The reason lighter cats are safer?

[smj]

. It’s not the weight of the heavy production cat that gives it good load carrying qualities it’s the width and volume of the hull under water. If it were built lighter it would be able to handle an even greater load.
As far as the heavier catamaran being better at anchor or better for living aboard? Not always true.

[HBrew]

In my view, like many things on boats, it’s never really an ‘either/or’ question, it’s a matter of degree to achieve your desired boat characteristics.

The first thing to say in favor of a lighter boat is that you can probably sail faster and at a wider range of sailing angles than a heavier boat. This will mean that you will have a better chance of reaching a safe anchorage or avoiding the path of a weather system. I would say that this is the primary safety benefit of a lighter cat. The other benefit from my perspective, which is less about safety and more about pleasure is that you will sail more and motor less. This was the driving factor for me and why I spent more money on a boat that has less living space than many cats that are considerably shorter waterline.

Having a boat with a longer waterline and with plenty of buoyancy in the bows with a good percentage of the waterline forward of the mast will help avoid burying the bows off a wave. As far as I can see, unless you are in a hurricane, in which case you are in trouble with any cat, the issue is not really the wind, it’s the waves. So a boat that can safely accelerate will bear less impact from a wave from behind and narrower hulls will cut through waves from ahead more effectively. Overall, I think this also reduces stress on the structure of the boat and consequent wear issues over time.

The downside of lighter boats is that you have to worry about managing speed in stronger conditions. What will you do to reduce speed once you’re down to bare poles? I have opted for a Jordan series drogue but before deploying that I would drop some lines off the back of the boat.

Once again, the safest thing to do is to avoid bad weather, which means if you can sail faster, you have less chance of getting caught up in some unexpected bad weather.

[clakiep]

For avoiding surfing and pitchpoling it is not the weight that makes any difference, but the hullshapes. Deep V displacement hulls don't surf, flat round hulls do. The weight should always be for the boat to float around its CWL.

Capt. Claus

[joelhemington]

Originally Posted by markiobe

If by light you mean also with easily driven hulls, i.e. a more performance focused boat rather than just a 'normal' boat built lightly, then I'd agree. What I mean is light weight on it's own doesn't make the boat safer.

If however you build a boat that has easily driven hulls AND is light then I'd argue that for most situations it's safer, a few reasons:

- for a given speed you will use a smaller sail area. This also gives a lower CofE which is fundamentally safer as it creates less heeling moment, less stress on all components etc.

- if a narrow bow is driven into a wave it will more likely drive through easily, slowing the boat much less, whereas a wider hull will struggle. The heavier less easily driven boat will thus have a higher pitch-pole moment of inertia which when combined with the higher CoE and more power in the rig is fundamentally less safe. Wave-piercing hulls are a thing in high performance cat design.

- if you are in a big wind and seaway and are running just for safety, maybe under bare poles, the lighter narrower hulls are again safer as they will much more easily drive through waves rather than tripping on them and slowing the boat causing either a pitchpole and/or broaching risk.

To those who say heavier is better in big wind, I would say that if you are in a big enough wind to literally pick up a boat then what's a couple of tons going to change? You have bigger problems at that point, but the faster boat would have had more chance of getting out of the dangerous situation in the first place. If you can average 200nm rather that 150nm per 24 hrs, that extra 50nm could mean the difference between safety and disaster. With modern forecasting that extra safety window could easily stretch to 3/4 days, 150/200nm distance. When you look at it that way speed suddenly does become your friend.

I think Mark touched on it nicely. I'm not going to argue the merits of a heavy cat versus a light cat but catamarans all have one main defense mechanism and that's the ability to outrun nasty weather. You normally get a three day weather window with modern electronics which means a faster, lighter cat can get you about 100nm farther out of harm's way than the slower heavy boat.

[fxykty]

Originally Posted by siggy

...
So I was thinking if there were still no consensus on drogues amongst people far more knowledgable than myself, what choice of hull could I make to lessen the chance of needing to make the decision to deploy a series drogue in the first place. ...

Not choice of hull: choice of route and of weather.

Plan a coconut palm circumnavigation and/or near coastal waters, and carry sufficient communication methods such that you can always get a weather forecast. Problem solved - extremely low likelihood of encountering conditions that could require a drogue.

[arsenelupiga]

Originally Posted by joelhemington

I think Mark touched on it nicely. I'm not going to argue the merits of a heavy cat versus a light cat but catamarans all have one main defense mechanism and that's the ability to outrun nasty weather. You normally get a three day weather window with modern electronics which means a faster, lighter cat can get you about 100nm farther out of harm's way than the slower heavy boat.

most of time no wind before storm so engines will be used to escape. Then will be hull speed at best unless you motorfreak and have oversized engines.

