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Old 02-02-2011, 16:22   #1
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Weather Helm . . . Can it be Lessened ?

I'm considering purchasing a Jason 35 for extended cruising and the little amount of info from owners that I have tracked down about this design mentions weather helm frequently. Seems one owner even moved the mast to compensate. So, with a few rig adjustments and sails properly trimmed can weather helm be significantly reduced?
I don't want to be fighting the tiller all the time, that would not be fun.
Trying to figure out how can I find out if this is an inherent design issue or inexperience sailing? I could go for a sail, if I had one available. But I don't yet.
Thanks in advance!
Shay
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Old 02-02-2011, 16:33   #2
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All excessive weather helm can be easily corrected; it's just a matter of how you set things up. Moving the mast wouldn't have helped, because the designer Ted Brewer was no mug. It's just their inexperience but if you're looking to knock the top off the price, don't underplay your concern.
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Old 02-02-2011, 17:32   #3
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Go to Ted's website: www.tedbrewer.com/sail_glass/Jason.htm. It appears that some of this boats were hand built and that might explain the weather helm or it could just be how that boat was set -up. You could also contact Ted directly.
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Old 03-02-2011, 06:42   #4
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Correcting Weather Helm
From ➥ weather helm, help !

Poor balance (Weather Helm) increases as the “Centre of Effort” moves aft of the “Centre of Lateral Resistance”, and can also be caused by warped rudders, skegs, and keels/centerboards, or even by baggy sails.

Sail trim to move the C of E forward, and reduce weather helm:

Remove mast rake (or even rake slightly forward).

Reduce wind pressure on the main, or increase the pressure on the head sail. This can be done by shaping (trimming) the sails, and dropping the main to leeward. As the wind increases, shape/position become more critical (should be flatter). If you can, tighten the backstay. This helps to pull the fullness out of the main and will flatten the head sail. The idea is to flatten the sails and keep the draft forward.

Tighten the outhaul to flatten the bottom part of the main. At the same time tighten the Main and Genoa halyard to keep the draft(s) forward. Bottom batten should line up with boom, top batten with masthead. Twist at the top of the mainsail will allow wind to spill.

Move the Genoa lead aft to flatten the lower section and twist off the leech.

Dropping the boom to leeward after shaping will reduce weather helm.

Add a boom vang (helps maintain shape when easing out).

More weight aft and windward, less weight in the bow (move anchor, empty the water tank in bow)

Reef (the main more than the jib).
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Old 03-02-2011, 21:38   #5
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I talked with an owner of a Jason 35 this summer in Hilo. They'd just sailed over from Oregon and were getting ready to sail back. Just a little sailing for the summer. There boat was totally modified and beautiful. IIRC, One of the changes they made was moving the mast forward. Apparently it was a pretty common change after a few of them were sailed and discovered to have a bit too much weather helm. From my conversation with them, it seems the forward mast position was adopted by the mfg later in the production run. Don't know how much of an issue this was but enough for some to do something about it. Might want to get hold of Brewer and see if he did the calculations for repositioning the mast.

Taking the roach out of the main and shortening the foot of the mainsail will cut down on weather helm. Personally, would rather live with weather helm than lee helm if I have to drive. Since I buy a self steering vane before I buy a boat, don't drive much, however.
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Old 03-02-2011, 21:43   #6
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Okay. So what causes weather helm on one tack only? Especially after 4 seasons of perfect balance on both tacks....
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Old 03-02-2011, 22:37   #7
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Quote:
Originally Posted by roverhi View Post
Might want to get hold of Brewer and see if he did the calculations for repositioning the mast.
That's an interesting post roverhi. Difficult to imagine the designer getting that calculation wrong; although I guess tolerance is an individual thing. I like next to none - others like a lot more. If the OP does make contact as suggested, I'd encourage him to post the response.
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Old 03-02-2011, 23:40   #8
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Quote:
Originally Posted by ShayW View Post
I'm considering purchasing a Jason 35 for extended cruising and the little amount of info from owners that I have tracked down about this design mentions weather helm frequently. Seems one owner even moved the mast to compensate. So, with a few rig adjustments and sails properly trimmed can weather helm be significantly reduced?
I don't want to be fighting the tiller all the time, that would not be fun.
Trying to figure out how can I find out if this is an inherent design issue or inexperience sailing? I could go for a sail, if I had one available. But I don't yet.
Thanks in advance!
Shay
Quick Fixes.
Flatten the main, Lots of foot Tension and lots of cunningham tension. Vang also . But if the main is old and bellied you will have no end of problems without getting it re-cut.

Move the traveller car to leeward

As the wind builds, reef the main rather than change down a headsail.

Bigger fix.
Move the mast forward. Hopefully some previous owner has just raked it aft and all you have to do is rake it forward to solve the problem


Also check the rudder is clean, If its coated in shell and weed, the laminar flow will be disrupted substancially and you will never be able to steer properly.

Cheers
Oz
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Old 03-02-2011, 23:49   #9
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It's not as easy a thing as you might think, to get the balance of a yacht right. It's as much experience as calculation.

