All the info you ask for about the Javelin 16

You can find all the official info (in English) about the new Javelin 16 on the new BIMARE web site:

www.bimteam.com

BIMARE chose to stay with the 9,00 m mast because BIMARE wants to keep its trademark:

the UNIRIG configuration.

I hope you all agree that there is no way to produce a competitive UNIRIGGED F16HP with an 8.50 m mast.

Maurizio

Congrat's on the new design.
I'm utterly confused.
The f16 rules were designed for sloop-rigged doublehanders. Otherwise they would have been open in placement of sail area like the a-class.
What I gather is that Bim has designed is a 16 foot singlehanded 16hp. Unlike the Stealth, T4.9, etc, they chose not to build a doublehander. Why would this be an "equally good" single or doublehander? I have trouble buying the concept that the ideal upwind sail area is the same for 300 lbs of crew weight and 150 lbs of crew weight. Could you explain?
The 16hp, from the start, has had the concept of just removing the jib to change platforms. It sounds like, with a .5 meter shorter mast, the boat would be on an even footing with all the other f16's (i.e. winning because of a better skipper/sails/hull design), and the owner could just add a jib (per the intent of the f16 rules). Why would this be a problem?
thanks in advance for the info.
Michael Coffman
T4.9#32
P.S.
I don't mean to start a bunch of trouble, but I don't see a boatyard's "trademark" of making unirig boats as being of greater importance than the wishes of the class. I mean, Nacra's trademark in the 90's was "massively overpowered boats with huge jibs," but I bet we'd all be opposed to allowing them extra sail area if they designed an f16...

I thought that the whole F16HP box rule concept allowed people to chop and change between sloop and uni-rig by removing/adding the jib. This adds a great deal of versatility to the concept as we don't always have a crew available, plus for teenagers growing in size allows them to keep the same boat. You may believe you have trademark with producing uni-rigs, but I think that you just producing to a specific market niche which is limiting your overall market.

The F16 class is about to vote on amendments to the current box rule design and the 8.5m looks likely to be adopted. Why continue with a 9m mast? Owners of the new Bim won't be able to compete against other F16s on an equal basis making the Bim a less attractive offering.

In regard to your new boat, why not buy an A-class and add a spinnaker? But you have already done that with the F18HT.

JC

Maurizio,

I've just got involved in the Formula 16 movement and so I'm not very aware of any prior history to this topic.

But when you say and I quote:"I hope you all agree that there is no way to produce a competitive UNIRIGGED F16HP with an 8.50 m mast" I think you overlooked one aspect.

Such a 9 mtr. setup would be unfair when the boats are raced single handed and without the jib, wouldn't it ?

And how, as the others say, would a double handed uni-rig with a single hander A-cat sail have any chance against a double handed sloop ?

It doesn't seem that a 9 mtr. uni rig boat fits the F16 class very well. To fast in one respect and to slow in another.

Besides on the webpage I see that the boat has a width of 2,3 mtr. Wouldn't an uni rigged platform with a taller mast at least have to have the full 2,5 mtr. width as allowed under the F16 rules ? To be competitive, as you say.

Actually, I'm more puzzled by this new design then concerned.

Jack

Maurizio,

Thank you very much for that info, I had completely lost track of Bims website but expected it to be somewhere as the Jav 2 is a so succesful.

Personally and as the chairman of the class I say that incluseness is one of the main goals of the F16 class and I'm personally looking forward to race against sailors like Sandra and her crew who sail a Bim 16 (or comparable boat)

Once again thank you for the supplied info.

Wouter

Lets see how these smilies work

Michael,
I would like to underline that BIMARE started to produce the BIM 16, in 1990, (some 12 years ago), well before the constitution of the F16HP. In this time some 250 boats have been built and sold mainly in Italy, but also in France, Spain, Germany, Switzerland etc. I know that more than 300 Taipans 4.9 are around, but what about the figure of the newcomers such as Stealthmarine and the other boatyards?
As you can understand in these twelve years a lot of work has been performed and many modifications tested in order to improve the original design, keeping firm only the UNIRIG configuration. As I already wrote, Mr Petrucci, BIMARE owner, believes, rightly or wrongly, that a jib adds only weight, stress, strain and cost to a good platform. The BIM 16 actually started with a 8.25 m mast; then a 8.50 stick was adopted, but the boat was considered still underpowered and consequently they went lately for a 8.75 m to arrive recently, in 1999, to the actual 9.0 m. The same about the boat width.
You complaint about BIMARE's choice not to build a new 16 footer cat fitting the MODIFIED F16HP rule you are going to adopt, but consider that doing so BIMARE would waste 12 years of work (they should have to learn to build sloop rigged boat from scratch).

