Ballast it!!

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9 May 2018 at 12:10 #4495
John O’C
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@johnoc
When to add ballast?
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9 May 2018 at 12:10 #77005
John O’C
Participant
@johnoc
Hello people.

I am still here plodding away on my various boats and 2 years or so after building I decided to make an effort and launch Smit.

So last Sunday (06/05/20) I started to check out the systems on board and everything was still working so Tuesday launch looked good. I then decided to do a floating test so the fish in my pond got disturbed but only for a very short time.

The first problem was water flowing in to the hull from somewhere and after several searchesI eventually discovered a leak from around the starboard prop tube.

The second thing was how unstable the boat was with the 12v lead acid on board.

I have fixed the leak after a bit of dental like work around the tube but am unsure about the whole balance of the craft.

Ballast maybe what I am short of but what is best to use???

All advice and sarcasm's gratefully received!

Cheers

John
9 May 2018 at 18:20 #77012
Malcolm Frary
Participant
@malcolmfrary95515
The heavy items need to be as low as possible. With SLAs, it is sometimes possible to mount then on their side – I've seen boats that were unusably tender be transformed by remounting an upright battery on its side. Batteries are usually good ballast since they also power the boat.

Any "passive" ballast needs to be dense,so lead sheet (or flattened scrap lead pipe) is good, but lead shot sealed in bags is handy for placing where required to get the trim right. The weight given by the battery might not easily go where really wanted to get the trim right, so bits of sheet or small bags can be sited as low as possible out at the ends of the hull.
11 May 2018 at 14:58 #77051
John O’C
Participant
@johnoc
Hi Malcolm
I like the small bags idea. Are they ready made or do you make them yourself?
I will make space and drop the battery on to its side first and see how that works. I don't remember it being so unstable when I first tested it so maybe it is the battery being upright. I dropped it in that way due to it being a bit cramped with electrics and controllers. The adhesive pads I used to hold things in place are no longer "adhesive" so if I cure that first it will help.

Cheers
John
12 May 2018 at 10:39 #77066
Malcolm Frary
Participant
@malcolmfrary95515
The bags are the small plastic ones that "stuff" comes in and are then re-purposed. Anything that will do the job is OK, it is going to be hidden out of sight. Small sandwich bags (what will hold a lot will also hold a little and can be cut down) or party balloons, but these will tend to decay over time.

I did a plastic Tuna boat a long tome ago – all was well regarding stability when tank testing (kitchen sink) until I put the mast on. It then needed about 1 oz of lead stuck in the bottom of the hull. Now tender in that it leans in any breeze, but stable in that it readily comes upright again.
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