Coastal Sailing vs. Blue Water Sailing

[robert sailor]

Yes Web is quite the boy but he really dances to a different drummer, I much prefer company rather than my own but you can't take anything away from that boy, he is a sailor. The real beauty about small boats is that they don't pick your pocket book to pieces and on average small boat sailors sail way more than the big boys who motor damn near everywhere. There is much good to say about small sailboats.

[ohYes]

OK... so I'm a bit of a math nerd but I would like to add that things like motion comfort (nice list of boats at below link)
http://www.cruisersforum.com/forums/...io-114288.html and capsize ratios (you can find all related formulas below)
Capsize Formula
are pretty important if you're ever planning on crossing oceans.

[stevensuf]

When I looked into all this "Blue water" nonsense, the conclusion I came to , was size matters!

Look at the Fastnet disaster, not one boat over 40 foot was lost, a bigger beamier boat takes a bigger wave to roll.

Blue water= 40 foot plus!

[robert sailor]

Well you are right of course a bigger boat is harder to roll however boats with lots of beam and lighter keels often have a tenancy to stay upside down for long periods of time if and when they are rolled. This was something else they learned when they studied the Fastnet disaster. Beam is for initial stability only on mono hulls, once the boat turns turtle it becomes your enemy. If you read the study you will have known that the benchmark boat they used was the Contessa 32, a fleet of them started that race and they all returned. The righting moment on the Contessa was something like 156 degrees compared to most of the larger boats that were in the range of 110-120 degrees.

[ohYes]

I found a calculator for angle of vanishing stability here: Angle of Vanishing Stability
My under 40' ketch, an Allied Mistress 39 (actually 38.5') showed a stability quotient of 16.24 with 174.16 as the angle of vanishing stability. For anyone not familiar, the AVS is the angle at which the boat starts giving up trying to right itself. I would think a good thing to know when considering a sailboat for offshore (considering Fastnet, especially an under 40' one).
Sharon

[valhalla360]

I had an incident last night that got me thinking. Walking down the dock, we heard a cry for help. On checking we found an elderly man had fallen between the boat and the dock. Tammy ran for help and I got him around to the swim platform. He was too weak to climb out with the ladder and the swim platform was a good foot off the water. I'm a big guy and pretty strong. There was no way I could drag him back on board. Luckily the police boat was in getting gas so in short order 2 officers and I managed to pull him out and he was fine other than a scraped up side.

This got me thinking, if we are going thru rare (but very much a possibility) events is to consider falling overboard.

Just like we would like to think a capsize is highly unlikely, so we would also like to think with jacklines and care, going overboard is highly unlikely. Reality is it happens.

In the event it happens, I would much rather be on a modern boat with a sugar scoop transom and easily reached swim ladder. The vast majority of "blue water" boats have gunnels at least 2', often more than 3', off the water.

You can mitigate the issue somewhat with a rope ladder trailed off the back or similar solutions but it will never be as easy as a platform 6" off the water with a nice deep 3 step ladder.

[Jim Cate]

Originally Posted by ohYes

I found a calculator for angle of vanishing stability here: Angle of Vanishing Stability
My under 40' ketch, an Allied Mistress 39 (actually 38.5') showed a stability quotient of 16.24 with 174.16 as the angle of vanishing stability. For anyone not familiar, the AVS is the angle at which the boat starts giving up trying to right itself. I would think a good thing to know when considering a sailboat for offshore (considering Fastnet, especially an under 40' one).
Sharon

Sharon, I'm not a Naval Architect, but even I can see that this calculator should be viewed with great suspicion. The simple fact that they ignore the vertical center of gravity indicates to me that it is meaningless.

Further, I have never heard of a sailing yacht design with an AVS anywhere near the 174 degrees that you have come up with for your Mistress. I very much doubt the accuracy of that number. Does not mean that it isn't a seaworthy vessel, of course!

Cheers,

Jim

[ohYes]

Thanks for bringing that up, Jim. I rechecked and didn't read/answer one of their questions properly. You need to plug in your draft "(not including the keel)". I draw 4.5' but don't know what it would draw without it. Any guesses?
That really did seem a little too good to be true...lol
I certainly hope I never find out my true angle of vanishing stability in the water... not that I could do much about it at that point!

I just found a really nice little calculator for people buying offshore cruising boats and wanting to compare specs here: Sail Calculator Statistics of over 2,800 sail boats

[accomplice]

I recently moved from a coastal cruiser (Caliber 28', 5ton) to a long distance cruiser (Tayana 58', 35 ton). I have many thoughts regarding the other replies in this thread.

First, with respect to older sailors choosing heavy "blue water" boats and not venturing out until the weather is dead calm, I see that as driven by experience. Once bitten, twice shy. I think the more folks experience rough weather, the more they want to avoid it, and the more they want a boat that can handle it comfortably should they find themselves in it. I used to like the excitement -- it wasn't really sailing to me until a rail was in the water. Then, after experiencing a particular nasty squall, I became hesitant for a few years to head out if thunderstorms were forecast.

The differences between coastal and long range cruising are many. Tankage is one big difference -- coastal cruising in New England I never found that 22 gal diesel and 35 gal water was a problem. My long range cruiser has more than 10 times the tankage, and I'm happy for it. I enjoyed the wide beam of the coastal cruiser (10'6" on 28'LOA), but prefer the motion of the moderate beam (16'2" on 58'LOA) at sea. The relative simplicity of the systems on the coastal cruiser met our needs -- for example, we would pick-up a new block of ice every few days to keep the ice chest cold. In the new boat, I'm constantly working to keep the systems operating, but not sure I'd want to give up the genset, water-maker, washer-dryer, SSB, navtex/weatherfax, sat-phone, dishwasher, a/c, icemaker, etc.. The deep 8' draft sails flatter, points better and is much more stable, but there are many more places I could go with the 4' draft coastal cruiser. The bigger boat is set-up for easy sail-handling, but tacking back and forth across the bay is still more work so when I get on a point of sail, I want to keep it for a few hours (or days).

