There are 3 issues to address with ballast:
1. Levelling the boat. We are currently back heavy therefore we will try to move the weight about.
2. Stabilizing the boat mediating roll. This is currently a big issue if we encounter waves from the side. Weight low down in keel.
3. Hull depth in the water. More weight everywhere.
Below is a cross section of our lifeboat. We got 10x50kg steel plates to add to our current foundation brick and concrete block ballast.
This is about 500kg we will be adding to the front and center of the boat as low down as we can.
The boat is specified to carry 61 people and supplies, likely more than 5000kg but the weight is evenly distributed throughout the boat.
With 2 people and our current ballast we likely have less than 1500kg in the boat. She is 80cm in the water and is designed to be 120cm in the water, so obviously more weight is needed for stability
The question we are asking is the distribution of the weight. Thinking of putting most of this weight in the front and center as this is where she is highest in the water. But we are worried about the structural strength of the single skin fiberglass on the keel to hold this much weight in a limited space.
The ballast has been a big sucess so far after testing with the wash of passing boats for a few weeks. The 500kg steel placed below the waterline has worked wonders for boat stability. She no longer bounces at all when hit by small waves from the side.
And she is now level (only 1degree up at the bow at cruising speed.
By eye she is 10cm ish deeper in the water. We still need to measure when we find a spot with clean water and a sunny day to go over the side with a tape measure 🙂
BUT she does shudder and we are worrying about the hull flexing if we hit big waves in our sea test. We are going to remove all the old concrete and bricks, maybe 300-400 kg which is now mostly above the waterline. Leave this in Lubeck harbour and take her out for a few days to sea in calm weather as there are a few nice sheltered bays 5-6 hours up the coast to anchor.
Then head back into town adjust the ballast and then batten it down so that it cannot move at all.