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1/31/2013

J/70 Tuning with Tim Healy

Article by Tim Healy

J70 tuning and trim from Midwinter Championship Key West 2013

The month of January has been a bit of a whirlwind for me and, though I’ve been busy making some changes in my life, one thing I did not want to do was to miss the 1st ever J70 Midwinters which were being held during Key West Race Week. I got excited about the J70 from the get go and purchased hull #2 last year and, with a lot of help from my teammates Geoff Becker, John Mollicone and Dave Reed we sorted out everything, hitched the boat up and headed for the sun and fun of the Florida Keys. Key West, as you can imagine, did not disappoint anyone who attended as the weather was gorgeous and the event was extraordinarily well run and professionally organized. The race committee for the event set an ambitious goal of 12 quality races in the 5 days and that is what PRO Dave Brennan and his team delivered. Monday the fleet broke its’ maiden with 2 races in a light and shifty 3-7 mph NNW breeze while the rest of the week delivered splendid conditions of 12-22  knots which created some terrific downwind rides and the opportunity for the fleet to learn all they could about making J70’s go fast!

Like everyone else at the event we were focused all week on learning what we could about sailing a J70 and spent a lot of time tweaking, changing and tuning to make the boat “feel” right. Though I think there is still a lot to learn I am excited about the progress we made as a team and was equally impressed by how quickly the teams using North Sails were able to get up to speed using the base tuning guide. Here are some things we learned and hope you find useful.

Rake and Rig Tension
We set our rake at 4’ 6-1/4” for the entire regatta (measured using the band as described in the North tuning guide). This is a ¼” longer than the tuning guide but, for our team, this seemed the best for us. We felt very fast for the last four days of the regatta but if there had been another light air day, like the 1st day, we would have loosened up the headstay about a half inch. Our uppers would only allow about a half inch more rake before we would bottom out on the higher rig tension settings so, for our boat, it looks like I may decide to shorten the uppers to give us more range so we can experiment with more rake and different tensions.

We set the rig tension according to the tuning guide to start out and we were pleased to see that this number was very close to what we ended up with. Truth is, at the end, we only deviated from the tuning guide when the wind was over 13 knots and even then we only went tighter a half step more than the tuning guide recommended.

One thing we learned quickly in the breezier conditions was that backstay tension alone was not enough to take the bounce out of the head stay for the rig settings over 13 knots. Therefore it was important to determine a way to get the headstay as solid as possible in the breeze. When the headstay sagged or “bounced” it only made the jib deeper and, in those breezier conditions, we already felt we had plenty of power! We found the solution was to go tighter that half setting which really helped get the headstay under control and kept the main from inverting (over flattening) when I pulled on maximum backstay. The shroud settings we used on the last day in 12-16 knots of wind had our uppers set at 26 and the lowers set at 20. This made the boat feel great and we felt like we were going the best on the last day. Another thing we learned was that we were faster when we could sheet hard and press on the jib, meaning we would sail with the telltales streaming back and not pinch.

Sheeting the Jib

Fig. 1
 

Fig. 2
 

Fig. 3
 

Fig.4
 

We found that the North Radian jib liked to be sheeted tight to get the upper leech working and to flatten out the bottom of the sail. My boat (hull #2) was made with the tracks a bit farther back than the stock boats now so we can’t really compare using exposed track holes with other boats. Therefore, I took a measurement from the center of the headstay pin on the roller furler back to the pin position on the jib car 8' 11 1/4" (See figure 1). I did have stripes on the spreader, which we used as a reference to keep our trim consistent, and we found that at the end of the week we were, for the most part, sheeting the leech to the tape mark that we put at 18” from the mast. One thing we learned quickly that, while we needed to ease the jib to get through some of the big chop, we had to be careful not to ease too much because the top of the jib quickly spilled and actually de-powered the sail. We would also sail with 1 ½ -2 ½ inches of weather sheet on until the breeze got up near 18 knots. This measurement refers to a visual of the clew moving inboard.  Weather sheeting certainly helped and was critical for pointing but, remember, if you have to ease off for a duck, be sure to blow off the weather sheet before you ease the leeward sheet!

In the windier conditions (15+ knots), we cross sheeted the jib to the windward winch so that I could do the final trim. This also allowed the crew to max hike all the time and not move around when the jib needed adjustment. For a crew with a lot of J24 experience, this was the natural jib sheeting setup. We had marks on the deck before the jib turning block and cleat, and marks on the sheets. We used the marks on the deck and sheets for both the leeward sheet tension and the weather sheet. (Fig. 2)

The halyard was fairly easy to adjust. We placed marks on the mast at the upper jib halyard block  to use as a reference (Fig. 4). In 15+ we would totally eliminate the luff wrinkles. As soon as we needed power to get through steep chop and started to ease the leeward jib sheet, we would ease halyard slightly until we noticed the wrinkles began to develop on the luff.

The Main
The North Radian main set up very well for the above rig settings. The draft was in the correct position when the backstay was both eased and fully on. This meant that the lowers were at the correct tension and that the battens were the correct thickness and taper to match the shape of the sail.

