What does the centerboard do...?

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Squidd

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Sep 26, 2011
890
AMF Alcort Paceship PY26 Washburn Wi. Apostle Islands
I have an AMF era Paceship, PY26 with an iron shoal keel and swingdown centerboard...

2200# of Iron Keel with a 2'7" min draft and swing down board for 5'7" draft...

I've only been sailing it for this summer, but always made sure the CB was down before the sails went up, thinking it kept me from blowing over in strong wind...not heeling, but an unexpected knockdown...

The other day I was in the islands, lunching at a dock second space in, so I had the CB up as I was sitting in less than 4' of water...when we left there was no wind, so we motored out for a bit till the wind picked up...(CB up)

When we got out in the open and there was a breeze, we put the sails up, heeled over and took off sailing...wasn't a strong wind, maybe 5-8 knots, but I noticed the boat seemed a bit faster (per gps) in said wind speed and that's when I noticed the CB was still up...

We were comfortable heeling, out in middle of lake so I didn't notice any "side drifting", and decided to continue the run with CB up to see what difference it made...

Wind never got crazy maybe a few puffs to 10k and we never felt "tippy", and seemed to do OK on most all points of sail...

So the question is...is CB only neccessary in higher winds/gusts, do I gain any actual speed (less drag) with it up, and am I giving up any/some control by sailing with it up...?

Is it neccessary all the time or is there any advantage to keeping it up...?
 
Oct 26, 2005
2,057
- - Satellite Beach, FL.
With a keel centerboard, where the ballast is in the hull, the centerboard provides more lateral resistance (preventing side slip) and lift for beating (sailing upwind).
Downwind, haul it up to reduce drag and on a reach, the benefit from the entra lateral resistance may be offset by the drag depending on the boat. My impression anyway as I never clocked it.
With a swing keel, at least a good portion of the ballast in in the keel and this helps to stabilize the boat when it's down. With it up, the boat isn't very stable.
 
Oct 10, 2009
1,035
Catalina 27 3657 Lake Monroe
On my boat, I use the CB for beating against the wind; it helps the boat point better and keeps it from sliding to leeward. I raise it for the most part on other points of sail. It has practically no effect on heeling, as it only weighs 60 pounds.
 
Oct 26, 2008
6,240
Catalina 320 Barnegat, NJ
In that light breeze, it was to your benefit to sail with it up ... especially if you were sailing with the wind aft. You will skid sideways far more with a stronger wind and when the wind is forward. You will improve pointing in a strong breeze with the centerboard down. Since you do have a centerboard, it is very worthwhile to experiment on all points of sail in all conditions. Take notes, and you will eventually learn by experience how your boat performs best.

It sounds like you have already found out that there are many ways to sail a boat! The key is to learn what works best for you and yours.
 

capta

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Jun 4, 2009
4,905
Pearson 530 Admiralty Bay, Bequia SVG
centerboards

We use our centerboard almost every day. Even at anchor it helps prevent the boat from rolling, considerably.
There are a lot of tricks to using a centerboard, but no rules other than don't leave it down in shallow water.
First you must realize that your board does not need to be all the way down to work. Being sort of pie slice shaped with the deepest point aft, even running dead down wind, if it is down only a few inches this puts a deeper point aft on the keel, allowing the bow to turn around a point more definitively than on the longer flat keel, giving more control in big waves and down more will lessen the rolling a monohull does down wind a lot. On a reach, with a big genoa and a reefed main for instance, your board can be used to move the center of lateral resistance aft or forward to help balance the boat. Even beating in relatively heavy weather (20 to 35 knots of wind) we do not often drop our board all the way. Ours is 24 turns of the winch up to down and we most often use only 14 turns. It does help significantly on leeway even in rougher conditions.
You are really going to have to constantly play with it to learn what works best for your boat, but I assure you that it is worth the time spent.
I originally suspected that the board cost us some speed when down, but after 3 US/Caribbean trips and a year of voyaging down here I do not now believe that. We even use it when motoring if we're rolling. But on a smaller boat, perhaps it does make a significant difference, but for my part, I'd rather be more comfortable going slower than rolling my guts out and going faster (a quarter knot?).
Hope this helps.
 