Damn wish this info had been available when I started building my thingy...
Looks like a blast..

maurizio,
fair enough. Your answer is kind of what I was getting at... like the T4.9, the jav16 isn't really an optimized, 1-or-2 up f16, but a boat that can fit that mold (although having a jib makes the 4.9 closer). It's based on the company's previous experience, and other designs.
I still don't get the mast height problem...why would it be a big deal for this 1-up boat to be ordered with a 8.5 meter mast? You even said that the Bim's originally came with smaller masts...
Re. the newcomers: actually, all the "newcomers" have 8.5 meter masts, and seem supportive of the new rules. And again, the rules have always implied the use of a jib in 2-up.
As far as the problem of being underpowered... yes, you're right, I really can't see how you expect the optimum sail area to be the same for 1 AND 2 people. That's why the other boats have jibs. Thus my original confusion
I'm not trying to be obtuse, but it really doesn't make sense to me.
Thanks, I appreciate the explanation.
Michael Coffman

Maurizio,

I must respectfully admit that I'm now even more puzzled than before. I've taken the liberty to surf to the handicap rating website specified in the new F16 rules and take a look at the measurements for the Bim 16. There I see a mainsail area measurement of 13,26 s.m. Considerably less than several older 16 foot designs.

Now I would expect a designer to increase the sail area of a design rather than it's mast height when he feels that the boat is underpowered. Or even to add a jib.

Of course a longer mast will also result in more sailpower, why else would the A-cats have gone that way ? But adding, say, 1,3 s.m. area to the main as the Taipan designer did could easily produce more sailpower while keeping the same mast length. Also allowing the class sailors of that time to improve performance without buying a new mast setup. Unless the amount of sail area was limited by class rules, of course. Is that the reason ?

By the way didn't the Taipan designers also start out as A-cat builders ? Howcome they did decide to learn how to build a sloop rigged boat if there wasn't a potential to be realized there ?

As a wise man once said :'Answers often only lead to more questions'

Jack

I would not have wanted to be the owner of a boat that chops and changes the mast heights every couple of years. 4 times in 12 years would turn anyone off purchasing a Bim. It would especially destroy re-sale value of second-hand boats as new masts and sails are considerably expensive, and by Maurizio's reasoning if you did not do this then you are uncompetitive.

At least with a box rule this kind of haphazard changes to the rules would be minimal. Maybe something for Bim to consider.

JC

The F16HP class uses an effective sail area measurement of 13 sqm for the main. The equation assumes that a longer mast will be more efficient, so longer masts are limited to less actual sail area where as shorter luff lengths are allowed more sail area. Under the rule the Taipan with an 8.5 m mast is allowed to have approx. 1sqm larger main than say the Bim with a 9m mast. A boat with an 8m mast could have even more measured sail area. In theory the boats would all produce the same power. The formula is part of the Texel rating system.

This is why the whole argument about mast length is so ridiculous. As long as the effective sail area is less than 13 sqm the different sails should be producing the same thrust. Different manufactures can choose the mast length that best suites their design compromises and the boats can still race equally.

The Jav 16 with a 17.5 sqm spi looks to be optimized as a single handed F16 HP that could be occasionally raced with a crew. The sloop rig boats may be optimized for double handed sailing, but removing the jib can be sailed or raced single handed. Set your priorities, pick your boat, and go racing.

I say reject the rule change that limits the mast length to 8.5 m. With the rated sail area rule boats with different mast lengths can race equally and we can include more builders.

e

You talk about the Bim class having 300+ boats build over 12 years. It would be an interesting regatta with 4 different mast heights and different sail areas??? How many 9m mast Bim have been sold. Lets compare apples with apples...

It appears without research the Bim 16 has followed the A Class development very closely in its changes of mast height. It is obviously easy for tooling costs for the Bim 16 to following the Bim A Cat to reduce costs / stock.

That to me does not mean the A Class rig is optimal for a 16ft Cat rig boat.

At the end of the day.. That is what has continued to hurt Cat sailing. The quest for speed instead of class racing.... The Formula 18 has been very successful and lets hope the F16 can be half as successful and it will be a great worlds in a few years.

