Not much activity recently, but I thought I'd post a question. I sail a 2012 C-309 wing keel, in-mast furling and 135% genny. What tacking angle are you experiencing? What speed on fastest point of sail in 8 kts wind. Still trying to get everything adjusted and feel we're not pointing well and going a bit slow.
Boat Speed and Pointing
- Thread starter Dave Powell
- Start date
What do you mean by 'tacking angle'? Are you referring to how well your boat points into the wind?
You fastest point of sail will be a beam reach, with the wind coming directly across your beam. With the boat sitting flat on the water, you will achieve maximum hull speed. There is a formula for you maximum hull speed.
You fastest point of sail will be a beam reach, with the wind coming directly across your beam. With the boat sitting flat on the water, you will achieve maximum hull speed. There is a formula for you maximum hull speed.
Tacking angle is the angle between opposite tacks, another way to look at pointing. I know a beam or broad reach should be the fastest point of sail. The question I'm wrestling with is what should I expect with 8 kts of true wind.
Dave.
Your are looking at tacking angle as if that is the metric. You best metric is VMG, Velocity Made Good. This is not a static angle. It is a performance metric that changes with each leg of the race.
If I say 38º off True and you go out on the course searching for 38º you may find that your boat is doing better at 45º on a given day, wind speed, gusts, puffs, headers etc all taken into account. You may find that the right side of the course is better than the left when you consider the lees of buildings, the currents, the chop.
With your sails and the way you are rigged, you need to go out and practice wit your boat finding the best set up you can accomplish. I recognize that all boats are not set up the same way even if they are the same brand and are using the same sails.
Work the problem over a set course. Test and record the settings of your sail trim. Record your VMG with that set up. Then go back and do it again. Did you have the boat pinching, were you rounding up because you were healing at 25º or 35. Were you constantly causing the rudder to drag trying to point as high as your competition only to slow down while sailing out of balance? Were you maintaining speed through the lulls and taking advantage of the puffs?
I would encourage you to read "Fast Handling Technique" by Frank Bethwaite
Your are looking at tacking angle as if that is the metric. You best metric is VMG, Velocity Made Good. This is not a static angle. It is a performance metric that changes with each leg of the race.
If I say 38º off True and you go out on the course searching for 38º you may find that your boat is doing better at 45º on a given day, wind speed, gusts, puffs, headers etc all taken into account. You may find that the right side of the course is better than the left when you consider the lees of buildings, the currents, the chop.
With your sails and the way you are rigged, you need to go out and practice wit your boat finding the best set up you can accomplish. I recognize that all boats are not set up the same way even if they are the same brand and are using the same sails.
Work the problem over a set course. Test and record the settings of your sail trim. Record your VMG with that set up. Then go back and do it again. Did you have the boat pinching, were you rounding up because you were healing at 25º or 35. Were you constantly causing the rudder to drag trying to point as high as your competition only to slow down while sailing out of balance? Were you maintaining speed through the lulls and taking advantage of the puffs?
I would encourage you to read "Fast Handling Technique" by Frank Bethwaite
In the absence of published polars experience will probably be the best way to find this data for your boat in its configuration. The shoal keel probably won’t affect your heading relative to the wind but it could allow a little more leeway than a deep draft. The in mast furling sail probably affects speed but not pointing. My guess is you’ll find a tacking angle around around 90 or 95 degrees will work. That will also depend on sea state, even at the same wind strength.
bimini?
dodger?
solid prop?
10 year old sails?
perfectly clean bottom?
crew on the high side rail?
cruising gear removed?
anchor in the bilge?
no windlass?
rig tuned?
tanks dumped?
then we can stsrt talking about reading the wind ........
dodger?
solid prop?
10 year old sails?
perfectly clean bottom?
crew on the high side rail?
cruising gear removed?
anchor in the bilge?
no windlass?
rig tuned?
tanks dumped?
then we can stsrt talking about reading the wind ........
Thanks for all the comments, but was just trying to manage my expectations. I've sailed for many years; the C-309 is the largest boat I've owned. It's a wing keel with 3 blade fixed prop, bimini, in-mast furling and a 135 genny. In 8 kts of wind I'm expecting it to point 50-55 degrees (a tacking angle of 100-110) and make around 4 kts reaching. Is this realistic
Dave. Your 50-55 (100-110) is realistic. Much depends on your rig being tuned, your sails properly shaped.
Speed is another thing. Converting 8 knots of wind into 4knots of speed on a reach (sailing at 90-130 from the wind on the bow) would be looking at the boat and saying do I need all this gear on the boat. Do we really need 100 gallons of water, can we dump the stove/microwave/refrigerator/holding tank/potty on the dock? Did the diver swab all the slime/barnacles/algae forest off the bottom before we untied the lines?
I’d find 4 knots boat speed on a reach in 8 knots of wind desirable but not expected in a boat set up for cruising. 2-3 knots more likely. Where fun sailing begins is 12-15 knots of wind on a boat set up to go cruising.
Speed is another thing. Converting 8 knots of wind into 4knots of speed on a reach (sailing at 90-130 from the wind on the bow) would be looking at the boat and saying do I need all this gear on the boat. Do we really need 100 gallons of water, can we dump the stove/microwave/refrigerator/holding tank/potty on the dock? Did the diver swab all the slime/barnacles/algae forest off the bottom before we untied the lines?
I’d find 4 knots boat speed on a reach in 8 knots of wind desirable but not expected in a boat set up for cruising. 2-3 knots more likely. Where fun sailing begins is 12-15 knots of wind on a boat set up to go cruising.
With 8 kts of wind I get 2.5-3 kts but then I also can get 8-11 kts going with the current. What are you looking for SOG? You will have currents waves and other factors that come into play.
You can go through all the math, and if you are racing, it is worth the trouble. But I find for everyday use, there is a point where you hit the knee of the curve as you point more toward the wind and boat stalls out. The worse your boat points, the harder it will be to define that knee of the curve where you start loosing significant amounts of boat speed. But the biggest issue I have is that I never sail on a lake where the wind direction is that consistent for any length of time, so you can't ever put the boat right at that edge. The RL pointed well, so you never want to get too close to that knee, as the wind would change and the boat would stall. I also rarely have real destinations when I sail. The wind direction usually defines which way I sail.
One of the significant elements in this discussion is leeway. My boat can point in the range of 35 degrees true when the breeze is up and 40 degrees in normal winds but analysis of our track shows it much closer to a realized 90 degree tacking angle based on our course. This is accomplished with a 6'6" fin keel and a very narrow sheeting angle.
Your keel will not be an asset on the leeway front so I suggest you analyze your track to ascertain your true angle.
Your keel will not be an asset on the leeway front so I suggest you analyze your track to ascertain your true angle.
Oh so true. Folks who have strayed to close to a lee shore struggle with leeway as they try to get out to open water. Sometimes they succeed. It can be tough. Remembering all your options takes a clear head.
This is a good discussion item.
One thing is certain: The faster you go the better you can point up until the physical limitations of windward sailing. So, if you want to point better, sail faster and to sail faster you need a clean smooth bottom and the least amount of weight possible on board. That's with your existing sails, sail trim and tune.