Over the weekend, us guys at the club decided to have a slug out between the 2 F16 designs, the Blade versus the Viper, both boats sailed in one-up configuration.
For a little background knowledge, the Viper was sailed in standard configuration, while the Blade was highly modified, sporting the bigger Viper beams and a set of Goodall sails. The 2 sailors, myself and Scott M, were comparable in weight, both at 78kgs but he is taller than me. The conditions we sailed in ranged from 3knots to 12knots with flat water to chop of around half a foot.
The first trial run was an 30 minute upwind leg in about 12 knots of breeze. What we found was that the Viper started flying a hull much earlier, why, I'm not sure, but I'm guessing due to the increased hull volume compared to the Blade. This meant that in the lighter winds, the Viper sailed higher than the Blade. The Blade however, sailed lower but faster and crossing tacks, it was actually pretty amazing how close we were despite the differences in angles. One of the reasons why I thought the Blade did well was because with the smaller hull volume, it got through the chop better, whereas the Viper took much more effort trying to get the boat through the chop well in one up configurations with my weight. This verifies my feeling before i bought the Viper that it was more suited for 2 up sailing, or solo sailing with a really big guy, ie, 90kgs plus. The Viper, flying a hull much earlier also meant that i was over powered much earlier than the blade, and had to pull in much more rotation and downhaul to keep the boat sailing well.
On the downwind run, due to the fact that the Viper could fly a hull earlier, we found the viper to have the edge in the lighter stuff, but once the wind came up to the point that the Blade was also flying a hull, all differences were negated and the boats were pretty much equal.
In conclusion, if I were to buy another boat, specifically for one up sailing in F16, I'd definitely be looking at the Blade due to my weight and size.
We'll be out doing more testing over the weekends for the fun of it. Just thought i would share our findings. Please take it in good fun.
Hi ckuang,
I am afraid your post has brought up a lot of questions in my head. You said crews where the same wieght, but are the boats the same weight?
What is the difference in hull volume between a Viper and a Vectorworks Blade?
Are the mainsails the same cut?
Are the spreaders at the same angle?
Are the diamonds the same tension?
Are the rotation and luff tensions the same before getting overpowered?
Are both sailors pulling the mainsheet on as hard, with the same purchase?
Did you swap boats between sailors and do the same tests twice?
I have found similar differences in hull flying and pointing ability, when I use to swap Mosquito's which are one design, with other sailors. I thought it was my boat that didn't point, but it turned out it was just me. <img src="<>/frown.gif" alt="frown" title="frown" height="15" width="15" />
Also it is probably worth mentioning, that the Blade hulls you are commenting on are Vectorworks Blade hulls, as they have small differences in shape and volume to Blade hulls built by others.
I am afraid your post has brought up a lot of questions in my head. You said crews where the same wieght, but are the boats the same weight?
What is the difference in hull volume between a Viper and a Vectorworks Blade?
Are the mainsails the same cut?
Are the spreaders at the same angle?
Are the diamonds the same tension?
Are the rotation and luff tensions the same before getting overpowered?
Are both sailors pulling the mainsheet on as hard, with the same purchase?
Did you swap boats between sailors and do the same tests twice?
I have found similar differences in hull flying and pointing ability, when I use to swap Mosquito's which are one design, with other sailors. I thought it was my boat that didn't point, but it turned out it was just me. <img src="<>/frown.gif" alt="frown" title="frown" height="15" width="15" />
Also it is probably worth mentioning, that the Blade hulls you are commenting on are Vectorworks Blade hulls, as they have small differences in shape and volume to Blade hulls built by others.
Same questions from me.
If the heavier boat (and I assume the Viper is) flying a hull earlier; the sails MUST be generating more lift and so they MUST be cut differently or trimmed differently.
we need more info to understand what was going on!
ok here are a few quick answers
- no idea about boat weights. Assuming blade would be lighter. Hull is vector works hull. But boat is modified so its got viper everything expect the hulls.
- mainsails are the same
- spreaders are same angle
- diamonds same tension
- rotation and luff probably not same. left to the sailor to adjust
- yes main sheet have same purchase, not sure if both pulling as hard. I'm sure over the course we were testing on, there were adjustments that meant sometimes the viper had less tension and sometimes the blade had less tension. i mean, when one boat hit a wave first, they would adjust the sheets to compensate first right?
Anyway, was just a quick and fun test so please dont take it so seriously guys. will do more testing over the next few weekends and see what differences there are.
