At the Michigan Cat fight... several teams were talking about the new Nacra F18 and future of level racing against Inter 18's with their stock main's and the Hobie Tigers. Indeed, Nigel Pitt commented to me that the 18 footers were appropriate for sailing with his wife and he looked foward to this class!
I just read about the development of the F16 rule and it appears that one of their goals is to have the boat rate the same as the formula 18 class (quite possible since these builders are knocking 150 lbs off of the boat?)
My question and concern is ... Are the *US builders and dealers jumping on the F18 bandwagon in the US .. 8 years too late!! Will they be selling a boat which will have little appeal to the sailing public in a few years (see history of all other 18 foot boats since H/P 18's) . What is the marketing strategy for selling a 400 lb boat (F18) to the public versus a 250 lbs or so F16. If the boats will compete boat for boat on the water.... This would seem to be a no brainer...
(BTW I just finished racing the Bim F16 at the catfight and had a blast on this little boat. I really enjoyed being able to move the boat around and really hated helping to move the 400 lb boats though that soft sand.)
Perhaps the US Market should skip the F18 generation of boats and pick up on the F16 to serve the demand for a performance boat in the 16 to 18 foot market!
What do you think?
Mark Schneider
The F16HP even restricted their genaker size area to stay at the F18 calculated performance. Under Texel rule for example a 21 sq. mtr. genaker is allowed (same size as F18's) but we have limited the genaker to 17.5 sq.mtr. for this is exactly the 83 % size of the 21 sq. mtr. genaker of the F18's. Why 83 % ? Because that is the ratio of wetted surfaces between the two designs and is expected to be the ratio of wave making drag between the two. These thesis are also supported by Frank Bethwaite (known for his book high performances sailing) and real life experiences thus far.
So the drag of the F16 HP is 83 % of that of a F18 and then the engine must be 83 % too in order to stay equal. That is done by limiting the genaker area, and the combination of rated mainsail area and rated jib area as they are specified now. The Texel and handicap is therefor equal to F18 by definition and the ISAF handicap is nearly always equal to the F18 unless abnormal sized boards are used.
We feel that this is a strong indication that the F16HP in its F18 setup will therefor be equal to the F18 in real life within the 1 % margin of uncertainty that will also exist (even between F18 designs themselfs)
This aspect of F16 HP will always be maintained as long as the F18 class is active and lively. Even when heavy F16HP crews are allowed to use bigger genakes and jib to make them equal with F16 HP crews of 150 kg's or less which are equal to F18 by definition.
To read more about the this class go to :
http:/
Wouter
Mark can you give us your comments on F16HP forum with respect to the CatF 2 race. Kirt already gave an quite elaborate report.
You find us at
http://www.catsailor.com/forums/postlist.php?Cat=&Board=Fleet45
Which is the F16HP sub forum on this catsailors forum
Many thanks ,
Wouter
Just a thought why doesn’t an organization get together and develop a new F18HP class. I think having a formula 16 group is great but why not develop a new lightweight Formula 18 class, seems to me that we are leaving the 18-foot cats in the dark ages.
It is not that simple and F18HT already exists but is hardly known in the USA.
One point is that you need grandfathered and foundation boats and both teh F18 class and F16HP had them. This is partly the reason why F18 was fixed on 180 kg's because Dart Hawk and such were of that weight.
F18HT designs now are Ventillo F18HT and BIM F18HT. Marstrom was suppost to build one to but made the M20 and M18 instead.
Mind you their is more to boosted performance than just goin lightweight. It is optimizing a set of parameters. One of which is width in relation to the rig. The F16HP might well have the best ratio thus far. Simply making a F18 lighter will surely make the F18 faster than it is now but not faster than the F16HP. It may well level of at exactly the same speed. It is even more complex than this but it is an example of how you should be carefull not to fool yourself.
Wouter
Let me put it this way going shorter helped the performance of the F16HP. Going F18 HP with longer hulls may have a reversed effect or give the F18 HP at nearly the same performance. It isto complex to explain. But look at this
iF20's can't beat F18's in heavy air despite their bigger rigs, longer hulls and the fact that the two classes are of nearly the same weight. F16HP is right up there with them.
