Boat rounds up in a puff. Why?

[Chris Patterson]

Odd thing. I guess. But in light air, just say 5kts, drifting basically, chasing the puffs; and when I do get one the boat lays over lightly as it should, but it will immediately take off to weather. I try and keep the helm from being hard over to prevent the rudder from stalling, but really, any less and the boat will round up. After that 5 to 10 seconds of madness, it'll straighten back up, sail like hell, and a gnat could hold the wheel.
Is there some trick I'm missing, like I should have eased one sheet or the other? Not doing the wind Voo-Doo dance the right way? You trimmers know something us diesel mechanics don't I guess.
Oh yeah, light spade rudder, common shoal draft keel about 4.5'. Other than that I never really have a problem. Maybe it's like the nips in golf..

 

[dlochner]

Sailboats will tend to round up in puffs. Usually you can just ride it out, but sometimes if it rounds up too fast and hard you'll go into irons or auto tack.

Rather than using the rudder, you can ease the mainsheet or lower the traveller. This will depower the main and reduce the tendency to round up.

It may be that you are sailing with an over trimmed main. The mainsail will tend to turn the boat to weather and the jib/genoa to leeward. It's easy to over trim the main which would make it more likely to round up in a puff. When trimmed correctly the leech telltales should be streaming aft and not sucking up behind the sail, except for the upper telltale which can flutter from streaming aft to being sucked forward.

 

[shemandr]

You maybe are describing the difference between how the boat behaves when the keel is stalled vs. what happens when it develops lift. When the puff first hits there is all drag from the hull and foils. Hence the initial heeling behavior. Heeled over the boat will want to head up. Once you are moving faster the foil develop lift, and the drag is decreased on the hull and you are sailing gnat wise.
I think Dllocner is on it with the mainsail. Dropping the traveler should reduce the initial bad behavior. Also, I found that on my H356, once I replaced the outhaul line with a very low stretch line (It had in mast furling), it acted like a different boat. So look for running rigging which isn't working i.e. stretching. Backstay tension, halyards, leads, could all contribute.
It sounds like your tune is OK based on the gnat thing.

 

[Gunni]

That initial heel that you experience is your notice to trim your sails. You are stuffing a lot of hull into the water, generating huge drag, stalling your underwater foils, and transferring the balance of power to your sails - which will round up the boat. In those conditions I would want to stay more off the wind to make better boat speed, keep my underwater foils working, and use the puffs to leverage increased apparent wind speed lift upwind in a carefully controlled manner. The technique is called scalloping. It requires careful attention to your boat. If you are not interested in moving to windward, then you just need to depower your sails during the puffs.

 

[Jackdaw]

Assuming you are basicly going to weather.....

Any increase (puff) pushes the apparent wind AFT.

You have to first deal with that with trim, not driving. First ease in the puff. Turn up. Trim in.

 

[RichH]

The Ericson 29 has a relatively short shallow keel but other than that its a quite well 'balanced'/designed boat. A Well balanced but short shoal draft boat shouldnt be rounding up with varying windstrengths, if the SHAPE (not 'trim') of the sails, especially the mainsail are correct.

From your brief description I would suggest this is NOT a 'trim' problem; but, a sail SHAPE problem.
This would lead one to suspect that the leech of your boats mainsail is 'hooked up to weather' which is caused by a too loose luff tension OR that you are applying too much mainsheet tension - both conditions promote a 'hooked up leech' - especially when beating the leech will not be flat and parallel to the boats centerline but the aft end of the leech somewhat pointing towards the weather side.
This mal-shape of the mainsail is usually caused by a shrunken luff bolt rope - quite common in 'old' & heavily used dacron mainsails. A thorough brief discussion about this is found here and how to assay and what to do about it: http://forums.sbo.sailboatowners.com/showthread.php?t=120970 see post #1

Once this shrunken boltrope syndrome is corrected or validated so that the boat is returned to nearly 'neutral' helm (at virtually all angles of heel and windstrength), then when beating/pointing the goal for further sail shaping is to align the mainsails leech by proper mainsheet tension so that the leech near the second from the top batten is approximately parallel to the boats centerline when beating -- watching near the #2 batten and getting this area parallel to the boats centerline when 'pointing' will set 'proper twist' for sailing/beating in 10-14kts. of windstrength on any well made / well designed / well shaped mainsail. The shape is always adjusted by whoever is doing the mainsail 'trim'.
Adjustment of the luff tension via the mainsail halyard tension to keep the leech 'open' and flat should be followed/readjusted so that leech section is dead FLAT; this 'shaping' can be aided by the use of a 'cunningham' if you have one. This final 'adjustment' is made while watching the speedo (or VMG) to arrive at the highest speed (VMG) out of the boat.

