Al not a good idea. Adding weight to any vessel will increase fuel consumption.
I don't think your boat is quite a FD boat. And as I recall you said she had a 12' beam. But it's the shape .... not the measurements that makes the FD hull. Many sailboats that weigh 10,000lbs more than Willy have better fuel burn numbers. And I'd get more performance from Willy if I removed some or all the ballast. Actually I do plan to remove about 5% of her ballast ..... in the lazerette. Since I replaced lead where ther was concrete it must be heavier. Later on when it's real hot I'll be down there scoop'in it up and out. I'll sell you some at bridge price.
Eric, we agreed, I thought, that debating FD/SD was set aside in the need to agree to disagree. Having so stated,
With the 58 HP Perkins running 2400 RPM and obtaining near 7 knots, the fuel burn was 1.5 gallons per hour. With the 85 HP Perkins turning at 1400 RPM the fuel burn is 1.4 gallons per hour.
The ballast added was in place before the engine replacement. So I conclude that were I to add additional ballast, there is an allowable gap of before and after fuel burn to compensate. And most important, I could care less if the fuel burn increased a smidgen. Fuel burn is the least of my expense, if the ride improves. As it is, the boat is at a point of being all that is required for this owner's satisfaction.
Al-Ketchikan 27 Marben Pocket CRUISER