Larson Thunderhawk

By Mick Ignatiuk

Built in 1957, my 15′ Larson Thunderhawk Jr. is a fiberglass runabout reborn. I launched her into the waters of Grass Lake, in Fox Lake, Illinois in late August 2010. But before this happened, the boat underwent a major restoration. I purchased this boat in August of 2009, after it sat idle for several years, collecting dirt, rainwater, leaves and snow. All that remained was its shell,

I purchased this boat in August of 2009, after it sat idle for several years, collecting dirt, rainwater, leaves and snow. All that remained was its shell, motor, and a rusted trailer. I found a group of Larsen enthusiasts who helped me locate my boat’s original specs, drawings, and
color charts.

larsen thunderhawk

1957 Larsen Thunderhawk before restoration.

I began the project in September 2009 by separating the deck from the hull. I had easy access to remove the old interior finish, remove and replace the deck supports, and complete the fiberglass repairs. The hull has three watertight chambers. Two of them serve as seats. They were full of water due to broken fiberglass tabbing. The transom board was entirely rotted, as were two back stringers. I repaired all of this with WEST SYSTEM 105 Resin and 206 Slow Hardener, thickened with 404 High-Density and 407 Low-Density fillers, and biaxial glass.

The interior finish coat is silver gray Zolatone®, which is a durable, easily worked product.

Next, I needed to put the deck and hull together. I glued the joints with epoxy thickened with a blend of 404 and 407 fillers for strong but flexible bonds. Screws were placed every six inches. The joint at the transom and those on two feet either side of it are glassed with WEST SYSTEM 105/206 Epoxy and 4” biaxial tape.

I set my Larson Thunderhawk bottom-up on a custom made stand, removed the old finish, and repaired the cracks. Then I applied Awlgrip® #545 primer. Several weeks later I did the final sanding and sprayed on Awlgrip Eggshell White. During this same time, the rusty trailer was powder coated, received a wooden platform up front, new wheels and new lights.

After removing the old deck finish, I applied a coat of epoxy, then another coat thickened with 407 filler over the entire surface. This covered the small cracks and pinholes. I followed this with Awlgrip #545 primer. After the primer was cured and sanded, I sprayed on a topcoat of Awlgrip. As the finishing touch to the painting process, I added vivid red stripes.

All of the boat’s original hardware was re-chromed and a new acrylic windshield was fabricated. I spent a lot of time refinishing the steering wheel to make it look like new because it was impossible to find a replacement in better shape.

To complete the interior, I varnished the floorboards and the boards that cover the battery and fuel tank. The instruments, hardware and electrical system were installed next, followed by the steering system and wheel.

An important and long-awaited aspect of this Larson Thunderhawk restoration was the complete rebuild of the outboard motor, an Evinrude 35hp Lark, also known as the Big Twin. John Monahan from Little Falls, Minnesota did the work. His shop is full of old engines in various stages of restoration to original condition. Monahan is a great man doing excellent work.

The last major refurbishing project was the seats, and they posed a tough challenge.  The seat backs are curved, and the original backrests were missing. I ended up fabricating new parts, which took a long time. I also had new cushions made and installed. All that was left to do was apply decals and clean the boat, and finally, it was finished.

On August 29, 2010, I launched the boat. The engine started and I finally got to see what this little boat could do. Everything went great and we topped out at almost 30 mph.

My Larsen Thunderhawk is 53 years old, but after the restoration (top image) I think it looks better than it did when it was new. I feel like just got this boat from the manufacturer.