Shallow draft vs deep draft performance

[barnakiel]

Originally Posted by SlashV

OK, but this was just a 1'1" difference in draft. The First 51 has a 3'3" difference. I guess wings can compensate for a one foot draft difference, but I'm quite sure a 3 foot draft reduction will hurt. The question is: how much?

Enough to lose any winward leeward club race.


Easily 5 degrees.



Racing? Take the deep draft First.


b.

[NedX]

Originally Posted by SlashV

OK, but this was just a 1'1" difference in draft. The First 51 has a 3'3" difference. I guess wings can compensate for a one foot draft difference, but I'm quite sure a 3 foot draft reduction will hurt. The question is: how much?

It was a bulb on the shallow draft, but I guess performance-wise same difference. The 1 foot is a big deal in Boston harbor (there are two or three useful channels where it makes a difference) but I see what you mean. It's off topic but I'm really curious to see how a Seaward or something with a retractable keel performs.

I loved your solo on November Rain, btw, Slash

[wingssail]

Originally Posted by barnakiel

Enough to lose any winward leeward club race.

Easily 5 degrees.

Racing? Take the deep draft First.

b.

AND... Enough to want to take the sails down.

Not racing? Take the deep draft if you want to enjoy the thrill of a great performing boat at all times.

It's not just the keel. Its the short rig and extra weight.

[sandy stone]

I have a Beneteau First 375, a design from the mid-80's, with the shoal keel. I wasn't crazy about the idea, but my sailing (and particularly berthing) venue made it almost a necessity. The standard keel was around 6-1/2 feet, and the shoal is around 5, without a bulb or wing. As it happens, the canoe body seems to be a bit less than 2 feet deep, so there is still a respectable lateral plane, but of course the aspect ratio suffers. The rudder is 3 or 4 inches shallower than the keel. IOW, not much, and you need to be careful.

I do some club racing and I think the rating difference between the deep and shoal keels is 12 sec/mi. With good sails, we actually don't do too bad, even upwind, although we are outpointed by a shoal keel First 36.7 and a shoal keel J109. I have to think the deep keel version would be a rocket, but overall I am quite happy with the performance of my boat.

That being said, that looks like a really significant difference between the two keels on the boat the OP is looking at, and my experience with wing keels has not been impressive at all. I think the shoal keel on that boat would a much tougher compromise than I had to make.

[Scaramanga F25]

Please understand that many French-built designs have iron keels, therefore, need a deeper draft. A lead keel as an available option you could have shoaler draft and have the same righting moment.

[MicHughV]

lead keels might provide a good righting moment, but you still need to have lateral resistance to go to weather...The Beneteau has a cast steel/iron keel....a foil shape with a thickened bottom...not quite a bulb, but thick. Though only 5'6" draft, it goes to weather well, something I attribute to hull shape.

[Carolyn Phillip]

Reply to
"I'd like to get an insight into (in particular upwind) performance differences between shallow draft and deep draft versions of a yacht. I'm currently looking at a Beneteau First 51. The shallow draft version has a draft of 1.8m vs 2.8m of the deep draft version, a mast height of 22.5m vs 23.7m and is a ton heavier than the deep draft version."

My response ....
I once owned and sailed extensively down island for several years a beautiful, large Beneteau "Idyll", and found her very responsive and fast; I also experienced her V-berth hull flex in a sea. It jarred me almost out of the bunk!
Penalties of shallow draft (esp without a centreboard or daggerboards I found may be drift/sideways slippage going to windward...but it is sure nice to have less draft for waters like Bahamas and many S Pacific tropical atolls, or getting close, right into shore in more protected anchorages!
A heavy, seaworthy boat with deep keel, on the other hand surely on long and deep sea passages, gives more ride comfort and better tracking, and perhaps safety--but may not be not as quick or responsive.
But then, what cruiser wants to hurry--except from nasty conditions? My own aged adage is that cruisers go everywhere slowly, while racers go nowhere fast. (haha)
Now past the age and glamour of racing and discomfort of many thousands of ocean passages, I surely do enjoy the advantages and flexibility of shallower
draft. I find this especially so currently when cruising around popular, often crowded anchorages and/or serene, pristine, but isolated and difficult to get to spots. My own bias and preferences are a result of a lifetime addiction to the sea, of oceans passages crewing, and of cruising on my own sailboats.
The choice between deep or shallow draft comes down to where and how you plan to sail. But whatever your choice, a wonderful experience it must be to be, dreaming of and buying ones own boat and going sailing on it! I wish you all the best.



Regards.[/QUOTE]

[sailorladd]

I built a Hartley "Tasman" bilge keeler which had a shallow draft and the designer assured me that with the aid of the large engine he included in the design of this motor sailor that it would perform well upwind....

