Any thoughts on how much force it would take to cleanly snap an I20 Dagger? While going about as fast as I have ever been on a catamaran (lots of humming Etc) my windward board snapped clean off (bent windward) I was in the channel traveling parallel to the waves and do not believe that I hit anything and no teeth marks in the part of the board that I still have. Thoughts anyone?



PS. I plan to form a replacement with and an aluminum core as I am unemployed and cannot afford not to sail or the $385 for a new one.

Umm... your windward board snapped off? The one out of the water? My head tells me something like this could happen to the leeward board... but the windward board? the bending windward itself makes sense because that is the direction of lift generated by the foil.



Using bending calculations and making some assumptions about uniform loading, you could SWAG the amount of force necessary. You'd need to know the materials used in construction and the cross sectional dimensions of the foil. If you know any structural engineers, they would probably calc it out for giggles.



Before you go making bulletproof daggar boards, conider the ramifications of making something that broke, unbreakable. Next time you may end up with a half sunk cat because the daggar board trunk got opened up instead of the daggar board valliantly sacrificing itself to the sea.



... my $.02

valliantly sacrificing itself to the sea.



Now I like that. Reminds me of the fate of many structures, biological or otherwise, that have been on my boat over the years.

Marc,

I wonder if any of the Worrell Sailors have a spare laying around??

Many people, as well as I, have broken boards in a similiar fashion.



Wouter once had a post, I'll try and summerize some of the points I took away from it that I now use in my sailing.



1. At high speeds, you don't need your boards all the way down. It in fact can slow you down some. With it up slightly, it really changes the stress point on the board, making it much less likely to break to windward.

2. If trying to point max as in going to A mark, in light to moderate air, then all the way down is good. But when your hull speed is great, slide the board up some, it'll handle better, and less likely to break the board.

3. Flame suit on



my 2 cents



Todd Bouton

N6.0na +

#111

several non inpact board failures in the past, none since adopting the above theories

Todd,



Did you break boards on your 6.0 from non impact stresses? Or was that another boat you refered to?

MArc,



A common event for I-20's down here inthe caribbean.



The St. Thomas I-20's,..dealer Kevin Raymond, John Holmberg( P-19 natl champ and brother of John, AC driver) and Terry Jackson ( VI Tornado rep to Olympics-hopefull) all snapped boards in the 2 years they raced I-20's, as a common occurance.....really.



I believe it is a combo of the boats power, wind 20+ and some decent waves to rocket thru,......something has to give with all that load being generated......it is still a great boat for big water/wind ocean cat sailing



In fact, in the 2001 Rolex in St. T., ...I sent my boat to Rolex but the weather/waves built up to were I sat out the regatta (..I had sailed BVI the week before) and went home to St. Croix leaving my boat at the St. Thomas Y.C.,.......to find out that boards did snap and they were using my I-17 boards on the I-20's because non others were available..........ugh..!



Maybe your boards stressed out earlier that day and the 'last straw' just occurred at that time.......anyway,..you have a great boat..



Bruce



St. Croix

Yes,



twice so far, non impact failures. I know of N5.8's (some board) that have done the same in heavy air situations.

yes, i have had a similar experience, in ruff seas i was hit broad side by a huge wave. broke the dagger and breached the hull inside the dagger well (which i didnt know the extent of the damage at the time), as well as knocking me off the boat. luckily i was hooked up! and luckily it was the windward hull and she didnt become awash. always bring a submersible vhf for these situations since it was febuary with water temp around 55! and luckily i didnt tack but limped to shore. this was the most truamatic event ever for me on a hobie, what was scary it that i was twisted up in the mainsheet and bungie from the hook trailing behind the boat. as i went aft off the boat i saw the bow do a wheelie and i thought it was going to do a reverse pitch-pole! and luckily it didnt. my heart rate went up to probably 275bpm. it felt jumping out of my chest! when it starts getting ruff now i keep the daggers only half way down. that was a $750 wave and yes, i learned alot!

Good Idea I will try it next time. no flame suit necessary (ask me about wing lift sometime). I still plan to fabricate my own boards cause I am cheap, (I did get my wheels done). and will consider making them to the same speck as the Performance (not) ones so that they break as expected. they are just fiberglass / Carbon / balsa / fillerglue. I now have a perfect cross section.

Do you have tomko's email address? or PH# (send offline)

Have you thought about cavitation? The weather board is bouncing in and out of the water, thus dragging a pocket of air down the length of the board. As the water pressure on the lee side of the board builds in a puff, there is not enough air pressure on the weather side to balance. Result: Broken board.



This theory makes sense to me.

Did the same thing to two weeks ago, though I snapped my leward board. Where did you see I20 boards for $385?

Email address for almost all Texas sailors can be found on Steve Piche's old website

http://www.catamaran.ws

specifically,

http://www.catamaran.ws/contacts.asp



Tomko's email is listed as :

mailto:[email protected]



Cannot guarantee the accuracy, however.

But the list is used by fleets & some clubs to send NORs of almost all cat regattas in TX area.

Is that High or low?

KO sailing 281 291.9500 I hope it is not the last one if it is a low price.

Hmm, from your description, it sounds as if you were close reaching. In this case, I agree with Wouter's post that minimal daggarboard is needed for two reasons: (1) at speeds in excess of 20 mph, you don't need that much lift unless you are similar to "team tons-o-fun" (excess of 375 lbs), and in that case you will be subjecting your boards to huge forces anyway, and (2) you will further unload your rudders and in a big puff could cause them to cavitate (and then disaster).



I have "tripped over the daggars" and cavitated the rudders a few times in moderate wind (15 kts & gusty) in even small waves while tight reaching. Usually it occurrs when we're too far forward on the hull (in front of rear beam) and boards are down greater than 1/2 way. Mind you, our team is barely minimum weight (327), so things are more pronounced in breeze than heavier crews. We'll crash and burn long before we break too many things!



In keeping with the sage advice already posted, in light air, those boards being down are good for lift and tracking, but as the wind goes up, so should the boards. Our last big wind we kept them down about 6" and screamed across the bay (small chop) while trying to stand on the rudder casting. White knuckle ride to say the least....



And to keep your rudder hum down, you're going to have to sand the trailing edge a bit. Look on other posts for techniques of sanding correctly.

The price list at performance has them at $459ea. (Part #4585) and that is the price KO quoted me, with none in stock.



Jon Domsalla

I20 329

That is bader news for me. she must have quoted me their cost when I called. Oh well should have ordered them at the time. I am now in the business of producing non-racing dagger boards, anyone want one? two? four?

Ok, I'll bite. Questions:



1. You doin' em just for Inter? How bout N5.5?

2. Rudders too, perhaps?

3. Whadda they weight?

4. Describe exactly the construction?

5. How much you want for 'em?



sea ya

tami

waterbug_wpb,



Great information... can you talk more about tuning in relation to the boards being up or down, whether going up wind or down wind?



I must admit that my crew and I are similar to "team tons-o-fun", since we look more like basketball players than sailors (6-5 at 240ish and 6-2 at 220ish).



I normally leave the daggers down all the way, until wind speed approaches 12 - 15knots or if wave conditions are over 1 foot. So far, I haven't experienced "tripping over the daggers" yet, althought, I'm not sure what that is anyway.



I was warned that the I-20 was capable of breaking the daggers when I purchased my boat. So far, I probably sacrafice speed, directions, etc, by not placing them deep enough.... Which is fine for now, once the newness wears off, I'll be more willing to push the boat....