Some yachts tend to develop these sort of issues more then others, which suggests that maybe the lead estimates used in the development of the sail plan, may have been too conservative. In the vast majority of cases, rig tuning and sail cut can cure this type of problem, but this wouldn't be the first yacht that had to have it's stick moved. My understanding of this design, is the mast was moved in subsequent production model runs, suggesting something wasn't right. I don't think it was the rig placement, as much as the stern quarters on the yacht, in particular her buttock angles. Since it wasn't practical to retool a new mold with the changes necessary, the rig was moved. It would be interesting to see if the stock plans have an update to include a moved stick.

The wise thing would be to call him, supply the sail number and or hull number for this boat and see what he has to say. It may be a home builder's mistake or something he's aware of, etc.
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Old 21-11-2012, 20:16   #10
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Re: Weather Helm . . . Can it be Lessened ?

I have Jason 35 #7, which has been a lot of fun here in Alaska, even with the heavy weather we sometimes get. Not long after it was built (Miller Marine), Ted moved the mast forward and added 500 lbs of lead to the keel, all to lessen weather helm (he not only told me about that, but also sent me sail plan drawings, which I did not have). On my old boat, which is for sale by the way, putting a reef in the main does wonders. I've also put extra chain and other heavy objects in the shallow bilge just aft and just forward of the mast and that seems to help.
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Old 21-11-2012, 20:42   #11
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Re: Weather Helm . . . Can it be Lessened ?

As stated in an earlier post, determining CLR was more art than science. I read that some of the earlier fin keel boats were off because of the traditional method of estimating CLR on a full keel didn't work well on fin keels.

The Cal 34 mark I I sailed on for years had weather helm. Lapworth wasn't known for messing up either. I later found out about the Cal 34 mark II. It has a significantly shorter boom, and it has a taller mast to make up the lost sail area.

The owner of the Cal I sailed on bought a used mainsail, turned out the only Cal 34 listed in their database was the mark II but wasn't indicated. Luckily the sail he bought was supposed to be a little short on the hoist (for the mark II), which made it barely fit on his boat with the gooseneck at the bottom of the track. The sail is short on the boom. He lost a little speed in light air, but the helm is much better.

A boat I test sailed had bad weather helm. When I called to cancel the survey, the surveyor said that would explain why he had seen some of these boats modified with a bowsprit.
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Old 22-11-2012, 00:10   #12
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Re: Weather Helm . . . Can it be Lessened ?

I should clarify that Ted Brewer modified the design, not the boats already built. So the vast majority of Jason 35's, if built much after 1975, should have reduced weather helm. Given that the mast is keel stepped, it would be a major rebuild to actually move the mast of an older one like mine, probably not worth the expense.
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Old 22-11-2012, 00:40   #13
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Re: Weather Helm . . . Can it be Lessened ?

Posts above are correct. And it is usually blown-out sails ... folks just don't know what a new sail looks like. Second to that is simply needing to reef ... to reduce heel.

That said, it can be something completely different. When sailing on a beat the rudder should be at an angle of about 5 to 10 degrees. Tiller to weather, wheel a-lee. More or less depending on all sorts of conditions and such. However the force required to hold it there is irrelevant. That force is sometimes confused with weather helm from trim. That force, while fatiguing, does not slow or hamper the boat. It is from the design of the rudder.

As an example I offer my old Cal 36. With the original Lapworth rudder (Lapworth probably never made any mistakes in boat balance) The tiller would be up about 7 degrees when winning a race to weather. It always took a little bit of effort to hold it there. The rudder was then replaced with a modern design from Schumacher (No mistakes there either). That rudder will magically hold itself at 5 degrees to weather, hands off. It had a very neutral balance. At 7 degrees it needs just slight pressure.

So what feels like the popular weather helm may not be sail trim or hull design. Just rudder design ... think of the loads on a steering oar setup ... that's unbalanced!
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Old 17-10-2014, 00:41   #14
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Re: Weather Helm . . . Can it be Lessened ?

I own Jason 35, hull # 10, which I purchased directly from the manufacturer, Miller Marine of Bainbridge Island, WA, as a bare hull. It is true that Ted Brewer placed the mast too far aft in the original design, which gave the boat too much weather helm. (By the way, Bob Perry made a similar miscalculation on his Valiant 40, a design very similar to the Jason 35 and from the same time period).

About three years after my boat came out of the mold, the builder, Earl Miller, called and asked if I had cut the hole in the deck for the mast yet. I said "no, not yet" and he said "good thing, because you are going to want to place the mast 18 inches further forward."

Even though I had not yet installed the mast, moving it 18" forward did entail extra work for me, because the new location had implications in the interior plan. I ended up moving the main bulkhead forward.

The recalculation of mast position was good, however. I have sailed my vessel, Norwegian Steam, offshore for about 8,000 miles, including passages from Mexico to Hawaii and from Hawaii to Washington State, with the boat balancing well and being steered by a Monitor vane.

On my boat, the distance from the foot of the headstay to the front of the mast (the J measurement), is 14' 8".

My mast is about 6' taller than the original design. The height of the mast (the I measurement) is 50'.

Some of the early Jason 35 boats that had the mast stepped according to the original design were improved, in terms of balance, by adding a short bowsprit.

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Old 18-10-2014, 11:49   #15
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Re: Weather Helm . . . Can it be Lessened ?

There is a sticky over on the rigging and sails sub-forum. It goes into rig adjustments that are short of mega buck mast moving. My second cruising boat had lee helm which was horrible. Good Luck. ______Grant.
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