Easy way to reduce rolling on bilge-keeler?

seasquirt said:

I was assuming this means she is forced to the lee, or maybe as gonzo suggests, is she rounding up instead ? If blown to the lee, set less foresail, or try the mizzen, if rounding up, set less sail area to the rear, and more at the bow. The mizzen may be there to balance it better, but more work single handed. Maybe you are pointing too high, and almost stalling, so going slower, and the rudder is not so effective with less flow over it. Maybe try pointing off the wind a few degrees more than usual, getting more hull speed, more effective rudder, and with the wind load setting a more permanent mast heel angle, riding more on the lee chine, then the windward side of the hull will more out of the water, and not causing so much roll. The hull shape may prefer running well heeled over in a beam swell. With the extra ballast plates added, more than its design, you shouldn't need any more.
What do other owners have to say about it, or is its designer still available to ask questions to ?

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You're right, she was being forced to lee by gusts, not rounding up. The genoa is fairly small, but maybe you're right, maybe I should focus more on using the mizzen to balance the boat. I have tried sailing to windward with just the mizzen and genoa and it worked quite well, though the mizzen does have a tendency to make her round up if sheeted too hard. Using all three sails is a lot of hard work, single-handed, for a short trip. Maybe, as someone else here suggested, a staysail set on my inner forestay would work better than the genoa, though again more work, unless I install a furler on it.

There are some useful tips to try there, thank you. Unfortunately the original builder has passed away, and as far as I know the boat is the only one of her class. I have talked to the owner of another boat from Cruiser Kits (who ceased trading long ago, when fibreglass hulls took over), and he says she was much too light and he had to add a lot more ballast under the sole. However lead is so expensive these days that could be a very costly exercise!

Richard Reed said:

That's really interesting. Do you think these would be more effective in reducing roll than adding a single, unballasted central keel?

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After being in a rolling anchorage for a year the 1st position went to Hanse new brand 50 something yacht, probably as consequence of the lateral overhangs in the wide stern, it rolled quite violently with little waves and created pendular momentum


The second position went to 80s IOR yachts probably because the high freeboard and cabin height compared to length and beam


I didn't know that ballasted bilge keels create rolling

A good new design bilge keel boat like we are talking here is the puffin 30



I have designed a similar concept tri-fin sailboat with large fins across the hull and with internal hull ballast and i think it would be pretty stable besides helping with reef collision with gradual slope like centreboards stern keels

Also a T or L profile in these fins like in wing keels would damp rolling and pitching motions

Interesting what you say about the rolling problem of a brand new (and very expensive) 50ft yacht! Maybe my 'new' boat is just so different to my old Moody 33. But I do like the idea suggested by someone of a couple of lateral bilge dampers on either side.

I like that design of yours – she's a lovely-looking boat and an interesting concept. There was at least one long-keel British boats in the 70s and 80s that had a lifting daggerboard within the main keel, the Barbican 33, but I've not seen a stern or forward daggerboard like that. As a layman, the only downside I can think of is the propensity to get tangled and damaged in fishing nets.

Richard Reed said:

Interesting what you say about the rolling problem of a brand new (and very expensive) 50ft yacht! Maybe my 'new' boat is just so different to my old Moody 33. But I do like the idea suggested by someone of a couple of lateral bilge dampers on either side.

I like that design of yours – she's a lovely-looking boat and an interesting concept. There was at least one long-keel British boats in the 70s and 80s that had a lifting daggerboard within the main keel, the Barbican 33, but I've not seen a stern or forward daggerboard like that. As a layman, the only downside I can think of is the propensity to get tangled and damaged in fishing nets.

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If you find a ghost net you should call local associations to retrieve it, these nets kill a lot of marine life and you can wait for them or give gps coordinates and place a fender buoy

These are "pivot bilge boards" i suppose guessing a name and the Puffin 30 is a new dutch sailboat, a very good design with good hull lines to be honest


my design is here, it has 4 bilge pivot boards and a bow pivot board too

Lately I have thought to pivot these boards in the hull and make the bilge fins more shallow



D Warehouse https://3dwarehouse.sketchup.com/model/ec49cb3c-06ba-4ae1-bcea-78def2b9932f/Oblada-8-sailboat

Looking at what you have, I think there are few things you can do about it other than learn how to set it up on any given day. The added weights on the bilge keels don't help. The rig looks to be very heavy for the hull style. It could be rerigged at half the spar and stay weight, but yours will probably last forever on that boat. If taking the added plates off is possible, I would definitely try taking the inboard plates off the fins. That doesn't cost anything to try.

