Making a ballasted centreboard...any views on carbon fibre and molten lead?

[dancrane]

He's thinking about it...

No, no I'm not. Although I appreciate RB's suggestion. I still admire Albacores very much, but the absence of a trapeze was one of the things that weighed against it in my mind.

I was certainly in a position to buy an Alb when I chose the Osp, so I know exactly how I feel about them both. The rarity of affordable Ospreys on the market meant that I called the chap as soon as I found the boat on Apollo Duck, rather than umming and arr-ing about possibly making an enquiry, as I had over several Albacores at the season's start.

The Osprey's size appealed to me very much, and I'm quite content to strain and puff a bit on shore (and worry more than necessary) as payment for my choice. I'm very sure that if I'd bought a smaller boat, whenever an Osprey passed (at quite a rate I suspect), I'd be thinking, that's what I really wanted. As it is, even though mine is elderly and rather tatty and terribly green, it's very rare that I look enviously at anyone else's boat.

I found a slightly interesting Youtube clip, of a chap sailing a Lightning dinghy singlehanded. These are big boats - 19ft x 6'6" and 300kg+, including a 60kg ballasted centreplate...

...not very common in the UK I think - I've certainly never seen one. Not to be confused with a much smaller singlehanded boat by the same name, here.

I think he copes quite well considering it's generally a three-man boat, with more sail than the Osprey...

 

[rwoofer]

Just to throw another spanner in, the Canadians put trapezes and even spinnakers on Albacores for training purposes.

 

[Neil_Y]

Sailing a bigger boat with lots of sail is easier than a small one as it reacts much slower to gusts so you have time to ease sheets or kicker, I managed to s/h a 14 a few times (with kite) and it was possible, fast and interesting. Dropping the kite was the tricky bit as you have to let go of the helm to go foreward and release the halyard. The Osprey has 13.3sq m upwind sail area so that's not much as long as the main is in a state where you can get it board flat, the 14 has over 18sq m upwind.

 

[dancrane]

...the Canadians put trapezes and even spinnakers on Albacores for training purposes.

I knew about that, it was one of the first modifications I had in mind, if I'd bought an Alb. Must be easier than hiking...that's a big mainsail on a narrow beam, round hull form, etc...

Sailing a bigger boat with lots of sail is easier than a small one as it reacts much slower to gusts so you have time to ease sheets or kicker, I managed to s/h a 14 a few times (with kite) and it was possible, fast and interesting. Dropping the kite was the tricky bit as you have to let go of the helm to go foreward and release the halyard. The Osprey has 13.3sq m upwind sail area so that's not much as long as the main is in a state where you can get it board flat, the 14 has over 18sq m upwind.

Thanks Neil. Various accounts I've read (and seen) lead me to think it's not impossible at all to singlehand a dinghy made for two, albeit limited to rather light airs.

For those interested in whether I've been exaggerating or wisely anticipating the difficulty of righting an Osprey, a thread from last year may be of interest...starting on the second page, the Osprey was suggested, criticised and defended as a novice/family choice. I'm not certain if the overall tone was more encouraging or warning, than the present thread... http://www.ybw.com/forums/showthrea...ns-please/page2&highlight=singlehanded+dinghy

 

[Neil_Y]

Mmmmm merlin rocket reasonably stable, not in my experience, a very narrow water line, even narrower one up. The 14 is quite stable with a wide waterline, but the height of mast and where the bouyancy is makes it a struggle to right on your own (I weigh 75Kg) the penultimate 14 came up much easier with a shorter daggerboard and heavier (but shorter) mast, so a lot came down to how the bouyancy worked. Bouyancy under the gunwale gives more leverage than a slim double floor tank.

Bit late now but the unbreakable Laser II is a very easy to handle and right boat, some people think it's fast as well?

If you're in Plymouth ever come out for a sail

 

[dancrane]

Cheers Neil.

The Laser 2 was a boat I fancied many moons ago, and I had the book in the 1980s with a cover-photo showing one guy sailing it with all sails up...a formative influence, perhaps!