As far as the angle of vanishing stability, static stability is only part of the issue. Dynamic resistance to roll is a key part of keeping a boat upright too -- and also contributes to a more relaxed motion.

One thing I would like to dispel is the notion that a long distance cruising boat is slow in light wind. Our bigger boat is much happier in light air than our smaller boat was. (This is important for long passages). The difference is that if we only have an hour to go to our next stop, we might not bother with the sails in light air.

As far as the ease of getting back on board, regardless of the style of boat, I suggest providing some way to get back into the boat if you find yourself in the water (swim platform/ladder/rope ladder/rope webbing/etc) when at anchor. If you've ever watched someone just try to climb up into an inflatable dinghy you'll appreciate the challenge.

[letsgetsailing3]

Originally Posted by Jim Cate

Further, I have never heard of a sailing yacht design with an AVS anywhere near the 174 degrees that you have come up with for your Mistress. I very much doubt the accuracy of that number. Does not mean that it isn't a seaworthy vessel, of course!

Cheers,

Jim

That number doesn't seem right, but I'm guessing that boat has a pretty good tendency to right itself.

I don't think it's a problem with the calculator, though. Notice that you have to subtract out the draft of the keel from the overall draft when you do the calculation.

[goboatingnow]

AVS is merely one factor and not a terribly significant one. I mean a moody DS has a vanishing angle of 0 or 360. Does that make it a suitable bluewater boat

Dave

[robert sailor]

Well if its the new Moody (Hanse) then yes it does make a huge difference because of the big cabin area but the new Moody doesn't strike me as what I would want in an offshore boat.
I will say having looked at one that it is a perfect Med boat, almost a middle ground between a Cat and a Mono.

[fgd3]

Originally Posted by thomm225

Also, if you do somehow lose your rudder on a full keel boat, you can still sail the thing in driving it with the sails. Try that on a spade rudder/fin keeler.

I lost the rudder on my Hunter 25 in the middle of the Florida Straits in a Key West to Cuba race. The rudder shaft snapped off right where it exited the hull. I sailed 40 miles back to Key West by trimming the sails augmented by dragging a bucket off one side. There's a lot of mythology about hulls with long full keels, but much of it is untrue.

Consider these paragraphs from John S. Letcher, Jr: "Self-Steering for Sailing Craft":

"The belief is widespread that a long keel is a desirable feature for self-steering because as the boat turns (angular velocity about a vertical axis) the keel generates an opposing yawing moment. An aerodynamicist calls this property yaw due to yaw, or adverse yaw, or yaw damping. I think the sailor will be more comfortable calling it yaw resistance, and I hereby coin the term to mean any yaw moment that arises because of yawing, proportional to the rate of change of the vessel's heading.

"Consider a boat with a long keel turning about a vertical axis and moving ahead at the same time. Let's catch her at the moment she's on course but still turning to port (Figure 2-13). Due to the combination of forward velocity of the boat and sideways velocity resulting from rotation, the forward end of the keel sees a flow coming from the port side and the aft end a flow from the starboard side. It is apparent that the lift forces due to these angles of attack will be distributed so as to oppose the rotation--hence adverse yaw results. Note, too, that portions of the hull are effective in producing adverse yaw in proportion to the square of their distances from center: the distance enters once in creating the sideways velocity by rotation, and again because the force acts at that distance from the center to produce yawing moments. So a short keel is very much less effective than a long one.

"But the keel isn't everything. If we had to use a long wing (long in the chord direction) to make an airplane have sufficient damping in pitch, we would have been a long time getting off the ground with all that wetted surface. A small surface like the airplane tail, placed a long way from the center of the wing (Figure 2-14), is a much more efficient way to achieve both control and adverse pitch and was universally used until supersonic flight speed made highly swept, low-aspect-ratio wings necessary. Similarly with the sailboat: from the hydrodynamic standpoint, it is more efficient (equal lift and satisfactory control characteristics with less drag) to divide the keel and rudder, so both can be relatively high-aspect-ratio foils. Certainly it has been amply demonstrated that boats with short keels and separate rudders can be made to steer themselves quite adequately by windvane or sheet-to-tiller gear, so length of keel for self-steering ability need not be a consideration in the choice of the design of a voyaging yacht. But such boats are quicker to turn off course when the helm is simply let go, and have less ability to damp out oscillatory yawing that might be induced by a self-steering gear."

Pages 26-29

Fabbian

[letsgetsailing3]

Originally Posted by fgd3

I lost the rudder on my Hunter 25 in the middle of the Florida Straits in a Key West to Cuba race. The rudder shaft snapped off right where it exited the hull. I sailed 40 miles back to Key West by trimming the sails augmented by dragging a bucket off one side. There's a lot of mythology about hulls with long full keels, but much of it is untrue.

Are you really using an anecdote about a Hunter 25 losing it's rudder to bash full keel boats?

lol

[robert sailor]

Actually as most on this site know I am not a lover of full keel boats BUT its just a personal thing. I have sailed them both offshore and coastal and in normal conditions they tend to like to travel in straight lines and need very little help on the helm. In my mind there is no comparison between the two when it comes to self steering, the full keel is just better. They do not maneuver in close quarters very well and many of them back down like a drunken elephant but when all trimmed up and sailing the autopilot or windvane almost goes asleep.