89er

[JulianB]

Sorry peoples, very busy doing maths WRT the fin, ISO require you to get over 220% safety margin, I want to be up around 250-300% so we are just fiddling laminates, and staying away from Carbon.

Carbon, Lead and SS are not a good combination.

SS and Lead seam quite OK.    Basalt is inert.

Plus we pick up the hull frames tomorrow morning and one of the things we comit to quite early is the possition of the fin, so maths happening on that also.   Happy to share it all once we stop messing about.     With a boat that is designed to heel to get RM, you pull the fin a long way aft, because the WL as you heel get very round.

I also did a flexiable TE fin 5 years ago with great results, so I more than likely will do 2 fin's, one tacking and one not.

Martin Argentinian SportsBoat is 2 tonne and has 46m² working sail area.   The initial sums on Don't Panic is it's 1 tonne and has 41m² of working sail area.    One of us is wrong, very likely me, so that is consuming some grey matter.

Just tried to down load a Mp4 of us laying up the deck, but it's too big, I need to get Alex to reduce it's size, hope to have that up in a day or so.    There a even bigger one of us doing the cockpit, so that will require work also.

                      jB

 

[neuronz]

Sorry peoples, very busy doing maths WRT the fin, ISO require you to get over 220% safety margin, I want to be up around 250-300% so we are just fiddling laminates, and staying away from Carbon.

Carbon, Lead and SS are not a good combination.

SS and Lead seam quite OK.    Basalt is inert.

Plus we pick up the hull frames tomorrow morning and one of the things we comit to quite early is the possition of the fin, so maths happening on that also.   Happy to share it all once we stop messing about.     With a boat that is designed to heel to get RM, you pull the fin a long way aft, because the WL as you heel get very round.

I also did a flexiable TE fin 5 years ago with great results, so I more than likely will do 2 fin's, one tacking and one not.

Martin Argentinian SportsBoat is 2 tonne and has 46m² working sail area.   The initial sums on Don't Panic is it's 1 tonne and has 41m² of working sail area.    One of us is wrong, very likely me, so that is consuming some grey matter.

Just tried to down load a Mp4 of us laying up the deck, but it's too big, I need to get Alex to reduce it's size, hope to have that up in a day or so.    There a even bigger one of us doing the cockpit, so that will require work also.

                      jB

Concerning the sail area I think you might actually be OK. We are at approx. 1.4T and 43sqm on a much narrower boat than yours, so your crew weight should provide much more righting moment. We carry a heavy bulb, though. 

Edit: I just checked the rating certificate of Martin Billoch's design and it shows an upwind sail area of about 64sqm and displacement of 3433kg.

 

[JulianB]

OK, neuronz, we are at cross-purposes, Martin is about to start a whole new SportsBoat, not the one I sent you a photo of, it's 2 tonne and 46m².

Certinaly the sister ship to Don't Panic will have a big stick and big sails and power up very early in 5-6 knts.

I plan to target 8-9 knts fully wicked, I spoke before about 95 or 110% set-ups, just about everyone goes for 110%, but I'm a minimalist!

                jB

 

[neuronz]

OK, neuronz, we are at cross-purposes, Martin is about to start a whole new SportsBoat, not the one I sent you a photo of, it's 2 tonne and 46m².

Certinaly the sister ship to Don't Panic will have a big stick and big sails and power up very early in 5-6 knts.

I plan to target 8-9 knts fully wicked, I spoke before about 95 or 110% set-ups, just about everyone goes for 110%, but I'm a minimalist!

                jB

I was actually expecting something like this as the weight was so far off. But still from my own experience on our boat, which is not extreme at all, 1.4T and 43sqm are very manageable. We are sailing double handed quite often without any issues. To me 2T and 46sqm sounds very conservative.

 

[Mizzmo]

Julian,

Thanks for being so open about the design process.  I am very appreciative of the time you are taking to post and answer questions. 