Other .... but follows after correct sail shaping of the mainsail: If your forestay is too loose the boat will have the tendency to SKID off to leeward when pointing and heeling over. A skidding boat's helm will 'feel' like its developing severe 'weather helm'; but, skidding is an entirely different problem. Forestay tension is adjusted by backstay tension.
Skidding off to leeward is determined by .... when the boat heels over and the helm start to get 'heavy' immediately look at the stern wake, especially look at the turbulence wake from the rudder. If that rudder wake turbulence is NOT coming straight off the back of the boat but is at an angle greater than about 4-5 degrees, suspect that the boat is skidding to leeward. If so, tighten down on the backstay !!!!!!!
Comprehensive rigging tune: http://www.riggingandsails.com/pdf/selden-tuning.pdf including how to set proper tension WITHOUT a tension gage. Then ....
To set proper backstay (forestay) tension: http://www.ftp.tognews.com/GoogleFiles/Matching Luff Hollow.pdf

Rx:
1. Start with CORRECT rig tension as correct rig tension will provide the proper 'stretch control' of the forestay, the shape of the jib is dependent on correct forestay (backstay) tension.
2. Evaluate the condition of the mainsail's luff boltrope as per the 'How to raise a dacron mainsail' article.
3. Dont be a gorilla when adjusting mainsheet tension --- watch that leech so that its not 'hooking up to weather' and if it does either increase mainsail halyard tension or apply cunningham tension. Same with jib sheets ... if you NEED to apply more than normal jibsheet tension then add more backstay tension to compensate.

This is a LOT of info to swallow at one time; so, take your time and patiently work through all the suggestions in sequence. The highest probability is that your mainsail boltrope is very 'shrunken' due to age and this causes: excessive heeling (skidding), severe WEATHER HELM, a draft aft sail (excessive rounding up)shape, a 'hooked up leech' (weather helm and 'round up'), excess sail draft (baggy sail - excess heel). The very LAST thing to adjust after all the sail shaping adjustments are accomplished/tried is 'correctly rake the mast'. DO NOT rake the mast until you are certain that sail shaping cannot restore the boats performance back to 'normal'. Shaping a sail is NOT the same as trimming a sail.

If you do follow this and it affects the correction needed, let us know.

hope this long winded post helps. ;-)

 

[Gunni]

Assuming you are basicly going to weather..... Any increase (puff) pushes the apparent wind AFT. You have to first deal with that with trim, not driving. First ease in the puff. Turn up. Trim in.

Yes, and you need to do it quickly, this is fairly tender sporty boat. I crewed and raced one in the 1980's and if the driver wasn't directing the trimmers it was easy to spin-out. They don't have the beam aft and high initial stability of the new designs, but do have plenty of sail, so they heel quickly in a puff. Get it dialed in and it moves!

 

[RichH]

Not to turn more eyeballs into glassy eyed stares ... and after all the previous post conditions are satisfied, there remains ONE MORE item that can affect such boat performance ..... The distance that the leech of the jib is operating in relation to the mainsail ---- the 'slot open distance', or how close the jib is to the mainsail ... and which 'optimizes' with varying windstrengths. In light winds and 'flat' water the clew 'comes in' and in 'heavy air' the clew 'goes out' --- all adjustments of the 'slot distance'.
A boat that has a narrow 'slot' when sailing in the higher wind ranges will be 'very cranky' when the 'slot' is choked or too narrow.

