[James Malloch]

We have a boat and it's in need of some additional ballasts. I'm thinking that it will require a sizeable amount, somewhere between 100-200kg perhaps, to help level it out.

Space isn't something we have a lot of so something dense would be best but this obviously brings the price up. Cast Iron weights would be good but are fairly costly. Something like old railway track would be good too (if it can be cut into short lengths).

I'm not really sure where to start looking for either cheap weights or where might have a bunch of scrap that could be bought. I'm based in Leeds but can travel within a reasonable distance.

Are scrap yards the best place to start? Or if anyone knows of somewhere that could supply something then I'm all ears.

[Alex Smurthwaite]

Id definitely start with scrap yards. Ive needed stuff in the past and have always found it. Might need to visit a few though

[Oldmanmatt]

What is the hull made of?
Length, beam and draft?
Keel type?
Sail or motor?

And why do you need the ballast?

Do you have stability calcs or have you done an inclining experiment?

(Caveat: I design ships normally, but I'm a small craft surveyor as well ( double caveat: I don't do it for a living anymore)).

[nik at work]

I know shit all about boats but I reckon concrete is going to be a fair chunk cheaper than metal.

Nice big chunks of metal are expensive to buy and (aside from lead (poison)) expensive to form. Even 'that old rusty lump over there' can be surprisingly pricey.

[Oldmanmatt]

Pouring concrete into the wrong kind of hull makes for some interesting corrosion issues...
As would steel/iron in an aluminium hull and so on.
(I used to sabotage aluminium minesweepers with special copper inserts, slipped into through hull fittings... ).

[Muenchener]

I used to sabotage aluminium minesweepers

Only ones belonging to the Queen's enemies, I hope.

[Oldmanmatt]

I used to sabotage aluminium minesweepers

Only ones belonging to the Queen's enemies, I hope.

Maybe.

[emoji6]

(Only on exercise, never in anger, so unless we've been at war with Holland or Germany in the last 30 years, I think I'm in the clear).

[James Malloch]

What is the hull made of?

It's a narrowboat so just a standard steel build.

Length, beam and draft?

57' length, 6' 10" beam, 1.5' draft (at a guess)

Keel type?

Flat bottomed

Sail or motor?

Beta Marine engine

And why do you need the ballast?

We have it as a liveaboard and the design is such that everything needs to be/is fitted on the left of the boat.
It was listing slightly when we bought it but since then we have added a washing machine, sofa and a big inverter which all needed to be on the left also. This has made the listing worse.
It's not very bad in the grand scheme of things but it would be nice to have a level boat. The washing machine doesn't enjoy being at an angle and simple things, like the shower tray not draining get tedious after a while.

Do you have stability calcs or have you done an inclining experiment?

No. I'm not sure where to start to be honest. My weight estimate was based on the boat nearly being level when we got it, and the weight of items we have added on the LHS is circa 120kg.

I'm sure there's a better way to do this though...
I

(Caveat: I design ships normally, but I'm a small craft surveyor as well ( double caveat: I don't do it for a living anymore)).

Matt - answers are above, thanks!

We have some concrete blocks there at the moment from when we bought it but they aren't very dense so take up a lot of room for not much mass. So I hoped that some metal could be squeezed in next to our water tank where there is space but it's limited.

[jonsse]

Old storage heater blocks are pretty dense .  . and cheap/free.

[remus]

On the concrete theme, could you just bag up some sand/gravel and use that? You'd probably want to double bag it in some meaty rubble sacks to avoid spillages.

[Oldmanmatt]

If you don't move, it's not an issue; just add ballast until level. Remember to check your draft doesn't become excessive though, every kilo you add will add to the draft. A slab sided vessel with a flat bottom can pretty much be treated as a box. So, sitting in fresh water (sg of 1) every 3.6 tonnes added increases draft by 10cm. If you 1.5' draft is right, it currently weighs ~ 16 tonnes.

If you ballast at the longitudinal mid-ships point (best) you can treat it as a normal lever. The distance from the keel to the center of the ballast is your lever, so ~3' in this case (aka not very big) so you might need quite a bit of weight!