Ben 

 

[huey 2]

The smaller , older version

https://www.gumtree.com.au/s-ad/richmond/sail-boats/sports-boat-vivace-79er/1272857869

 

[JulianB]

The smaller , older version

View attachment 471869 https://www.gumtree.com.au/s-ad/richmond/sail-boats/sports-boat-vivace-79er/1272857869

Fabulous boat, may have even considered buying it a year ago, but now

 

[JulianB]

I have not been a very engaging storyteller, my apologies.

As you can see from the previous photograph, we are now at hull building stage. I expect this to take 10 days to develop the plug, and then another 10 days to develop the hull.  

As with the deck and the cockpit, I had all the frames CNC milled, sure you can do it yourself with a jig-saw, but the simplicity of getting the MDF frames CNC milled is well worth the $2k it cost.

Basically, Al and I initially got some 100 x 40 LVL’s 6m long (max length they had) but they were too bouncy, so we went back and got 150 x 45 x 6m LVL, and within 3 hrs we had set up all but the front 1.5m of the boat using a Laser light.   Some fine adjustment is needed, LVL’s even though being super straight and 150mm deep is very rigid, there is still tweaking, and the laser leveller exposes all sins.   That was Friday, Saturday morning I extended the LVL fwd 2.5m with some 95 x 45 DAR timber, simple plate sleave extension, and re positioning the laser (you can see it in the photo) shot it fwd and positioned the front 3 frames.    Frames are at 600mm centres, couple of reasons, the biggest being if you have a problem you can get up and in between them. 500mm is just too tight, and 750 - 1m is too flimsy.

Tomorrow, we will simply but joint and splice stringers together (max length timber we can get is 6m,) so we will have to make up some 8m stringers and strake up the hull,   Keel line is 42 x 19 material, chine/transition fwd is that also, everything else is 19 x 19.

While getting the frames CNC milled we also got side panels cut, so this is where we have “virtually” band-sawed the boat at 2.4m to meet AUS towing regs.

I commented before about upping the plating material from 3mm to 4.7mm (old 3/16”) MDF, that should allow for a far more stable plug and once the plating and then glassing is done, it should be very ridged, we could probably remove the LVL’s and be none the worst (and they are not cheap) (but we won't).

Last 2weeks have been interesting.

I may have commented before about the Issues surrounding the ABSA in Australia and the requirement that we meet Cat 5 or ISO cert regulations.    There has been a pretty profoundly advancement in this, and one has to credit the President (Andrew York) for finding, managing and doing a “Knock Down Test” [KDT] under ISO cert conditions.

[SIZE=12pt]https://www.youtube.com/watch?v=IcjkQPoHWxc[/SIZE]

This will have an equally profound effect on the class here.   It’s simple, it can be down on the end of the jetty with all the deck chair commodores in witness in the event of dispute.


Credit where credit is due, I believe it’s important and great step in the right direction.

But what it does is re-set the bulb weight requirement, so whereas before I was guessing that I needed 140kgs on a 2m fin, to get Cat 5/ISO cert, to do the KDT and pass won’t require anything like 2m or 140kgs and probably less of both.

I spoke before about making sure you remain in flux and not locking down anything until you had to, this is exactly where the actions of “Yorky”, which I totally applaud, will have a significant bearing on what I am doing.

The first thing is that I can design and build a Fin which is Fit for Purpose” [FfP] rather than one that allows me to meet Cat 5/ISO Cert.

So I made some calculations and conferred with Martin in Argentina.

 In addition to that there are a suite of empirical “tweaks” which I had become aware off in Sportsboats where people modified their keels and in just about every case reduced span and area with great results.

I know people are going to ask me how I do this calculation, and I do have a formula which I have refined over the last 30 years, it did all my 18 teens, Vivace, OCL, 49er 29er SKUD etc etc etc.