In light air the iF20 beat the F18's but not with the ratio that is expected of their size. The F16 HP without a genaker and jib limit will be right between the F18 and iF20 which is shown at the Piers regatta in England were A Stealth finished only 8 min behind a torndo and less behing two iF20's in light air on a 6hour :30 min race !! The first F18 was only a couple minutes behind the Stealth (Stealth 5th and F18 6th on elapsed)
The F16HP genaker size (as well as jibsize) is limited to 17,5 sq.mtr. To prevent this class from having an advantage over the F18's in light air. The F18 can go lighter like the F18HT did and max out on genakerarea with respect to sheet loads etc. but when the smaller F16HP upgrades to a slightly larger jib and genaker the performances are equal again. This is because the F16HP was also optimized in the drag part of the equation. Is it the most optimal ? Maybe not but it will surely be close.
Think of it in this way : Bigger boats always need a bigger engine than a smaller boat. Sp the bigger boats will alsway reach a construction limit like trailorbility before a smaller boat will. This is used in the F16HP to make sure the class is always eqaul to bigger boat despite what new developments they may incorporate.
Hope this explains things in more detail.
Mind you, F16HP was partly discovered by luck. But it seems to be at a optimal point by coincidence. The finetuning was engineering.
Wouter
An additional thought is what about crew weight? Can a F16HP handle more varied crew weights or are are we going to start seeing 16, 18, 20 length boats doing about the same performance based on crew weights. Also would an A class cat be more optimal at 16 feet than the current 18 ft. I've been told that the longer the boat the faster they will be - 16 is slow than 18 feet, etc. now this seems to not be the case. Interest though!
No boat can handle a wide range without a weight equalization system which limits engine power when the crews get lighter as used by F18 now.
hull drag can be assumed to be made up of two different drag principals. Wetted surface drag and wavemaking drag. Low wetted surface drag means you need to have as little wetted surface as possible. Ergo short and Fat hull. Wave making drag however is mainly influence by crosssection size and the rate of change of this. Reduceing this means decreasing crossection surface area which at an given displacement can only be done by lengthening the hulls, ergo waterline length.
Lets look at the extreme cases : 10 ft long 2 foot wide hulls. Very low wetted surface drag but a disproportioned high wave making drag. Not good.
30 ft long and 0,67 ft foot wide hulls small crossections but disproportionate big wetted surface area. Also draggy so NOt good.
No the optimum is somewhere between these extremes and dependend on the expected conditions.
So you see a long hull may have the appearance of being fast but really isn't because it is wetted surface area is limiting it. That is when weights are the same and not to high. Heavier boats still need to be longer. A F18 at 16 foot wouldn't work, weight and length go hand in hand
THe F16HP foundations boats were , by shear coincidence, on a special mathematical point where both the wetted surface area as wavemaking drag prediction formula were predicting a value 84 % with respect to the F18 that was equal with engine power 84 % sailarea. This really is a special case and rather uniek. More so because the width was smaller now and put the F16HP right inside the trailor width of nearly all countries in the world which is limiting speeds on the iF20 for example. The I-20 would go faster with its big rig where it not for it limitation in width. That is why Storm, tornado and such are so wide and this is also why the M20 at 2,6 mtr. width is unable to shake the Nacra 6.0 and such in the stronger winds upwind.
Personally I think that the A-cat class might well be better of at 16 foot now that its weight has dropped of from way above 100 kg many years ago to 75 kg now. The boat may not need the full length anymore for it's crosssection is already very small and it's length might now only create more unneeded wetted surface area. May this is just why the flyer A-cat is so succesful ? its strange bow is effectively shortening it's waterline length. This is just a theory I'm working on right now , but it seems to fit the facts the best. and it would explain why the heavy boats like the FX-one and Fox aren't capable of forfilling their intended advantage over the I-20's and such.
An interesting point is that while I worked on the F16HP concept in the beginning I found that a 25 kg heavier F16HP sailed 1-up had 103 % of the wetted surface area of the A-cat with crew. So a 16 % weight difference was only causing a 3 % difference in wetted surface. Were the A-cats of equal length of the F16HP's than the difference would have been 8 % (108 %) So the fact that the F16HP was shorter gave it a near equal wetted surface area to the A-cat. Now F16HP sailarea is also 103 % of the A-cat so F16HP can be expected to be near A-cats in light to medium air. Only in stronger winds wouldl the A-cats pull away. I wrote
would
for the F16HP is wider than the A-cat and so can develop more power in heavy air. THis way the F16HP can make up for its disadvantage in the stronger winds. Not enough though, and this is where teh genaker is needed to tip the balance towards the F16HP again.
As I said it is all in the balancing of different design parameter in such a way the contribute to each other and not work against eachother.
Are you beginning to understand what the F16HP is all about. I must sauy that we were very lucky to have 3 foundation boats Stealth, BIM 16 and the Taipan that were near this expception mathematical coincidental crossing of parameters.
Wouter
Wouter