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Build Your Dream Boat #25

On September 14, 2010, in Build Your Dream Boat Series, News From Gayle, by Gayle Brantuk
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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.

Related Images:

Your Thoughts?


8 Responses to Build Your Dream Boat #25

  1. PaulBrinkman says:

    Great article and outstanding designs.
    Thanks, Paul

  2. Richard Downer says:

    Your articles are always very informative. They address questions i did not know i had. Boating safety is some times not considered when choosing a design.

  3. John Wilder says:

    Hey Allen
    Skiing works best at about 20 mph well below the speed limit that Gayle is talking about.

  4. Allen Peterson says:

    This is great information because these are the very boats I have been considering. I am looking for a cruiser that I can also pull a tube or skier. However, I don’t know boats well enough to know what speed range I need for skiing. Can you point me in the right direction for a good all-round boat? Thank you.

  5. Ndukwe says:

    Thanks dear,i realy appreciate all the lessons so far. The bow design is realy important for a faster boat. Is this also aplicable to a catamaran? Also planning boats always have its bow raised out of water when speeding.

  6. Richard B says:

    Great topic. I love discussions of boat design and always thankful to hear designers share their opinions and experience on the finer points of boat design.

    Thank you, Mr. Witt.

    Rick

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