Slainte97

J97 Tuning Hints

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On 8/22/2018 at 12:14 AM, Slainte97 said:

Just started racing a J97, looking for any tuning or performance hints or ideas. 

We are in the same situation and also looking for tips. Downwind seems to be the easy part, upwind is a bit twitchy and the groove area is narrow. That said, basic text book trimming seems to be mostly ok.

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That said, do you have pica or instructions for a good jib inhauler arrangement for the 97? Ours is not good as it pulls the jib sheet forward towards the mast foot. Would be nice with some J/97 specific ideas before I start drilling.

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I'd reach out to Paul Heys, owner of Key Yachting in the UK.  There's a lot more J/97 racing going on over there, and he is one of the main European J/Dealers.  I suspect they have a ton of info/contacts that can help you...

 

https://www.keyyachting.com/contact-us/

 

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have you loaded the polars yet in your system? that should at least give you an idea on the target angles and speed.  I agree to call Paul Heys after this, for more tips&tricks on how to make the boat go fast. 

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Couple of big batteries in front of the mast step to trim the bow down

Race with 7 minimum, sheet the main hard and hike like hell.

Fly the A sail tack high downwind and heel the whole lot to weather, 170twa is your target angle

Practice sailing wing and wing downwind

 

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13 hours ago, JL92S said:

Couple of big batteries in front of the mast step to trim the bow down

Race with 7 minimum, sheet the main hard and hike like hell.

Fly the A sail tack high downwind and heel the whole lot to weather, 170twa is your target angle

Practice sailing wing and wing downwind

 

Interesting with the batteries, is this actually something practiced on J/97s? 

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On 9/7/2018 at 5:23 PM, JL92S said:

It has been known to make them faster, they don’t even need wiring in

Supposedly making the waterline longer then for upwind and reaching? The J/97 bow indeed floats quite high:

 

j97-evolution-2.jpg

 

1_4.jpg

 

 

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On 9/5/2018 at 7:19 AM, Nubben said:

Interesting with the batteries, is this actually something practiced on J/97s? 

 

On 9/7/2018 at 10:23 AM, JL92S said:

It has been known to make them faster, they don’t even need wiring in

Does anyone know if you are adding two more batteries infront of the mast or is it best to move the existing batteries infront of the mast. Mine are a little behind the mast now. 

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Considering the optimal shorthanded setup for a J97. To start with, I hate changing headsails. 

Currently we have a reefable full size jib, specified to cope with 30kts of wind if necessary. Very nice sail.

In addition we have some older North M/H jib and a true heavy jib, with 1,5m short luff.

Downwind we have North A2 and masthead kite which is about 85% of the A2. Uncertain what the correct classification is of this one.

Currently I am considering what to add for the optimal shorthanded setup for distance sailing in the Baltic sea, e.g. mostly light winds. And again, I hate changing sails so I prefer sails which have wider usage possibilities.  

Options:

1. J0 from sprit on a furler with an additional clew patch. Could go upwind and reach, but is not optimal for twa 70-100 especially if designed for going upwind?

2. C0 from sprit on a furler. Not for upwind but better in really light and is better on open reaches?

Other ideas?

What would you prefer and why?

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I don't think you can get enough tension on the sprit for a code 0 to effective in higher angles. consider flying it from the bow instead

 

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If sailing in the light airs why the small A2? The J0 idea looks good although like jmod said sprit tension might be an issue, consider an over specced bobstay and overspec all the bits of rope related to the J0! Other options include fitting a small fixed bowsprit just for the J0 or to use a collar round the bowsprit similar to that used by @Blur, hopefully he can chime in on his setup.

I’m guessing your jib’s reef is a slab reef and the jib is on hanks? If so that’s a decent headsail setup.

I always felt the mainsail on the J97 was slightly small so would consider a larger main for light airs. If the backstay is a big issue then a longer boom would be my next step.

 

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On 5/17/2019 at 11:22 AM, JMOD said:

I don't think you can get enough tension on the sprit for a code 0 to effective in higher angles. consider flying it from the bow instead

 

Perhaps, you don´t think fitting a bobstay would enable enough halyard tension?

