Daggerboard Question

[Tisrael]

I'm now sailing my Sunfish in a large, but shallow cove. Wind is great, but the water never gets deep. Much of the cove is about 3 1/2 - 4 feet and in places there is a lot of aquatic plant growth.
I'm wondering if its possible to use a "short" daggerboard. What's the impact on performance? Does anybody sell short dagggerboards? Is it possible to modify a standard one?

 

[Wavedancer]

Just pull up the board.


When you are reaching or running, the board should be (partially) up anyway.

 

[Royal]

Just pull up the board.


When you are reaching or running, the board should be (partially) up anyway.

Would you elaborate a little more? I've seen the boards up in videos on the class website but I've never heard the reason explained. I assumed that reduced drag when running is the main reason, but don't you need it on a reach?

 

[Zeppo]

With the board up there is less drag, however when your sailing to weather you need the board fully down or you will be going sideways as fast as your going forward. Don't forget to lower the board enough so that the boom can clear it on gybes (assuming your sailing with the boom close to deck level.

 

[Fred P]

Thank you Wavedancer and Zeppo for the to-the point answers!

Tisrael:
Pulling up the board you have gives you the most flexibility. If you use a shorter board you a stuck with it on reaches and other points of sail. That fact negates your last question.
Fred

 

[Wayne]

Would you elaborate a little more? I've seen the boards up in videos on the class website but I've never heard the reason explained. I assumed that reduced drag when running is the main reason, but don't you need it on a reach?

Just pull up the board.
When you are reaching or running, the board "should" be (partially) up anyway.

I am not in agreement. Not to be argumentative, but to consider the style of sailing being practiced.

This tactic is for efficiency as Royal has deduced, however it is reserved more often for competition and advanced sailing where jumping up on a plane quickly benefits from the move.

On the other hand, for general sailing, employing racers edge strategies has no perceptible benefit except to make otherwise leisurely sailing busier than a one armed paper hanger.

Of course this is a personal choice, but that doesn't make it a "should" it makes it a, "you can if you realize a benefit and desire to". Most general sailing is done leaving the board alone. Royal has a special case sailing dangerous shallows which may dictate this and other mitigating behaviors.

I'm now sailing my Sunfish in a large, but shallow cove. Wind is great, but the water never gets deep. Much of the cove is about 3 1/2 - 4 feet and in places there is a lot of aquatic plant growth.
I'm wondering if its possible to use a "short" daggerboard. What's the impact on performance? Does anybody sell short dagggerboards? Is it possible to modify a standard one?

The daggerboard is a large part of the boat's lateral resistance equation. Along with the hull below the waterline and the rudder, these surfaces make up the counter elements to the wind's force on the sail. It's the directional conversion of these forces that make sailboats go pointy end first.

Realizing this is also an unballasted board boat, the daggerboard's lateral resistance in a heavier media counteracts the wind's leverage against the sail. Reduce the resistive surface below the water line and you also need to reduce the wind's leverage (ease the sail) and/or hike out more to keep the boat in balance.

There are other considerations, lateral drift, reduced ability to point, and going into irons more easily are probably next on the list. So, if you choose to sail marginally navigable waters these are the primary adjustments you will likely need to cope with.

.

 

[Wavedancer]

Wayne is right of course, in the sense that I was looking at the issue from a racer's perspective. But I also note that many 'cruisers', at least the ones that post here, like to go fast(er). And don't we all want to become better sailors?

Now I will try to respond to Royal's question: how far to raise the board reaching or running? It's trial and error, and you learn by experimenting.
If your board is up too high you will be using the rudder to stay on course. You may not notice it, but this is SLOW! You really want a neutral helm as much as possible and racers move around the boat, adjust the heel and the board to do that.
The board can be up higher on the run than on a reach, because there is less force moving the hull sideways if the wind is from the back. Nevertheless, with the sail out at 90 degrees, racers lean the hull to windward going downwind to keep a neutral helm. If you are just out for relaxation, this may not be for you. Moreover, you do run a chance of capsizing to windward when you lean the boat too much (and even if you don't capsize, you may get your bottom wet).

Beware of jibes with the board up; you may capsize simply because the boom can't sweep across. I have done that; it's VERY SLOW....

 

[chiefypoo]

I sail in an area with a lot of shallow bays and bars ( back behind a beach in oysters and mud) I made a dagger board that would just fit the slot and about 30" total length. lots of time I am creeping along along the marsh grass and over a few open areas, there are people who try to catch me and go aground. I proceed to the inlet and then usually come back the same way . they will come out and ask me how I sail back in that shallow areas I show them my shorten board and they say It's wrong specks. I say It gets me where I need to go and back.

you do what you need to do to enjoy a good sail. Oh, I don't race and I don't belong to any clubs.
Just make a board out of ply and bevel it up then cut it off till it fits your needs.
Life is short live it love it.