Boat faster on Port Tack...

[braol]

I have noticed this year that my boat is much faster on port tack...especially in lighter air. So the family and I go out yesterday evening. Breeze is about 7kts and Lake Michigan is pretty flat.
As we leave the harbor (going about 2kts on the meter), we notice a sailboat race is going on and we tack over to port to stay out of the way and it's like we threw out an anchor. 0.7-0.9kts...maybe 1.2-1.4kts here and there, but definitely slower. It was almost like the sails went slack and the wind was steady. I experimented and the same thing happened time and again.
I figure that the mast /rig needs to be tuned. (Mast was put back in this spring.) What I was wondering is just what about the rig would be out of wack so as to cause this scenario? Mast canted off to one side? The mast looks straight. It can't be mast rake or forestay tension because that would just make the whole rig slower...but not on one tack only.

 

[Ron20324]

In lite winds, do you put the crew on the leward side? Helps shape the sails somewhat.

 

[Benny17441]

Was there a current? Opposite tacks are at 90 degrees which can be enough to vector your course by components in favor or against a current. Common in light airs. Have no explanation why this would happen through the season other than you may be sailing in an area with pretty stable characteristics where conditions repeat themselves.

 

[Steve_Catalina]

If you have telltales, I assume they are flying the same on both tacks for the main and jib and that the position of the traveler and boom in relationship to the mast position are same on both tacks.
I would use your telltales and sail shape / position before I would look at my windex.
My 2 cents

Steve

 

[JohnVTX]

When on each tack get to mast and eye up the mainsail slot to look for lean or twist or bend especially at top of mast. Tune to make corrections

 

[markwbird]

This is not uncommon. Could be anything from a off center windex making you thing you are on the same point of sail each way to poor left-right weight distribution to a tilted mast to hull unsymmetrical hull/keel. Check all of these things.

 

[Jackdaw]

Assuming the 1) the sail trim is the same on both tacks and 2) the speed difference is real, the most likely cause is that the mast is not in vertical alignment with the keel. Either one not being right (or worse both!) and you'll get this.

Some keels are 3-5 degrees off. Having your mast going the other way by the same amount and you'll have massive trim problems.

Some say to make sure your mast is plumb with the water... that's true 100% if your keel is perfectly vertical. Speed/trim mavens make sure the mast/keel alignment is spot on.

 

[braol]

I will check my "Plumbness" again tomorrow.

 

[whatfiero]

Are you right handed or a southpaw I think all boats have that attritube

 

[braol]

Ha, ha...right handed...

 

[Joe]

You can eliminate the external factors..... current, waves. etc.... by running a reciprocal course. If it's not that, and your telltales show trim consistency.... it's your rig.

 

[Davidasailor26]

we notice a sailboat race is going on and we tack over to port to stay out of the way

I know I'm not the only one who read that and thought "oh god not again"

Back to the question - We have similar behavior with our boat. Do you have a speed transducer and/or GPS to validate that there is a difference and whether it could be caused by current? In my case I suspect it's a combination of off center water and fuel tanks and transducer location next to the keel. Just a couple things to think about in addition to what's above.

 

[Rick486]

Also is your speedo paddle on the centerline? Is it forward of the keel? I owned a boat once where the speedo paddle was off center outboard the keel so the recorded speed through the water was over a knot difference from port to stbd tack.

 

[AWalker]

Might try using the gps speed on your phone to eliminate false speedo readings.

 

[LakeMurraySailor]

BR, I had a boat like that once and I tried everything to get her to perform the same on both tacks to no avail! When I took her out of the water to do the bottom, I could see the curvature in the keel! So I eventually planned my races around the "favored" tack if possible. It was the boat in my avatar, a Choate 27! She could even beat the spinnaker fleet on a good light wind day!

 

[Head Sail]

I think your speed is to low to draw the conclusion there is something wrong with your rig. Get er up to 6 or 7 kts and recheck.

 

[braol]

I know I'm not the only one who read that and thought "oh god not again"

That's exactly what I thought!! As an occasional racer I sympathize with a racing fleet and don't want to be the cause of some boat to alter course and lose a close race. The problem is that to get out of the way required tacking over to port...which is when the boat just seemed to die and the telltales go limp...and then the breeze slowly pushed me downwind closer and closer to the obvious racing line to the mark. I ended-up turning on the iron sail and motoring out of the way.
With such terrible performance on port tack I also realized (with the shore close by) that I just could not make any headway upwind AT ALL. In order to get any forward momentum I could only get as close as 90* to weather on port tack, but could sail nice and close on starboard....towards the shore though...
I guess it might have been better to say that I barely point upwind on port, as compared to starboard....or maybe say that I can point higher on starboard than I can on port... Either way, very unacceptable performance....and annoying/confusing.

 

[Jackdaw]

In 7kts breeze you should be doing WAY better then 2 knots..... if that's what your getting on your best tack, I can see how the bad one would be really bad. Figure how to move at closer to 4 kts, then attack the other problem!

 

[frankies56]

I had a 66 19 ft o, day mariner, and it had the same problem. though not as bad as yours but it was an inharent problem with all of those models, as other owners complained about the same thing. best I can come up with is the keel may have an offset. it did have an iron centerboard

 

[jssailem]

How did the "plumbness" check go?
I'd suggest you stand where you can see your boat and see if she is standing straight and level. See if the mast appears to be vertical and raked "not leaning forward". If the visual is all ok then you can test for the actual. I know I can tell if something is a miss just walking down the dock and looking at the boat.
Use your Main halyard. Stretch it to a spot on the Port side. Tie off the halyard at the mast then take the end on the Port side and move it to a matching spot on the Starboard side. The lengths should be identical If not you Mast is leaning. to the side you have more line.
Using the main halyard, check the rake by hanging a weight on the halyard and letting it hang in a no wind environment. It should hang above the boom towards the stern more then the mast. You can measure the distance and then convert to degrees for the rake angle of your mast. Allow a bit for the halyard sheave on the mast head. But you should be able to get a good approximation.

If your mast is standing vertical then look to your sail trim. Are the port and starboard jib/genoa blocks in the same position along the track. Moving these forward to back will change the sail shape and change the power produced by the sail.
Try sailing without the use of the traveler, trimming the main sail only with the main sheet. Strive for maximum boat speed using only the main sheet to trim the sail. Try this on several angles to the wind. Bow port side, beam port side, and aft port side. Now do the same for starboard. As the wind angle moves down the boat side you should see a speed difference. Try to match the speed of the boat to on either sides (tacks) based on matching the wind angles.
Next on a port tack with the wind near the bow adjust the traveler drawing the boom closer to the center line of the boat. Check for changes in boat speed. Do the same for Starboard.
You should be able to match the angel and speed for all conditions by adjusting your sails. When in doubt ease the sail a bit for speed.