Hansjolle
Have made some reasonable progress so far and would be interested in hearing from anyone else who has built one of these kits, especially concerning the ballast.
The kit contains a plastic keel, which I have replaced with one made from 3mm stainless steel, to add some weight low down. The hull shape allows for lead shot and resin to be added, as on the real boat. The kit also does suggest an added "clamp on" weight to the end of the keel, which I'm planning to do. I'll drill a small hole in the lower area of the keel and use a two piece weight that can be clamped around the keel, with a pin going through the hole, to ensure the weight can not drop off. This is most likely to be made from brass.
Its the relative weight of the keel and lead shot that needs to be considered. Current thinking, is to add the weight to the keel, do a float test, with batteries and RC equipment etc on board, and then add lead shot to bring the boat down to its water line and correct trim.
I have found a couple of "build blogs" on German sites, but they seem to follow the instructions and just add lead shot in the bottom of the hull.
Any other suggestions or experiences? - thanks