Here's what you do.
Have you got a smart phone?

Get an inclinometer app for it.

Measure your list now, with no one on board.

Get some mates round, weigh them (4/5 should do, 10 better).

On deck, find somewhere you can muster them n each side in mirror image at a known distance from the Keel line.

Get them all to stand in the spot opposite the current list. Measure your new list.

The the weight of your mates, times the distance from the keel line, divided by the change in list; gives you a moment per degree.

So, now you know the moment per degree, you can work out (depending on the space which you can fit the ballast into and it's distance from the keel line) how much you need to put in that position to right the vessel.

(Terminology and principles greatly simplified for clarity and not suitable for vessels operating in open water, or of a hull shape other than a simple box).

Regarding the materials. Don't put any metal in the bilge/hull without first painting the bilge, painting the ingots/ballast and lay an insulating layer (to electrically isolate) such as a sheet of rubber, between ballast and hull.

Pouring concrete is easy, but will lead to corrosion issues behind/under that you won't be able to see or deal with; much better to keep it movable. The smaller the bits, the more portable.

If you are going to spread it out along the hull, you might need to calc the cumulative moments of each placement and remember to keep it even around the midships point or you'll dip the bow/stern.

Edit:
That might sound really patronising depending on your ability in Mathematics! I really simplified it, possibly too much.

[James Malloch]

Thanks for that - it's really useful and a sensible approach to take.

I'll try to get a bunch of people around one evening and steal some scales from someone. I just got an app too which I'll test out this evening.

The simplification is good! I studied maths at uni but this is very clear. I was thinking about moments yesterday but wasn't quite sure how to do it.

From what you've said about "moment per degree", that means I can use a few people to move the list by x-degrees and work out the full mass required to move the list to zero degrees, correct? If so I'd not considered it that way which makes things a lot easier (less people needed).

Also when you mention spreading it around the hull. Is it okay to have some in both the stern and bow as I think it will be hard to have it in the center due to how the boat is laid out?

Thanks a lot for this advice!!

[Oldmanmatt]

Thanks for that - it's really useful and a sensible approach to take.

From what you've said about "moment per degree", that means I can use a few people to move the list by x-degrees and work out the full mass required to move the list to zero degrees, correct? If so I'd not considered it that way which makes things a lot easier (less people needed).



Also when you mention spreading it around the hull. Is it okay to have some in both the stern and bow as I think it will be hard to have it in the center due to how the boat is laid out?

Thanks a lot for this advice!!

Yes, it allows you to see/calculate the turning moment that created the list and therefore the required correcting moment.

Remember I've glossed over a lot of variables though! For instance, the list changes the underwater profile and shifts the center of buoyancy (that point through which buoyancy acts to oppose the moment causing the list). So there are inaccuracies in the calculations and if you decide to, say, take the boat across the channel and explore the canals of Europe; you need to get a surveyor to perform a proper inclining experiment. You should know the characteristics before venturing out to sea.
Or any open water, including lakes, if your GM (distance between the vessels center of gravity and it's Metacentric height (a theoretical point (hopefully) above CG) is too small, it will take very little force to capsize. Even a sharp turn in open water may induce capsize. It has happened...

Spreading it along the hull is fine, just remember it might not all be the same distance from the keel line, so check the moment of each batch.
If it is unevenly loaded, forward/aft, it will also induce a pitch (make the bow or stern, sink) and checking the Trim as well as the List is important.

[tomtom]

IIRC the arse has dropped out of scrap prices (indeed copper pipes lasted in next doors skip for a full 4 days before someone nabbed them - though that might say more about the refined type of skip diver we have in West Didsbury nowadays... anyway..) as I think you now have to pay to have your old banger scrapped rather than someone pay you...

Old engine blocks... cast iron ones (not new fancy alloy ones with a liner). Maybe also ask at a garage (ie small ones not chains) - they may well have old lumps of car components that are worth nothing but weigh quite alot. Crankshafts, old drum brake outers etc.. Anything iron will have a good density and weight. They won't hang onto any moisture unlike sandbags (which would be my next option..).