NA in Portland OR area?

OK, I get it now. I remember those steam locomotives from my childhood.

I agree that the I-beam should be the mounting platform. I still would like to avoid to attach anything to the hull directly, but that could be a bit difficult.
Look at this photo:

 

It started as a sailboat hull, doesn't it have ANY BALLAST?
Gizmos like fins, bilge keels etc., can reduce rolling underway or at anchor, but they do nothing to add stability.
Stability only comes from ballast, (and/or hull form.).

 

It does. About 5-6000 lbs.
See more info here:
Rolly custom steel motorboat https://www.boatdesign.net/threads/rolly-custom-steel-motorboat.69323/page-5#post-974775

 

5 to 6K ballast? That's a joke on something that size even if it would have been left as a sailboat.
My own little 35' sailboat has a bit over 6K.
Someone took a sailboat hull that already had insufficient ballast then added huge weight up high, then added a sponson to add flotation.
It was just adding up mistakes hoping to arrive at the right answer.
I'm bowing out of this, I've seen enough.

 

@rangebowdrie , don't give up! The subject is very difficult, but now more than ever we need experienced people like you.

 

Don't leave. Every opinion counts.
A NA was involved in the modifications. Only the beginning was done by ' beginners '. It was certainly not easy for the NA to suggest the best corrections, but owners decide what goes where.
I think your point is correct. There should have been more ballast. Someone gave me a rough estimate of 7-8 tons additional might be needed. Hopefully less.
I still have hopes.

 

I think most of the ballast comes from these keel tanks. One on each side 2 x 245 gallons. They are full with water right now.

See photo.

 

Water tanks for ballast work well in submarines and freighters.
Not so well in small volumes.
Fresh water = ~62 lbs. per cu ft.
Typical 3K psi concrete mix = ~150 lbs. per cu ft., (19 lbs. cement, 58 lbs. sand, 59 lbs. 3/4" stone, 14 lbs. water).
Lead = 708 lbs. per cu ft.
You can't get enough water low enough to do much good, you need "Real" weight.

 

That explains, why it is still tender.
More ballast is needed, I think we can agree on that. The question is; how much and where to put it?

 

Fill those keel tanks with lead shot and add ~26 000 pounds.
Subtract the water you'll displace in the tanks ( ~4000 pounds )
and you'll have added 22 000 pounds to your keel.

And no, I'm not a lead shot salesman.

 

Quite an amount. The total weight of my boat, based on the survey, is 67000 lbs. 1/3 extra weight will bring down the waterline significantly.
The lead in my area is 2-3 dollar/lbs. A $44000-$66000 sum for ballast is not really for my budget.
Thanks anyway.

 

@LeoKa, a sailboat can carry a ballast that represents a third of its weight. It depends, of course, on other variables, but it should give you an idea.
Lead is very expensive, but there are other materials, of lower density but much cheaper and more malleable, that can also serve as ballast (Water weighs very little and is only justified if variable ballast is needed). But until you know the amount of ballast needed and the position of its CoG, as you rightly point out, there's no point in discussing what and how to place it.

 

I see, so there is hope.
I am working on the details. I will know more after my haul-out in August.
Thank you.

 

With the boat hauled out and fairly level you should be able to ascertain the "real" waterline where the boat actually floats pretty well.
Go around the waterline, (you only need to do one side,) and put pieces of tape, (or marks,) down the hull, pick a distance that'll give you 10>12 intervals that'll easily work for the scale you're using.
Then at each mark drop a plumb bob down to the ground and measure the distance between it and the centerline of the keel.
Record each measurement. Get a sheet of cardboard or thin plywood and make a scale drawing, plotting those measurements.
Use a scale that'll give you something to work with that's reasonable, producing a shape perhaps 2>3' long.
Draw a fair curve thru the marks and cut that shape out, you'll have a fair representation of 1/2 of the hull at the waterline.
Balancing that scale representation over a straight edge will give you the existing CG, and that's where the CG of the additional ballast needs to be, (assuming the boat is not now floating way out of kilter).
Calculating the scale area of that curved shape and doubling it will give you the waterplane area.
Now you'll be in the ballpark, (careful work will put you in the infield,) of knowing how much weight it'll take to sink the hull down 1", (the flare of the hull will increase the weight needed for each additional inch, but in your more-or-less slab sided hull it won't be a great deal).
(Recommended,) If you want to be more precise you'll need to make your measurement down the keel at equal intervals instead of on the hull, but you'll need to ensure that the plumb bob is hung at 90 degrees from the centerline at each mark.
If you make a giant wooden "framing square" things will go smoother.

 

The CoG of the waterline is very, very interesting, but I'm afraid that with that, you won't be able to determine the boat's CoG or the center of buoyancy, which is what you need to know. Not to mention the total weight of the boat, which, I'm afraid, you'll need to know. If you also wanted to check any stability-related points, I'm also afraid you'll need to draw many more curves. Well, that's just an opinion. Oh yes, I almost forgot, the best way to determine waterline, if that were necessary at all, would be to mark it while the boat is afloat, don't you think?