If there is wind and have to run motorsail can produce amazing averages. Heard that Lagoon 50 that made >1000nm trip at 15 kn average motorsailing.

[44'cruisingcat]

Is heavier safer? I don't know, let's find out.

Take a boat. Any boat.

Add weight to it....

Keep adding weight.....

Keep adding weight.....

See what happens....

[chrisr]

Originally Posted by 44'cruisingcat

Is heavier safer? I don't know, let's find out.

Take a boat. Any boat.

Add weight to it....

Keep adding weight.....

Keep adding weight.....

See what happens....

i know what you are saying : yes, any overloaded boat is not safe...but i'm not sure that's the question

consider different designs / styles, for same size. is a, say, spirited 380 safer than a, say, lagoon 38 ? the answer is not simple but runs on the board says NO

cheers,

[CatNewBee]

Originally Posted by 44'cruisingcat

Is heavier safer? I don't know, let's find out.

Take a boat. Any boat.

Add weight to it....

Keep adding weight.....

Keep adding weight.....

See what happens....

Ok, lets do it the other way around. Take a boat and remove stuff, to make it lighter. thinner bulkheads, hulls, leighter mast, remove material everywhere... you think it will float in a storm?

There are light racing boats, that disintegrate on the run.

[smj]

Originally Posted by CatNewBee

Ok, lets do it the other way around. Take a boat and remove stuff, to make it lighter. thinner bulkheads, hulls, leighter mast, remove material everywhere... you think it will float in a storm?

There are light racing boats, that disintegrate on the run.

If it breaks it was built to light, if it doesn’t break it was built to heavy. There’s no winning!

[siggy]

I could have been a little clearer when I posed the question but yes, I was looking at it from the point of view of a potential liveaboard cruiser.

My understanding of the responses so far is that light weight does not automatically convey extra safety but does give such a boat the advantages that we have considered, such as extra speed. This does give a safety factor but only if the skipper actively uses it to evade bad weather. But only up to a point, extreme light weight performance boats may possess speed but might be too much to handle for a sailing couple so it’s just a matter of choosing a boat that has the right compromises for the sailing I intend to do.

Thank you everybody for your responses, they have given me different ways to think of this issue.

[siggy]

Originally Posted by donradcliffe

I haven't any offshore experience in cats, but I once took an ultra light mono to New
Zealand from the US. We were going downwind in 45-55 knots for a day. I was a little concerned about pitchpoling until I saw that the light boat never got on the steep part of the waves, which were 4-6 meters. We were doing 14-18 knots with just a reefed main and the autopilot couldn't keep up, so the biggest problem was doublehanded driver fatigue.

Hi Don,



Can you explain a bit more about this situation and what you did? Thanks.

[smj]

Just a thought, if you used exotic materials and were able to build a Lagoon 450 10,000 lbs. lighter and just as strong would it be safer? It would be faster but the speed would still be somewhat limited by hull design. It would ride more on top of the water rather than through. If all else fails it would have the load carrying capacity increased by 10,000 lbs?

[sailjumanji]

Originally Posted by siggy

My understanding of the responses so far is that light weight does not automatically convey extra safety but does give such a boat the advantages that we have considered, such as extra speed. This does give a safety factor but only if the skipper actively uses it to evade bad weather.

We bought a faster boat because it allows us to cover more miles during daylight hours. To make it to anchorages that we otherwise would have to leave in the dark to make it to before sundown, or arrive after sundown. Both carry additional risks. That's a more practical and frequent use of the speed advantage.

[donradcliffe]

I will pass on some words from Lowell North (founder of North Sails), who did a circumnavigation on a Tayana 55, but who also spent a lot of time on his son Danny's 40 ft cat. He said that based on the weather he encountered, he would choose a cat next time, a minimum of 40 ft for bridge deck clearance. I carried a drogue and a parachute anchor on my circumnavigation, and used neither. OTOH, neither Lowell nor I sailed around in hurricane season looking for trouble, or in high latitudes during the winter. It was never his or my goal to sail around Cape Horn.

If you obsess with safety, you end up with a crab crusher steel monohull which you have to motor to weather. A cat demands more seamanship if you put the sails up, and a light cat demands a bit more. Any cat can be flipped if you press it hard enough, and its easier to flip lighter ones, but my choice would be based on which is more of a joy to sail.