Overtrimmed jib prevent pointing?

[danstanford]

Disappointed that we don't have more participation here and missing JackDaw input!
We feel we are pointing just a little less than we would like and are working (mostly successfully) through changes which are helping and the results are showing. Trimming harder on our flat top main has helped height and more aggressive use of our in-haulers has really helped us to see course made good tacks of about 90 degrees which is close to 10 degrees higher than we had been looking back over our old tracks in Charted Sails.

As we trimmed harder on our main we also trimmed in the jib and have perhaps a little less twist than I would like so I am looking for feedback on jib twist as a tool to point a bit higher? For sure our inhaulers add draft (power) and remove twist so the thought is perhaps the more powerful jib is moving the COE forward.

Thoughts?

 

[Davidasailor26]

Twist has basically two purposes - to accommodate for different apparent wind angles between the top and bottom of the sail (primarily in light wind), and to dump power from the top of the sail when overpowered. Do you feel like you should be pointing better across the whole wind range or does it seem more pronounced at lower or higher winds?

If you’ve taken too much twist out with the inhaul it’s possible that the top of the sail is stalling, pulling you sideways more than forward. I presume you have multiple sets of telltales up the luff; how do the top ones look relative to the bottom?

 

[danstanford]

Twist has basically two purposes - to accommodate for different apparent wind angles between the top and bottom of the sail (primarily in light wind), and to dump power from the top of the sail when overpowered. Do you feel like you should be pointing better across the whole wind range or does it seem more pronounced at lower or higher winds?

If you’ve taken too much twist out with the inhaul it’s possible that the top of the sail is stalling, pulling you sideways more than forward. I presume you have multiple sets of telltales up the luff; how do the top ones look relative to the bottom?

I would say lower breezes (5-8) are a bigger concern than higher (10-15). We are not far off, just looking to sharpen up this height issue and it looks like we have too little twist to me but the jib cars are already way behind the middle of the track. We have a jib luff tell-tale which we keep an eye on for stalling in the upper leech.

 

[JRacer]

Found this, might be of some assistance: J88_QuickTuneChart_2022_FINAL.xlsx (quantumsails.com)

And this:US-Tuning-Guide_J88_6.15.17.pdf (j88class.org)

 

[danstanford]

Thanks J, we are using the North Guide as we are fitted with North 3Di Raw sails. I presume the differences in shroud tension between the 2 would be the luff curve on the main needing more mast bend for North.

Admittedly, we set things to the base and should be taking the time to ease when we get our typical light airs. I have been somewhat reluctant to do so as the forestay has lots of sag as it is and I would rather add rake to help with the point so that all seems conflicting.

 

[JRacer]

Have you discussed with your North sailkmaker? Can you get him/her on board to sail with you? Do you have other J/88's in your fleet that you can sail against side by side setting up the boats similarly and making adjustments to one boat or the other in a "test and tune" session?

 

[danstanford]

Have you discussed with your North sailkmaker? Can you get him/her on board to sail with you? Do you have other J/88's in your fleet that you can sail against side by side setting up the boats similarly and making adjustments to one boat or the other in a "test and tune" session?

We don't have any other J/88's close or in our fleet so that avenue is kind of closed to us. I am not wanting to abuse the sailmaker so I will wait until I have some more observations of my own to make very clear questions they can answer without too much back and forth. Being a couple of hours away I may have to hire them to come and sail with us.

 

[JRacer]

You already hired them, bough their sails! Might just have to offer to pickup travel expenses, put them up if necessary and feed them. We have often had sailmakers come to our place to put on programs sometimes had to cover expenses and sometimes not just depended on their interest and availability. - they get the benefit of getting in front of prospective customers and showing their expertise and level of customer service. Once had Buddy Melges and Gary Jobson come and put on an on-the-water clinic. We promoted it at our club and other area clubs so we could get a crowd in front of them.Talk to your sailmaker.

 

[danstanford]

For those of you finding this in a search some day, here is our official answer posed in the original question. We looked at our setup with a critical eye and decided that our main was underpressed and our jib had too much draft/camber, particularly when in-hauled. We moved the jib cars back and sheeted the jib much harder which really flattened the foot and gave us a bit more twist in the jib. We still don't have much weather helm but our upwind angle came right up to where we had expected it to be and very similar to the rest of the fleet with speed right at targets.
Next step will be tightening the D1's to hopefully take some of the bend in the lower portion of the mast where we currently see an overbend wrinkle when the winds are light.

After assessing this result, following step will be easing the V1's and D2's to straighten the mast a bit which will hopefully give us more camber in the main which may give us the feel in the helm we need. We have been running the base setting from the guide in 3-8 knots where it is really meant for around 10 knots of breeze so we expect this will be helpful.

 

[danstanford]

Further follow-up and improvement for those searching.

I used the sailmaker's tuning guide to set up the boat but always felt the forestay sagged too much which relates to the original premise of the jib as too powerful. Since we had been struggling to point as high as we thought we should I focused on how to add rake so I did not really focus on the forestay length. A thorough review of setup led me to notice that though I had used the swing method to set the length I used a spin halyard rather than the jib halyard which made the forestay a little more than an inch longer than it should have been.

Once I fixed this the forestay felt right and the boat feels so much better and is faster while pointing where we thought we should be. It is written many places that seeking balance in the sail plan was the secret but this was a difficult one to ascertain when blinded by following the setup guide.

 

[Davidasailor26]

Interesting. Thanks for following up.
Do you find you have more weather helm with the proper forestay, and the lift from the rudder is therefor helping point better? Or do you think the longer forestay was just making the entry too round and keeping you from pointing up to a good wind angle?