The key element in Fin size is speed.  The ability for the fin to resist side load goes up as x² of the boat speed.    So if you have a boat that’s going to do 5knts with X sideload and another that’s going to operate at 7knts with the same sideload then the area of the fin in the 5knts boat needs to be almost exactly double the size of the board in the 7knts boat, and if the 7knts boat gets to 9knts, then it will have 165% the area it needs and that’s all parasitic drag, (plus weight and complexity).   Get to 12knts and it’s 3 times to big, get to 16knts (which we will) its 5 times too excessive.

Coming in very close 2nd in terms of importance is sideload which is a factor of RM (righting Moment) / Arm (distance between the CoE of the sails and the CLR of the hull (in my case the fin and rudder)).

I cheat and get the computer to find the CLR for me, and its 653mm below the keel.   Similarly It can find the CoE and that gives me an ARM of 6135mm

Boat is 3.5m wide, ½ ve that (CoB -> gunwale) so 1750mm, you then add on almost ¼ m for energetic hiking and shift in CoB to leeward of the CL as the boat heels even 5°, so KISS 2m.

500kgs of crew, x 2m = 1 tonne/m RM

1000kgs/6.135 = 162kgs sideload that the board must carry.




Pretty obviously I know the 49er very well, and it has undergone a range of refinements, and one of those is C’Board size, shape and section.    And it just happens to hit it’s “straps” at 7knts BS.

The area of a 49er Centreboard below the keeline is within 0.001% of 0.3m² (purely by chance)

49er is 3m wingtip to wingtip, so 1.5m CL to wingtip, add 1m toes to CoG of the crew, so 2.5m, and the mean crew weight is 165kgs so 412.5 kgs/m RM (approx. 40% of the 89er).

ARM is 4378mm (https://9eronline.com/library/49er%20working%20sail%20dynamics.jpg)

412 / 4.378 = 94kgs sideload.

162/94 x 0.3 = 0.51m² is the area needed by the 89er to resist expected sideload at 7knts hull speed.

And in some ways it is that simple, and we are extraordinarily lucky that we have such a great model with the 49er in that it has this sweet spot at 7knts which is the expected sweet spot of the 89er.

But, the 49er is far lighter, roughly ¼ of the weight of the 89er with ½ the power, so in the event of a change in circumstances, the 49er will accelerate or decelerate far faster to accommodate that change and you can cut the tolerance that much more. (in the case of the 49er to almost zero, 29er not so much)

89er is 5 fat old bastards out to have some fun, so we need some buffer room.

Cut a long story short, Martin suggests we go for 0.7 – 0.75m², I will probably target 0.68 -0.69m².

But we both agree that we don’t need any more than 1.5m below the keel and that in turn dramatically alters the construction and the weight of the fin.






Just as a cross reference, Vivace had a fin length of 1.8m which was latter cut done to 1.5m, and it started life with surface area at 0.72m² which was also cut back when they reduced span, (but they also increase cord, so not all that much).    Don’t Panic should be ½ knts at least faster than Vivace a) because it’s longer, b) because it’s probably going to end up lighter, but b)ii) a massive amount of that weight reduction will be in the rig, so inertia will be far lower and c) Don’t Panic is 20+ years younger and if we can’t do better than WTF are we doing.  (one of those things will be square head)

So Don’t Panic should hit 7 knts sooner, more simply and with less fuss, and therefore Fin area and Mast height can be (read should be) smaller, by definition!

That’s enough for now, but there are a whole bunch of other variables that come into play.

Possible reduction in bulb weight (to comply with Cat 5 /ISO post Yorky), but we have decided to stay put, a) because I have it and b) need to go play first.

Section shape, smaller span (down to 1.5m) means far less complexity WRT structure, in-fact even a moderate use of unies glass or Basalt will easily get us to 300% safety margin on the fin and that then allows us to set the section shape and % to what it should be rather than what it has to be.

The ability for the unies to completely resolve all the structural issue WRT the fin mean we can get rid of a SS spar, so away goes cost and away goes weight (about 16 kgs).