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On 5/17/2019 at 11:51 AM, JL92S said:

If sailing in the light airs why the small A2? The J0 idea looks good although like jmod said sprit tension might be an issue, consider an over specced bobstay and overspec all the bits of rope related to the J0! Other options include fitting a small fixed bowsprit just for the J0 or to use a collar round the bowsprit similar to that used by @Blur, hopefully he can chime in on his setup.

I’m guessing your jib’s reef is a slab reef and the jib is on hanks? If so that’s a decent headsail setup.

I always felt the mainsail on the J97 was slightly small so would consider a larger main for light airs. If the backstay is a big issue then a longer boom would be my next step.

 

Sorry, was unprecise, we have a 90m2 A2 and 77m2 A3/A4 or similar. So the A2 is not so small, although I have seen J97s with 105m2 kites. 

Had looked at a second fixed bowsprit, but feels like overkill. On the other hand it could perhaps be used to land on islands which is quite popular around here when cruising and solve the problem with the vertical bow. I have looked into Blurs setup yes... 

Slab reef yes, hanks no because we have a facnor flatdeck furler. So the sail has sailtech horizontal furlable composite battens. Would prefer hanks(and perhaps a structural furler) but that is not in the plans at the moment. 

We have a new main which is 2m2 larger than the standard one to cope with the light airs around here, did not want to do a fathead though not to change the balance of the boat or cause a need for double backstays.

If the upwind light weather performance is ok then I might just opt for the code(cableless perhaps) for a bit more open angles making it a versatile sail. Still need the bobstay though but then the normal sprit is probably fine. Still a question though in that case if it should be hoisted at the end of the sprit or middleish as Blur for example. Need to discuss sail size and design with my sailmaker here.

 

 

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If it were by boat I would use the collar idea round the bowsprit and run the tackline as a 2:1, but I would have the code 0 flying off the end. The 97 has a proportionally shorter bowsprit than a 111 or 88 so I feel the whole bowsprit would be better. It should also improve helm balance having the sail pushed further forwards and also it ensures the tack is on the centreline. Cable less works well and should carry lighter loads than a cabled code 0 which should be kinder on the bowsprit and bow structure. 

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Thanks for the advice (last Summer). 

Anyone with picks from the foot upwards of J/97 jibs? Would be interesting to see the shape especially of a North J1.

 

Ordered a C0/J0 crossover(47m2 mid girth ~63%) for light wind beating and reaching in all other conditions. Will fly it off the end of the sprit and furl on a Facnor FX.

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22 hours ago, Nubben said:

Thanks for the advice (last Summer). 

Anyone with picks from the foot upwards of J/97 jibs? Would be interesting to see the shape especially of a North J1.

 

Ordered a C0/J0 crossover(47m2 mid girth ~63%) for light wind beating and reaching in all other conditions. Will fly it off the end of the sprit and furl on a Facnor FX.

Your local North loft should have the designs on file? North did lots of design work over a few years on J97s in the UK. Your C0/J0 sounds like a fantastic sail for the boat

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Anyone who has installed barbers for the assymetric/spi sheets on a J/97 and would have tips on the best setup?

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No one really interested here in J/97 it seems. Well I will continue this as a documentation thread in any case for future reference. 

I managed to install barbers for the sheets to be used with the code coming from the toggles at the shrouds, no problem. I also installed a bob stay by removing the U-bolt at the end of the sprit, replacing it with a huge ring and then drilling a hole in the bow at the bottom of the anchor locker. So far so good. I then decided to check it by stretching it using the halyard/tackline. Then I noticed the ring was coming up from the bowsprit regardless of how I adjusted the stop knot. Conclusion was that the sprit outhauler is stretching. It seems to be a 6-8mm polyester rope as a 2:1 configuration. Decided to swap and make it 4:1 at least for the high compression loads due to the bobstay. Easier said than done though as it seems that the end of the outhauler is attached in the front of the watertight laminated sprit box with the inspection hatch being in the back end. Any suggestions other than sawing a hole and installing a new hatch in the front part of the sprit box in order to be able to change the rope?

