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Drawing for Bandit 17 guy


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I can’t post this in a  p m so I am posting it here 

the “pivot pin” is like an old fashioned toilet paper roller rod

it has two one inch long 3/4 inch diameter stainless tubes

the outside ends of the tubes are rounded in 

there is a spring inside the two tubes 

there are keyhole shaped sockets molded into the trunk walls 

the installation

put the spring loaded tubes through the centerboard 

swueeze tye tube to its shortest possible length and slide the board up inside the trunk

slide the tube to the round part of the keyhole openings

the tubes  will pop out into the keyholes and Koch the pivot pin in place 

 

to remove the board 

put a screwdriver up into the keyhole slots and compress  the spring

slide the board out 

if this doesn’t make sense I will have to make a better explanation 11A2372A-B8F5-4B92-8982-C5C5B0915A5A.thumb.jpeg.92f274fccdbb14778cb1b620e2c60ee8.jpeg

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Awesome! Thanks. I honestly thought I was going to have to cut open the deck or cut out the centerboard. 

It makes sense to me that it be like a toilet roll, I was definitely having issues with the idea there wasn't some easy way to replace it.

At least now making a new Centerboard will be that much easier.

Cheers!

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6 hours ago, spankoka said:

Just kidding...you got the job done.

 

 

Actually,,, my ten weeks of mechanical drawing in  seventh grade was just enough so I can make a barely sufficient Shop drawing but if I ever really need to draw

much I will have to learn how to do it on computers 

 Hey Siri draw a cube  in this little note 

Damn!! Didn’t work 

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  • 9 months later...

So the pin didn't work.  I had to cut out.  The Teflon side of pin was so damaged it wouldn't compress. 

It lasted another year so that was good, but it had to be done this spring.  Sadly the center board was also damaged pretty much beyond repair, so I've decided to remake from cedar strips and Carbon Fibre, the sculptural parts are what I'm very good at. 

Any advice against making a daggerboard longer than what is original as I"ve scaled below based on original?

The daggarboard was from internet on some hydrodynamic read on the new designs for AC racing. Seems appropriate. haha

I recarved the mahogany rudder years ago then layered with FG and it went very well, doing this daggerboard shouldn't be an issue.

 

This is my idea. I understand finding the new pivot point might be forward or back an inch or two based on the mass of existing vs proposed.
The boat is so much fun to have on our lake and owes me nothing, but sure fun to see if I can keep it going and I'd rather a studio project in the time of COVID, than watching netflix.

Would the extra length help from getting flattened quickly in big gusts while also being able to point tighter into the wind?.

 

1254325916_dasbootdaggerboarddropin.thumb.jpg.58427aef0609b3c9c566ee9f9ed8fa89.jpg

 

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7 hours ago, Peter Plump said:

So the pin didn't work.  I had to cut out.  The Teflon side of pin was so damaged it wouldn't compress. 

It lasted another year so that was good, but it had to be done this spring.  Sadly the center board was also damaged pretty much beyond repair, so I've decided to remake from cedar strips and Carbon Fibre, the sculptural parts are what I'm very good at. 

Any advice against making a daggerboard longer than what is original as I"ve scaled below based on original?

The daggarboard was from internet on some hydrodynamic read on the new designs for AC racing. Seems appropriate. haha

I recarved the mahogany rudder years ago then layered with FG and it went very well, doing this daggerboard shouldn't be an issue.

 

This is my idea. I understand finding the new pivot point might be forward or back an inch or two based on the mass of existing vs proposed.
The boat is so much fun to have on our lake and owes me nothing, but sure fun to see if I can keep it going and I'd rather a studio project in the time of COVID, than watching netflix.

Would the extra length help from getting flattened quickly in big gusts while also being able to point tighter into the wind?.

 

1254325916_dasbootdaggerboarddropin.thumb.jpg.58427aef0609b3c9c566ee9f9ed8fa89.jpg

 

Any improvement in pointing normally comes at a with a resultant increase in heeling For a given amount of wind, the less leeway a boat makes the more it wants to trip over the board. The longer board could well make the helm feel a lot lighter in steady breeze, but as you start lifting the board upwind as the breeze picks up you could easily end up with lee helm as the centre of lateral resistance will move faster then with a shorter board, so more mast rake would be necessary to balance the helm.

