Post date: Sep 21, 2015 4:38:37 PM
In a study I recently found, a group of people decided to measure wakes for different types of boats. The majority of the boats that they tested were larger motorized boats, which are not necessarily found in Venice; however, their findings are quite applicable and interesting. They studied five different boats and measured the height (amplitude) of the wakes and how much energy each wake held.
The general consensus of most studies on wake production is that the higher speed a boat is traveling, the more wake is produced. This may be true, however the information this study found proves that even if there are more wake, the wake itself differs. Their findings show that each boat has a 'hump' speed where the wake energy and height is the greatest. The speed seems to occur from a span of 15-25 knots. The interesting part is that the each boat has a very different hump speed. So posting one speed limit for all boat types is actually quite inefficient, because it may work for one boat type, however that speed could create more wakes from another type.
What's even more interesting is that in their charts, they show that once the boat is past its hump speed, the wake energy/height drastically decreases. So in actuality, posting a lower speed limit for some boat types may actually be producing less wake, but the wakes themselves will be higher up on the canal wall, and create more damage due to their higher energy.
Another thing the study concluded was that wake energy/fuel efficiency had a direct correlation with vessel pitch and stern draft. Vessel pitch is the rocking up and down of a boat, so the more it rocks the more wake is produced. Stern draft is the distance between the waterline and the bottom of the hull(keel) including its thickness. The larger the distance, the larger the wake production.
This study will prove to be very useful in our research because even though it does not include Venetian boats, it gives us a basis of knowledge on wake production. We could potentially mimic their graphs and data with the boats that are used in Venice, in order to come up with direct information that would greatly increase the validity of our research. Also, we now have an idea of what to focus on in hull and boat design in order to produce less wake.
-Jacqueline