Robi,

I believe your statement about the Taipan 4.9 having a roller furling jib as a stock item is incorrect. I know of only 2 boats that have one. I have a roller furler on my Taipan 4.9 but it is a custom add-on. I added it for safety and convenience. I wanted to have the option to roll the jib when the weather gets bad. It is also nice to roll it up in between races or on the approach to the beach. The only issue I have with it is the jib doesn't roll very tight because of the 2 short horizontal battens in the leach of the sail. Taipan 4.9 class rules say the jib leach battens much be horizontal.

Jennifer
Taipan 4.9 #262

I don't think adding wings to an F16 will encounter any limits in the way of load or stresses. Especially not if they are secured directly to the beams.

I think the bets option would be to just copy the FX-one wings. These seem light weight and sufficient.

Personally I'm not very much interested in wings but I would love to see some-one give it a try.

Wouter

I will never give any garantees without running all the numbers on such an additions in detail. Besides the original builders of these boats will undoubtably have something so say about this and warranty. But Having said that, if I were to add wings to my own boat (hypothetical situation) then I would probably not even bother doing to math on what my beams and hulls would take and only do the math on the design of the beams itself. If you catch my drift here.

Wouter

Jennifer I stand corrected then.

Thanks everyone for your input and the lively discussion.

I do think that adapting the Hobie sport wings would make the most sense, and also would be a relatively low cost option compared with the larger wings which use more tubing and use seats made out of tramp material.

It should be possible to copy the sport wings but I wonder how far off the Hobie sport wings might be from fitting the various F16's.

Tony - would you mind measuring OD of the sport wings tubing that inserts into the beams and the center to center distance between the main beam and rear beam? Are the beams round? Do the wings mate directly with the ID of the beams or is there an insert/adapter that makes the connection? Are they held inplace by a spring action/friction like the H17 wings or is there some kind of detent that locks them in place? Finally, what did you pay for the sport wings? Thanks for your input.

Does anyone have beam ID and spacing data for any of the F16's so one could get an idea "how far off" the Hobie sport wings might be?

It may not be for everyone but it would be great if someone could try it and share their experience with everyone. If it's feasible I'd certainly consider giving it a go. But I'd like my boat builder to agree that if used properly (ie, singlehanding only) that it wouldn't void the warranty!

Thanks,

Jerry

Jerry,

You're right to be cautious, but you should be fine if only used for single handing. The thing to worry about is the rig, rather than the hulls or beams - assuming you can find some decent way to attach the wings to the beams.

Wings have the ability to increase your righting moment. The maximum force in the rig is limited by the fact that as the power increases, the moment of the rig will become equal to your righting moment, and the boat will start to tip over. The more you increase the right moment, either by becoming heavier, or by moving further away from the leeward hull, the greater the force in the rig before it starts to heel.

On the back of an envelope: when on the trapeze on an F16, your centre of gravity is about 11 foot from the leeward hull. Add a 1 foot wing and trapeze off it, and you'll increase your moment by less than 10%. Put a crew on the trapeze with you without wings, and you'll increase your moment by 100% - so I think you should be safe in 1-up mode.

Failure to do these calculations can be expensive, though - I've seen the remains of a Hobie Pacific mast after it was taken out 3-up in a force 6.

Paul

A good rule of thumb for righting moment is :

Righting moment RM = 0.5 * boat width * boat weight + (boat width + 1) * crew weight

The formula uses SI units, so meters and kilograms, if you want to do it with feet and pounds then replace (boat width +1) by (boat width + 3) (this a rough approximation)


The results are :

F16 sloop two-up with 150 kg crew

RM = 0.5 * 2.5 * 107 + (2.5 + 1) * 150 kg = 133.75 + 525 = 658,75 = say 659 kgm



F16 sloop two-up with 150 kg crew and 1 foot wings (=0.3 mtr by 5 kg each)

RM = 0.5 * 2.5 * 117 + (2.5 + 1.3) * 150 kg = 146.25 + 570 = 716,25 = say 716 kgm = 8.6 % more than standard F16

Is comparable in righting moment to putting a 166 kg crew on the wire of a wingless F16

RM = 0.5 * 2.5 * 107 + (2.5 + 1) * 166kg = 133.75 + 582.5 = 716,25 = say 716 kgm = 8.6 % more than standard F16



F16 uni one-up with 80 kg crew

RM = 0.5 * 2.5 * 104 + (2.5 + 1) * 80 kg = 130 + 280 = 410 = 37 % Less than standard sloop 2-up F16


F16 uni one-up with 80 kg crew and 1 foot wings (0.3 kg by 5 kg each)

RM = 0.5 * 2.5 * 114 + (2.5 + 1.3) * 80 kg = 142.5 + 304 = 446.5 = say 447 kgm = 32 % Less than standard sloop 2-up F16 and 9 % more than standard 1-up.


Don't make out too much aof 10 % higher rigting moments in the way of performance enhancements.

A good rule of thumb giving the UPPER limit to windward leeward gains is :

0.5 * (Sq.rt (new sail drive) - 1)

so

0.5 * (Sq.rt (110%) - 1) = 0.5 * (sq.rt (1.1) - 1) = 2.4 % or about 90 seconds per hour when doing everything else just right.

This is an upper boundery as increases in overall weight, windage and the fact that the relationship is "stronger" than a sq.rt take away from the gains.

Typically I use a power relationship of 1/2.5 instead of of the normal sq.rt that is a powerrelationship of only 1/2

So

0.5 * (110%)^(1/2.5) - 1) = 0.5 (1.1)^(1/2.5) - 1) = 1.9 % = 70 seconds per hour bouy racing when doing everything else just right.

This number I would use as a relatively accuracte estimations of the performance gain IN HIGH WINDS only ! Of course in all conditions where normal trapping of sitting on the luff hull is sufficient the winged catamaran will have no advantage at all, rather it is expected to be disadvantaged.

Wouter

Paul and Wouter,

Thanks for your confirming my cruder calculations.
It's always nice to see how the problem should be solved correctly!

Regarding limited performane gains, I suspect you are right, but then again that is only important racing (for which it would not be used). My experience with wings on the H17 for recreational sailing is that the reserve leverage they provide "feels" like much more than 10%; even if it doesn't let you go 10% faster, it feels like you have much more control in higher winds (almost like having a lightweight crew along).

Thanks,

Jerry