So today I made my way up to a different lake than I normally sail at today and while I was there I hitched a ride with a guy on his 5.2, the wind was blowing a steady 25 and gusting much higher, probably above 35 regularly. Our run went great even thought we had never sailed together and the winds were crazy.

But later while he took another guy out they broke both daggerboards. It happened when huge gust hit them. The boards broke off just below the hull. One on one tack and the other on the other tack. Also before I had gotten there he had broken another board.

So what caused this, just the pressure on the board? Would pulling them up some have helped to keep them from breaking? Or should you just not be out in conditions like that? Also the boards didn't break with him and I on it, but I am alot lighter than the other guys who were sailing with him.

When it's that windy, the boards should come up some. Unless he hit something, they broke from the pressure. I've seen boards take a LOT of abuse, but if they were older, they could have become weaker.

These were 80's vintage Nacra 5.2 boards.

(Disclaimer: This is my opinion and if you don't like it, please don't flame me. Correct me if you might, but don't fault me for expressing my opinion.)

The average beachcat, the ones that we are familiar with on this forum, has boards that are designed to be used in conditions where you have two average sized men going 4-11 knots of boat speed upwind in 3-15 knots of true wind. Go faster, travel with extra crew weight, or sail in higher winds or in very rough seas and then you are over exposed when it comes to your dagger boards.

Bring the boards partially up and this will not only reduce the amount of stress upon them, but will reduce the amount of leverage that they have against the hull at the boards' base where they pass through the hull's keel.

It is my understanding that these boards are designed for 10 knots of boat speed, with standard crew weight. That boat speed will allow these boards to produce a certain amount of lift and that lift will be accompanied by a proportional amount of side force and drag.

If you overload your catamaran, if you go faster than 10 knots, or if you have more than 15 knots of wind, you should probably begin to reduce the amount of dagger board surface area that you have in the water.

This is especially true with high-aspect ratio dagger boards. The forces acting on the bottom end of the board have so much leverage upon the keel line section of the board! Give them a break; raise them up a few inches.

GARY

Amen, broke a 6.0 board the same way. Big wind and it just gave out and snapped at the hull. If I had the capacity to learn from my mistakes i would lift the boards when it blows harder. time will tell... <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

pull them up on beam reaches on the nacras

Move to Florida. Dagger boards don't break here.

Florida is just a fad. Pretty soon it will be under water.

Jeeeeeeeez, Thanks for the warning - I've got a friend who was planning a holiday to Disney - I'll warn him <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

Does anyone know what percentage of land in Florida is less than 10 feet above sea level?