Please teach me something

[bigeasy1]

Originally Posted by Terry England

Yes Jon. Sailfish, Helms, Seawolf, Sarasota Skiffs and 17 others have copied Carl's Moesly's patented VDH design once the patents ran out. If you were a boat builder, why would you copy a "Euro-Design, Micro-wave Melted Cheese" Bayliner?

"Microwave melted cheese" ha ha I love that line.I think a lot of these new boats look like a big bleach bottle, or kind of like the old American motors Pacers built then put in a big furnace to make the melt into a blob with wheels.

[Bushwacker]

Welcome aboard Scott and keep asking questions! Lots of wisdom on this site!

The key to the the SeaCraft's soft ride is that it traps air as the water comes off the vertical steps. The way Carl Moesly explained it to me is that if you lay a straightedge on any panel at any point along any Moesly-designed hull (21, 19 Bowrider, 20, 25 Seafari, 27 Seamaster) and extend it outboard to the next panel, you'll notice that it just touches the outer edge of the next panel. The straightedge represents the path of the water as it comes off the inner panel, and the triangular space between the straightedge and the adjacent panel represents trapped air. This trapped air not only cushions the ride, it also reduces friction between the water and hull. Tests done at Mercury's Lake X back in the 60's showed that the SeaCraft Variable Deadrise hull (VDH) was 10% faster than constant deadrise hulls of the same weight and horsepower! This was proven repeatedly by SeaCrafts nearly total domination of the outboard powered classes in the Offshore Power Boat Races in the 1960's! You can learn more about the early SeaCraft history from the Moesly SeaCraft web site. If you read the patent description on that site, you'll find more information on how the VDH design works.

I spent a lot of time under the hull of my boat when I painted the bottom a few years ago, and I discovered a couple more subtle details that Moesly incorporated into the 20' hull which demonstrate his brilliance as a designer and his understanding of hydrodynamics:
1. If you look aft along the chine from the bow, you'll notice that there is a slight wedge built into the outer panel which would act like a trim tab to increase lift and help the boat get on plane easier! (All the Moesly designs I've seen will plane at about 12 mph with original power! I doubt a Regulator will do that!)
2. If you lay a long straightedge along the keel, you'll notice that there is a bit of rocker built into the innermost panel. As speed increases, a deep-V hull will develop more lift and rise higher out of the water. Once you get up to about 40-45 mph, the chine and entire outer panel are out of the water, so the trim tab effect of that wedge is gone, but the rocker in the inner panel will allow the bow to rise and reduce wetted surface and drag for more speed! If you look at the running angle plot in the Boating Magazine test of the Seafari 20 in the Literature section, you'll see that running angle does in fact increase at maximum speed!

It looks like some flat strakes and spray deflecting features have been added on the Sailfish and Potter designs (the 23 & 18), so they may ride a bit drier, but those features also increase lift and will tend to hurt ride a bit.

[McGillicuddy]

Seems a few guys here on csc are familiar with the owner/ founder of Sailfish, who clearly and unashamedly acknowledged the Moesly hull. They claimed and patented a very clever design. Nowhere does Sailfish claim the the inventive genius of Variable dead -rise.

I think Thresher Boats may be doing something with the SC 20 hull down here in Newport beach. Haven't talked to anyone or seen a good pic of hull yet...