After all the 'other' conditions of sail shape and rig tension (see above post) are satisfied .... there may be a 'barber hauler' in your future if youre looking for 'optimized' and 'safer' boat performance. Follow the link and read-up on the use of a 'barber hauler' (or two track jib fairlead system). The following article dwells on IN-hauling, but in the higher wind ranges, that barber hauler (jib clew) goes OUT, sometimes beyond the the cap rail: http://www.ftp.tognews.com/Publications/Arvel Gentry Articles/09_Achieving_Proper_Balance.pdf
The serialized article that precedes this one concerning the usage of a *complete* set of tell-tales: http://www.ftp.tognews.com/Publications/Arvel Gentry Articles/08_Checking_Trim_on_the_Wind.pdf

 

[Ward H]

Chris, Great question and great answers. RichH, I appreciate your being so thorough with your answers. I may need to read them a couple of times to understand them and transferring them to actual use on the boat isn't always easy but if it were easy everyone would be doing it and not asking any questions.

 

[LANCE ON CLOUD NINE]

I also thank RichH

and can attest to the shrunken bolt rope issues. I have been racing an AMF Sunbird 16' sloop, with older sails. After reading Rich's info, I looked my sails over carefully and it was obvious they were puckered up - both at the luff and the foot. I eased the bolt rope as per instructions. It was shrunken about 4" along the luff, and 2" along the foot.
The boat now converts much more energy to forward movement and has much less heeling. Thank you for your time Rich, it sure makes sailing more fun, and more interesting.

 

[RichH]

Ward - Let me make this as simple and efficient as possible - in all probability, 95% of all mainsail shape problems that cause weather helm and rounding-up problems can be easily corrected by going to the previously mentioned/listed: http://forums.sbo.sailboatowners.com/showthread.php?t=120970 post #1 - "How to 'correctly' raise a dacron mainsail". ;-)

Thanks Lance, its alway good to hear positive feed back. Much appreciated.

 

[Ward H]

Rich,
I have seen you refer to that post several times. The first time I read it it was all Greek.
2nd time I read it I thought, nope that is not my problem.
3rd time I read it I finally understood what you were saying and it probably applied to my situation. I copied it into my iPad for refresher reading at the boat.
My issue now is that when I raise the main, it feels like it comes to a hard stop that no matter how much I try I cannot get another 1" or 2" on the halyard. I am waiting for a calm day when I can play with it in the slip to see if there is a reason for the hard stop or I need to apply more tension than I am, up to this point, comfortable with.
Jim McGee recommended M and M Sailing so I called them and they explained how they check and set the bolt rope. I just need some down time to get the sail to them or wait until this season is over.

Thanks again.

 

[Scott T-Bird]

Ward, you might need a winch to really tension the halyard. I pull up 'tight' when luffing into the wind under power. Then, I use the winch to take up another few inches. I mean, I really take the stretch OUT of the halyard. I don't play with the halyard tension ever when I sail.

I also find that the genny can more easily be pulled tight without the winch, but if the wind is blowing more than 10 knots, I still need the winch on the genny halyard to take out the scallops.

If you have your halyard led aft, the coach top winch is your friend. On boats like ours, I highly recommend that halyards be led aft mostly because I think the small coach roof is no place to be while raising your sail. If you don't have a winches on your coach roof, they make a good addition (along with the halyards leading aft). On larger boats, the area around the mast is far more secure, but we're perched in a precarious location when we climb up to ours.

 

[Brian S]

Chris, original poster, mentions he's having this problem in very light zephyrs, just drifting along.

I suggest that he may have his sails over trimmed due to the lack of wind. Sailing in light wind is really difficult, because you don't get the kind of feedback that you normally get, and even telltales may be too heavy to work properly. I feel I have been successful in such light wind because I set my trim where it ought to be based on wind direction, and kinda leave it. Many sailors, especially newer, inexperienced ones, tend to over trim as a matter of course. I see this translate to light winds especially, due to the lack of feedback.

Also, as RichH notes, with a hooked main leech, you could be seeing problems. It's common on no-wind days that the boom weights down the main, and over tensions the leech. It may or may not be enough to hook the leech, but it's generally pulling too much leech tension and removing desired twist for the light conditions. An easily adjustable topping lift, or a Boomkicker or rigid G-nav style vang, can lift the boom and help induce some twist.

Remember, twist in light wind is necessary because the wind at the top of the mast is faster than the wind at water/boat level, due to boundary layer friction. Therefore, it is coming from a different apparent wind direction, hence the need to have to top of the sail twist off more than the bottom.