What I am trying to say here is that one unrelated action, in this case by Yorky, and again all credit to him, has sent me of on 2 weeks of maths and re-optimisation that will more than likely reduce totally system weight by atleast 50kgs possibly more (and that’s 5% and that’s massive) it has reduce price, probably reduce rig height, increased simplicity and just is going to make the boat that much more fun.

Still trying to get Al to convert Mp4 into YouTube, it should happen tomorrow plus I promise some photos of the Hull plug taking shape.

                    jB

 

[JulianB]

Promissed you a video of laying up the foredeck, it carries onto the 2nd skin and then the cockpit

 

[WCB]

6 hours ago, JulianB said:

Promissed you a video of laying up the foredeck, it carries onto the 2nd skin and then the cockpit

Thank you so much for sharing the process, Julian. 

What is that green core that you're using. I'm assuming it's core. It's so flexible. One can see it bending easily in your hand around the 3:15 mark.

 

[JulianB]

It's PET foam, so recycled soft drink or mineral water bottels, no idea how many times it been recycled, don't really care, I expect this boat to last 20+ year.

It's trade name is Kerdyn Green, made by Gruit, in reality all foam, regardless of make or manufacture all comes from one region, about 2 hrs nth of Beijing.

I am using 80kgs/m³ and 115kg/m³ and have been playing with this stuff, mostly in Italy (Nautivela) for the last 4 years with great success.

Really tough, we have 1/2ved the laminate schedual and it's still tough, so to some extent I'm building the 89er out of it as a trial for future 9er building as we go green. 

It is a interesting material, yes flexiable prior to being skinned, but seriously tough once skinned.

One of the big reasons the sailors pick moulded mains and jib was they believed they would get far greater longivity, and alot of that feed back came from the Moths (mostly ex 9er sailors) with their 3Di sails, Slingsby said something like, "hammer them for a year and they are still just fine, sure, get a new one for the worlds but 4-5 days sailing a week for a year no problem."    If we can duplicate that with the 49er, then we will 1/4er our sail consumption.     I will be very happy with 1/2!

Same with the carbon mast, Southerns are fabulous and we are hugley indebited to them but I think that CST is the next step up again, and all my research into mast for the 89er bear that out, so where as now you have sailors going to their 3rd Olympics with the same mast, and they only carrying maybe a top-mast as a spare (especially with the FX) now every sailor will have one mast across 2-3 hulls.

The whole point of that, is the weak link is now the hull, so to speak, they are still good 10 years later for silver fleet racing, be nice if we could get longivity in the 49er hull up so those Silver fleet racers can take on and beat some gold fleet racers and not have the hull holding them back.

Spoke with Turner last night (Ovington) he is planning to make a OK out of it, and go thrash it himself, McMillian here in Australia has already started on that project (building a OK out of Kerdyn Green).

Maybe, once the 89er project is done, I will get onto my long awaited Bat-boat project and build a 49er type boat but with Kerdyn Green core, Basalt skins, 50mm OD mast, have the possibility of foiling because if you build a test bed, why not, and I have Joaquin Zerbo (Martin's design partner in ARG) to draw on ideas.

But there is a cost benifit basis to foil or not to foil, being 49er's already do 26-27knts down hill, and they do it with big bright colourful sails (spinnakers) so they tend to be the media darlings.   Put them up on foils and maybe you would have Cuban Fiber flatties as downwind sails and that aint fun.   And all for maybe at best 5 knts extra.

Actually the Bat-boat project is exciting on a range of fronts, also in class managment structure, could be a water shed.

Sorry to go off point, but it's what my brain dose!

                         jB

 

[WCB]

It's PET foam, so recycled soft drink or mineral water bottels, no idea how many times it been recycled, don't really care, I expect this boat to last 20+ year.

It's trade name is Kerdyn Green, made by Gruit, in reality all foam, regardless of make or manufacture all comes from one region, about 2 hrs nth of Beijing.

I am using 80kgs/m³ and 115kg/m³ and have been playing with this stuff, mostly in Italy (Nautivela) for the last 4 years with great success.

