J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment weather helm

I would like to also comment on weather helm. Rig Tuning, Sail Trim and apparent wind angle all work into being able to sail the boat. My wife and I sail the boat all the time and we struggled with weather healm when we first bought the boat. First thing I did was tune the rig tight like a piano (using the tuning guide). I then worked with my sailmaker and went over my sails and we made some mods to the luff curve, batten lengths and reef points (I inherited the sails from the previous owner). But most important he worked with me and my wife on sail trim and sail plan balancing based on *my sails*. What we have found is that balancing the sails and pinching the boat is *very fast* and comfortable when the wind picks up. This boat will eat up the wind for a 30 footer. So much so that often the only issue with the tiller is getting my wife to let me drive because she is having so much fun.

Now my wife and I have only been sailing larger boats for about 5 years so some of this extra work my have been due to our inexperience so you may already have worked through this or it may seem perocial. But needless to say some of the best sailing we have had has been in winds of 18k to 25k on Buzzards bay and we have no problem hanging with the 40 footers with my wife driving (-:

David

Regarding auto pilots, I use an Autohelm ST4000. If I installed it today, I'd like to install the drive further forward on the tiller. With the extra lever arm, the unit won't have to work so hard. It will sacrifice some speed. Can you imagine how hard it would be to steer a J/30 with an 18" tiller?

Regarding center of efforts in sails, if everything else stays constant, bigger jibs/genoas move the overall center of effort aft, increasing weather helm.

you telling us that if you sail with the main alone you dont have weatherhelm ?

hardly


thor

I have an ST2000 and it seems to handle the loads fine. My only problem is that it is terrible at driving downwind in a quartering or following sea. It is better than my old ST1000 but I still do not trust it.

David

same here s 2000 ... works great for sail changes ( gettin the main down ) and stuff like that. works wonderful in calm air, I only use it for small portions when I sail alone .. probably a little undersized for real duty... but i am happy with it

thor

Yes, with only main, the center of effort moves way aft. Compare 2 configurations. One is full main and #1 genoa, the second is a #3 jib and full main. The center of effort of the #1 is aft of the center of effort of the #3, creating more weather helm. This logic falls apart if the jib becomes too small, but I think it works for conventional inventories with nearly full hoist headsails.

Hi, Here in the Caribbean we regularly have winds over 20 knots. On "Blue Peter" we have had our North Main re cut twice to get it flat enough. Partly because of the rateing system we use here we only sail with a 110% Jib, mostly because we do not need any more. we also like to race with 7 on board. With our heavyest at B-Max. in this configuration we are usually going up wind about 6.2 Knots SOG on the GPS. All of this with quite a comfortable helm.
Iain

I am not talkin about 6 people on the rail in full race mode .... The whole boat feeling changes dramatically with the right wind and lots of rail meat.... ( still it doesnt change the law of physics either )

Again with the main alone the boat has no weatherhelm, and with a jib alone is has a lot of weatherhelm... ????????????? DO you actually have a j 30 ? ( by that matter any other sailboat ?)

Sorry I do not want to start name calling here, or start writing the same style as I would on SA .. but this is ridicoulous

thor

What I'm saying is that the further aft the sailplan's center of effort is, the more weather helm develops. With just the main up, you have the c.e. all the way aft and have a lot of helm. Similarly, if you have a larger genoa up, with or without a main, your c.e. is further aft compared to a similar configuration with a smaller jib.

Dyk, You are partially correct, the CE of the #1 genoa is slightly aft of the #3 jib. But I think the increased force of the #1 counteracts that.

Sketching out the CEs on graph paper, I find that the CE on a class-legal #1 is slightly more than one foot further aft of the CE of the #3, measured perpendicular to the luff. Its higher too, so on deck it's about 3 feet further aft. But for both sails, the CE is still forward of the mast, and forward of the center of resistance (keel).

The class #3 is supposed to be 196 sqft and the #1 is supposed to be 294 sqft. Almost 100 square feet larger. Is their any doubt that the #1 generates significantly more force than the #3?

I haven't taken the math any further, but I have to believe that the increased force of the #1 although slightly aft, imparts more force forward of the CR than the #3.