The ballast plates should be faired into something approximating a foil shape. They should have large flats on the inner surfaces and more shape on the outboard surfaces. The trailing edges should not be blunt. Getting the foils to work better at higher specific loads when pointing will help considerably. That's the first thing I'd do. Nothing fixes handling problems faster than going a little faster through the water with the same applied sail power.

The sails need to be cut pretty flat. Particularly the mizzen. It could be a sheet of aluminum and work just fine. If the mizzen has much of any draft, it won't help you. Reefing basically goes main sail reef, second mainsail reef, switch to a standard jib if you have one, then dowse mainsail and run jib and jigger. Jib and jigger is also how to sail off the hook and out of the anchorage when short handed.

The hull shape is very versatile and can carry a wide range of loads and sail well with a simple set of sails. But it achieves that by sailing at substantial heel angles by modern standards, and will be tender and a bit rolly at the dock. Get her heeled over to 14-17 degrees and she will settle down nicely. Rail down is normal sailing for this hull shape. She can probably trundle along nicely at 25 degrees of heel and water up to the cabin ports.

When sailing in beam seas, your weapons are flat sails. As the boat tries to roll, the sails will provide the damping. A non-overlapping jib is handy here. Properly profiled foils will also provide damping at speeds above about 2 knots. But if you get caught in a rolly anchorage or are facing a dying breeze in a left-over sloppy seaway, you are out of luck. That hull is just going to roll.

@Herreshock

"80s IOR yachts probably because the high freeboard and cabin height compared to length and beam"

80's IOR yacht - <3' freeboard, about 13' beam. These were seriously build-down designs. And even with a big cheater mast (not counted as sail area) and 57' air draft on 33 WL, they didn't roll badly unless you were way overpowered under spinnaker.

philSweet said:

@Herreshock

"80s IOR yachts probably because the high freeboard and cabin height compared to length and beam"

80's IOR yacht - <3' freeboard, about 13' beam. These were seriously build-down designs. And even with a big cheater mast (not counted as sail area) and 57' air draft on 33 WL, they didn't roll badly unless you were way overpowered under spinnaker.

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There were different IOR yachts in late 70s and during 80s, ones "beamier" like that stable hull shape you posted and others with high freeboard compared to beam or length and plenty of lateral and bow-stern overhangs that create pitching and rolling

Richard Reed said:

Interesting what you say about the rolling problem of a brand new (and very expensive) 50ft yacht! Maybe my 'new' boat is just so different to my old Moody 33. But I do like the idea suggested by someone of a couple of lateral bilge dampers on either side.

I like that design of yours – she's a lovely-looking boat and an interesting concept. There was at least one long-keel British boats in the 70s and 80s that had a lifting daggerboard within the main keel, the Barbican 33, but I've not seen a stern or forward daggerboard like that. As a layman, the only downside I can think of is the propensity to get tangled and damaged in fishing nets.

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The big issue is that every vessel has a "period of roll" created by her shape, metacentric height etc. Each wave also has a period. Every vessel rolls significantly, sometimes dramatically, more when her own period of roll is the same as the wave periods.

The effect of this, known since Froude's paper of 1861, is that it's useless to say "this 50 footer rolled in this anchorage and therefore it must roll because of its design". The vessel in question could normally be much MORE resistant to roll than usual, but merely be anchored in a place where the wave period is close to the vessel's individual period of roll, but not close to the period of roll of other vessels moored nearby.

The effect of this is that any account that a particular vessel rolled more in a particular anchorage must be treated with extreme caution - it could just be that the normal wave period in that particular anchorage coincided with the particular period of roll of that vessel more than of others.

philSweet said:

And even with a big cheater mast (not counted as sail area)

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???? With respect the rig height was measured and high aspect rigs penalised under the IOR. Can't see that as a "cheater mast".

Herreshock said:

There were different IOR yachts in late 70s and during 80s, ones "beamier" like that stable hull shape you posted and others with high freeboard compared to beam or length and plenty of lateral and bow-stern overhangs that create pitching and rolling

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So which "IOR boats" had high cabins? None that I raced against.

Here comes the paper of the arquime-freudian theories.... These wide beam sailboats roll like crazy, all pogos, hanses, etc with whatever the size of the waves that arrive they start a violent pendular momentum, and both cases are different

-pogo with big span mast and keel and ultra-wide beam with stern lateral overhangs even if having low freeboard

-hanses with medium-high freeboard and with wide beam stern lateral overhangs at considerable height, basically an inverted wide piramid which is the most unstable shape

There's some cases in an anchorage where a boat rolls more and probably related to the coast refraction , always there's a "sweet spot" where sailboats roll more than the rest

In the case of these IOR yachts the high freeboard (related to length and beam) makes the cabin height

Herreshock said:

Here comes the paper of the arquime-freudian theories...