Well done to the team who have driven ahead and got the rules to where they are. I think we all hope if accepted some of the manufactures standing on the side line will join in the race to have the First F16 world title.

Cheers Willy

In a perfect world two rigs with the same effective sail area should produce the same amount of 'thrust' but in reality its just not going to happen.

The reality is that the further off the water level you get the greater the wind speed. You just have to read Frank Bethwaite's book to find that out. If you have more sail area higher up you can take more advantage of it. Why do you think that square top mainsails were invented??? Why do spinnakers have broad shoulders??? If the wind speed at different levels off the water was the same we'd all be running around with triangular sails

The discussion about mast height is far from rediculous. The reason that the A class masts have, to a point, evened out in height is because you need a certain width of sail area to make it controllable. There is nothing to stop them having 40 or 50 foot masts its just that having a sail on the back of them that is a foot wide would just be silly. Plus there is the pitching moment to contend with.

Anyway, the point remains that the height of the mast affects the height of the sail area which makes a 9m mast potentially more powerfull than an 8.5m one. Its not hard to see why people have concerns over this rule.

At least BIM recognise that they at least can design and build a 9 meter rig that is strong enough to handle a genacker..

You missed the formulae rules on sail area .. The higher you go the less allowed sail area..

Okay, and this is just the reason why a limit is introduced.

I've read and studied Bethwaites book from back to front and it is indeed a valuable sourse of good practical information.

"The further of the surface level the higher the windspeed" is very true although it's effect on sailpower is far more pronounced in realy light winds than in wind of abou 6 knots and higher.

Go to the following link and take a look at the (simplified) excel sheet I developped to run the numbers on this issue :

http://www.geocities.com/kustzeilen...ulent_improved_accuracy_f16_vs_jav16.xls

I've also run the numbers on modern and older A-cats and found that lengthening the mast while keeping the same sailarea did improve sailpower by some 8 % in the laminair conditions while retaining about 100 % (with respect to older rig) power under in turbulent winds and depowering.

The setup compared in the sheet are a Full compliant F16 with jib and the prospected Javelin 16 setup with just the mainsail.

By replacing the jib widths of the F16 by zero's you compare the uni rig F16 to the uninrig Jav 16

This model doesn't not take into account tip vortexes, but this effect can be assumed to be rather small as both sails have comparable sized squaretops although the aspect ratios are different. I don't expect this difference to account for more than a few % say 2-3 % in a sail power (Not speed).

A rough estimate of resulting gain of speed can be calculated by taking the square root (or 3rd order root) of the sailpower ratio. This decreases the gains made by excess sailpower alot. For example : 108 % power = 1,08 => root (1,08) = 1,039 increase in speed; Third order gives => 1,0259 increase in ratio speed. Real increase in speed will be somewhere between these limits.

What this sheet is showing, to an reader that know how to intepretate the data. Is that the Jav 16 as given will have equal sailpower to slightly more in laminair winds and equal sailpower to slighlty less in turbulent winds when both classes sail in uni-rig configuration. In general the % of advantage in laminair winds is mirrored by an equal disadvantage in turbulent winds. Ofcourse most races are held in turbulent winds.

With the F16 is fitted with a jib (as shown in the excel sheet) the situation becomes :

The Jav 16 in laminair winds can hope to have equality in sailpower. Yes that jib of the F16 doesn't do much but it still results in some 6 to 8 % increase in power which should be sufficient to compensate for the vortex and aspect advantages of a few % of the higher aspect jav 16 sail. Assuming that both mains have been equally optimized in sailshape design ofcourse.

In turbulent winds the jib easily accounts for 20 % more sailpower at relative low costs in righting moment ; 10 % and depowering of the F16 mainsail doesn't affect the jib untill very late so the F16 rig retains large portions of its sailpower to considerably higher windspeeds.

So my personal opinion is that that the Jav 16 will not have a unfair advantage over the F16's. Especially in doublehanded mode without a jib I rather see rather a disadvantage than an advantage.

But this is in relation to the Jav 16 design as present on the Bimare website.

The F16 rules ofcourse need to take into account the fact that a sloop design could be fitted with a taller rig. This fact will set such a tall rig design apart from the Javelin 16 and is resulting in a slightly different performance situation. It is this situation that is determining the mast limit in the proposed rules. Remember it is the jib that takes away much of the advantage a the taller rig has. And the Javelin 16 is made fairer in comparison because the designer choose to not fit it with a jib. Remember this when looking at the rules.