I re-rigged a 3 to 1 gross adjuster for the backstay from the existing line and hardware (See video below).  I just cut the line and tied a truckers hitch on the backstay leg, and a bowline on the fitting attached to the transom (a shackle would work here too). I then used the tail end on the backstay leg to make a simple purchase system that can be tied off with half hitches. As mentioned earlier I think this was key to get the correct amount of backstay tension necessary in the windier races. The main liked a lot of twist to get the boat up to speed and once the boat was moving, then the main could be trimmed tighter. I was vang sheeting the entire time for the last four days of the regatta in 13+knots of breeze and used the main sheet to keep a constant heel angle and also to help steer the boat up and over waves. In other words, trimmed a bit to head up the face of the wave and eased a bit to bear off over the back.  It was not uncommon (and actually necessary) in the larger puffs to have the top 1/3 of the sail wash out (luff) during a big ease and have only the lower 2/3 of the main be working. (See video below.) The main and the back stay were my main controls to balance the boat. We did not play the vang much at all because I found that after it was set for any given wind condition, I could balance the boat with backstay and main. Soon after the start it was set, and only in big lulls was it eased. I never pulled it so hard as to test its breaking point.

The Traveler
The traveler was always set between 3 and 8 inches to windward of centerline. If we needed to bow down and get over another boat’s bow, or if we were slightly overstood, I would keep it closer to 3 inches up. When we needed to have the ability to point, I would go closer to 8 inches up. I found that when it was up in the 8” range and the breeze was heavy, the main needed a lot of twist. We were able to change from fast forward mode to height mode with the traveler adjustment to weather. We also found that it did not hurt (at least temporarily) to sheet a bit tighter and let the boat heel a few more degrees to get out of a tight spot. I think the keel stalls easily when the boat is too flat in point mode.

Crew Weight and Placement

 


Our crew weight was 690 and I believe the best crew weight is between 650 and 700. There were teams over 700 but they did not seem to have an upwind speed advantage in 13+knots and I am guessing that over 700 will start to hurt speed in light wind.

Generally speaking we had our team in two basic crew positions. The first position we used primarily off the line and in tight tacking situations. This position had the bow and #2 crew hiking legs out and the #3 crew sitting with legs in, trimming jib to the leeward cleats by the blocks. This was good when we had to make quick tacks.

Most other times we  had our team set up so the forward crew was sitting with legs in and forward by the cabin house, #2crew and #3 legs out. This was the best position for longer tacks to get the maximum weight to weather. The jib would be sheeted to the windward winch so I could do the final trim and the crew did not move for a jib trim adjustment. The #3 crew would hold the tail end of the sheet so it was never cleated and he could ease and I could winch it back in as needed.

Downwind we sailed with the bow man all the way back at the stern when we were full planning, bow up mode (17+knots wind). We would then stack the rest of the crew all the way back. I think this helped keep the rudder in the water and the bow from plowing into the waves. At this point the vang was almost totally eased (See video clip #3). As you can see in the video, the vang is almost completely eased when we were sailing downwind in 17+ knots. This is because I lost steerage when we had a little too much vang on in one of the early windier races. After that, when the breeze was 16+ we would ease the vang a lot on the offset leg, and not touch it unless we came off a plane. This allowed me to steer the boat up and over waves downwind and not worry about the rudder stalling out. The #3 crew would play the main down wind and only trim it to keep a constant angle of heel.  After the first day of good breeze, we moved the spinnaker ratchet blocks to the back position (attached to the stern rail) and because of the tighter angle that the sheet passes through the block, it was much more effective holding the load of the sheet. When we could not keep the boat on a constant plane, we would quickly move the bow man forward and attempt to “lazy plane”.  This is not quite displacement mode, but it is an attempt to sail lower and be planing at least 50% of the time.  When it is light enough that we weren’t able to ”lazy plane” we would go into displacement mode.  We would move weight forward again, in order to get the bow knuckle in the water, and sail as low as possible without losing too much speed or pressure in the spinnaker.  In this mode we could make much better VMG to the leeward gates in the lulls.  We were really pleased with the range of the North spinnaker and it performed very well in all of the above conditions. We never felt off the pace downwind the whole week.

Overall, my crew and I agree that this boat is destined to be a success for years and decades to come.  I enjoy it in many respects: I had a blast sailing it in Key West in a highly competitive performance racing environment, and I also look forward to having another fun summer sailing the J70 with my wife and two boys on Narragansett Bay.

I would like to give a special thanks to my team mates on J/70 Helly Hansen,  John Mollicone (rig tune and jib trim), Geoff Becker (tactician and spin trim) and Dave Reed (bow and pit). 

Team Helly Hansen Tuning Notes
from Key West Race Week 2013

Day One, Monday 1/21
Wind 7-12 kts, slight chop
Uppers 18
Lowers Handtight
2+ inches of windward sheet
Day Two, Tuesday 1/22
Wind  12-16 kts, choppy
Uppers 22
Lowers 12
1-1.5 inches of windward sheet at times
Day Three, Wednesday 1/23
Wind 17-22 kts, choppy
Uppers 27
Lowers 22
Little to No windward sheet
Day Four, Thursday 1/24
Wind 12-16 kts, choppy
Uppers 24
Lowers 16
1-2 inches of windward sheet at times
Day Five, Friday 1/25
Wind 13-17 kts, choppy 
Uppers 26
Lowers 20
1- 2 inches of windward sheet at times, off when bow down

 

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