Author Topic: Oh God I Need Help! - Images Added  (Read 21159 times)

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freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #30 on: July 12, 2014, 09:44:19 »
Laurn,

Scroll down mate, for some reason there's a page of nothing before the images show. I can see them here ok.

Andy
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olscuzbut

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Re: Oh God I Need Help! - Images Added
« Reply #31 on: July 12, 2014, 11:28:44 »
Yup Lauren,  I get the same message, except I can see the photo with the battery standing up.

Norm

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #32 on: July 12, 2014, 12:03:09 »
Sorry guys, try this. I missed a square bracket out  ???
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Jarvo

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Re: Oh God I Need Help! - Images Added
« Reply #33 on: July 12, 2014, 12:38:11 »
Hi Andy

Had a close look at your photos, the battery is still high above the centre of balance, what about doing away with the gel battery and replacing it with a set of MIMh cells. lighter and very much lower.

Also do you know a roofer? ask him for off cuts or scrap lead sheet, put strips of lead between the bullheads on the floor of the hull, this will get your centre of gravity as low as possible.

You might be talking a pound or two in weight.

Just so you don't feel left out, test sailed my restored Amsterdam yesterday, total disaster, she very nearly capsized, switched batteries to lower ones, slightly better, added a total of 3lbs of lead in the rear and centre compartments, went well after that, still needs more in the stern, as the prop is cavitating as you go astern.

Its not you, it happens to all of us. Keep experimenting, but mostly think its going to happen

Mark
Etherow Model Boat Club

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #34 on: July 12, 2014, 12:49:00 »
Hi Jarvo,

What sort of MAh NiMH batteries mate and are we talking stick packs? I need a 12V supply for my cold steamer unit. Are you referring to something like this? This is a 12V 5000MaH stick pack........

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Andy
« Last Edit: July 12, 2014, 12:59:12 by freightliner009 »
Proud  father of a new Hobby Engine 1/35 scale Southampton tug and 1/24 scale hand crafted Zeeland tug


freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #36 on: July 12, 2014, 13:16:53 »
Calimero,

thr 3700/3800 wouldn't give much of a run time would they, especially with the smoker puffing away? I'm running 2 x 550 screws.

Andy
Proud  father of a new Hobby Engine 1/35 scale Southampton tug and 1/24 scale hand crafted Zeeland tug

Calimero

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Re: Oh God I Need Help! - Images Added
« Reply #37 on: July 12, 2014, 13:36:21 »
Yep, you'd have to get two or three and cycle through them.

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #38 on: July 12, 2014, 13:45:13 »
I'm going to start another thread on this as I want to keep this thread open for the buoyancy issues.
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Calimero

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Re: Oh God I Need Help! - Images Added
« Reply #39 on: July 12, 2014, 16:19:02 »
Don't worry too much about power. Get you boat to waterline.

"Worst" case scenario: you can move to LiPos (ESCs with cut-off highly suggested, but these things are cheap). A 3S/5000mah will be close enough in terms of voltage and will only weigh 400g if you can't afford much more.

Run times aren't an issue if your tug can barely stand upright ...

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #40 on: July 13, 2014, 04:11:14 »
I accept that running times are unimportant 'if your tug can barely stay upright', my point is I am not prepared to waste 40 odd quid on a battery if it is going to make little difference in helping to solve the buoyancy problems I'm having when the superstructure is put in place. I have nothing else to us]e such a battery on so I have to be careful that I don't end up with something I can't use.
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Calimero

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Re: Oh God I Need Help! - Images Added
« Reply #41 on: July 13, 2014, 04:58:02 »
Again fix you buoyancy issue first, get an appropriate battery later. Don't you have some scrap metal that would help you simulate different battery types ?
Once you get something decent, buy the battery.

Jarvo

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Re: Oh God I Need Help! - Images Added
« Reply #42 on: July 13, 2014, 11:24:17 »
HI Andy

Your loosing sight of the problem.

You don't have a buoyancy problem, its a balance problem.

If you are down to the waterline you need to lighten ship. You have removed the inside of the cabin, so thats as light as its going to get.

Next remove the smoker, that buys you some extra ballast to put in the bottom of the hull, right down along side the keel.

If possible get a 12volt or 2 x 6volt NiMh cells, this will free up more available ballast weight, as your gel battery weighs 2lb the cells only half that.

If you are in a club, could one of the members lend you some cells to try???

Mark
Etherow Model Boat Club

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #43 on: July 13, 2014, 12:43:08 »
Hi Mark,

You're right, I have opened another thread on batteries in the appropriate place rather than here. I have 7 x 200g lead ingots coming early next week, I'll probably need more I thought as the batteries are quite heavy then that would go towards the final ballast weight which it does but I can replace some of the lead with the battery once I'm in the ballpark and have a rough idea of the ballast weight needed I guess.
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des

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Re: Oh God I Need Help! - Images Added
« Reply #44 on: July 13, 2014, 15:23:35 »
Hi Andy

I don't entirely agree with Mark's response above.  Your battery is indeed part of the problem, but using a smaller, lighter weight battery is not the whole answer either.

One way or another you need to reduce weight in the upper regions of your model.  The lower you can get your CofG the more stable the boat will be.  You can do this by adding weight low down, but this is likely to result in the boat being too heavy overall.  Or you can do it by removing weight from higher up.  Reducing weight higher up will also reduce the rolling "moment" - the weight multiplied by height above the centre of buoyancy - thereby helping to make the boat more stable.  The higher up that you can remove any surplus weight, the less of it you will need to remove.

Can you post of photo of the interior of your upperworks - superstructure, wheelhouse, etc.  Assuming you have already removed some (or all) internal bulkheads etc, maybe you can get your dremel inside and start thinning the remaining material - eg if the remaining walls are 1/4 inch thick, sand them down to 3/16 or so - this could remove a lot of upper weight.

Take a look at real-life tugs of your Zeeland's era.  They have a steel hull containing lots of heavy machinery.  Main superstructure may be of steel construction, but basically hollow, containing only crew facilities.  The wheelhouse was usually wooden - to keep weight to a minimum higher above the waterline.  Similarly with more modern tugs - mostly steel, but many have aluminium wheelhouse construction.

Des.