Questions About the Wider Beams on Newer Boats

[minaret]

Originally Posted by Cheechako

Yeah, those beams carried aft are slow and cant survive the southern ocean!

Obviously these boats racing "down there" is more of a testament to the crews than the boats. After all, Shackleton proved you can do it in a dinghy with the right crew. Doesn't mean it's wise, or comfortable. Just look at the litany of gear failure, lost rigs, and lost boats in that sort of racing. Then compare to the rate of loss in the cruising set, who tend to set out for such locales in more sensibly designed boats.

[Blue Crab]

"Southern Ocean" ... sounds quite pleasant ... palm trees ... nearly nekkid island girls... sailing fun in the sun ... penguins????????

Happy Monday or Tuesday.

[Weyalan]

Questions of build "quality" are hardly relevant in a discussion about wide beams. The hull shape says nothing about the build quality, nor vice versa.

Like all things, hull shape is a compromise. There are few aspects of of yacht design that are win-win. Wide beam, carried aft has certain advantages in sailing performance (greater form stability, ability to plane) and comfort (greater internal volume - bigger cabins, etc) and certain disadvantages (greater form stability upside-down, harder ride in heavy conditions).

Personally, I reckon that the current trend towards production yachts being beamy, with that beam carried aft (with chines in some cases) is motivated more by the internal volume considerations than by the sailing performance, and I'm not saying that is a bad thing.

Happiness is about being satisfied with what you have. If you are happy with your boat, don't worry about the other guy.

[mrohr]

Weyalan :You post says it as well any.

[SecondBase]

Originally Posted by goboatingnow

12 ' ruler test lol.

Its important to point out that high prismatic boat types have to be sailed differently. They are designed to be fast and flat. In heavy weather you need to reef down often a lot.

Sometimes in heavy weather you'll even stop sailing and hove-to or lie-to. There are a couple ways I connected build quality into hull initial stability.

First is that in snotty weather I use two initial stability calcs for two different configurations.

Under sail - your regular stability calcs as described earlier in this thread.

Under heavy weather - I actually add in an additional righting moment off the bow and midship cleats. The line on a sea anchor bears significant tension parallel to the oceans's surface. My hypothesis is that a cruiser's hull with a sea anchor or drogue on Mr Pardey's "50 degree angle" off the hull is harder to roll than the same hull without a sea anchor because of this force. As the boat rolls, the righting force of the sea anchor line increasingly becomes directly opposite the direction of roll: Unless a low quality cleat fails at say 90 degrees. I would not trust half of the production cleats I see today to remain attached and not deform under load. Mr. Jobson also discusses using a sea anchor or drogue so I don't feel it is a stretch to include this tactic in blue water hull stability.

The second way I connect build quality to wide hull performance that the cleats were funded by the same design approval committee that blessed the scantlings. I estimate there is a 75% or higher correlation between undersized scantlings and undersized cleats. Clears are easier to inspect. I know this is unfair to designs that highly value scantlings but don't think a cleat needs to stand up to the rolling moment on the high seas. LOL It does save time in boat show lines.

I hear that "waves 60% of the LOA can roll the boat" and my question is has anyone tank tested a change to that equation with a drogue? Interested to hear from the testers on that question.

[Roy M]

Wide beams all too often simply mean a longer distance to fall across the cabin when heavily heeled and bashing to weather. They are empty space generators.

[Mal Reynolds]

When the wind is forward of the beam, wider beam typically translates into more pitching as the waves will push the wider bow sections up. Narrow boats will tend to slice through waves and the motion will be easier. Wider boats can be more dangerous down below when wind is forward of the beam in a breeze as people can fall farther. Handholds, braces, and sharp corners should be thought out if the vessel is going offshore. But gentlemen don't go upwind anyway.

When the win is light, wider boats have higher wetted surface and will be "sticky" and slower in light air (all else being equal). So more time motoring.

Off the wind, wider boats will be able to carry more sail due to form stability and likely be faster, provided there is enough wind. However, when heeled the rudder can be pulled out of the water (unless there are 2 rudders) and can lose steerage capability, necessitating sail reduction & offsetting speed advantages when reaching in stronger breezes.

In survival conditions, the wider boat will tend to stay inverted for longer than the narrow boat, but here it's really more about the skipper than the boat.

But these sailing characteristics are offset by the large advantages of space and comfort in the marina and at anchor, where the vessel spends the bulk of it's time. So for most, the wider boat makes more sense. The exception is if you want to go offshore and be able to more comfortably take whatever nature throws at you.

[Curmudgeon]

They should emulate cats and put escape hatches in the bilges, so that when these new designs flip over, they can be used as life rafts. No need to carry one separately.

[goboatingnow]

Originally Posted by Mal Reynolds

When the wind is forward of the beam, wider beam typically translates into more pitching as the waves will push the wider bow sections up. Narrow boats will tend to slice through waves and the motion will be easier. Wider boats can be more dangerous down below when wind is forward of the beam in a breeze as people can fall farther. Handholds, braces, and sharp corners should be thought out if the vessel is going offshore. But gentlemen don't go upwind anyway.

When the win is light, wider boats have higher wetted surface and will be "sticky" and slower in light air (all else being equal). So more time motoring.

Off the wind, wider boats will be able to carry more sail due to form stability and likely be faster, provided there is enough wind. However, when heeled the rudder can be pulled out of the water (unless there are 2 rudders) and can lose steerage capability, necessitating sail reduction & offsetting speed advantages when reaching in stronger breezes.

In survival conditions, the wider boat will tend to stay inverted for longer than the narrow boat, but here it's really more about the skipper than the boat.