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12 hours ago, Major Tom said:

Any improvement in pointing normally comes at a with a resultant increase in heeling For a given amount of wind, the less leeway a boat makes the more it wants to trip over the board. The longer board could well make the helm feel a lot lighter in steady breeze, but as you start lifting the board upwind as the breeze picks up you could easily end up with lee helm as the centre of lateral resistance will move faster then with a shorter board, so more mast rake would be necessary to balance the helm.

Thanks Major Tom This is exactly what I was hoping to hear.  I need to rationalize all this as I'm not new to sailing, but somewhat new to the dynamics behind sailing.

OK, lee helm is definitely not what I want when the wind picks up as this boat has no backstay to counteract on fly nor any vang (it's a shockingly simple boat from 70's).  I seem to get flattened all the time if I"m not paying sharp attention to water in the punchy gusts.  But when solo sailing I let out my main so I can go up to bow to clean up the spinnaker and the boat pleasantly smears sideways even if gusty.  I suppose this principle will affect that as well?  Wait- does that mean I'm using the boat to lee helm when going up front to clear sail?

Since this is a new daggerboard and I"m not using the pin in hull for the pivot, and making a new one on deck, I guess I will likely have to trial this by moving the board fore or aft to get the right balance?  I understood the relationship of boat helm is based on the center of mass of sails vs center of mass of board is how a board or keel performs?

So if all things equal a longer board will help keeping boat flat and point?

image.png

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2 minutes ago, Peter Plump said:

Thanks Major Tom This is exactly what I was hoping to hear.  I need to rationalize all this as I'm not new to sailing, but somewhat new to the dynamics behind sailing.

OK, lee helm is definitely not what I want when the wind picks up as this boat has no backstay to counteract on fly nor any vang (it's a shockingly simple boat from 70's).  I seem to get flattened all the time if I"m not paying sharp attention to water in the punchy gusts.  But when solo sailing I let out my main so I can go up to bow to clean up the spinnaker and the boat pleasantly smears sideways even if gusty.  I suppose this principle will affect that as well?  Wait- does that mean I'm using the boat to lee helm when going up front to clear sail?

Since this is a new daggerboard and I"m not using the pin in hull for the pivot, and making a new one on deck, I guess I will likely have to trial this by moving the board fore or aft to get the right balance?  I understood the relationship of boat helm is based on the center of mass of sails vs center of mass of board is how a board or keel performs?

So if all things equal a longer board will help keeping boat flat and point?

image.png

No, a longer board generates more heeling moment as it is not a ballasted keel, if you lift your board completely up when beating the boat will skid sideways and there will be no heeling moment, the more you put the board down the more the hull wants to stay in one place and the  more the rig wants to fall over to leeward.

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4 hours ago, Major Tom said:

No, a longer board generates more heeling moment as it is not a ballasted keel, if you lift your board completely up when beating the boat will skid sideways and there will be no heeling moment, the more you put the board down the more the hull wants to stay in one place and the  more the rig wants to fall over to leeward.

Thank you.  I get it now.  I'll read more tonight before I cut to length.

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  • 4 weeks later...

I didn't cut the daggerboard and went with the intended version, mostly to see what would happen.  Since I made it, it didn't matter if it needed to be cut down later or not.

All the physics at play made it too interesting for me to have to understand what was 'exactly' at play especially for a week on the lake post-Covid shut down.

Turns out the boat holds line way better than before and is quiet as silk till 5ish KN in the flat water. The boat starts to hum somewhere past that.  It didn't do it like that before as I'm sure the crude slab of a centerboard wouldn't allow for it. 

I think I realize now what was happening when we were getting slammed over all the time or unable to hold it into the wind during gusts, other than being a poor helmsman.  When we brought the boat to heal pointing into the wind the boat would basically get pushed over or the tiller wasn't able to be precise enough to manage gusts and it would luff and we'd stop like a tonne of bricks.  I think the centerboard was loosing pressure underwater and releasing when too close to the surface.  Through the week of testing, I was able to bury the rail in the water and hold the line unlike ever before and the boat still tracked. 

The only problem now is the rig and daggerboard is likely now starting to overpower the rest of the boat as I added a tweaker to tighten the sail for point but left the car too far back and in a big gust, we ripped the entire track right off the boat.  Gladly I just moved everything 3" forward and went right back out.  Holes and all, I"ll fill them next for next summer...

SO FUN.  However, I"d love to sail a real racing dinghy more by the day.

 

Anyway, thanks for your time. 

Now I"m curious if I dig out an area at the bottom of the daggerboard and add 20lbs of lead, then CF over it.

haha.

 

 

 

 

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