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Wrong. No person with any capacity for reason and knowledge of boats would confuse Froude with Freud.

IOR boats in general did NOT have higher distance from waterline to top of the deckhouse than modern boats in general. IOR boats were regularly designed down to IOR minimum interior height requirements. Modern boats in general are designed for more interior space and height and since they have proportionately shallower hulls they end up with higher freeboard or deckhouse than IOR boats of similar length.

This is clearly shown by the progression of Beneteau 30 footers, for example, which show that your claim is complete codswallop. Look at the difference as the Beneteau 30 footers aged from the low hulls of the IOR era to the high-sided later boats;

Early IOR era Beneteau 30 of the early '70s.


Later IOR 30' Beneteau First Evolution IOR racer of the early '80s



The extremely popular non-IOR Beneteau 31.7 of the late '90s.



Current 30ft Beneteau cruiser, the Oceanis 301



Current Beneteau cruiser/racer 30



Original First 30. LOA 8.95m; midships freeboard .985m; cabin top 1.37m above WL.
First Evolution 30. LOA 9.4m. Midships freeboard .7m; cabin top 1.41m above WL.
First 31.7. LOA 9.6m; midships freeboard 1.05m; cabin top 1.57m above LWL
Oceanis 301. LOA 9.53m; midships freeboard 1.19m; cabin top height 1.74m above LWL.
New First 30 LOA 9.35m. Midships freeboard 1m; cabin top 1.5m above WL.

The IOR boats had the lowest freeboard and overall height, and this is quite typical. The currrent cruiser has 120- 170% of the freeboard of the mid-era IOR boat.

There are some people that have some comprehension issues related to understanding the term "high freeboard related to beam (overall beam, not just midship beam) and length and longitudinal and lateral overhangs hull lines".

Most of late 70s and 80s sailboats were influenced by these midship beam, high freeboard and overhang boats while there were also narrower shorter freeboard and taller deckhouse designs.

And that high freeboard form stability "was corrected" by stern beam increase ending in todays "shoebox" sailboats to maximise interior design

However wide stern form stability is initial lateral stability appreciated under rolling conditions but IOR influenced boats don't slam into waves and have final lateral stability and can heel without reefing because these overhangs canoe shape while the other wide stern boats need remove sail or prepare to broach

Freeboard to length and beam ratio is a big issue for stability thats why Beneteau boats started to reduce freeboard and increase deckhouse height to keep same cabin interior height, however freeboard and beam went out of hand and thats why Hansen boats are very unstable under static roll

Herreshock said:

There are some people that have some comprehension issues related to understanding the term "high freeboard related to beam (overall beam, not just midship beam) and length and longitudinal and lateral overhangs hull lines".

Most of late 70s and 80s sailboats were influenced by these midship beam, high freeboard and overhang boats while there were also narrower shorter freeboard and taller deckhouse designs.

And that high freeboard form stability "was corrected" by stern beam increase ending in todays "shoebox" sailboats to maximise interior design

However wide stern form stability is initial lateral stability appreciated under rolling conditions but IOR influenced boats don't slam into waves and have final lateral stability and can heel without reefing because these overhangs canoe shape while the other wide stern boats need remove sail or prepare to broach

Freeboard to length and beam ratio is a big issue for stability thats why Beneteau boats started to reduce freeboard and increase deckhouse height to keep same cabin interior height, however freeboard and beam went out of hand and thats why Hansen boats are very unstable under static roll

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You have comprehension issues related to comprehending reality. The IOR boats did NOT have high freeboard related to beam, as the samples above indicate. You have presented no data for your other claims and they are probably as false as the many other completely untrue claims you have made here. You have been throwing false insults at many, many people from your castle of ignorant arrogance and it's extremely tiresome.

You are incorrect when you say "Beneteau boats started to reduce freeboard" and the figures above show that. Beneteaus and many other boats have increased freeboard.

Since 1861 other people have known why a particular boat may roll in a particular anchorage. You are 160 years behind in your understanding but that is your problem and no one else's.

I cannot see the pictures of the 1980 beneteau 30 and noticing his rectilinear deck profile while 1990s beneteau 31.7 has a curved longitudinal and downwards deck profile lowering from bow to aft and so reducing freeboard and increasing deckhouse height and also i cannot see the 31.7 flattening the bilge longitudinal curve to create more space and initial form stability, and reducing pitching while increasing slamming


I also cannot see the boat increasing total longitudinal beam because I cannot differentiate midship beam with total longitudinal beam midship-to-stern

I haven't lived in a IOR yacht testing all fake rolling damping techniques worthless ( bucket,etc)

The last Beneteau creates a lot of rolling because they traded less aft beam and more rocker with less rocker and more aft beam with lateral overhangs