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Post by Mark on Aug 13, 2007 15:06:32 GMT 1
I wouldn't worry, she's wide enough and even if she wants to roll over you can add some lead in the keel it's not like it's going to sink her immediately.... if you need to add ballast to make the ship lie stable it is best tu use lead shot and use epoxy or something similar to glue it to the bottom of the hull, it's easier to get the ballast as low as possible that way... it's also easier to get the exact amount you need in the hull... lead shot can be easily made yourself, al you need is an old metal s****, a blowtorch, a bucket of water, some pieces of lead, and something to attach the s**** to.... then you should drill a 1mm hole ( a 2mm is possible too but I think the lead shot will be too big...) in the s**** and attach it to something sturdy and heat resistant... put the bucket of water underneath it and put a piece of lead in the s****... after that you must liquidize the lead with a blowtorch making it drip through the hole into the bucket of water, where it should harden again.... mind your hands though as you could get some nasty burns!!! this method is also used to balance model airplanes as the amount of lead can be precisely measured and it is much easier to get the lead in tiny places this way edit: why on earth does spoon get censored hint: you can eat soup with it.... Poon was in the banned word list - no idea why. An Americanism ?? Anyway, you can say spoon with impunity now
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Post by swanrail on Aug 13, 2007 22:11:03 GMT 1
I am keeping a watch on the weight of my model as I progress. Today, with all motors, control gear, receiver and batteries plus all decks fitted (with magnets in place) and my own reinforcements I have reached a weight of 2.6kg. To come: second planking, all hull fittings, all superstructure. bow and stern resin parts, paint, etc. so looks like we are heading towards 6 or 7kg. Never had any problem lead ballasting, use old lead sheet (NOT off church roofs I hasten to add!!), cut into small pieces with shears or heavy duty scissors, dropped into hull until correctly loaded and then "glued" into final place with the same resin used to waterproof and strengthen the inside of the hull. Being tight fisted and not wishing to set myself on fire, this is my easy way out........
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Post by bob on Aug 14, 2007 19:16:49 GMT 1
Amati appear to indicate that 5.5 to 6 kg is the correct weight of the model for it to sit right in the water. I dont think we need to worry about any ballast. It seems to me that things like battery weight will be critical. I am intending to use a five cell stick of U2 sized ni-cads giving 4500mAh at 6v. I have yet to confirm with Markus if the v-mixer and speed controls will function ok at 6V. Also by having the batteries low in the Hull I will be able to move them forwards or backwards to get the right trim. If weight concerns allow it, then I will add a second stick wired in parralel to give more running time.
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Post by markus on Aug 15, 2007 15:59:26 GMT 1
I have yet to confirm with Markus if the v-mixer and speed controls will function ok at 6V. no problem at 6V, minimum operating voltage for both is 4,8V (4 cells) markus
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Post by bob on Aug 15, 2007 17:17:39 GMT 1
Thanks Marcus for the info. Will be ordering a few more bits when funds permit.
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viper
Deck hand
Posts: 18
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Post by viper on Sept 4, 2007 1:48:42 GMT 1
Hey all
Back to the adding weight, in my rc model club we use sand in plastic bags mixed with a bit of resin. The sand forms to the shape of the hull (when resin is still wet) so it will not move but stillcan be taken out for transport if needed and it is cheap.
Cheers
VIPER
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Post by trev on Sept 4, 2007 9:06:06 GMT 1
Im not having mine as Rc but if i was doing an rc version dunno that I would be melting lead though as it got banned for use in paint and kiddies toys for quite a good reason.
Sure I would do it if i knew what i was doing but alas i dont
Trev
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Post by bob on Sept 4, 2007 17:52:14 GMT 1
Thats a handy tip Viper might try that if ballast needed.
Also I have some bits of scrap brass bar which are quite heavy that I could resin down.
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Post by markus on Sept 4, 2007 19:01:07 GMT 1
wow, GREAT idea with those plastic bags - respect !!!
markus
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Post by steamboatbob on Oct 2, 2007 6:29:35 GMT 1
with my experience it is easier to get an exect ballast by the following. -using the sand bag method above to get correct weight tie these off and remove them labeled to where they go. -using plaster of paris and plastic bags again get the shape of the hull where the sand bags were and let it set. -remove plaster of paris positive moulds. -weigh the sand bags and using lead shot or some other weighty material match the weights. -make the negative moulds either with plaster or wetsand in a large bucket from out the back yard. - melt down lead into you hullshaped moulds and wait to cool. -result - perfect ballast conforming to your hull which will lower your centre of gravity. i know this process may seem a little longwinded but i used it on my steamboatand it has close to 15kg ballast including gellcell batteries and she is as steady as a rock. another posotive about this is that the weights will not move around on you while on the water. sand is just as good but ive had a bad experience with a leaky bag and the lead takes up less room.
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Post by bob on Oct 3, 2007 20:55:20 GMT 1
Got some lead weights from the local tyre place that they use for balancing car wheels they had a box full of old used ones that can be melted down. The mechanic gave me about twenty alsmost a kilo in weight. Can easily be melted with a blowlamp.
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viper
Deck hand
Posts: 18
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Post by viper on Oct 24, 2007 0:47:13 GMT 1
Has anyone tryed to remove weight from the superstructure? There seams to be a fair bit of useless timber that can be drilled out, even if it is only a few grams. It is always easier to add weight than take it out after the first sea run, and the lower the weight the more stable the boat is on the water.
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Post by bob on Oct 24, 2007 8:38:13 GMT 1
I dont think that will be needed the centre of gravity is pretty low with all the radio gear and batteries in the hull. See the video Marcus posted in German Radio Gear, his model has already made its maiden voyage. Admittedly it was minus superstructure but he added six fairly large stones to make it sit in the water correctly.
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Post by bob on Oct 24, 2007 8:38:29 GMT 1
There is a letter from Amati in an earlier post I think it said about 700 grammes of ballast will be needed even with radio gear fitted.
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Post by eric on Oct 24, 2007 9:52:20 GMT 1
besids, you don't actuall want all the weight down low, it would give the model a very sharp quick rolling motion, some weight higher up raises the matacentric height, and gives her a longer slower, more realistic roll.
Just imagine one of these old piano metronomes, the weight down low on the arm produces a quick beat, the weight higher up at the top, a long slow beat. The princaple is the same.
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