Sail size question

[Randy Church]

All,

After a few years with a 155, I've raced this past season with what Doyle says is a 107 headsail. I still have periods of excessive weather helm (wheel with up to a 180 degree turn) with apparent wind around 15. We are constantly adjusting the traveler, vang the main, let the sheet out, and adjust the genoa cars. We re-tuned the rig to what we feel is correct and only have a slight bend to starboard above top spreader we just can't make go away. So the question is, if the main causes weather helm, can having a too small headsail make the situation worse? Will going back to the larger headsail counter the large main and balance the boat out better?

Thank you,
Randy

 

[markwbird]

Great question

I also have a Hunter 34 and have been struggling with weather helm as well. Just this past weekend I made an interesting discovery on the subject. SF Bay is a windy place and I have kept the genoa cars back to keep my 110 depowered with the idea that it would help keep the boat under control. In a rare light air afternoon I moved them forward. Later in the day the wind picked up to 18 and I left the genoa cars forward. The helm, as it turned out, was much lighter than it had ever been in that much wind. Very exciting! My deduction is that powering up the headsail moved the center of force forward reducing the weather helm. I am not sure where the sweet spot is with this formula but I intend to keep experimenting with it.

 

[Jackdaw]

All,

After a few years with a 155, I've raced this past season with what Doyle says is a 107 headsail. I still have periods of excessive weather helm (wheel with up to a 180 degree turn) with apparent wind around 15. We are constantly adjusting the traveler, vang the main, let the sheet out, and adjust the genoa cars. We re-tuned the rig to what we feel is correct and only have a slight bend to starboard above top spreader we just can't make go away. So the question is, if the main causes weather helm, can having a too small headsail make the situation worse? Will going back to the larger headsail counter the large main and balance the boat out better?

Thank you,
Randy

It can, but not as much as you might think. The CE (Center of Effort) on bigger genoas is much farther aft than a smaller genny or jib, so the plan stay balanced with different sails.

I'd guess your main might be blown out and has too much draft. That would cause overpowering and weather helm. Try and flatten it as much as you can.

 

[RichH]

The design of the H34 and especially the H34SD tends to skid to leeward when hard pressed and heeling over, this includes sometimes 'violent' luff-ups when over-pressed when beating.

Before your weather helm evaluation, Id suggest to examine if your boat is or isnt 'skidding' off to leeward and the side pressure on the rudder due to a 'skid' isnt mimicking 'weather helm'. If youre not already aware, the evaluation for skidding is to simply watch the turbulence wake of the rudder/keel coming off the stern. If that turbulence wake is exiting at much greater angle than the rudder angle (about 3-4°) and that wake is at a 'noticeable' greater angle than the boats centerline ... then consider that the boat is skidding - the lateral movement of the (unbalanced) rudder to leeward will develop essentially the same 'feel' as weather helm.

If skidding, then your course is to
1. tighten the backstay to effect the appropriate reduction of 'sag' in the forestay wire, or
2. recutting the luff (luff hollow) of the jib/genoa to 'match' the sag of forestay wire for the close to the wind/wave conditions you are racing in, especially if your rig tension is approaching 25-30% when at your customary 'maximum' heel.
3. flatten down, etc. to reduce heel (heeling increases skid) - increased forward pre-bend in the mast when racing in the higher wind ranges; recutting the mainsail luff to match the curve that the mast is taking when racing in the higher windranges; if a woven dacron mainsail sail - easing the boltrope preload (slightly increasing the functional length of the luff boltrope) for 'flatter' luff entry shape.
4. keeping the 'gorillas' off the jib sheet winches -- as grossly over-tensioning jib sheets can cause the forestay wire to further sag off to leewards + aft which causes the leech of the headsail to grossly to 'hook up' to weather (increased heel) and the headsail will be 'draft aft' (!!!!) all causing a partial detachment/disturbance of air flow AT the leeside of the headsail leech.

The first 'test' for sagging forestay wire after noting at the divergent 'rudder/keel' wake turbulence - is to look to see if the leech section of the jib is FLAT and mostly parallel to the boats centerline when beating, followed by estimation of the amount of forestay sag and 'closed' leech due to the amount of forestay sag.

Evaluate for a skid FIRST before you evaluate 'actual or true' weather helm - look at that wake when you begin to develop 'more' helm pressure.

Here's a fairly bombproof method of evaluating, etc. a too loose forestay when beating: http://www.ftp.tognews.com/GoogleFiles/Matching Luff Hollow.pdf

 

[Dan Johnson]

Randy...

I can pretty much validate what Rich H said. With just the main up (no headsail-storm damaged) in 20-25 knots apparent from the southish, sail flattened, traveller down with a 15* heel 3 foot seas from a long fetch, I tacked quite a few times between the Sassafras River mouth and the Still Pond area. From shore to shore, each tack seemed to gain only a couple of hundred yards of headway distance, but the fun level was extremely high.

Yes, mine's a shoal keel. If I wasn't single handing, I would have probably gotten up on deck and reefed the main to stay more upright and not slide off to windward. Having the 110 headsail would have helped to point much higher, with the jib cars back to induce more twist off at the top of a very tall blade masthead jib sail.

I only flew the 155 I got with the boat once. The slightest puff and anything over 8 knots would put the boat on its ear. The 110 proved to be a much better all around sail on this boat.

 

[Randy Church]

The main is fully battened and only has 5 seasons on it. Tom and I have discussed whether Haarstick took into account the mast pre-bend when he made the sail. After all, he also sold this sailing newbie a 155 the year after because "that's the sail that should go on the boat". Anyone out there looking for a very slightly used 155 with only 2 seasons on it?

 

[RichH]

To answer your original question about small vs. larger headsail vs. helm balance .... usually not much; but, with the qualifiers that
1. if the sails are set and 'shaped' perfectly, it really wont matter
2. the extra area from the larger headsail in the CE vs. CLR relationship is 'windshadowed' by the main (on a 'static basis'). The CE vs. CLR relationship is 'nice' for static sailing (heaving-to) but sailing is a 'dynamic' entity once the CE/CLR relationship is set.
3. increased heel from the larger sail causes the NON-symmetric (fat assed stern) hull form to develop the additional helm pressure when 'over'.

Usually in most situations as you describe there will usually be found a 'cross-control' or sail SHAPE error.
Pictures, from directly under each sail and the combo of sails, during max heel when beating would help greatly in the evaluation .... and a zoomed-in pic of the stern wake. Would need to know how much rudder angle is being held when the pics are taken.

Until or if you add the pics., go here to evaluate the mainsail and to set/shape the position of exactly where its location of *point of maximum draft* occurs (fore or aft) via mainsail halyard tension: http://forums.sbo.sailboatowners.com/showthread.php?t=120970
Id also do this evaluation with varying 'slot open' distances .... as at 15kts T, and especially with a BIG headsail, that 'slot open distance' should be well 'open' due to the excessive sail overlap.