I'm no longer so fond of the Laser's shape, but it's certainly been singlehanded many times, without requiring a fat man on the wire:

 

[CreakyDecks]

Don't underestimate how dangerous molten lead is. If your mould is damp the lead WILL explode in your face! I'm not sure how you would melt and pour 100lb of lead in one go and obviously if you do it in small pieces they wont "stick together". If you did manage it in one go it will take a hell of a long time to cool down and who knows what that would do to the epoxy?

 

[dancrane]

For myself, I made no bold claims about knowledge of lead. Nor did I presuppose that wetting the mould would help!

I'd read that carbon fibre wouldn't suffer from the temperatures in mind, but I hadn't considered the epoxy. Presumably the CF 'halves' of the new board could be clamped together while the lead is poured in, taking days if that was convenient...and when the lead has set and cooled, epoxy or an outer layer of carbon/resin would keep it all together?

Don't laugh, I was asking because I know I don't know.

 

[Neil_Y]

Great effort in the Laser, there was also some guy who cruised his a few hundred miles in the Med I think.

My composite bearing experience (high temperatures)suggests the resin would soften/melt then cook, turning to carbon and loose all its strength at around 180/200C with lead at around 320C. There are other resins that will withstand those temperatures like Polyether ether ketone (PEEK) but it's expensive.

 

[CreakyDecks]

For myself, I made no bold claims about knowledge of lead. Nor did I presuppose that wetting the mould would help!

I'd read that carbon fibre wouldn't suffer from the temperatures in mind, but I hadn't considered the epoxy. Presumably the CF 'halves' of the new board could be clamped together while the lead is poured in, taking days if that was convenient...and when the lead has set and cooled, epoxy or an outer layer of carbon/resin would keep it all together?

Don't laugh, I was asking because I know I don't know.

I don't think anyone was laughing because I don't imagine anyone has tried it. You could always try making a small mould out of carbon fibre and see what happens to it when lead is poured in. Wear goggles! I had molten lead blow up my face when I first tried making fishing weights in a cement mould that wasn't quite dry. I was lucky. I now use a proper aluminium mould and get it really hot with a blowlamp before each pour. Nasty stuff. It runs through your clothes as a liquid and then solidifies red hot against your skin!

 

[Iain C]

For myself, I made no bold claims about knowledge of lead. Nor did I presuppose that wetting the mould would help!

I'd read that carbon fibre wouldn't suffer from the temperatures in mind, but I hadn't considered the epoxy. Presumably the CF 'halves' of the new board could be clamped together while the lead is poured in, taking days if that was convenient...and when the lead has set and cooled, epoxy or an outer layer of carbon/resin would keep it all together?

Don't laugh, I was asking because I know I don't know.

Er, no. For about 25 reasons.

Seriously, go and read any of the Moth/Cherub articles on building foils, you will see what you are proposing just cannot be done in the way you describe. And why on earth build a carbon foil with no bulb but with lead in the middle? That makes about as much sense as fitting dumper tyres to a Caterham 7.

 

[dancrane]

I don't think anyone was laughing because I don't imagine anyone has tried it. Wear goggles! I had molten lead blow up my face when I first tried making fishing weights in a cement mould that wasn't quite dry. I was lucky. Nasty stuff. It runs through your clothes as a liquid and then solidifies red hot against your skin!

Very nasty stuff! Thanks.

...why on earth build a carbon foil with no bulb but with lead in the middle? That makes about as much sense as fitting dumper tyres to a Caterham 7.

The relative lightness of carbon fibre wasn't something I was striving towards. It just struck me as a very strong structural material, even when very thin...and obviously there'd be more room for lead inside the shell, if the casing is significantly thinner. Of course, a handy detachable lead-bulb would be great for breezy weather...not so sure how it would self-level though, or slide up into the centreboard case.

