Steel beams in the Leopards

[Sand crab]

This came up on SA and I'm sticking it here for your info and comments. It was interesting to me because I was unaware of any structural steel used in any other cats. I'm not saying it's bad but it is interesting.
Leopard uses a steel beam assembly in some or all of the newer cats with the forward porch. I'm not calling it a cockpit because it really isn't, it's a porch. The beams would look like a rectangle seen from above and they bridge the porch right at the door and again just forward of the porch. I think. They glue and bolt fiberglass to it and tab it to the hulls. These are stills from a Gone with the Wynns vid. The beams are at the 3:50 mark. I don't know what specific model these are for.

https://www.youtube.com/watch?v=W4LpuBy3TM4

[BillKny]

For a weight sensitive boat like a catamaran, there is only one reason for using steel structural members: It is the cheapest way to go.

In addition to the extra weight in the long term, these WILL have corrosion issues...

[rslifkin]

I'd definitely worry about corrosion. But I wonder if it's actually cost savings, or if an equally strong all fiberglass structure would have needed to be larger, making it a space-saving decision. Going to carbon fiber or other stronger materials likely would have been too expensive.

[Rohan]

Originally Posted by BillKny

In addition to the extra weight in the long term, these WILL have corrosion issues...

It's not an issue I would be concerned with unless the steel reinforcement is not fully sealed and at the same time not accessible to be inspected. Nearly all ships in every navy in the world are made of steel. Some sailboats are too.

[KC375]

Originally Posted by rslifkin

I'd definitely worry about corrosion. But I wonder if it's actually cost savings, or if an equally strong all fiberglass structure would have needed to be larger, making it a space-saving decision. Going to carbon fiber or other stronger materials likely would have been too expensive.

ergo, a cost saving measure


That may not be a bad thing. I love the performance that aluminium and composites enable in a Lotus Elise, but I chose to buy and drive a minivan for cost and capacity reasons.

[jim King]

I never knew. Fun seeing how my boat was made (another Leopard 45). Not sure if the steel beams made me feel better or worse about it.

[wathey]

We have a leopard 48. There is a steel beam. There is light (have to look closely) corrosion on it. The steel is very thick so I have not even bothered to wire brush it given that by triage standards there are two dozen items higher up the list needing corrosion control before I can get to it. Large bolts tie it into the fiberglass bulkhead, it's definitely there to reduce flexing across the window and door. One minor but important note; on the bigger leopards I would call it a cockpit. On the smaller ones it is noticeably smaller and would agree with perhaps a different term. We just crossed last night from the Bahamas to Jacksonville. 290nm open ocean and were comfortable leaving the door open in the following seas. We put three surf boards, two wing foilers, large box of dog food, 4 sup paddles and 2 cases of beer in there and you could still walk out easily onto the front trampoline if you wanted to go fwd. It's bigger than the cockpit of the average, older, non-hard chined 40' aft cockpit monohull. After having the front door I would never buy a catamaran without one regardless of the size of the cockpit for it's airflow into the main saloon. And yes, we cross oceans in nasty weather, have filled it several times and it drains quick. The bigger issue than how fast it drains when you fill it is the occupant's discussion about their views and how they 'feel' about hitting a ten foot wall of sq ft chop at 9kts. Comment is not defensive just don't underestimate it's value, it's huge.

[roverhi]

That looked like Stainless Steel not good old soon to rust Ferous Steel. SS won't have the corrosion problems of plain steel barring crevice corrosion. Plain steel would be a problem because salt water gets in somehow and the rustermite attacks. Structural plain Steel components were often used in boats built in the '60s early '70s like the Cal 40 and some Columbias. They have proven to be a corrosion problem and very costly to repair/replace. Though most of these boats are going on 60 years old and I'm sure some still have the original steel in place.

[Pauls]

Two points on this:
1. Corrosion is not an issue if the steel is properly prepped and coated. As a previous poster noted, steel is the most common material used in the marine environment today. The technology for using it successfully is fully developed.
2. Modern jet aircraft still have - on an average - about 15% of their weight made up by steel components. There are reasons for this. Steel is far superior to aluminum as regards fatigue life. Aluminum structure WILL fail from fatigue, given enough load cycles of a given force level. Steel is different in that it has what is called an endurance limit, meaning that below a certain load level a steel structure will survive an infinite number of load cycles without failure.

When you look at the number of load cycles that a cat's beams see from waves - ie a cycle every few seconds - steel has some advantages.

[jmschmidt]

More proof that the Forward Cockpit, Porch, Fox Hole or whatever you want to call it, is a bad idea. I've owned one and half 47" Leopard cats, one sail and one power. I wouldn't mind buying a new one but without the Porch. Its only use is to please the ladies and make the boat flip easier after burying a hull coming down off a big wave in a blow.

[Simi 60]

Originally Posted by jmschmidt

More proof that the Forward Cockpit, Porch, Fox Hole or whatever you want to call it, is a bad idea. I've owned one and half 47" Leopard cats, one sail and one power. I wouldn't mind buying a new one but without the Porch. Its only use is to please the ladies and make the boat flip easier after burying a hull coming down off a big wave in a blow.

I always thought of them as a swimming pool.
Having once been in the "Green Room" on a previous cat and coming out with no more than brown pants and a healthy respect for the weight of water I wonder how these would go in a similar situation.
I reckon I know the answer.

[BigBeakie]

Putting steel beams into cats is laughable. The only justification is cost savings. It won't be stainless due to cost. I believe Lagoon also used steel beam starting with the L39 to support the aft mast. What a joke[emoji849]
Steel when contacted by the catalysts used in fiberglassing, corrodes very aggessively.

IMO, after having discussions with NA on this issue, there is no reason carbon composite structures could not have been used to achieve the same stiffness design goals. The reason carbon isn't used is cost & time, pure and simple.

[flightlead404]

Originally Posted by Rohan

It's not an issue I would be concerned with unless the steel reinforcement is not fully sealed and at the same time not accessible to be inspected. Nearly all ships in every navy in the world are made of steel. Some sailboats are too.

Having looked at a few Endeavours in my recent boat shopping errrr endeavors I saw several exposed steel grids.

There is going to be water intrusion. Period. Epoxy etc is not completely waterproof, hygroscopic for some types I think(?), plus there are always fittings, through bolts and so on, and 20 years on hairline cracking maybe.

Either way once water gets in, particularly salt, there will be corrosion which will cause the steel to increase in volume prizing apart GRP, causing delamination, even bursting. Saw it on several boats.

Now the question is, is it any worse than various coring products used around the vessel?

The Endeavours used mild steel whereas this is stainless. Still, that only slows down nature.

There is never a way to 100% seal something for all time. There are two approaches to water, try and make it water proof, and let the water in but provide a way for it to escape easily.

The second approach favoured by British car marques, the excellent Lotus mentioned above NOT being one, but the Lotus 7 derived Caterham Superlight R that I drove in the 90's definitely being in that category.

[smj]

Our old Cherokee 35 had a steel I beam sitting on top of the bridgedeck that took the compression of the mast and the shrouds were also attached to it. We sold her when she was 30 years old and there were no signs of corrosion.
Yes it is a way to save money and yes it does ad weight, but seriously, would the added weight really affect the sailing performance of the Leopard that much?

[Tupaia]

I believe Lavranos uses steel beams inside the fibreglass rear arches on his designs. Maybe to allow for the central transom cutaways, Admiral, St Francis, so it is not that uncommon. There are obviously cost benefits and on boats that are not lightweights to start with does it make that much difference to the overall performance. Longevity and corrosion aside.