tendency to lean back and forth??
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If this is the same tug as in my photo check your waterline against photo to get a rough idea. O0
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Hi Richard
No it is different mine is older i think it has longer funnel maybe a steamer but it certainly does not sit that low in the water
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Help...I have a model Tug "brocklebank" which i did a bath test today.Apart from a very slight list when the superstructure was added and i corrected this with lead weights the boat seems to sit evenly in the water.However when the superstructure is added the boat seems to lean over when pushed very easily.It seems to sit evenly in the water with the screw covered and the top of the rudder is just level with waterlevel.The load markings on the bow go from 1-10 and the waterlevel is 0n 4-5.
As a newcomer i would welcome any advice on how deep they should sit and do they have a tendency to lean back and forth??
Try turning the battery over.
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If it is too light and you have the room try adding ANOTHER battery.
This is useful as it is removable ballast and will increase the duration.
Bob
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Hi Brock
You say it leans over easily when pushed.
Does it list? - stay leaning over.
Or does she right herself, and maybe rock back and forth a few time?
This would suggest you have too much weight to high up, and could also show you need more ballast.
It helps to get the ballast as low down as possible. ie next to the keel.
If you are using a sealed lead acid battery then you can lie them on thier side to bring the entre of gravity down. I think this is what Bryan means by turning the battery over.
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Hi,
Thanks bob and tigertiger for the info.
I have added another 6v battery unfortunateley there is no room to lie down as suggested and i raided the loacal tyre depot for some old lead balance weights which i have laid down by the keel in bags and does seem to have heped although i think it still needs more weights.
As regards the rocking it does return to the upright position without a lean and does seem a little better with the extra weight making it sit deeper in the water,so hopefully with a little more weight will solve the problem.
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Try sea fishing weights, set them is silicone when happy
Stavros
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Hi,
Thanks bob and tigertiger for the info.
I have added another 6v battery unfortunateley there is no room to lie down as suggested and i raided the loacal tyre depot for some old lead balance weights which i have laid down by the keel in bags and does seem to have heped although i think it still needs more weights.
As regards the rocking it does return to the upright position without a lean and does seem a little better with the extra weight making it sit deeper in the water,so hopefully with a little more weight will solve the problem.
As another suggestion for weights that I find works really well are shotgun pellets. They can be had at sporting goods stores in 25lb bags. The beauty is they can be poured into any nook and cranny to trim the hull off just as you like it. I keep mine in place with fiberglass resin. Some don't like this because its hard to remove, but I don't expect to remove the stuff from the hull once everything is set.
Don'tforget, tugs do set very low in the water as a rule.
oldiron
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... or, if you just need a view ounces (Gramm) use the lead-ballance-weights from car-wheels.
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I like to use plastic 35mm film cans filled with the lead shot the other fellow suggested. I have used silicone to attach the cans in the hull. They can be removed easily. I like to build simple (Cheap) easy build models, and when I tire of them , I salvage what I can and give the remains to a kid , or just toss it out.
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I use folded up lead sheet to ballast, worked in conjunction with batteries as well
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Brock
It isn't crucial in a tug to lay all the batteries flat on the keel.
Tugs by design have a large displacement for their length so are usually inherently stable for their length.
My theory is to ballast with batteries as these are removable so makes transporting easier and the duration is doubled.
You could try her in the bath.
Bob
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From what you are saying it sounds like the superstructure is a bit on the heavy side and there probably isn't a great deal you can do about this now. Your best solution is to get your ballast as low in the hull as possible to get the centre of gravity as low as possible.
However you achieve this is up to you but you should be looking at getting your ballast weight as low down in the hull as you can. Batteries could be laid flat if possible and even try to get lead shot, lead sheet or maybe sand right in the base of the hull. You can tell what effect you are having in the bath by the amount of pressure you need to apply to the top of the mast to heel the model over. If it needs very little pressure and the model pushes over easily and returns to the upright slowly then you need to get your ballast lower.
I have a similar issue with my model slipways Envoy Tug. I have the RN version and the white metal gun fittings make the superstructure quite heavy. My ballast is a large 12v motorcycle battery, laid on it's side in the middle. Don't forget that the real ships will heel over slightly in a turn as well so a small degree is quite realistic. There are also those who say you cannot lay a battery on it's side but I have never had a problem with mine and it has been in there for a few years now.