The Polar Diagrams on the Association web site say they are for 155 genoa. Are there polar diagrams for a 135 genoa?
More to the point, I'm not getting anywhere *near* the speeds indicated on the polar, with my 135 genoa. I'm trying to figure if it is poor rig tuning, poor trim (e.g., user error), old sails, or some combination of all of the above.
At slack water with 8-12 knots of true wind I can't get the boat going much above 4-5 knots SOG, regardless of point of sail, and realistically my speed is often closer to 3 knots. Until its really blowing (e.g., 15+ knots true wind) I can't get anywhere above 6 knots.
Furthermore -- and I think this one is particularly odd -- in light or moderate air, close hauled is by far my fastest point of sail. I can go from 5.5 knots SOG close hauled to 3.5 knots SOG on a beam reach, in identical conditions. This doesn't make any sense.
Is this normal? Any thoughts?
Thanks!
David
s/v Portmanteau
Hull #2133 -- 2003 MKII
Seattle, WA
In light air you tend to go fastest just off of close hauled as you are generating more apparent wind by sailing into the wind. Almost always the case. VMG to windward is still usually dreadful in that situation though!
When a boat is underperforming it is almost always the bottom that is causing it. Can you see the rudder? Is there any growth there? A small amount of slime on the bottom will cut half a knot off. Short hairs on the bottom are good for a knot. Long hairs or a particularly nasty keel and rudder will cripple you.
Next up, genoa - does it look even half decent? Are the cars set right - I still see a lot of our boats with OEM genoas where the jib tracks simply don't come far enough aft for the way the OEM sail was cut - makes no sense but its a fact. Cars too far forward = stalled airflow = very slow boat. The 135% on my boat needs the genoa sheeted to the toe rail right beside the primary winches to work properly.
After that, yeah, I'd look at the software in the cockpit...
But its probably the bottom.
Jason V
Vancouver, BC, Canada
Had the bottom cleaned and painted at the beginning of the season, and noticed it then too.
Bottom issues should affect the boat similarly along all points of sail though, right?
Genoa appears OEM and isn't in the best of shape (10 years old by now). I usually keep the cars set at a mid-track position... That could be a big part of the problem.
David
s/v Portmanteau
Hull #2133 -- 2003 MKII
Seattle, WA
You're not a wing keel are you? That would also be a major source of the slows.
It does take a bit of breeze to get a Catalina 36 moving over 4.5 knots sometimes.
Bad bottom hurts the most upwind as you are screwing up the flow across the foils. Once per year cleaning doesn't really cut it either. Like I said, you should be able to see the rudder at the dock. Run a boat brush down one side and see how much stuff is growing there, it will be a good indicator of the rest of the bottom.
For mostly casual racing, I usually haul and presure wash the boat every 3 months and rub the whole bottom with a big long PVC brush every week. If we don't, we notice.
Jason V
Vancouver, BC, Canada
No, not a wing keel.
Your boat-cleaning regimen is intriguing as I believe we're in largely similar waters (things can't be *too* different across the strait). I have my bottom gently cleaned when I do my zincs, but not more frequently. I have ablative bottom paint, so the more I have it cleaned the shorter the paint will stave off the hard growth...
Still, I'm really curious as to speeds. The polar shows significantly faster speeds than what I'm getting, and so I'm trying to figure out if that's the 135 / 155 or if I'm just an awful sailor. Before the C36, 95% of my sailing was in daysailors or dinghies, so I'm used to thinking about trim somewhat differently, and could always *feel* my way to the boat's trim pretty easily (I find this much harder in our larger boats).
David
s/v Portmanteau
Hull #2133 -- 2003 MKII
Seattle, WA
Empty the boat of as much weight and have a clean bottom and try it again. Polars and phrf numbers assume the boat is in race condition.
When on a reach in light air the telltales can hard to figure out. In that case I let it out till it luffs and pull in until it stops.
Another thing, are the polars reading true wind or apparent wind? True wind is hard to know if you are moving. Like a previous post said, the apparent wind is relatively stronger in light wind.
Set the genoa leads so that when you are close hauled and you slowly luff into the wind all the genoa telltales should lift evenly. This means the sail is trimmed right all up and down its height. In heavy air you would move the leads back from this position if you want to spill wind off the top of sail to depower. (don't forget to move them back).
Good luck. I would like to see the polars.
Catalina 36 MK1
1984 Hull #306
[QUOTE=mike37909;20120]Empty the boat of as much weight and have a clean bottom and try it again. Polars and phrf numbers assume the boat is in race condition.
When on a reach in light air the telltales can hard to figure out. In that case I let it out till it luffs and pull in until it stops.
Another thing, are the polars reading true wind or apparent wind? True wind is hard to know if you are moving. Like a previous post said, the apparent wind is relatively stronger in light wind.
Set the genoa leads so that when you are close hauled and you slowly luff into the wind all the genoa telltales should lift evenly. This means the sail is trimmed right all up and down its height. In heavy air you would move the leads back from this position if you want to spill wind off the top of sail to depower. (don't forget to move them back).
Good luck. I would like to see the polars.[/QUOTE]
The polars are on the association web site... I think you have to be a member to get them? They have them both for true and for apparent.
David
s/v Portmanteau
Hull #2133 -- 2003 MKII
Seattle, WA
So to confirm, based our experience, some of the items already mentioned:
1. Setting the cars so the headsail tell tails break evenly, with our OEM 155 we have settled on setting the the cars with 4-5 holes showing aft of the block. The top telltail doesn't always behave properly and is "pinching" but this position seems to be fast when we race against other similar boats.
2. Keep bottom clean, we have a diver do ours every two weeks and there is still paint on the bottom when the boat is hauled out in the Fall.
3. Mast rig tension, if you are not in a generally windy area, don't make it too tight. Up wind, let the mast fall off in the center about and inch or two.
4. The OEM sails are made from low end material and will stretch, alot. Ours are 12 years old and don't hold their shape very well when the wind gets over 10 knots.
5. A 135 is good when the wind gets up over 10-12 knots. Under that, they can be slow. It is a good sail size for cruising and visibility, but not a great sail in winds under 10 knots. PHRFNE has a 3 sec handicap difference between the 135 and the 155, but in reality, it is more like a 9 second or more difference depending on how light the wind is.
6. On a reach, move the cars forward and maybe to the outside track. This will tighten the leech so you aren't spilling air off the top and help the upper tell tail.
7. Make sure the 4 tell tails on the main are always flying, the top one may only fly about 50% of the time. Try dropping the traveler on the reach, the car will probably be 3/4 of the way down or so. We have found it difficult to get the main trimmed properly on a reach. Up wind, if the main's tell tails are flying well, let the main out or traveler down an inch or 2 and see if they still fly. If they still fly, then this new position is probably faster than the old one.
Barefoot Children
Pat and Roy
2001 FK, TR Hull#1994
Kittery, ME
The other item is the prop - a fixed 3 blade will take up to 0.75 knots off your speed in many conditions especially in lighter winds. Polars are written for a folding prop.
Jason V
Vancouver, BC, Canada