Ballast for Luna Blu

[Port-Na-Storm]

Of course if we are discussing melting lead, then we can't miss the opportunity to revisit the day we went to Chris Peacock's forge to melt CW's stash.

Lead on CW.

 

[Chris Waite]

Well Jason

Sorry to be a tad late on the scene, but I've been doing something really strange this weekend - sailing

30 kilograms doesn't seem like a lot to me.  Polly Wee has about 140 kg of waterballast and I would not be inclined to reduce it.  The average bloke is meant to weigh about 80 kg. so I reckon I've got two smallish ones in the bilges under 80 square feet of sail.  It does slow her down a tad, but not overly....

I would suggest you should be heading for perhaps two hundred kilograms?!!??  Water is nice and soft and you don't have to carry it around inside the boat while trailing, or at all in the light.  In fact pratically the only time it is pressing on the hull is when she's got the same pressure outside the hull pressing inward as well; how convenient.

So you shouldn't need to worry too much about the hull strength, though I can understand and if you really do, what about lining the compartments concerned with anything from carpeting to, (I use rubber matting inside Tit Willow; she has the advantage of three layers of 6 mm ply on the garboard strakes, but no [internal] lapping of course and I keep a third of a ton of lead in there).  The other thing I do is to take the lead out and put it in the towing vehicle for long trips and do short ones carefully, bearing the extra weight in mind....

No sleeping policemen at ski-jump speed -



Or you could strenghthen the hull in the space with glassfibre, or a simple curved layer of ply

Food for thought

Chris





 





 

[Jason Mayer]

Hi Chris,

I agree, the lead was just to give me a headstart without taking up any space.  30 kg of lead plus some camping equipment is just a baseline that I will always carry, just because the boat goes so fast and is scary downwind on my own.  Water ballast will take me up from there.

I have worked out a very simple, cheap and easy 40kg water ballast by putting 2 x 20 litre drums of water just behind the bridge deck in the cockpit where it very conveniently fits and I can tie it down.

Now if I can get another 40 kg into each of those two lockers either side of the bridge deck then I'll be in business (30kg fixed plus 120kg water plus some camping gear).  This last bit is the hardest and of course I have left that till last....

Jason

[Jason Mayer]

Righto, it's time for the water ballast.

I some options.....interested in your views.

I could place the water ballast in the side lockers immediately aft of the bridge deck but I'm wondering if ballast out wide is a good idea??  I can potentially get 60 litres into each side locker (the red circles).

Or I already have a 100 litre bladder in my shed which I could lay on the cockpit floor more centrally but about 100mm above the hull floor (the blue shape)






I am leaning towards the 100 litres in the cockpit floor despite the obvious obstacle it creates.  My idea is to epoxy some routed timbers along the floor well walls and slide a piece of plywood in there to restrain the bladder and create a mezzanine floor that is still usable.  Cross section sketch below.  To release the water I just open the valve and it drains out through the scuppers in the transom.



Please comment.  Groups tend to make better decisions!

Jason

[Chris Waite]

I'm not so sure Jason

That "groups make better decisions"; it's too close to committees failing to reach a conclusion about anything and doing it very succesfully.  I once worked in a prison medical centre and every Thursday we'd have a long staff meeting where we'd discuss the problems and produce solutions.  Then at the end, the administrator, (who'd driven over specially, from the next town), would say of the prisoners - "But what about their human rights?"  Instantly all our solutions for dealing with the impossible would disintegrate into a dissipated cloud of scrapped imaginings....

The problems would sit back down gloating and we'd all get back to work solving the impossible, as usual.

My input would be that you need all of that ballast and more.  You have your work cut out though, as she's been carefully built with a web of fine egg-box type reinforcement to provide strength, while saving weight.  

It means that trying to fit a bag full of water anywhere leaves you on a hiding to nothing, so it might be better to interconnect all the available compartments, add sealable lids so you can get in there if required and have one system for flooding them as a unit with useful baffles already in situ....

You might need a reversible pump so that you could pump in or out as required.  This depends on how much she'd naturally settle with the ballast aboard.

The other way would be to take out the egg-box-work and glassfibre reinforce the hull where the water bags are to lay.  Not so bad, as the pressure of water inside and out is about the same when in action??  

In fact trailing seems to do much more damage than sailing.

How about that?

Chris W

[Jason Mayer]

Chris are you suggesting that I use the area under the cockpit floor as a giant ballast tank?

There are already scuppers between the compartments (on each side and against the keelson) and two bungs on the transom that drain that area.  I'd just have to plug the scuppers that drain the cabin into that space.





You can see the bungs with the blue arrow (only port side visible).  The cockpit scuppers are the ovally shaped flaps above.

I'll find out what epoxy treatment he did in there but it looks well coated.

Jason

[Port-Na-Storm]

Who doesn’t enjoy a good Committee Meeting, I know I do but only if I’m in the chair.
 
My thoughts seem to tie in with CW’s comments. I was going to ask how you intend to fill the bladders, it would seem that wherever you fit them you’ll end up with some complex plumbing or at least a lot of spillage. Plenty of Ply hulls have water ballast tanks incorporated but of course they are designed with that in mind. You obviously need to get that water out before she is on the trailer, either by pump or gravity.
Having said that if you already have the bladders laying around it wouldn’t do any harm to see what effect the extra weight makes by just temporarily fitting them in the floor well.
 
Good Luck.
G.
 

[Port-Na-Storm]

Also;
You will need some kind of vent to ensure the air can get out when she is filling up.
May I suggest a vertical plastic pipe preferably transparent with a floaty ball inside so you can see the level, placed close to the highest point of the tank. A valve on the end of the tube, above the waterline will help to control things.
Cheers. G.

[Paul H (admin)]

As for group meetings, aka arguments, that's where the good ideas pop out

Two random guys at a computer database conference where in the lunch queue. They started talking about the best way to search a database. They argued, each having strong views based on success.
After a long chat they realised there was a third way, better than their own.

The two guys formed a company and called it google, reduced from googolplex a massive mathematical number.

Worked out well didn't it?


MilliBee has multiple compartments. Best place for water ballast would be under bunks

Wayne, bless him, built Ever Hopeful. Twin masts + a lot of rocker. He put bags of gravel in the hull midships.
She became more stable.

Best results where Graham, Chris and myself on board to really weight her down. 5 or 6 people in total, can't remember.

I squeezed under the jib lying down, everyone else on the floor each side. In the gust she went like a runaway train, smiles all round. It was a fun day.

If we were in Oz Jason, you could use the smart ballast option, to find the best balance point. Payment in beer and cakes gratefully accepted.😎

[Jason Mayer]

I'm sailing tomorrow with a couple of work mates, I will do a capsize test at the ramp on the way home with them holding the bow and transom steady and see what happens to the gunter yard head and if my floaty foam thing is enough to keep her steady at 90 degrees on her side.  

Then I'll chuck the most acrobatic one of them into the bottom of cockpit floor and do it again and see what happens.

Will report back.

Jason