26s Hollow Center Board? Lead Shot?

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KingRichard
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26s Hollow Center Board? Lead Shot?

Post by KingRichard »

I haven't been able to find much about the centerboard's construction. I would like to know if it's hollow. If so I want to put around 50lbs of lead shot into it. Seems like it would improve the general dynamics a fair bit.

I have the early 26s with visible mounting. Hopefully I can add a little reinforcement. Assuming the center of the additional ballast is 6ft (worst case) from the mounting point, 50lbs would add a bit of torque when heeled over hard.

My other issue is I have to pull really hard to get the rerouted board to come up now. I'm afraid of breaking something...

If anyone has tried or read about something similar I'd love to read about it.

Thanks!
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Russ
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Re: 26s Hollow Center Board? Lead Shot?

Post by Russ »

We have 20 years of Mac experience on this forum.

I'll save you the search.

VERY little gain from adding weight to the board. The "cost" of firming the board to support the lead not worth it.
--Russ
KingRichard
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Re: 26s Hollow Center Board? Lead Shot?

Post by KingRichard »

Just in case, does anyone know is the center board hollow? If so how wide is the cavity

Thanks
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Stickinthemud57
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Re: 26s Hollow Center Board? Lead Shot?

Post by Stickinthemud57 »

I'm pretty sure the centerboard for the S is solid. The specific gravity of fiberglass averages around 1.5 depending on how much glass there is in the mix, so I think having a cavity in the the centerboard would risk having it float up.
The key to inner peace is to admit you have a problem and leave it at that.
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Highlander
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Re: 26s Hollow Center Board? Lead Shot?

Post by Highlander »

Are the D/B , C/B & rudders not all hollow with holes drilled in them top & bottom to allow air to escape & water to fill them like on the :macm:
I know the :mac19: Rudders were pretty much solid they were very strong & heavy as they were pinned in the down position before launching & stayed down for W/O powering or sailing & the C/B was pretty much mostly solid as it weighed a ton but still had vent holes in the C/B so was about 1/3rd solid on the bottom section I believe& had vent holes on the trailing edge & drain holes in the front edge

J 8)
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Russ
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Re: 26s Hollow Center Board? Lead Shot?

Post by Russ »

The M dagger is hollow. Very hollow and sacrificial as it will break before damaging the trunk.

Others have filled the void with lead shot. But that also required beefing up the dagger because it bowed out from the weight. In the end, the result wasn't worth all the trouble to fill the board with epoxy to hold it from expanding.

I guess my concern would be the board would no longer be sacrificial if you hit something hard.
--Russ
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Stickinthemud57
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Re: 26s Hollow Center Board? Lead Shot?

Post by Stickinthemud57 »

Russ wrote: Fri Jul 01, 2022 8:08 pm We have 20 years of Mac experience on this forum.

I'll save you the search.

VERY little gain from adding weight to the board. The "cost" of firming the board to support the lead not worth it.
I agree with Russ. 50 lbs will not help the dynamics (by which I take you to mean the amount the boat heels) to any significant degree, and will make the centerboard considerably more difficult to raise, which you do not want either when you are approaching a shallow area or preparing to trailer.
The key to inner peace is to admit you have a problem and leave it at that.
KingRichard
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Re: 26s Hollow Center Board? Lead Shot?

Post by KingRichard »

Thank you all for the replies, sorry I thought this would email me if there were more.

@Highlander - I was wondering about the holes, that makes sense.

I share all of the same concerns...but I am surprised that there isn't more of a real or perceived effect.
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Stickinthemud57
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Re: 26s Hollow Center Board? Lead Shot?

Post by Stickinthemud57 »

Stickinthemud57 wrote: Sat Jul 02, 2022 7:40 am I'm pretty sure the centerboard for the S is solid. The specific gravity of fiberglass averages around 1.5 depending on how much glass there is in the mix, so I think having a cavity in the the centerboard would risk having it float up.
I was wrong on this. Having recently pulled my centerboard, I found that zebra mussels had set up housekeeping in the two holes near the lower end. Over the course of the next few days, after everything had dried out, I would hear their shells rattling about in the board as I turned it end on end. Using a tack hammer to sound the board, it appears that the board has a good-sized hollow section around the drain holes and in the trailing edge going up almost to the lifting cable insertion point. I don't know if they are all this way or not.

As to your surprise over the lack of effect, real or perceived, keep in mind the fact that countering the force of the wind in the sails to any noticeable extent would take a good deal more than 50 lbs, even at the end of a 6' lever.

The Mac 25 has a swing keel weighing 650 lbs, requiring a winch mechanism to lift. Keelboats in the same size range use around 1000 lbs of ballast. 50 lbs just is not very much in this context.
The key to inner peace is to admit you have a problem and leave it at that.
KingRichard
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Re: 26s Hollow Center Board? Lead Shot?

Post by KingRichard »

The board being hollow w/drain holes does explain why it seems like board lowers at a different rate when first off the trailer.

With that said, If we a assume 1-1/2" thick x 15" wide x 66" long cavity then the board fills with about 50lbs of water... Which is interesting. Between the water weight, board weight, and frictional resistances to raising the board now, 50 more pounds certainly wouldn't make it twice as hard to raise. With mine already rerigged aft, maybe only 50% more force required, good to know.
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Jimmyt
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Re: 26s Hollow Center Board? Lead Shot?

Post by Jimmyt »

Remember that the weight of water, when submerged in water, is zero. You are only lifting a minute amount of water before it builds enough head to run out of the drain holes.
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