keel plate

[Ixneigh]

Who had the plate attached to the bottom of the M daggerboard? I've been thinking about that one. Probably easy to do.
Ix

[Crikey]

I remember that! I think it was someone from Queensland (Aus) long ago. In addition to Americas' Cup 'Wings' it would also remove ingestion of over one hundred pounds of water, during motorized speed. What is the effect of wings on a lightweight keel? Shaped into a 'U', like a Winglet.
An aluminium plate, shaped to fit, mounted to the bottom of the Dagger Board. Sacrifice-able.

[Ixneigh]

Actually I was thinking a delta wing shape about 18 inches wide. It would be fastened by tapping studs up into.the the keel end after I poured a mixture of resin, lead shot and milled glass fiber into the bottom foot of it. It would not impact draft. Instinct tells me not to match the curve of the hull. The wing could be just glassed over plywood. It should reduce slippage at moderate heel angles, however I'm not sure how much drag penalty there would be. But its such an easy mod someone should figure it out. Also possible it might be a problem while loading boat on trailer.
Ix

[Crikey]

Ix, 18 inches seems like a lot! I'm not sure that you would plane, under power, unless it was completely conformal with the hull. If caught by the water doing a power-turn, I think even the best fiberglass types would snap off quickly. That means sailing only.
R.

[Divecoz]

Sorry Ix. but I disagree
1. 18" across? To Big..
2. Non Hull Conforming? Too many issues and as Crikey said.. Only sail use. Never beach ...better never even go to a soft ground..
3. Glass over wood? No way Jose.. It will in time rot.. Proven for many years with millions of boats.. Even Vacuum molded it will rot.. I Just looked at an issue the other day on a 7 year old boat ( ?) that no doubt was built to better standards than any of us could replicate.. Shi-p happens..
4. Correct Non- Hull conforming design raise issues with loading on trailer..
Aluminum or SS plate.. smaller.. Maybe covered with glass..

Actually I was thinking a delta wing shape about 18 inches wide. It would be fastened by tapping studs up into.the the keel end after I poured a mixture of resin, lead shot and milled glass fiber into the bottom foot of it. It would not impact draft. Instinct tells me not to match the curve of the hull. The wing could be just glassed over plywood. It should reduce slippage at moderate heel angles, however I'm not sure how much drag penalty there would be. But its such an easy mod someone should figure it out. Also possible it might be a problem while loading boat on trailer.
Ix

[Ixneigh]

Well, making a conforming hull one would be so easy it could almost be considered cheating.
It has to be at least 18 inches wide to do anything. Don't ask me how I know this.
I might consider the beaching issues and settle for a conforming one made of solid glass, even though I can build in wood with no problems.
Its the drag I'm concerned about.
I actually never beach the boat, or rarely. I just anchor it off in the shallows. I'm going on a trip soon. It will give me time to study the issue.
Ix

[Crikey]

It has to be at least 18 inches wide to do anything. Don't ask me how I know this.
Its the drag I'm concerned about.

I'm asking, I'm asking! From what little I've thought about this I feel the main benefit would come from blocking out all that water on an
The rest would be from a turbulence reduction at the end of the keel, similar to a winglet or fence on an aircraft. Same principal, different operating medium. I don't think a fixed keel 'wing' is intended to hook into the water to reduce leeward drift.
If made out of sharpened aluminum 1/4" plate, bent to fit, there wouldn't be very much cross section to increase drag over that of the daggerboard itself.
Correct me if I'm wrong because I'd like to explore this idea sometime this year when I begin to play with a retraction and slop reduction system.
Ross

[Nathan]

Not sure this is what you are looking for but I am interested in doing a similar mod on my future boat.

http://www.macgregorsailors.com/modt/in ... ?view=1109

[Crikey]

Exactamundo!
Want to do that. It's brilliant!

[Hardcrab]

What will this mod bring to improving sailing on the boat?
It looks like it just impedes the boat from any vertical boat movement.
Am I not seeing something more obvious?
I'm thinking it should act like the control surfaces on any aircraft, or more like the in-water planing surfaces of a hydrofoil type boat.


One question, how to get the "angle of attack" correct for different boat loading/attitude conditions?
It seems to need some sort of way to keep it slicing through the water without sending the daggerboard back up the trunk or wanting to dive the boat deeper into the water if it's angle to the water flow is wrong

Would zero angle of attack relative to the boats attitude at any given moment would be the goal?

Just wondering.

[Highlander]

Here's one I designed for my but then bought an . So I never implimented it any further but would also work on an
http://i78.photobucket.com/albums/j95/m ... 0002-1.jpg

http://i78.photobucket.com/albums/j95/m ... 010001.jpg

http://i78.photobucket.com/albums/j95/m ... 010012.jpg

http://i78.photobucket.com/albums/j95/m ... 010007.jpg

I still have that fin in my shop some where !

J

[mastreb]

One thing about Jack Sparrow's mod to understand: The "slop" in the daggerboard is intentional. It allows 3 degrees of change to the angle-of-attack of the daggerboard which improves it's lift characteristics and reduces heeling. I discovered this when I was considering a modified daggerboard with a trailing-edge flap to help with heeling and pointing and came across a quote from Roger talking about it. Building up the top of the daggerboard to remove it may get rid of thunking noises, but it will also increase heeling.

Matt

[Crikey]

Terrific idea using an efficient outboard hydrofoil. Too bad it couldn't have been a snug fit, and controlled by a computer. (laterally)
Still going to take a very heavy load while grabbing under power - because of non-conformality.
If you could use a heat gun to mold it into a hull matching shape, which way for the lift generated would be more beneficial? Pushing the hull out of the water, or straightening downward instead, by pulling. Those things are fairly cheap, and expendable if impacted (but I think you'd have a handful going on at this point).
Just saying it's about attachment because I don't think it would be easy to use less metal than what you're doin. That's not a hinged shaft attachment either! And, most likely, the entire end of the Daggerboard is going to rip off anyway.
Best not hit anything!
R.

[Ixneigh]

That is sort of what I had in mind. Any report on how effective it was?
Ix

[Crikey]

One thing about Jack Sparrow's mod to understand: The "slop" in the daggerboard is intentional. It allows 3 degrees of change to the angle-of-attack of the daggerboard which improves it's lift characteristics and reduces heeling. I discovered this when I was considering a modified daggerboard with a trailing-edge flap to help with heeling and pointing and came across a quote from Roger talking about it. Building up the top of the daggerboard to remove it may get rid of thunking noises, but it will also increase heeling.

Matt

Not so sure about the 'intentional' being so accurate here? On the yes, because of the positioning and play of the hinge pin. Until the actual possible variables are measured I think it would be possible to have this 3 degrees (X 2?) end up at either the leading edge, or the trailing edge with detrimental performance issues possible. Not to mention what's going on when things are rocking around.
If there's repeatable lift to be had - it needs to be held, and oriented (remembering an earlier thread). Still, ...easier said than done!
Ross