Which Daggerboard Down in Heavy Weather

[tsmwebb]

Originally Posted by dana-tenacity

I've done two long deliveries in Catanas, both happened to have the "factory manual" aboard - one I picked up from the factory. Both said to raise both boards if boat speed was over 8kn, said they were not necessary and might be prone to damage, confirmed by the Catana people doing the handover.
To help the boat in really bad stuff, both up definitely.

That is interesting. Do you recall how much they suggested raising them? Certainly the loads on the boards get quite high. But I find the full boards are very useful at higher speeds than that when beating on my boat. I am sure there are design and build specifics that make a difference. Agree with both up when worried about safety.

Tom.

[dana-tenacity]

Yes that was going to weather. The boards were marked but from memory about 2/3 up , I remember thinking it wasn't much to leave in the water. But with long narrow hulls (compared to a mono) it really made imperceptible difference to leeway - checked by GPS.

The board that broke was fully down going uphill in 35-40kn, pushing hard at the time to get around a nasty corner before dark which was also why I left it down thinking that would help me crawl around a headland. Wouldn't do it again. The boat went airborne out the back of a wave and while in space the high windage meant we were moving significantly sideways by touchdown which I am sure is why the (carbon) board snapped off at the hull.

Since all boats are different it would be interesting to experiment with another, use GPS to check leeway board down, up and halfway on different days.

[tsmwebb]

Originally Posted by dana-tenacity

...
The board that broke was fully down going uphill in 35-40kn, pushing hard ...

That'll break stuff

Originally Posted by dana-tenacity

Since all boats are different it would be interesting to experiment with another, use GPS to check leeway board down, up and halfway on different days.

Yes, one thing I've noticed when I reduce the boards is what seems like a significant reduction in boat speed. I have a theory (ahem..) that a new equilibrium is reached with increased leeway and reduced speed as a result of more hydro drag and less apparent wind. What I think I see mostly on my instruments is the speed change. But, it is hard to measure these things in isolation and I have preconceived ideas about what should be happening which probably cloud my perception. I have convinced myself that my boat is fastest upwind with both boards fully down in all conditions. But there are certainly times when slowing down and surviving without breakage is the right answer!

Tom.

[Steve Strand]

Boy have I learned a lot, thanks to all of you, I certainly have a much better idea about how to use dagger boards and some interesting experimentation to perform. We have always been big on slowing down and surviving.
Steve

[dana-tenacity]

Originally Posted by Steve Strand

We have always been big on slowing down and surviving.
Steve

Good call!

[Multitalent]

in several Trans- Atlkantics in catana I was once in a storm where we were hit athwartships by a wave and the boat skidded sidewards. No drama we only realized what had happened (nighttime of course) because one crew was knocked or slid right out of his bunk and we staggered on deck. We discussed what would have happened on a Pricilege but will never know.

[webejammin]

I understand on our cat that in big swells 20 to 30 ft to use two thirds to half down on both boards to slow the surfing to keep good stearage and again I was told to keep boards up to let the boat slide sideways to make the boat more forgiving in rough conditions. I guess it is try and see achording to conditions. Our boards lift the bow some so in the bottom of a steep wave the bow does not dig in as much but not more than half way down. If there is floatsom like in the PNW or BC Canada boards down can hit half sunken logs NOT GOOD where the boat can slide over.

[Intentional Drifter]

Hi, Steve -- Hope the build is going well!

You might also find this interesting -- written by Gregor Tarjan (his book is pretty good, too). Esprit Marine - Daggerboards for Safety and Performance

ID