This was the biggest mistake I made during the construction. Long story short, no matter what I did, she never sailed well to windward, with or even without the motor. I eventually hauled her up in the yard a few years later, in order to rectify this situation. If I could not sort it out I knew it was the end of my dream of building a boat and sailing around the world.

I ended up grinding off these metal plates which the twin keels were made of, and created a normal, long, deep draft keel (5 feet from waterline to bottom of keel), with a cut away forefoot just below the mast position and built in an extra ton of lead in ingots and concrete, to stabilize her as she also was rather tender. The rudder was rebuilt and now fitted to the trailing edge of the keel.

The difference was incredible, like a totally different boat! I have since completed my dream, and still own my lovely Deja vu, some forty years later.... moral of the story, if you are considering blue water cruising do NOT hesitate to get the deeper drafted vessel..I described the whole incident in my book Days of Deja vu..

[Sailing4Jesus]

Mates,

When ya run into a full-blown Hurricane, it's The Lead Deep Down In Ya Keel what's gonna see ya through safely to sail another day. Though we all like the benefits of a shallow draft I personally believe that bosts with shallow drafts ought best to stay close to shore. Mind ya, this is only my convictions, however, two plus two is still FOUR. Right?

Senior Chief Moanbac, U.S. NAVY, RETIRED

[Pete7]

Originally Posted by Sailing4Jesus

Mates,

When ya run into a full-blown Hurricane, it's The Lead Deep Down In Ya Keel what's gonna see ya through safely to sail another day. Though we all like the benefits of a shallow draft I personally believe that bosts with shallow drafts ought best to stay close to shore. Mind ya, this is only my convictions, however, two plus two is still FOUR. Right?

Senior Chief Moanbac, U.S. NAVY, RETIRED

Utter rubbish IMHO, the chances of a small yacht surviving have more to do with luck in a "full blown hurricane" than anything else.

Pete

[lewisa]

IMHO, deep draft is always better for performance upwind. The price you pay for deeper draft is fewer places you can navigate. When I lived aboard in Long Island Sound, anything greater than a 5 foot dreft seriously limited where I could anchor and, sometimes, the ability to take a short cut to a destination. Now that I am in Maine, draft is rarely an issue. I currently moor in 30 feet of water and almost never need to anchor in less than 15 feet. But I still have my 45 year old boat with a 5 foot draft and watch the "go fast" sailboats point higher than can I. But I still get where I'm going, it just takes an extra couple of tacks.

[Cool Hand Luke]

I have a Jeanneau SO409 (39 feet) with a 6'11 draft (approximately 2.1 meters) and I love it. In an opean ocean, she'll plow through anything. Yes, I did get stuck in some sand bars when going close to shore, but the bulb keel made it easy to reverse and move on to deeper waters. Do I wish I could go closer to shore? Sure!! Would I change her for a shallow draft? Never. At least not on the SO409. Just my 2 cents...

[chasfgr]

The only direct comparison between the two, for me, was comparing the versions of the Deep Sea Dog with its bilge keel version - the deep kel version tacked through a true 90, the bilge keel was closer to 110 degrees. To windward the deep keel version was about 8% faster, offwind the bilge-keeler slightly the quicker.
My current boat has a lifting lead wing keel. Only try sailing with keel down, tacks through 65 degrees, is fast offwind and quicker to windward than any comparable LOA boat, except a few round-cans-racers with good crews.95% of the ballast is 1805mm below the waterline.
The fastest I've been offwind, over a 65nm sail was 7.38 mean speed - surfing at 14kts, on GPS, when you could catch a breaker. It was blowing Bf5-6 though.
Keel up it floats in 750mm water, but is uncontrollable as the rudder blade has to be lifted.
I've owned the boat for 30 years, sailed it about <65K nautical miles, round the Western Approaches, usually single handed.
Now in the Med where she is, almost literally, a fish out of water.
Still it's amusing to watch boats trying to anchor as close to the beach as mine.

[Seabeau]

Originally Posted by Sailing4Jesus

Mates,

When ya run into a full-blown Hurricane, it's The Lead Deep Down In Ya Keel what's gonna see ya through safely to sail another day. Though we all like the benefits of a shallow draft I personally believe that bosts with shallow drafts ought best to stay close to shore. Mind ya, this is only my convictions, however, two plus two is still FOUR. Right?

Senior Chief Moanbac, U.S. NAVY, RETIRED

Actually, per Adlard Coles in his "Heavy Weather Sailing", the vessel with absolutely no keel, is by far the safest in extreme conditions accompanied by breaking waves. It's simply basic physics. A vessel with no keel can simply "slide sideways" when struck by a breaking wave. Subsequently, a multihull with very shoal or no keels or a mono-hull with a lifting keel/centerboard would be the safest, all other factors being equal.

[Jim Cate]

tacks through 65 degrees,

Kinda hard for me to believe. So, please some more info on this fantastic design.

Jim