Build Your Dream Boat #25

Posted by Gayle Brantuk on Sep 14th 2010

I had a conversation with my father the other day about mahogany runabouts and what determines which hulls have more speed potential. Sounds like something you all would be interested in…
 
I remember back when we were working on the Riviera and one of the ideas for this design was to have a boat that would be faster than the classics it was styled after.
 
One feature that can limit hull speed due to safety reasons, is the bow rake. The bow rake is the amount of angle at the bow as shown on the profile drawing. Here are a couple of examples:  
Riviera bowBarrelback Bow
 
 
 
 
 
 
 
The Riviera is at the left, the Barrelback at the right. You can see the obvious difference in the shape of the bow.
 
On designs with a deep forefoot like the Barrelback above, this hook can cause the boat to "submarine" at higher speeds. Yes, that means just what it says--the bow can submerge and boats have been known to flip, particularly when crossing a wake. Back when this type of design was popular, motors weren't as powerful as today. Keep that in mind--your safety is very important to us. Boats like the Riviera, Monaco and Tahoe are best to about 50 mph, while designs similar to the Barrelback, Biscayne & Key Largo, we recommend running in the 30 mph range. There are always exceptions and we realize that many of you are going much faster than that--we tend to be conservative. I can already hear some of you thinking, "so, can I change the rake of the bow?" The answer is no, we wouldn't recommend it. Altering much more than the length or cabin/cockpit arrangement on a design is not recommended. We have a very good detailed explanation of the how, why and why-not of changing a set of plans.
 
Glen-L Word of the Week:
BULBOUS FOREFOOT
 
A convex entry at the keel/stem junction (as opposed to a sharp vee) incorporated to soften the ride. When used in conjunction with a reverse curve at the chine, it usually makes sheet materials impractical requiring other planking methods in the forward section.