Adding weight to a keel: idle thoughts

[armchairsailor]

Whislt browsing a boat, I found out that the particular marque in question had a tendency to be a little flighty, as it was an early fin and skeg configuration and they hadn't quite got the hang of things handling-wise. TBH, it just doesn't look like the keel's not substantial enough to grip and provide enough counter force for the rig. The boat in question has a parallelogram-style keel, so it's not a paricularly complex shape. I got me to thinking about modifying the keel (cast iron, I think) by attaching a bulb/ shoe of lead through the base to tame the boat a little.

Could one theoretically bolt on a bulb/ shoe to improve stiffness? I'd imagine that 2 weights of 100kg (one applied to each side) would improve things considerably, if bolted through low down on the keel, and as long as you could form a curved surface that mimiced the keel, casting wouldn't be insurmountable either.

I see the difficultlies mainly lying in:
1: Ensuring the keel bolts are strong enough to take the additional forces
2: Getting the right materials (bronze bolts?) to bolt lead to CI
3: The casting process

Any thoughts?

 

[Woodlouse]

The problem here is ensuring that the keel and the means of attaching it to the boat are strong enough to take the extra loads. This doesn't just mean the bolts, but also the hull around them. An extra 200kg of weight that low down is going to cause a lot of extra stress. If you're serious about doing something like this you'd need to get some proper experts in to crunch the numbers and work out what effect the weight will have. If not then you might end up like Hooligan V.

 

[armchairsailor]

After a quick google, I think what's I'm trying to mean is a stability bulb.

But I agree with Woodlouse's concerns about ensuring the hull is up to it.

Probably not worth it on a boat worth 10k, even if it's advertised for a lot less. Probably better to sail it, learn how good it is and then consider structural work a couple of years down the line.

 

[Flying Penguin]

After a quick google, I think what's I'm trying to mean is a stability bulb.

But I agree with Woodlouse's concerns about ensuring the hull is up to it.

Probably not worth it on a boat worth 10k, even if it's advertised for a lot less. Probably better to sail it, learn how good it is and then consider structural work a couple of years down the line.

Or just stuff the bilges with FB pies, great for stability and long journeys...

 

[bbg]

It isn't only the keel bolts that will feel extra force - it is the whole boat.

Sitting at the dock it is only the keel bolts. As soon as you start to sail, that extra stiffness will be translated into extra stress experienced by the mast, stays, chainplates, sails, running rigging etc.