MacGregorSailors.com

No... you don't win anything if you guess right.

Center skeg to install behind the D/B going aft !

Close!

Here's a couple of new clues fresh off the printer.




A new perspective might be helpful.

Rudder buck to make a mold for a new rudder?

looks like he is trying to make a daggerboard

skeg to b mounted in front of D/B for better pionting

J

Well... Boat gets the Boobie prize.

So... I'll try to assume you're not being a wet rag on other people's work. Why the wording, "trying"? versus, just saying, "It's a daggerboard."

Is there a history of bad attempts? I researched the forum some time ago and found many good ideas that I have incorporated... some I've chosen not to.

VBR

well, the best ideas have been tried by the factory and BWY and Captain Sparrow but honestly I have many times felt there is still a better dagger board out there waiting to be invented.

The main feature of most daggerboard inventions has been adding lead to them.
Another idea attempted was to add wings to the board for control.
An untested idea I was always wanting to try was to add a trim tab to the daggerboard that can be controlled from the cockpit with a line.

I think there is still a possibility that the factory DB can be improved but the magic design just has not been discovered yet

I feel that's a fair assessment.

Actually, I feel the factory built many things from the philosophy, "It worked well enough in the last iteration." I don't believe any real analysis came into the assessment to really push the envelope. Though... the Mac is not about being cutting edge.

From my simplistic standpoint...
I broke my daggerboard. I drove up on the trailer with it partially down. Beat me... whip me... make me chase chickens. I WAS STUUUPID! What's left, I cleaned up, fiberglassed to be about 60" long (instead of 70"). Frankly... I didn't notice a difference sailing.

So ACADEMICALLY... I want to do better. Unfortunately, I don't know what that is.

1) The boat isn't going to go that much faster. Hull Speed is a bitch.
2) I can make the daggerboard a 3 decimal place NACA foil using the 3D printer... but will that make a difference? That was rhetorical... F' No!
3) Will it point better? See 2.

But, maybe with some black-magic engineering voodoo (from someone) we will see a foiling Mac doing 25 knots while sipping a glass of wine.

I'm just trying to push that boulder up the hill a few inches...

Not that anyone is ready to go through the trouble... before seeing if I crash and burn...

I will be providing the 3D Printer models and the fabrication steps will be in this thread as I proceed to victory or defeat.




At this point... I am projecting it to be around $100 and to work better than production. The problem is, how do you gauge "better" if I don't have a production one for comparison?

Inquisitor wrote: ↑Sun Oct 18, 2020 5:26 pm I broke my daggerboard. I drove up on the trailer with it partially down. Beat me... whip me...

You are not the only person that has done this, by the way...

Jimmyt wrote: ↑Sun Oct 18, 2020 8:23 pm You are not the only person that has done this, by the way...

The $710 punishment for a BWY replacement was more than I could stomach.

The current plan is to seal the D/B instead of flooding it like the production unit. I plan on using concrete to just fill the bottom enough so that it doesn't float up in the trunk. The designed D/B displaces 36.3 pounds of seawater. This much concrete is about as much volume as the elliptical portion.

I am considering adding a pulley to the D/B so that I get a 2:1 lifting advantage. I'd like to get just the pulley wheel and use a bolt into the D/B. Has anyone seen a bare pulley wheel like the one used on the Mac's daggerboard, rope pulley / hinge? I don't need all the bearings and frame of a real block.

McMaster-Carr sells a wide variety of bare sheaves. My oldest just bought a handful of wire rope sheaves with ball bearings and built a specialized bit of workout equipment with them, running 3/16” dyneema.

Have you considered using single-part to the daggerboard, and two-part above the deck? That way you can use standard blocks, and keep them out of the salt water.

I’ve often considered doing that with my centerboard, but I’m still strong enough to pull it all the way up with some authority. But that won’t last forever.

Google returns a fair number of possibilities. Here is one...



We have a pulley/bearing store here that might be a local source. Don't know if you might have such a place where you are.

You can always have a machinist make you one, also.

Tomfoolery wrote: ↑Mon Oct 19, 2020 4:38 am McMaster-Carr sells a wide variety of bare sheaves. My oldest just bought a handful of wire rope sheaves with ball bearings and built a specialized bit of workout equipment with them, running 3/16” dyneema.

Have you considered using single-part to the daggerboard, and two-part above the deck? That way you can use standard blocks, and keep them out of the salt water.

I’ve often considered doing that with my centerboard, but I’m still strong enough to pull it all the way up with some authority. But that won’t last forever.

I'm right there with you. Pulling up 40 pounds isn't a big deal now... but I plan to sail as long as I can. Coincidently this is about as much weight as carrying a 5 gal bladder of water onboard.

Jimmyt wrote: ↑Mon Oct 19, 2020 4:45 am Google returns a fair number of possibilities. Here is one...
You can always have a machinist make you one, also.

I used the wrong keywords... didn't know it was called a "sheave". All I got were full blocks.
I don't have anything like a local place of marine gear. This is bass fishing country. They've never seen a Mac around here.

Since I can design/define the internal structure, I can recess a full block mechanism down into the D/B if I need to. I may try an fiddle with 3D printing a Nylon wheel. I'm sure its strong enough for the 40 pounds, but I'm not too sure about the material creeping over time in hot weather. Maybe worth trying. If I make it the standard size, I can always drop in something like you have above.