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4 hours ago, Nubben said:

No one really interested here in J/97 it seems. Well I will continue this as a documentation thread in any case for future reference. 

I managed to install barbers for the sheets to be used with the code coming from the toggles at the shrouds, no problem. I also installed a bob stay by removing the U-bolt at the end of the sprit, replacing it with a huge ring and then drilling a hole in the bow at the bottom of the anchor locker. So far so good. I then decided to check it by stretching it using the halyard/tackline. Then I noticed the ring was coming up from the bowsprit regardless of how I adjusted the stop knot. Conclusion was that the sprit outhauler is stretching. It seems to be a 6-8mm polyester rope as a 2:1 configuration. Decided to swap and make it 4:1 at least for the high compression loads due to the bobstay. Easier said than done though as it seems that the end of the outhauler is attached in the front of the watertight laminated sprit box with the inspection hatch being in the back end. Any suggestions other than sawing a hole and installing a new hatch in the front part of the sprit box in order to be able to change the rope?

I raced used to race a J122 and to get round the problem it used a 4:1 purchase (or 3:1 but I think it was standard on larger models?) and used a tapered SK78 line with cover coming into the cockpit but had a Spinlock XX clutch side mounted onto the back face of the coach roof with a large pad glassed in behind it. They had experienced the problem of pulling the cam cleat through the bulkhead. Rather than use a stop knot I would splice in a dog bone instead. Also what line are you using for the bobstay? 

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1 hour ago, JL92S said:

I raced used to race a J122 and to get round the problem it used a 4:1 purchase (or 3:1 but I think it was standard on larger models?) and used a tapered SK78 line with cover coming into the cockpit but had a Spinlock XX clutch side mounted onto the back face of the coach roof with a large pad glassed in behind it. They had experienced the problem of pulling the cam cleat through the bulkhead. Rather than use a stop knot I would splice in a dog bone instead. Also what line are you using for the bobstay? 

Yes, was considering to either increase purchase or install a clutch on port side of cabin (starboard has one for the tackline). SK78 6mm pure dyneema for the bobstay.

 

Still looking to here if there are other solutions than introducing a new clutch in order to change the outhauler rope? 

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34 minutes ago, Nubben said:

Yes, was considering to either increase purchase or install a clutch on port side of cabin (starboard has one for the tackline). SK78 6mm pure dyneema for the bobstay.

 

Still looking to here if there are other solutions than introducing a new clutch in order to change the outhauler rope? 

I would extend the bowsprit fully and mark the sprit with a pen and repeat your experiment. Maybe a few marks at 5mm spacings to work out how much if anything the bowsprit is retracting. I have a feeling that it is the bobstay is stretching, if I understood your description correctly the bobstay dyneema also holds the ring the tackline goes through? I am more inclined to think that it is the bobstay that has the stretch in it. Knot, the rope itself, the splice for the ring, all areas that can stretch 

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Two things to think about the bob stay will stretch unless you use something like pbo, but then uv will kill it.  We have had success with heat set but we still stretch it after to spice it. 
 

the pole out system is under huge load. We put a constrictor clutch on the ceiling of the cabin top. The cam cleat is good around the cans. But it’s not up to the job on long legs.  
 

last Transpac we broke the dog bone on the bob stay. The water box held so we lowered a guy over the side and filled the whole with wet setting epoxy. 

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On one of our boats we used 12mm SK99 for the bobstay on a short fixed bowsprit, overkill but the factory bowsprit (this is a sf3600) kept cracking under too much flex so we went for the zero give option. Also when you test using the tack line I guess you are attaching it aft and then winching it? If so you’re giving it a lot of aft loading rather than the vertical loading you’ll see from a sail and essentially creating a 2:1 purchase on what you winch

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On 8/21/2018 at 5:14 PM, Slainte97 said:

Just started racing a J97, looking for any tuning or performance hints or ideas. 

Hows it going? Did you figure it out ?do you like the boat? Im very interested in how this boat does in PHRF

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