But these sailing characteristics are offset by the large advantages of space and comfort in the marina and at anchor, where the vessel spends the bulk of it's time. So for most, the wider boat makes more sense. The exception is if you want to go offshore and be able to more comfortably take whatever nature throws at you.

This is one of the most biased and factually wrong posts I've read in a long time.

Dave

[Jim Cate]

Originally Posted by goboatingnow

This is one of the most biased and factually wrong posts I've read in a long time.

Dave

Agreed!

Jim

[El Pinguino]

Originally Posted by Mal Reynolds

Wider boats can be more dangerous down below when wind is forward of the beam in a breeze as people can fall farther.

When the win is light, wider boats have higher wetted surface and will be "sticky" and slower in light air (all else being equal). So more time motoring.

Off the wind, wider boats will be able to carry more sail due to form stability and likely be faster, provided there is enough wind. However, when heeled the rudder can be pulled out of the water (unless there are 2 rudders) and can lose steerage capability, necessitating sail reduction & offsetting speed advantages when reaching in stronger breezes.

I don't really know where to start.. I have owned both types.
My first keel boat ( 10 years with her) was a long keeled 25' Vertue... went to windward like a witch, pointed high, never slammed, a joy to sail uphill or downhill.

My present boat ( 19 years with her) is a fat old fin keeled sort of a thing... 39' LOA with a 13 ' beam.
I once went to windward for 10 days in the SE trades... cracked the sheets a bit... didn't try to pinch her... sailed flat... went fast. She didn't pitch but about once a day she would get a bit of daylight under the forefoot and when she slammed would damn near knock your fillings out.

I think she has less wetted surface as a factor of length than the Vertue.... she pokes along in a very satisfactory manner in light airs... and I must say I have never ever come even remotely near getting the rudder out of the water.... repeat after me... flat is fast... flat is fast.

And no she doesn't live in a marina, and yes she has done a lot of ocean miles, 90% of her time in my ownership has been south of 40 south( ok south of 39 south....)... and about 5% of the rest on the Patagonian coast of Argentina.

Some fat boats are horrors designed for the charter trade...some skinny boats would be shockers downhill in a blow....

[Dockhead]

My present boat has a quite conservative hull form for a modern boat, with a fairly traditional beam/length ratio and a relatively narrow transom for a modern hull.

However! It took me years to learn to sail her correctly after a lifetime in older-fashioned "lead mines", with narrow transoms, deep forefeet, high ballast ratio, long keel, etc.

The main thing is -- and many people told me this, it just didn't sink in sufficiently -- you can't let them heel too much. Beyond 30 degrees heel and in stronger wind, my boat develops terrible weather helm. She also has a very powerful rudder, so I've never come close to broaching, but nothing good happens beyond 30 degrees of heel.

I finally understood this sailing with reefed headsail alone -- something I would have never done without the wind well abaft the beam, but I had to make an unexpected change of course in a strong wind and did not want to faff around putting mainsail out again. So with just a little yankee out and nothing else, so with center of effort just as far forward as it could possibly be, I was still getting strong weather helm whenever the boat was heeled beyond 30 degrees. Boy, talk about a light bulb going off in my head.

So as others have said, you have to sail these boats flat. As much as you may hate to reef, as I do. My previous boat liked to heel about 45 degrees, and as the waterline length increased she would go faster. Not this one!

[noelex 77]

Its more constructive to point out the parts you disagree with.

I would contend that wider boats generally have less displacement because their improved form stability allows for a lower ballast ratio. Rather than "increased pitching" upwind the flatter sections show increased pounding.

Originally Posted by Mal Reynolds

Narrow boats will tend to slice through waves and the motion will be easier. Wider boats can be more dangerous down below when wind is forward of the beam in a breeze as people can fall farther. Handholds, braces, and sharp corners should be thought out if the vessel is going offshore. But gentlemen don't go upwind anyway.

Agreed

Originally Posted by Mal Reynolds

Off the wind, wider boats will be able to carry more sail due to form stability and likely be faster, provided there is enough wind. However, when heeled the rudder can be pulled out of the water (unless there are 2 rudders) and can lose steerage capability, necessitating sail reduction & offsetting speed advantages when reaching in stronger breezes.

In survival conditions, the wider boat will tend to stay inverted for longer than the narrow boat, but here it's really more about the skipper than the boat.

But these sailing characteristics are offset by the large advantages of space and comfort in the marina and at anchor, where the vessel spends the bulk of it's time. So for most, the wider boat makes more sense. The exception is if you want to go offshore and be able to more comfortably take whatever nature throws at you.

Agreed

[El Pinguino]

So...... you agree with Mal that beamy boats can lose steerage due to the rudder coming out of the water?
OK....

[goboatingnow]

Beamy boats ( and were not talking about extremes ) show no particular issue with rudder ventilation

Form stability means better sail carrying ability and flatter sailing , light wind performance is enhanced by lower wetted surface ( less immersion( and ability to carry more sail

Underwater , fin and spade provide high dynamic performance and superior hydrodynamic characteristics

Beam carried aft provides for increased waterline length and hence more speed

Improved buoyancy forward as well.

Drawbacks include tendency to pound ( which isn't really a beam issue , more flat underwater profiles )

Wide beam does require improved interior handholds Etc and the lack of them is more a design issue then a beam one

Note that inverted stability is very much determined by the cabin structure, modern yachts with significant top hamper actually exhibit better numbers then the hull AVS suggests ( from the incline tests etc) take for example the moody 45 DS which has no negative curve. ( ie it will never stay inverted ) yet its a typical beamy boat with the beam carried right aft ( and hence twin rudders )

Dave