Outremer 45 daggerboards

[44'cruisingcat]

Originally Posted by catsketcher

Of course induced drag and skin friction of boards are important too but I feel these are often overstated on large cats. As we bear away the side forces reduce and our boards are under reduced loading and can be retracted. The easiest way to check is to pull the boards up and down and watch the GPS. I think that most cats need little board when the apparent is aft of 135 degrees but it will depend on the boat. As our cats have different boards areas and different hull cross sections one has to experiment.

If your cat has tiller steering you can feel when you are making lots of leeway. The sideways movement of the hull imparts an angled flow over the rudder which we feel as weather helm. I had the boards up one day and wondered why the helm was heavy. I saw the boards were partially raised on the beam reach and put them down - the helm then went much lighter.

You can't sail without leeway but it doesn't make you faster.

cheers

Phil

When the AWA is aft of 90', the TWA will be well aft, and any leeway will be roughly in the direction you're going. (ie. downwind) Having any board down will make you slower.

[Stumble]

I am not sure how it translates, but it is very clear in the A-Cats that you want the boards up in light air when running. Not only does it unload the rig, but the slippage to leeward adds to vmg.

This is true right up to the point that you start flying a hull downwind when I think the comparison starts to fall apart. When there's is enough wind to fly a hull while trapezeing we start putting the boards down to limit slip, build speed and start flying (litterly in this case with lifting boards).

[catsketcher]

I think we are all getting close to saying the same thing. When the wind is way aft the boards come right up - it is just a question of when to bring them up. I also have raced Tornados along with many decades of mono racing and Stumbles observations of pulling the boards up in light winds and then ensuring they go back down a bit in heavier breezes seems consistent with normal practice. At low speeds skin friction drag is the most important part of the drag equation. You can reduce it by pulling up the boards (downwind). You often see Hobies racing in light winds with one rudder in the air.

My point about leeway is that it always increases the drag of the hull. What one wants to do is to find the sweet spot where the reduction in drag from retracting boards is greater than the increase in drag from leeway. When the hull slips sideways too much the drag will increase markedly and the boat with some board down will produce less drag.

I guess the point I can't seem to get across is that there is no difference between bearing off 7 degrees more and having 7 degrees of leeway. The generation of apparent depends only on your boat's track and not your boat's heading. But the point is not worth worrying about or getting unfriendly over.

In reality I tend to pull my boards up at a broad reach and forget about them. On a beam reach I put them half down and they go fully down to windward. I really like to have the boards fully up downwind because we have lots of crab pots of the NSW coast. With our kick up rudders we can hit one of these hidden floats, pop up one rudder, curse the fisherman who doesn't put a pole on them, put the rudder back down and sail on. When I hit one with the board down I spent 20 minutes with getting it off the board. Not fun.

I have a trick to knowing when to put the boards down - if they are hard to move down (or up) - put or keep them down. If the board is generating lots of lift it will be harder to push down or retract - that is its job so make it work and keep it down. If they come up relatively easily to move then they weren't doing anything so they are just being pulled along and pulling them up will be faster and let you jump the fish traps. As always, listen to your boat.

cheers

Phil

[admiralslater]

I also have an original 45 and last year I went to the factory to get some spares .I asked that very question and one of the experienced people people there said that the top of the board should be no lower than the upper stringer .I was not able to get an answer on wether it is one or two boards at a time . We use one at a time on our PDQ 36 .
As for inducing leeway when going to windward I am not sure How I feel about that ,I may have mis read the posts.
On the 36 I like a little board down when going down wind as it helps me pop onto a surf

[Stumble]

Originally Posted by admiralslater

I also have an original 45 and last year I went to the factory to get some spares .I asked that very question and one of the experienced people people there said that the top of the board should be no lower than the upper stringer .I was not able to get an answer on wether it is one or two boards at a time . We use one at a time on our PDQ 36 .
As for inducing leeway when going to windward I am not sure How I feel about that ,I may have mis read the posts.
On the 36 I like a little board down when going down wind as it helps me pop onto a surf

Again it's hard to translate because the speeds are different, but the A-Cats race with both boards down upwind and just pull them up a bit in survival conditions. Part of that is that we race them solo and the time to swap them isn't worth it, part is we are always flying a hull, and part is for lift.

On a cruising boat my default would be both boards down upwind, but I might play with it and see I find the track changes with one or both boards in. There should be a bit of speed advantage to just one, but the slippage may harm vmg.