This yacht was designed by Scarano Boat Builders, and is an 88’ long, plank on frame and fiberglass sheathed hull, 2-masted schooner used for sailing excursions. MarsKeel is very proud to say we had a part in making this yacht for the customer in collaboration with our long-time customer Scarano Boat Building.
The keel has a cast from ballast antimonial lead, a weight of 28,930 lbs. and was approximately 19’ long, 2” wide and 3’ tall. The keel had 11- 1.75” diameter 2205 duplex SS keel bolts, and custom machined 2205 duplex hex nuts.
The process begins with us receiving the keel geometry and bolt positions from Scarano design office. At this point, we move forward with the in-house design of the tooling and fixturing. The tooling includes designing the molding and making sure our in-house pattern shop has the drawings they need to make the pattern. The pattern maker adds all necessary allowances for possible shrinkage to the pattern so that the part finishes at the correct size. We also designed the fixturing bolt rack assembly.
The process starts with the pattern and mold. The mold half is shown below.
After the ceramic is poured into the prepared mold box that is around the pattern, it is allowed to cure. In this case, the mold was left for 3 days before opening it. The mold is opened, and the pattern is removed in the photo. Now it will be dried before casting can be done. It is dried to reduce the moisture content of the ceramic so that we don’t get steam explosions from trapped water getting turned into steam inside the ceramic this is both dangerous for the casters and causes mold degradation or void in the casting.
This Ceramicast mold is approximately 23’ long, and the entire mold weighed approximately 33,000 lbs. The mold is dried through a MarsKeel-invented method. This improves the casting density and the quality of the casting.
Once the mold is cured, it is assembled, and port and starboard sides are brought together. The in-house designed and CNC cut parts are welded together and reinforced. The bolts are inserted, and the under-lead armature is completed. Then the complete rack and bolt cage is set in place in the mold. This more complicated bolt rack design was needed because the keel bolts are so tall above the top of lead, and the bolts are only threaded on the top. We needed to hold them both for height and position. There was also additional re-enforcing below lead, holding the bolts both in the casting and in the correct position from bolt to bolt. A CNC cut SS continuous spacer holds the bolt bottoms, as well as sections of the bolt material are welded between the bolts to help resist the shrinkage pressure from the lead as it cools.
Special care was taken to ensure that we did all we could to keep the keel bolts in the designed location. This project was a little more complicated because of the 5’ tall keel bolts, threaded at the top portion only. This just made securing the bolts more complicated while still offering the casters room to pour the keel. Balancing strength with access is essential.
The bolt rack is sitting upside down, as it is easier to store.
The bolt rack is set and secured to the mold by the head caster, and the lead pouring is being done by 3 men under the close supervision of the casting foreman, shown in the photo below. It was a long slow pour to minimize the leads pull on the keel bolts as it solidified, as well as reduce overall shrinkage and maximize density and weight.
The finishing of the keel was stopped approx. 12” from the top of lead to allow Scarano to faire and glass the keel onto the required keel fin. You can also see the 2-custom designed, engineered, and manufactured lifting brackets on the keel. These were used by us for removing the keel from the mold as well as moving it into the finishing room, and then finally placing the keel in the delivery cradle. They are included in the keel to allow Scarano Boat Building to offload the keel from the truck safely.
The image below shows the keel loaded in the drop deck flatbed. The keel is now sitting in a MarsKeel custom-designed and fabricated delivery cradle, you can see the steel cross bracing holding the top of lead and a pair of keel bolts. A double layer of stabilizing braces on the tall keel bolts was added after cradling to help stabilize the bolts during transportation. The bewing is secured by bolted-on cross braces. The custom-engineered and manufactured lifting brackets are also left on the keel so Scarano can lift the keel off once it is delivered. The keel was successfully delivered by our chosen carrier, Logistics Decsions Inc.
The final keel resulted in another successful project completed by MarsKeel alongside Scarano Boat Building Inc.
MarsKeel Technology is North America’s largest keel manufacturer, supplying keels to the top production yacht builders and offering repair and modification services for over 40 years.
Contact us today for your keel production, repair, and modification needs.