weighted keels??

[Wayne nicol]

ok, so i know this topic has been discussed at length here. i have searched the pages and the mods, and can find the threads, but cant seem to find an answer to my question.
how will a weighted dagger board effect the righting action of the - i realize that physically it will assist, the figures i have read are for every pound at the top of the mast you need an extra 6 pounds in lead.
no, i am not mounting anything up the mast, and am not planning any blue water trips, and i do realize this will not effect the heeling. just want to add a bit of security to the righting action of the boat in sailing mode, from a possible knockdown!
i would be happy to improve the purchase system for the extra weight.
what sort of weight would be a good idea, some of the naval architects i have been talking too say a 100 lbs would go along way.
didnt the "black pearl" have a huge lead bulb on a stronger dagger board?

[BOAT]

The dagger board is water ballasted.

It seems that right after we buy our MAC M boats the first idea that pops into the head is to ballast the daggerboard with lead. We all have considered it. It's a normal thing to consider since lead is heavier than water. I even made plans to buy a new daggerboard from BWY and ballast it and only use it occasionally.

Some have done it, but the vast majority like myself that have considered ballasting the daggerboard always come back to the same issue: "I bought this boat because I want to pull it on a trailer so why am I adding dead ballast to tow around?."

I guess the whole point of water ballast is to leave the ballast in the water and only tow the boat. I dropped my idea to ballast the DB.

I don't know what the water capacity is of the daggerboard, but if you knew you could easily calculate the difference between the weight of that much water and the same amount of lead. It just might be more than 100 pounds, I really don't know.

[Obelix]

The water inside the dagger-board just enables the hollow board to sink, not adding additional ballast.

Obelix

[RobertB]

Check out the Didi 26 - a very similar sized home-built high performance sailboat http://www.dixdesign.com/26didi.htm. I was about to build one when I found the This boat has a nearly 900 pound lead bulb on the end of a daggerboard. IMO, all is great until you are badly knocked down and that suspended weight can slide back up since it is not locked in place.
Also recommend if you do add weight to you daggerboard, more than several pounds, you may likely need a more robust daggerboard.

[Y.B.Normal]

The Black Pearl did have a weighted daggerboard, however, it also had reinforcing around the daggerboard well, and I believe, in the hull.
Looking at my daggerboard, and the damage it sustained when I hit a submerged object, I wouldn't add ANY weight to it. It's not structurally sound enough for the extra weight.
Generally, if you're knocked down, the rudders will become ineffective and the boat will round up.

If you look on the board, very few, if any owners have been knocked down.

[Russ]

Generally, if you're knocked down, the rudders will become ineffective and the boat will round up.

If you look on the board, very few, if any owners have been knocked down.

Yup. The boat will pop back up and getting knocked down is extremely rare.

[padge]

The dagger board structure is really quite thin
I wouldn't put much extra weight in it.

The picture is before and after the dagger board dropped while towing (only 5 miles)

[Seapup]

IMO, all is great until you are badly knocked down and that suspended weight can slide back up since it is not locked in place.

100%, Weight has to be locked down to keep it from slamming back up and causing even more problems.

I would not add daggerboard weight for the purpose of preventing a capsize.

The dagger board structure is really quite thin
I wouldn't put much extra weight in it.

There was an old post or mod page where someone filled an M board with lead shot and it bowed so wide it would not fit in the trunk. They ended up dumping the shot out, reinforcing it, and trying it again.


I did add 75lbs of #8 lead shot to the board on my .I used lead shot so I could drill a hole and drain it back to stock if I didn't like it. I have no plans of going back

I don't know what the water capacity is of the daggerboard, but if you knew you could easily calculate the difference between the weight of that much water and the same amount of lead. It just might be more than 100 pounds, I really don't know.

No idea on a M, but for my 02 X 75lb of lead shot pretty much filled it. Lead is a little over 11x denser than water, so about 7lbs of water would fill it.

I found of interest the first 25lb bag all fit in very tip of the board. The rest spread out fairly evenly once the cavity at the tip was filled.

[mastreb]

The simplest method to weight a daggerboard is to use epoxy and lead shot, adding both an inch at a time--Inch of lead, expoxy, let harden, add next inch. This prevents the daggerboard from bowing out as you add weight, and the expoxy makes the board structurally stronger as you go, so it can stand up to the additional weight.

The "Black Pearl" did in fact point much better than a typical Mac by about ten degrees thanks to its ballasted daggerboard, which weighed 430 lbs., according to Mike Inmon.

But the factory did not think that the performance improvement warranted the additional cost, lifting complexity, and towing weight, and it created a safety problem: When planing, you either have a bulb in the water which is dangerous at speed because it changes the turning characteristics, or you have hundreds of pounds of weighted dagger hauled up above the center of gravity, which causes the boat to roll farther when planning. On a power sailor, the weighted daggerboard was a liability for that reason.


According to Mike Inmon, the existing daggerboard trunk is more than capable of handling a stronger daggerboard, as it is surrounded by the permanent ballast which is epoxy and sand--essentially, the bottom of the daggerboard trunk in the Mac where it holds the daggerboard is solid epoxy.

[RobertB]

Epoxy and sand or polyester resin and sand? I am really not trying to split hairs here but would be much happier if it indeed was epoxy. Thinking back to when I damaged my daggerboard and found the solid pours of polyester resin had fractured apart since it is so brittle. I do not believe epoxy would fracture the same.

[Ixneigh]

I say forget the ballasted board. I had the chance to do it and declined. I put the weight in the bottom of the boat along each side of the water ballast. It is strictly a safety reserve that will only kick in past 50 degrees. It does make the boat ride better under sail, in my opinion.
Ix

[beene]

IMHO

It is not worth the hassle

Leon did it in his M

Lots of issues

Thing was a B@#$% to get up

Had a 18-1 to get it up IIRC

Would get stuck from time to time with just a bit of sand wedged between the keel and the housing

And there is no way I will believe they could point 10 deg higher than stock with the Pearl, no way

I can hold 28 deg apparent, slow, but I can.
Better speed at 30 off apparent

So to say with a heavier daggerboard they got 18 apparent?????
Or even 20.... riiiiiight

The only thing Leons mod did for him was decrease heel and maybe kept the boat driving into the waves better as it was overall heavier

That is the one great weakness of these boats
They are so light
When on a beat, hit a wave, can stop you dead if its high enough
Take a 20,000 lb keel boat in the same sea state
She will bash right through that wave and keep right on trucking without breaking a sweat

[mastreb]

RobertB--My bad--he said resin, my brain interpreted epoxy.

As for ten degrees higher, that was 30 degrees off apparent vice the boat's more typical 40 degrees. I've never been able to hold better than 40 degrees according to my solid state anemometer.

If you've been able to, I'd sure love to see your data logs and method.

[beene]

If you've been able to, I'd sure love to see your data logs and method.

Raymarine i40 & autopilot
Full main and hankon jib, not genny
Boat at 30deg heel
10kt wind true speed
15kt apparent wind speed
holding 150,151,149,153,149,150 on i40 display using apparent

Like this, I could tweak the auto 1 deg at a time
hit 1 and wait
hit 1 more and wait
If I went higher than 30 off, she would drop .5 to 1 kt boat speed, which of course started to change everything else
So best I wanted or was willing to do was 30 ie 150 displayed, give or take a degree as it would never stay 150 150 150 150 150

She looks like this


G

[mastreb]

That's awesome! The autohelm must be key to this. The Mac is so wondery that just a second's glance off the prize and you're ten degrees off on the helm.

But no, Mike wasn't claiming better than 30 degrees.