Ckuang,
Best test would indeed by to switch boats when the conditions are still the same and see if the changes remain. This is also easy to do.
Wouter
Ckuang,
I think they guys are very, very, interested in these things, which perhaps explains the quick replies and questions.
Like Wouter said, you really need to swap boats and see if anything changes. It will, no doubt, there are no two sailors who are identical even if the boats are, there are fast guys and not so fast guys, and in certain conditions, some guys are fast, and in other wind, not so fast.
I did this a long time ago when a group of us were all sailing
one design
Nacra 5.5's. I got on the
champion's boat
and it felt like a completely different boat, it felt lighter, faster, flew a hull quicker, etc, yet we all had Nacra 5.5's. We even measured the sails, pretty much the exact same size, but all his stuff was -brand new- and all my stuff was 5+ years old. It makes a huge difference.
I'm sure your two boats are both new, but still you should try his boat and he should try yours, see how they feel.
Hey Ckuang,
Thanks for the comments. Did you already did the same with 2-up configuration?
@Gary: I'm not sure the wetted surface of the USA and Aussie blade differs... They sure look different, but I'm not sure if they really are.
Regards,
Gill
Thanks for another informative write up.
But I have to agree, that a true evualation is when you swap boats after a lap or two.
Phill and I often found,when testing the Taipan against the Blade, that it was the skipper that sailed better on some points of sail and not the boat.
It's all useful information.
Tony
Hey guys, don't worry, we'll probably be doing a boat swap in the next few weeks or so. the first test was only an hour long and something we did for the fun of it because we were thinking of something fun to do.
Perhaps one of the major questions I have as a result of this testing is does more hull volume cause a cat to fly a hull earlier as the leeward hull is not depressed as easily? if anyone has any idea on boat design can chime in, that would be great.
Which boat has the deeper dagger boards, and how much deeper?
Hey Gilo, sorry haven't done a 2 up face off yet. There was a short session that Scoot M did, but I wasn't there. It as between a Nacra F18 (not the infusion) and a new viper fresh out of the box. It can be seen here
http:/
In that test, I believe the Blade lead the way through the entire test, but the F18 was still not done being setup right and the Viper crew was brand new to the boat, so I think our one on one face off was probably a more accurate comparison
Hi Timbo, the Viper has deeper centreboards by far. Maybe around 25% longer boards. The blade had wider boards. However, that being said, the boards are the vectorworks boards. The Australian blade looks like it might have longer boards than the vectorworks ones.
Blade length has a bit of impact with heeling from a purely geometric point-of-view. The longer the board the greater the separation between centres of pressure of the rig and board so the greater the heeling moment. But this is highly simplified.
Volume doesn't affect rate of sinkage, waterplane area does. Say you have a barge that is sitting on the water and you add some weight, it will sink a bit. Now take a
narrower
barge of the same length and weight and add the same weight, it will sink more than the first barge.
Sinkage = Weight Added / (Area of Waterplane x Water Density)
So to get a hull for a F16 out of the water with a Area of Waterplane of approximately 1.5m^2, total weight 260kg and sea water density 1025kg/m^3.
Sinkage = (260/2) / (1.5 x 1025)
= 0.0846m
= 85mm
With a waterplane area of say 1.2m
Sinkage = (260/2) / (1.2 x 1025)
= 0.1057m
= 106mm
With respect to cats of the same general overall beam and length, they will heel the same angles under the same heeling moment but the one with the
wider
hull won't sink as much so the windward hull will fly slightly earlier. In the above situation, the wider hulled F16 will fly a hull about 0.5 degrees of heel earlier than the
narrow
hull F16.
All other things being equal (and that is never completely possible) the shape of the respective hull lines at their respective
waterline
determines when they first heel to the point of lifting the other hull out of the water.
This can be seen very dramatically between hulls with
tumble home
(and hulls with different tumble home at different
heights
) and those without as well as the difference between hulls with a hard chine and ones without.
My Blade has the deep boards and I race against guys who have the short, wider boards as you have. I have noticed that I will fly a hull earlier than they do in the same wind.
But I also fly the hull too much when the wind comes up, and have to lift my boards up a bit when it's blowing hard, just to keep from flying the hull too high. I also have to pull them up half way going downwind in a blow to keep from stuffing the bows in a good gust. I'll bet that is why the Viper was flying the hull sooner.