Light winds and 'happy' breakages... and video

 We did manage to get out again a couple of days ago. The winds were still light but we made an effort for the practice as much as anything. You always learn something. On one hand we don't want to expose the boat to risk... on the other, not practicing as a team exposes the boat to risk.

The wind was moderate and we went on standby at the yacht club for a period before deciding just to go for it. The wind at speed-spot was once again around 17-22 knots... generally around 19-20.

A brand new GoPro 2 let us down by simply freezing up just before we started. Swearing at electronics has become part of my 'pre-flight' ritual. I don't know how many cameras this project has eaten through. The GoPro's are great bits of kit... essential really... but they earn their swear-time too.

The start up went very smoothly again. The back skeg had been chopped down by Ben after the previous run. The back of VSR2 still kicked around as it lifted out of the water but I will put this down to sailing in lighter winds. I was seeing wind gusts as low as 15 knots just before I released from the RIB.

Once I was on the course she felt fast and slippery once again. The speed was more constant than the previous run. The peak speed was 46.22 knots and the average was 43.85. Nothing flash in outright terms but very impressive for us considering the wind strength.

I had the little TACKTICK wind vane mounted just in front of the cockpit where I could see it... and I still didn't look at it! One of the cameras did catch it however and it was obvious that we are now sailing at a level of efficiency where the apparent wind is lining up perfectly with the fuselage. We are fitting all the little aero aids now as they will begin to have an effect.


Once the run was over we had an issue with the wing. A retaining collar had failed on the mast. It normally wouldn't be an issue when sailing but when at rest the wing can sometimes put the support strut under compression. This puts an up-force on the mast. The mast proceeded to rise up off the lower curved section. The rigging went slack. We all froze as our minds raced to what had failed and what was now being loaded abnormally. So often you can do the wrong thing at this point. The situation sort of stabilised in a wobbly way. Fortunately it was only light winds and we managed to understand the issues and get the whole thing down without causing any secondary damage. The wing has been under heaps more load than this before so it was quite surprising to see this. I'm glad we did as it would have no doubt ruined not only our next windy day (if it happened then) but also caused a lot more carnage and therefore ruined a week or so. The new part has already been made by Jose at BRUMAR ENGINEERING in Walvis and the wing will be re-assembled tomorrow. We haven't missed anything.

Here's the video of the run...


We remain plagued by light winds. Tomorrow is a maybe and Monday is playing with us. It looks like we are right on the edge of some strong stuff but it comes and goes with each forecast. I can't wait to let this boat go in a 25 knot plus day. Meanwhile we go over the boat... and sit and wait... and watch the news coming up from Luderitz where they are getting plenty of wind. Great to see the windsurfers beating their own records and edging ever closer to 50 knots. I look forward to sending some big numbers back down their way soon. Come on Walvis... jokes over.

Cheers, Paul



Ready ?

The last run ask me some questions ?
Why did you abort the last run ?
what happens during the abort and the standby for next run ?
You didn't post some news about Friday ? Were you working on some repairs on Saturday ?
Is VSR ready and full capacity for next weather window ?

Best regards

Reply... Re: Ready

 Hey Florian,

I aborted the last two runs as the conditions were just plain messy. I thought we might have been in for a big day as I saw a gust to 29 knots on the course when we first set up the weather station. The trouble was that we also saw low's around 16-17. The direction was also swinging way into the West i.e. making the course more downwind. When we got the wing up at the top of the course I noted that it simply didn't feel that windy. The odd gust would come through quite strong though... so we went for it. The start went OK although the acceleration wasn't great. A good gust came through and I was very keen to get the large, retractable rear skeg up quickly. The pull-up line is near the mainsheet and a slight fumble on my part caused the wing to be eased as the skeg came up. I need one more hand some times! Anyway, this slowed the acceleration and hence the build up in Apparent wind speed. When I turned down the course... the apparent wind didn't come with me. I put this down to the wind dropping off and the westerly component... and the lack of boatspeed during the run in. VSR2 sagged down and I aborted the run stopping just in front of the timing hut.

We lowered the wing and sat and watched the wind for a couple of hours. It was a dodgy day.

For some reason Helena's phone wouldn't send the 'tweets' to keep you all updated. She was trying.

Conditions weren't that good but we decided to try again. The second run just simply didn't get going at all. The boat felt heavy... but then the wind wasn't very strong. I aborted again in front of the timing hut.

It was disappointing. Once again we rode the emotional roller-coaster of 'today could be the day... not it isn't'. We washed VSR2 down as always and went and had a beer.

No breakages, no issues, no exciting speeds. We had made improvements to the data acquisitin and comms. but that is about it.

Today is very flat. Tomorrow might deliver.

Yes, VSR2 is ready and at full capacity. All the little aero gadgets are on. We're going for it now.

Cheers, Paul.

Who ate all the πs?