Really tough, we have 1/2ved the laminate schedual and it's still tough, so to some extent I'm building the 89er out of it as a trial for future 9er building as we go green. 

It is a interesting material, yes flexiable prior to being skinned, but seriously tough once skinned.

One of the big reasons the sailors pick moulded mains and jib was they believed they would get far greater longivity, and alot of that feed back came from the Moths (mostly ex 9er sailors) with their 3Di sails, Slingsby said something like, "hammer them for a year and they are still just fine, sure, get a new one for the worlds but 4-5 days sailing a week for a year no problem."    If we can duplicate that with the 49er, then we will 1/4er our sail consumption.     I will be very happy with 1/2!

Same with the carbon mast, Southerns are fabulous and we are hugley indebited to them but I think that CST is the next step up again, and all my research into mast for the 89er bear that out, so where as now you have sailors going to their 3rd Olympics with the same mast, and they only carrying maybe a top-mast as a spare (especially with the FX) now every sailor will have one mast across 2-3 hulls.

The whole point of that, is the weak link is now the hull, so to speak, they are still good 10 years later for silver fleet racing, be nice if we could get longivity in the 49er hull up so those Silver fleet racers can take on and beat some gold fleet racers and not have the hull holding them back.

Spoke with Turner last night (Ovington) he is planning to make a OK out of it, and go thrash it himself, McMillian here in Australia has already started on that project (building a OK out of Kerdyn Green).

Maybe, once the 89er project is done, I will get onto my long awaited Bat-boat project and build a 49er type boat but with Kerdyn Green core, Basalt skins, 50mm OD mast, have the possibility of foiling because if you build a test bed, why not, and I have Joaquin Zerbo (Martin's design partner in ARG) to draw on ideas.

But there is a cost benifit basis to foil or not to foil, being 49er's already do 26-27knts down hill, and they do it with big bright colourful sails (spinnakers) so they tend to be the media darlings.   Put them up on foils and maybe you would have Cuban Fiber flatties as downwind sails and that aint fun.   And all for maybe at best 5 knts extra.

Actually the Bat-boat project is exciting on a range of fronts, also in class managment structure, could be a water shed.

Sorry to go off point, but it's what my brain dose!

                         jB

Thank you for the comprehensive response. I'm working on a new boat building plan/project, a couple actually, and thanks to you we're going to spec PET core on both of them.

 

[JulianB]

Close to plating time.

 

[WCB]

View attachment 472636

View attachment 472638

Close to plating time.

Jealous of your work space too!

 

[Jethrow]

What are the catamarany things stacked up in the back of the bottom photo?

 

[Dex Sawash]

And what are the boats piled up that you can see in the still image for the foredeck video, 4ish meter with hiking wings

 

[JulianB]

We call it a WING   (my fathers name for it)





This is me sailing a Ovington built hull, December 2018, in HK, (Clearwater Bay) with a W6m² rig in 5knts of wind.   (I'm way to fat, hence building a 89er)

It's what I have been playing with for the last 8 years, 4 of them in Italy with Paolo Portiglia at Nautivela where we developed all of our green technology, so PET foam cores and learning to use Basalt.

This rig is what became the C-Rigs (for the Laser/ILCA)

I will see if I can find the video from Italy (near Rome airport) that was taken January 2020, (right before Covid went crazy)

Bloody quick, it catch's a 29er going up-hill (in HK).

 

[Bill E Goat]

I spoke earlier about running into GT for coffee most mornings.   This morning, both of us where early, and while sitting down, good mate who was in Garda in an infamous drinking hole looked up and there was a photo of Banana Republic taken in 1989 in Bandol Sth of France, GT saw the photo as it came in on WhatsApp, as I did and we both laughed a lot! He was the sheethand, I was the skipper.

View attachment 468848

Here is one from 1990 tour, me Neil Mac and Aido

 

[JulianB]

Yep, got that poster in my roof.

 

[Bill E Goat]

Yep, got that poster in my roof.

So many good stories from that tour