With respect to the Javelin 16, which even has less sailarea than allowed under the F16 rules, I see absolutely no reason to exclude it from racing on the fact that it has a 9 mtr. tall mast.

Wouter

http://www.geocities.com/kustzeilen/Laminair_turbulent_excel_sheet.html

and click on the excel link presented.

Seems like Bimare has really thrown the cat among the cat sailors !
Reading most of the replies there seems to be much confusion about the boat - Looking at the web-site pic it looks like Mr. Petrucci designed a double-handed boat with no jib, not a single-handed boat as many seem to think. The relatively narrow beam & long mast also lead to this conclusion. In my opinion the boat looks like it is a baby Jav 2 - not for single-handed sailing unless you are over 120kg, or only sail in less than 5 knots. Whether the boat fits into F16 rules / design intent is debatable. Firstly, the fact that the prototype has been launched, sailed & photographed proves that it was designed before the F16 class members decided to change the rules - something Bimare did not know would happen unless they were kept informed, which I doubt, as the decision to change the mast length rule within the class is a fairly recent thing. If Bimare intended to design a boat that would fit within the class rules then it seems unfair to change the rules after the launch of the Javelin 16. I do not believe the boat was designed to fit within the F16 box-rule, as the boat is underweight, corrector weights would have to be added to comply. I also do not believe the boat was ever intended to sail single-handed. I may be wrong, but a 9m mast & 17,5sqm spinn. is a bit of a handful ! Regarding the mast length, I believe that as long as the sail area & mastlength produce the same mainsail efficiency ratio, it should be allowed to race within the class, provided that it also complies on all other levels ie min. weight. This was the original spirit of the F16 class rules - to allow different designs to sail against one another on equal handicap, without limiting design creativity, but maintaining a level of equal performance.
Why did the class members originally believe that a 9m mast would be acceptable, until someone actually built one ? Why not let the boat be handicapped according to Texel & ISAF, if it`s h/cap is the same or within 2% of F16, then allow it to race against you, even single-handed. All boats have their own optimum wind range, this boat may perform better than another boat in lighter wind, but may be slower in more breeze. Only by sailing against it will you really find out. If you change the mast length rule now you prevent this builder from boosting the growth of your own class, a strange idea indeed ! If this is the intention of the class then you may well rename the class to "F16HP - for Taipans only".

Let me start by welcoming you to this forum Steve, I certainly hope you'll enjoy the discussions and contents as much as we all do.

Now to the issue at hand;

I want to defuse the situation here, guys. Obviously the Formual 16 rule is a formula rule and not another Taipan 4.9 one-design rule. The last would be something remarkable as the first full compliant design in the class is the Stealth F16. So if we needed to rename the class than it would have to be renamed to "F16 for Stealths F16's only".

With regard to the Bim Javelin 16 design I have no problems with that design as the local class head for the Netherlands. I have a Bim 16 crew in my local class and I'm looking forward to seeing them race in the Dutch F16 class. As the local class head for the Dutch F16 class I won't prevent them from racing with us in this any way. And I personally think this is in the spirit of the Formula 16 class; inclusiveness remember ?

I'm also confident that my excel sheet has shown that the perceived disadvantage of F16 rigs in relation to 0,5 mtr. taller uni rig setups with the same or less rated main sailarea is unfounded.

I also wish to underline that the class has some experimental data of a sloop taipan (yes, that boat again) against a modern wavepeircer A-cat, both sailed by very good sailors and that the Taipan was in no way disadvantaged. The resutls were gethered in very light to medium winds. So we don't only have theoretical data but also experimental data showing that the perceived inequality is mostly that "perceived". The rated sailarea rules has thus far proven to hold up.

It has been the decision of the bimare yard and related officials to stay with the 9 mtr. uni -rig setup. And that is their good right, and it their javelin-16 class, if they feel that that is more competitive than a sloop version, so be it. And like Steve says let them proof it on the race course. It must be remembered that it is not a declared Formula 16 design and it wasn't declared as such when I mailed the Bimare yard much earlier this year. And I have a few interesting e-mail clippings from that time to proof it. And I do keep them informed about new developments by the way; (Have done so in the past too). From this perspective it is an single manufacturer one design class, as was their mission statement on their former website; remember the creation of the Jav A class as a One-design A-cat ? Now it also has comparable performance to the formula 16 class and will be welcomed as such. Again, I'm looking forward to racing them.

