Tuesday, April 21, 2009

A New Bow for Thumper????

The weird weather has given me time to Photoshop a modification that I've been thinking about since the boat first landed in our driveway. I bought it specifically for Utah Lake where the average depth is under 10'. The swing keel is perfect for the water depth but the short waterline length and light weight will be a big disadvantage upwind when the wind cranks up. In a fresh breeze the chop turns into steep breaking rollers that are very difficult for a small boat to make headway against. Because of that, I've been obsessed with the idea of putting a new bow on Thumper (here's where boat design professionals should begin rolling their eyes). A Naval Architect would prabably say that a new bow would add wetted surface area without a means of compensating - since we can't change the keel shape.

I don't understand boat design on the level that would guarantee a specific result but, for the sake of what if, let's say that I'm going to wing it. It would take the process back to the days before Pierre Bouguer (no Jerry it's not pronounced booger) when boat building was an intuitive seat of the pants thing. I could template the hull, enter the info into my CAD system, and produce the geometry for fairing the new bow into the existing hull. I read about a construction technique where template plates were attached to an existing hull and low density foam was used to fill between them. This created a faired surface that could be fiberglassed over. I'm comfortable working with the materials but as far as the design goes - complex hydrodynamics and characteristic equations are over my head. In other words, there would be a lot of guessing and probably a little trial and error. Of course, I can always rebuild it or even restore it to it's original shape if I really screw it up.

This is the existing bow shape.
Bow option with a slight rake to the stem.
Bow option with a plumb stem.
Bow option with a tumblehome stem. This one could be even more radical and extend the water line by 3 or 4 feet.
The reality is that this will most likely remain a Photoshop modification only - but it's interesting to think about.


  1. Kevin, I will be glad to give you encouragement! I think you are definately talented enough to get the job done. It will be back in the water someday, I just know it!

  2. Thanks for tuning in Sis - and thanks for the encouragement.

  3. The bow shape boat looks good.