 

[RichH]

My issue now is that when I raise the main, it feels like it comes to a hard stop that no matter how much I try I cannot get another 1" or 2" on the halyard. I am waiting for a calm day when I can play with it in the slip to see if there is a reason for the hard stop or I need to apply more tension than I am, up to this point, comfortable with..

Could be that your luff was cut too long and that sail's headboard shackle is AT the throat of the masthead sheave. Use a pair of binocs and 'look' to see if this is or isnt the problem.
What ever you do dont JAM the shackle or the tapered splice into the sheave ... or its up the mast you go with a knife in your teeth. :-(

 

[jibes138]

Chris,
To simplify matters think of it this way. The sum of the forces on your combined sail plan (mainsail and jib) can be represented as a force vector with magnitude and direction. This vector is instantaneous meaning it is constantly changing with changing conditions. There is an opposing force vector acting on your hull. The distance between these two vectors creates a rotational moment trying to turn the boat. When your boat is upright the distance between these two vectors is small so the rotational moment is small and it doesn't take much rudder to resist the moment. As the boat heels the distance between these vectors gets much larger and the magnitude of these vectors also gets much larger as wind speed increases and hull velocity increases. So the rotational moment increases dramatically with heeling, wind speed, and hull speed, thus causing much greater rudder demand to maintain equilibrium. As the boat heels the rudder becomes less effective as it is now flowing water downward trying to force the bow of the boat into the water instead of turning the boat. So your goal should be to reduce heeling through sail trim and as Rich mentioned sail shape. Old sails that get stretched out change the location and direction of the force vector on the sail and will effect heeling and rotational moment. Use about 20 degrees as a maximum heel angle, more heel than that will just strain the rig and not give you more speed as you reach theoretical hull speed. If the wind puffs cause more heel on your desired course you may want to reduce sail by reefing or continually adjusting sail trim for optimal sail conditions with constantly changing wind speed. Get a copy of Don Gillettes Sail Trim Chart from this site, it helps a lot.

 

[dlochner]

Rich,
I have seen you refer to that post several times. The first time I read it it was all Greek.
2nd time I read it I thought, nope that is not my problem.
3rd time I read it I finally understood what you were saying and it probably applied to my situation. I copied it into my iPad for refresher reading at the boat.
My issue now is that when I raise the main, it feels like it comes to a hard stop that no matter how much I try I cannot get another 1" or 2" on the halyard. I am waiting for a calm day when I can play with it in the slip to see if there is a reason for the hard stop or I need to apply more tension than I am, up to this point, comfortable with.
Jim McGee recommended M and M Sailing so I called them and they explained how they check and set the bolt rope. I just need some down time to get the sail to them or wait until this season is over.

Thanks again.

If you have a cunningham, use it. The cunningham will tension the luff of the sail by applying tension to the sail fabric and not the bolt rope. Very useful in trimming old sails.

No one has directly mentioned one of the chief causes of poor performance, old blown out sails. Sails that are old with stretched out fabric do not have an efficient shape and no amount of pulling and tugging at strings will return them to the designed shape.

 

[shemandr]

I just need some down time to get the sail to them or wait until this season is over.

Just do it. Your sailing will be so much more enjoyable for the rest of the season it's worth it.

 

[Chris Patterson]

Wow, cool advice all. I have not got back to this thread earlier, simply because it has poured rain non stop since. My God, I don't see how you PNWers take it.
I'm sure I was not specific enough about the sails. Poor ol things, and have seen a hard life. Actually the foresail is e decent piece of equipment. About a 150 it appears, and rolls in and out nicely. The main on the other hand has been liberated from a C30. Wanna know how I know this? Of course you know. Now don't get me wrong, I have nothing against Catalina's, have owned three, and another wouldn't be out of the question. It does burr me when that sail goes up though. Anyway..
I have read Rich's words on alleviating the rope, and I think that may actually be a bigger part of the problem. That rag has got to have propelled a Catalina until someone got tired of it, and it's been on this boat since The Lord came over on the Mayflower.
However.....it is still raining. Crazy weather. I don't know about your climate, but mine damn sure is changing..

 

[bffatcat]

round up

I dont know if anyone mentioned this yet but besides baggy sails loose stays will contribute to the problem