If the apparent wind is aligned with the hull and you are going 90º to the true wind as I think you said you were before; then as the hull is at 20º, in order to achieve alignment you need to do 2.7x wind speed. But you are only doing about 2x wind speed according to your figures. Does this mean you have realigned your boat so that it points less than 90º (84º?) into the wind at full speed. Incidentally, I have watched your posted video but cannot see the TackTick you describe.
I have seen it proved mathematically elsewhere that the fastest course for a sailboat is π/2+angle between aero/hydro foils, so in your boat that would be about 102º to the wind. Could that explain your observation that the boat speeds up a little as you bear away at the last minute of your run?
I suspect some error in my analysis or interpretation and look forward to your response, keep up the good work.


Reply... Re: Whoa ate all the ns?

 Hi SL.

The fuselage is angled at around 26 degrees from what I remember. I would have to double check as the actual centerline of the boat is more determined by the chord of the foil and the leeway angle than the direction of the floats.

When designing the aeedynamic package of this boat we took into account the wind shear and twist of the location. We went out onto the course and measured the wind shear from ground level up to around 20'. It turned out to be very close to predicted levels found in text books (Whadya know?).

So as we get lower down... especially at the float level, we need to orientate everything for tighter apparent wind angles(AWA).

Funny thing about that little 'yaw string' wind indicator in front of the cockpit... I forget it every time. I need to climb/slide up the bow to get in the cockpit so I remove the indicator every time. It has a small drilled hole which it is pressed into. I keep the indicator stowed in the cables in the cockpit when it is not in place. I remind myself every time to put it in place as it is a key indicator as mentioned. Even when I do remember to put it in place... I forget to look at it. It's right in my face too. I don't know why I struggle with this. Now I get Alex in the RIB to remind me as part of our double-check-list once I am seated in the boat and being 'lowered' out onto the course. Practice will improve all this. So, the masthead video you have is from a run where the indicator is not present. It was in the last 46.2 knot peak average run and I could see it from the masthead.

We now also have the onboard wind data being recorded. You would think it was easy. Getting real accurate wind off a boat is actually extremely hard. We have all sorts of interference issues with the amount of GPS, vhf, intercomm, wireless etc stuff bouncing around the cockpit. I think we have it resolved now.

In reply to one of your earlier posts, a huge amount of work has been done on the aero modelling and general VPP (Velocity prediction program) for this boat. It is our second boat. The first boat's VPP provided a great starter platform for this boat. I am very confident in the work done by AEROTROPE in modelling the overall performance of VSR2. We chose to include numbers bordering on the pessimistic to include in the VPP. I would rather the boat be likely to overperform than the other option.

I have often questioned Chris (AEROTROPE) about how much difference it makes to performance if the fuselage isn't aligned... and I'm often disappointed by the low overall effect of it in comparison to the hydrodynamic issues.

The wing angle is of course more critical. Obviously if we aren't achieving our polars i.e. 60+ in 26 knots then we need to reconsider how the boat should be sheeted. This is pretty basic stuff on any sailing boat regardless of speed. We do still use tell-tales you know;) The fact is that once I am properly hooked into the wind and have turned away down the course, the acceleration comes with each little bit of sheet pulled in. The tell tales are quickly referenced during runs as they are always refenced during the strart up phase. AWA changes quite quickly from rest whilst AWS (apparent wind strength) builds slowly. As the AWA moves forward of 45 degrees the balance begins to go the other way. From the cockpit I pretty much use tell-tales and the feel of the boat i.e. if I sheet in more, do I accelerate... if not, check tell-tales and ease a bit. Like I said, pretty normal stuff.

I agree that there are potentially some losses and refinement that could currently be made here... but on the other hand... this is not the reason we are stuck in the low 50's. We shouldn't start setting the boat up just for this speed. There are far bigger issues and we should remain focused on 60 knots. If we thought all these problems were causing a mid-high speed hump then I would be more concerned. Sailing in more wind has shown us that it is not a power thing (Yes, we know that higher TWS leads to bigger AWA's for the same speed). The aspects you have raised have all been discussed in detail. Once we have finished sailing on the water... the data gets processed and sent back to Malcolm and Chris who then proceed to go sailing in the VPP to see how things match up.

I haven't checked your maths... but I am confident they have checked theirs... and then cross-checked each others. We encourage our team to find faults in each others reasoning or calcs. We do it in a healthy and constructive way.

If you like I can perhaps send any further queries you might have onto Malc who can be more specific on the maths.

Cheers, Paul

light wind sailing

Is it my imagination or is there a lot less spray off the foil on these runs?
It looks very good roll on the breeze

Reply... re: Light wind sailing...

 Hi Mike...

There is less spray and also a distinctively different pattern.

This is no doubt caused by the fences and the effect they have on the flow off the foil. You can really see it from the masthead camera. It's not only the amount of spray but also the orientation of it. We aren't hitting the back float with spray off the underside of the foil anymore for starters.

I'll sned some pictures through in the future to show you some of the great footage we are getting onboard that shows all this in amazing detail. The new GoPro's 2's give incredibly detailed images. That said... they do have some pretty big issues i.e. they freeze up all the time. We can take still images that show all sorts of fascintaing interactions between the wake, spray off the front float, rudder wakes, fence spray etc. well worth the effort.

Cheers, Paul.

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