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traction battery and boat stability


happyboris

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Hi, I have a 60 foot narrowboat. I plan to install a traction battery that weighs approx 1200kg, my question is if this battery was place free standing on the back deck would it alter the centre of gravity of the boat to such an extent as to make it dangerous. The battery consists of 24, 2 volt cells each cell weighs approx 50kg. Has anyone any ideas?

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14 minutes ago, happyboris said:

Hi, I have a 60 foot narrowboat. I plan to install a traction battery that weighs approx 1200kg, my question is if this battery was place free standing on the back deck would it alter the centre of gravity of the boat to such an extent as to make it dangerous. The battery consists of 24, 2 volt cells each cell weighs approx 50kg. Has anyone any ideas?

On the back deck - may be. I have 60 1.2v cells on my boat, but placed forward of the engine on the base plate and I get no stability problems...  

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34 minutes ago, happyboris said:

You are probably right better to find a way of installing the batteries lower down. Thanks for the advice.

If you mount them within the hull, you have the sides (mine go edge to edge) to contain them. The thought of several hundred Kgs rocking from side to side with nothing much to restrain them (a wooden frame would have to be quite substantial) would frighten me somewhat.

I'm assuming yours is a cruiser stern, so where would you put them anyway?

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The general idea was to encase the batteries in a welded steel box mounted on the deck in a horseshoe configuration around the transom then the batteries would serve as a seating area. Something like that. My other idea is to locate them lower down in the engine room area however it would make access difficult. I was considering offsetting the weight imbalance by fitting a large around 1000 liter water tank amidships, very low down in the bilges to act as a counter weight........ But i'm open to suggestion. Perhaps putting them on the roof as suggested is the best way ahead the lack of stability could be countered by filling a balloon situated above the boat and attached to the roof mounted battery with the degassed hydrogen from the battery.

  • Greenie 3
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3 minutes ago, happyboris said:

 Perhaps putting them on the roof as suggested is the best way ahead the lack of stability could be countered by filling a balloon situated above the boat and attached to the roof mounted battery with the degassed hydrogen from the battery.

I like it, good sense of humour, have a greenie

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Why not ask 16 of your average sized friends to stand in the location your are suggesting then ask the number of people that would be using the seating to join them plus a few to allow for the metal housing and see what happens?  Worth also filling the water, diesel and pump out tanks (if you have one) to get a true feel.

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Was thinking more on the idea of putting a 1000 litre container on the back deck and filling it with water that would give me a pretty good idea how she would behave. Also i don't know 16 people and i'm not sure inviting the same person round 16 times would work. Maybe i should get a dog.

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Wherever you put that sort of weight, the boat will sink by about an inch if located centrally or a fair bit more if at one end or the other.

 

How will you get your balancing balloon through Harecastle?  Of course it may be that  Harecastle is not wide enough for the boat to capsize so  the balloon can be detached and walked over the top on a lead.  You may need some heavyweight crew for that though.

 

N

 

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Your centre of gravity must be kept at all costs, like an aeroplane. near the centre of the boat, low down. If its in the way it can't be helped. A box fitted over it with a little flight of stairs front and back would help you to process up and down the boat, a bit like the useless little staircase landing in Faulty Towers where they're taken up to a higher level and back down to the same level.

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2 hours ago, happyboris said:

The general idea was to encase the batteries in a welded steel box mounted on the deck in a horseshoe configuration around the transom then the batteries would serve as a seating area. Something like that. My other idea is to locate them lower down in the engine room area however it would make access difficult. I was considering offsetting the weight imbalance by fitting a large around 1000 liter water tank amidships, very low down in the bilges to act as a counter weight........ But i'm open to suggestion. Perhaps putting them on the roof as suggested is the best way ahead the lack of stability could be countered by filling a balloon situated above the boat and attached to the roof mounted battery with the degassed hydrogen from the battery.

Now that's a Bizzard type suggestion. Roles have bee reversed and his one above makes a good alternative!

Your solution above might well suffer from a dumbbell effect for and aft. Depending on what accommodations you have at the rear end - how about having the cells arranged in a string either side of the rear of the boat. They're not very wide (?) so could be fitted behind a bed or in kitchen units without too much loss of space. Cable runs could be a pain as would be topping up - but it's a solution.

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I'm horrified at the thought of 1200kg on the stern deck from a stability POV. 

When I fitted the Kelvin in my boat to replace the BD3, the 18" rise in CoG of only the engine resulted in the boat being noticably more tender. Even people who were not especially boaty commented on it. God nose how tender the boat would be with 1200kg aded 2ft above the waterline!

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Thanks for all the advice, having considered everything I have decided to relocate battery amidships under a bed. Will have to get a slightly smaller battery than anticipated however i am confident that it will be a safe and stable solution.

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49 minutes ago, Mike the Boilerman said:

WTF is your main engine then!!!

 Ah yes the old 'WTF' engine. A friend had one of those in Jetski. It did 60mph over the water on the river and when it went past people said ''WTF !!''.

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6 minutes ago, happyboris said:

I'm an ex submariner I'm planning for armageddon something like "mad max" on the trent and mersey, thems with the most power survive...... 

Ahhh a " Sludgemariner " Proper Diesel Boat or those modern pretenders?

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