Now I also wish to set some other things straight. That picture on the website is a picture of a Javelin 2.

With respect to Steves statement :"Firstly, the fact that the prototype has been launched, sailed & photographed proves that it was designed before the F16 class members decided to change the rules"

Despite my intensive search for information I have not been able to confirm this fact and the fact that a Jav 2 picture is displayed above the Jav-16 comments does not "proof" to me that the design (prototype) has been photographed. I see no point in reacting on the other "facts"; all other builders (Stealth, AHPC, Blade) will confrim that I kept all of them very well informed. Now I don't really understand what lead Steve to make a comment in the other direction or how as a bystander he should be in the know.

With regard to our class intention; it is the intention of the F16 class to garantee general equality between boats of different make and a (suggested) speed rating difference of 2 % can be considered to be pushing it a bit. I haven't checked this myself yet, I admit. Maybe I should make the time in the next couple of days and do so.

I do know however that all the measured Bim 16's up till this time arrived at a rating equal or slower than the F16 and that is the most important consideration when welcoming a non-fully compliant design to our open and inclusive class.

As for the rules, every rule in there has been adjusted for the better as a result of clear and unanimous agreed upon principles. They will improve equality between fully compliant designs and direct development towards refinement of the designs rather than outclassing the others by having more of something.

But I can assure the Bim 16 sailors that the outcome of the ballot will certainly not automatically mean their exclusion.

Now lets focus on the ballot and the upcoming events.

With kind regard,

Wouter

W can you confirm that the new rules will allow a slighly faster boat on your own calculations being called a "foundation boat" than a fully complient F16?

I can confirm the opposite and that is that your statement is not true.

Wouter

As Wouter said, The pic is of a Jav 2 not the new Bim 16. A little deceptive of them, had me believing it was a pic of their new boat ! That`s what led me to write that they have launched their new boat, I don`t have any evidence of that other than the misleading pic on their web-site, but I bet I wasn`t the only one fooled !
Thanks for putting me straight. Truth is that a boat with a taller rig WILL perform better than a shorter rig in lighter wind and vice versa - a lower aspect rig works better in a blow as you get more power lower down.This is the case where I sail, mostly against Dart 18`s, with a mast length of 8m, approx 12sqm mainsail area. I sail a 16 foot cat called a Mosquito - the Aussies will know the boat as it was designed by one of their own & was the boat which the Taipan was developed from. (Check history of the Taipan on the Aussie web-site.) My mast is 7,3m with approx. 12sqm sail area & my boat weighs 99kg. In light breeze I compete with the Darts on an equal basis, but in more than 15 knots I tend to run away from them.
The difference is my boat is about 40kg lighter. The Taipan rig looks high-aspect enough, if not too much for me (combined crew weight of 125kg 2up), in more than 18 knots I would be wasting half the power just to stay upright - a boat with a shorter mast & longer boom providing the same sail area would probably be faster in heavy breeze.
I expect that a Bim 16 with a 9m mast would be faster than a Taipan if sailed solo in light wind, and slower upwind in a stiff breeze (overpowered). Since both boats are similar in weight the comparison between my Mosquito & a Dart 18 doesn`t apply in this situation. Likewise, a Bim 16 sailed double may be slower than Taipan in light wind, but may perform better in a breeze - It will definitely point higher.
I think the mainsail efficiency ratio is the key here - In order to be F16 compliant a boat with a 9m mast must have less sail area than a boat with 8,5m mast - I think in time the boat designers will settle on 8,5m anyway as I think a 9m mast is a bit extreme unless you always sail in less than 5 knots.
The reason the Bim 16 is creating a stir is probably that it has been designed to be sailed 2up with no jib. How does that affect the solo sailor ? Only on-the-water comparisons will tell, so we`ll have to wait & see.
What I do see on this forum is that the majority of those involved sail Taipans, so it`s only natural that they would be concerned about any new boat that fits within the F16 framework & is faster than the Taipan / Stealth / Spitfire. This would not be good for the class, as I don`t see Taipan sailors all buying 9m masts & new sails if this is the faster route. The original intent of the class was to provide cost-effective racing on similar boats that have similar speed-potential, if a different rig configuration proves to be much faster it could hurt the class. Based on this I would have to agree that limiting the mast height to 8,5m is probably a sensible thing to do, however it seems ill-considered given the fact that Bimare have spent considerable time & effort developing their new boat which until recently did fit into the class box-rule. Based on Wouter`s post it seems they are not concerned with being involved in F16 class, but it would be a pity to exclude them if they have similar performance, as their numbers could help your own class grow.
That`s all I was trying to say.