Jun 22, 2012
39
Catalina 27 std dinette mission bay
The centerboard's function is to discourage the boat from sideslipping.

If you had begun your sailing career on a dinghy you'd have learned that the center board, dagger board, lee board, or whatever.... is adjusted depending on your point of sail. These type of boats have no ballast, except for the crew, and the board is used to prevent sideslip. The further you turn downwind the less board you need.

On my dagger board boats (laser and Nacra) I ran with full extension when close hauling or close reaching, half way on beam and 1/4 down on broad reach or running.

You should experiment with your boat with different centerboard settings, marking the postions if needed. When motoring you won't need any...... and there's less drag with it up so you'll bet better mileage.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
You can compare your compass heading with your gps heading and determine you leeway.
 
Jul 7, 2009
218
Catalina 30 Mark I Stockton, Mo
We had a Catalina 25 that was a swing keel boat, which we sailed for pleasure. We kept the keel down most of the time because it seemed more stable that way. It was also much more stable in the slip with the keel down...we didn't have as much side to side roll as we would if it were up.
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,768
Alden 38' Challenger yawl Rockport Harbor
You can compare your compass heading with your gps heading and determine you leeway.
It's not unusual for someone to say they can't tell if their centerboard does anything. That's because it's effect is not what they are expecting.

Our compass heading may not change when we lower our centerboard going to windward, but if you watch the GPS heading, often we'll get another 5 to as much as 10 degrees increase to windward.

The boats compass heading, sail angles may all stay the same(I usually do this with the AP steering a compass course), as you watch the GPS course move to windward.

This is simply less leeway showing up on the actual course over the ground which is the result of the lift from the centerboard.

It is the centerboards actual lift increasing the boats windward ability, that lessens leeway.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I have been sailing at right angles to the ebb tide and heading east by magnetic compass and south east by GPS. That wasn't leeway that was set.
 
Dec 4, 2008
264
Other people's boats - Milford, CT
Another way to measure leeway is to look at the wake off the stearn. You can then see the angle of your side slip throught the water.

GPS vs compass requires no current and well calibrated instruments to give good data.
 
May 27, 2012
1,152
Oday 222 Beaver Lake, Arkansas
Try sailing with head sail only and you'll see how much that board does.

I took the boat out a while back and did just that. I wanted to sail with only the head sail just to practice. I got out there but absolutely could not turn up wind to any degree. Then it dawned on me I had forgot the keel up. Duh! I locked the rudder and started letting the keel down and immediately the boat came about and started heeling to windward.

The main would allow more windward sailing but your going to have more side slip the stronger the wind and the more you heel.
 

McZube

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Apr 5, 2012
119
Hunter 31 Chesapeake Bay, MD
Interesting. I thought a centerboard was to let you know when to turn toward deeper water before running aground. Kinda like a curb feeler.
 

Joe

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Jun 1, 2004
8,161
Catalina 27 Mission Bay, San Diego
Interesting. I thought a centerboard was to let you know when to turn toward deeper water before running aground. Kinda like a curb feeler.
yeah, that too.... thanks for reminding us.
 

Joe

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Jun 1, 2004
8,161
Catalina 27 Mission Bay, San Diego
Duh! I locked the rudder and started letting the keel down and immediately the boat came about and started heeling to windward.
Man....... that's a strong center board to make your boat heel to windward...
 
May 27, 2012
1,152
Oday 222 Beaver Lake, Arkansas
Im not saying it was anything powerful, it was rather slow in fact, only a tick over 3 knots or so slightly close hauled. And it wasnt "heeled over" hard, but it was over close to 10 degrees. Im only pointing out that it wouldnt go anywhere but about straight downwind without the keel down. I was actually somewhat surprised it would have that much effect. I felt the boat turning before I let much more than a foot down.
 
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