I'd much rather pay for the materials required to do it in GRP...but when I've mentioned other jobs previously, carbon fibre was often suggested as a stronger, better alternative.

 

[DownWest]

As for melting lead in 100lb lots, I use a 13kg gas cylinder with the top cut off and a 24kw gas burner. Next keel is 420lbs...I will let you know how it goes.

If doing Dan's stuff (unlikely..) I would cast a plaster plug in the held together sides of his board, then make a female mould in cement/plaster (well dried.) and cast the lead. Assemble the board with the lead inside.

Quite common to pour lead into wooden moulds, as long as they are well sealed. A coat of the stuff they used to preserve eggs(senior moment..) helps to protect the wood.

Ah, waterglass is the stuff, sodium silicate for the serious.

 

[Daydream believer]

I do not think the op has costed carbon fibre
He could buy a keel boat for the equivalent cost
plus he has not worked out how much lead he could get into the void- not a lot I suspect

 

[dancrane]

I do not think the op has costed carbon fibre
He could buy a keel boat for the equivalent cost
plus he has not worked out how much lead he could get into the void- not a lot I suspect

Well, I don't say my calculations would necessarily result in great success, but I've given it some thought...

...I read that a £40 carbon fibre kit provided approximately 1000mm x 300mm of finished carbon...and the description said that the structure was up to car-bodywork strength, which seemed a decent starting point. Obviously I'd have needed at least twice that much to do both sides of a centreboard, plus very likely more to seal & reinforce...

...as far as weight/volume of lead goes, I don't think I'm wildly off-course. A hollow board which is 25mm x 1000mm x 350, will hold several litres of lead, each weighing 11kgs.

I mightn't want the process of pouring all that lethal muck into the board to be filmed...sounds like a viral shock-horror accident video...but is my maths really so far out?

 

[Iain C]

Dan

I suspect your "kit" was fake stick on carbon. Carbon is strong, but only in certain ways. It has different modulus to glass and Kevlar. You have zero, zip, nada, not a cats chance in hell whatsoever of building carbon foils for £40. I know, I've done it...remember my Cherub build website? You would be looking at a minimum of 3 staggered layers of UD and a couple of layers of twill weave, vac bagged, over a decent HD foam or cedar core, each side. Plus resin. Go and price that up from somewhere proper. Budget a good few hundred quid at least...wasted. Someone I know has just built a set of Moth foils using high modulus carbon and it cost him over a grand, in carbon alone. There's a reason why a carbon 5o5 centreboard is well over a grand, why a set of moth foils is four grand, and why people don't build yacht keels by pouring molten lead into what is essentially a plastic mould, or use lead as a core material.

Seriously, go and do some proper research on it. Go and make something simple out of carbon such as a compass bracket or similar. Thinking that one measly layer of "carbon" over a lead core will work is a mile wide of the mark. I suspect that if you capsized the boat the centreboard would probably collapse under its own weight and sink to the bottom before you even got onto it!

You have done a capsize drill, right?

 

[dancrane]

Alright, it was sounding like too much bother anyway.

I've got a bad cold. Won't be doing any capsize drills until 2014. Can't promise I won't be asking any slightly nuts questions round here though...

 

[Daydream believer]

...as far as weight/volume of lead goes, I don't think I'm wildly off-course. A hollow board which is 25mm x 1000mm x 350, will hold several litres of lead, each weighing 11kgs.

I mightn't want the process of pouring all that lethal muck into the board to be filmed...sounds like a viral shock-horror accident video...but is my maths really so far out?

With all due respect--there is your first mistake the board is only 25 Th for a small percentage of its area. i suspect that the average is more like 12mm less thickness of the skins. The thickest part remains in the centreboard slot so has no useful purpose if filled with lead ( negative in fact)

As for melting lead - i regularly used to make lead joints in cast iron pipes but due to a lapse of concentration one day I spent 4 hours in A & E when a length of old lead pipe was found to have water trapped in it.
Fortunately it missed my eyes but I lost some skin off my hands & face
So you do need to be careful