I followed closely all the discussions threads and came to the conclusion that I will not consider anymore a F16HP boat simply due to the fact that you guys can't get your act together. I will go for a good old 'boring' F18 - 5.5m, 2.6m, 9m, 17m2, 4.15m2, 21m2 -> and no discussions about mast length, sail area, etc. . I can go back to the basics and measure myself against other sailors and if I loose, there will be no excuse.

Pipo

the IF18s have just changed a few rules themselves.. It would appear to be a way to ban a boat that was designed to their rules and found to be too quick.. If the weight isnt problem good luck and enjoy...
Im sure we will settle on a final set of rules soon..

I'm really sorry to hear that.

But may I ask how the :

good old 'boring' F18 - 5.5m, 2.6m, 9m, 17m2, 4.15m2, 21m2

is different from the :

Just formed and improving F16 : 5.0 mtr. 2.5 mtr. 8.5 mtr. 13,00 rated m2, 3,65 rated m2, 17,5 m2

As are the specs of the Stealth F16; Blade F16, Taipan 4.9 Spi and also the Ventilo Zipo design who make up the true F16 class.

And if anyone thinks that the F18 is void of controversy than I advice everyone to take a good look at the "F18 class versus Capricorn F18 with foiling boards" issue. That one is developing into a right soap opera with much more damage potential.

Wouter

Hi Pipo,
You say:
"I can go back to the basics and measure myself against other sailors and if I loose, there will be no excuse."
Sounds like you want "One Design" racing.
If you live in the UK and if your crew weight suits F16HP, you can combine One design and Formula racing. You might find that the Spitfire suits your needs - a grandfathered F16HP and a class that had 16 cats at the Grafham Water Inlands last month.(15 raced).
Dermot.

Dear Pipo,
Before you make any decisions on what boat to buy, consider a few factors :
The F16 class is a newly emerging open formula class , currently updating their class rules after a year of development. The fact that this would happen was made clear at the beginning, when the class was first formed. The guys involved are doing an amazing job, there will always be differences of opinion, and this forum allows those opinions to be known. I, for one, do not own a F16 boat, my interest is in any 16ft cat that performs better than it`s design size leads one to believe it will, mostly in modern design lightweight 16ft cats.
If you read the old class rules which are currently being revised you will see that whoever dreamed this class up has done a lot of homework on performance equalisation, admittedly mostly theoretical & not fully tested yet, however it allows boats of very different designs to race on equal basis as long as their rated performances are similar, even taking crew weights into consideration. I think the idea is great, it allows sailors with different ideas on what is faster to experiment within the rules. Most of the boats are one-design with minor modifications ie standard Taipan with spinnaker being the only add-on. Sure a Taipan sailor can max his boat out to F16 specs but then he won`t be Taipan class compliant. This is no different in the F18 class - Hobie Tiger can be modified to race F18 but won`t comply with Hobie class rules. But he can sail a standard Tiger in F18. The same as F16.
I think what happened in this thread is a bit of a lack of understanding from outside observers like myself who were not aware of all the facts before making comment. I personally believe that the class should allow all boats that rate at a similar ISAF/Texel rating to race on equal terms, irrespective of how long/short/fat/thin a mast is. If they have equal ratings they should be closely matched in performance. The alternative is to tighten up the rules so that all the boats are identical, then we`re back to one-design or worse still, one-manufacturer classes.
Don`t forget that F16, like F18 is made up of (mostly) one-design boats like Taipan, Stealth, Spitfire etc, so if you owned one of these boats you could race in your own class events AND in open regattas against F18`s & F16`s on an equal basis. I can think of nothing more rewarding than sailing a 16footer faster than a F18 !
Another factor to consider is your intended crew weight - If you & your crew are 2 big heavy strong guys F18 may suit you better, F16 allows lighter crews to compete - father & son teams, husband & wife teams etc. If your wife weighs 80kg+ & can handle a F18 spinnaker in 20knots then that`s your route to go - If she`s 55kg then F16 will suit her better. Do you intend to ever sail single-handed ? This puts F16 forward as the better option than F18.
All things considered both classes are amazing, however one will suit your personal needs better than the other - that`s what should influence your decision. All other arguments should be settled on the race-course !

Happy sailing.
Steve