|
SITB
Prototype Installation
Paradise Cove Marina
Lake Travis, Texas
|
Submerged Inertia Tube Breakwater (SITB) As Manufactured
by Galleon Engineering, Inc. Much has been written on the arcane science of Wave Attenuators and Breakwaters and their
use in various applications. Generally speaking, most “studies” commissioned have been at the behest of a particular dock
manufacturer seeking to legitimize it’s particular design in application to a particular circumstance. In almost all cases,
the experts, performing the “study” are quick to divorce themselves from any real engineering liability but just as quick
to endorse a particular design or device, which just happens to belong to the concern paying for the “study”. This makes trying
to distinguish between fact and fiction very difficult indeed. To be sure, irrespective of motivation, these studies, do
indeed, have some validity primarily in compiling specific information about a specific location that otherwise, is not available.
In reviewing many such studies and their conclusions, we have found that, although the information provided is good to have,
the conclusions arrived at, without exception, are made in consideration of the use of conventional wave attenuators; those
being wave attenuators that attempt to “block” the waves progress with various types of vertical flat surfaces and which,
regardless of total ballast weight, are rendered positively buoyant by means of adding positively buoyant flotation to negatively
buoyant ballast and structures. Consequently, few if any, heretofore performed studies, have ever taken into consideration
a wave attenuating structure with properties exhibited by the proprietary, “Submerged Inertia Tube Breakwater” (SITB)(Patent
Pending) structures manufactured by Galleon Marine, Inc. which is comprised of approximately 80% neutrally buoyant ballast
contained in a round tubular structure offering an arced surface to the oncoming wave or wake. The SITB’s neutrally buoyant
ballast, having no effect on flotation requirements acts as an inertial mass not effected by the momentary fluctuations in
wave or wake uplift nor side impact or rolling motion caused by waves or wakes. Since flotation is only necessary for the
|
|
NO LOOSE BOLTS OR RESETTING OF ANCHORS - LOWEST MAINTENANCE
OF ANY BREAKWATER IN EXISTANCE
|
20% of the structure which is negatively buoyant, the reaction
of the structure to wave or wake action is confined to the reaction of this proportionately, very small, amount of flotation.
Consequently, when a wave or wake encounters the SITB, regardless of size, once the total amount of flotation, including reserve,
is overcome by the waves or wakes surface action, the SITB, by virtue of the Inertia of the confined water ballast, ceases
to react to the imposed loads. Below the surface the tubular ballast containment structure, containing 80% of the total weight,
1) remains fixed by means of inertial forces, 2) deprives the wave or wake of the ability to regenerate itself by interfering
with the elliptical, almost circular, internal wave action and 3) offers a radial surface to the horizontal forces of the
wave or wake, mitigating the affect of these forces. Other wave attenuators, which are 100% positively buoyant, continue
to react to the wave or wake action by bobbing up and down relentlessly. The loads resulting from this relentless bobbing
or the relentless effort of the massive amount of flotation to stay on top must be dissipated in some fashion. In the case
of structures connected in short lengths (less than 80 ft.) and able to move at these connections the vertical forces result
is a residual wave. In the case of structures connected in long spans (80 to 200 ft.) the vertical forces result in a bending
action, damage to the structure or loosening of bolts in lateral connections. (Hence the requirement of most manufacturers
to retighten bolts at regular intervals). Lateral forces which in the case of large cruiser wakes and frontal wave action
are absorbed first by the structure and then the anchorage system, these systems having no neutral ballast to counteract
the imposed forces. Vertical flat surfaces offered to the oncoming wave take the full blunt force of wind wave action and
wakes and offer no mitigating effects. Basically, any structure, regardless of design, anchored sufficiently will have some
wave attenuating effect. The question becomes, how much is enough. At what point does it become unfeasible to continue to
pile negatively buoyant ballast on top of positively buoyant flotation cells to attenuate or stop the waves. CASE IN POINT
PARADISE COVE MARINA, LAKE TRAVIS, TEXAS PROTOTYPE SUBMERGED INERTIA TUBE BREAKWATER In the summer of 2002, Paradise Cove
Marina was experiencing extreme problems with a wave wall type wave attenuator furnished by a leading manufacturer of floating
docks. Paradise Cove in conjunction with Galleon Marine installed a Submerged Inertia Tube Breakwater (SITB) in an effort
to test the attributes of the structure and provide protection for the harbor entrance at the marina. A 48 inch Polyethylene
tube provided the inertia tube and was attached to a structural box truss frame 12’ wide and 200’ in length. Under the assumption
that for this test, winches should be installed comparable to other manufacturers, a total of 18 winches were used, eight
on the rear of the structure and 10 on the side encountering the waves. The SITB was assembled and towed to the location
as designed to protect the harbor entrance. However, due to delays in setting anchors, only 5 of the eighteen winches were
ever attached; 3 on the front and 2 on the rear of the structure. The SITB performed flawlessly in this location and in fact
the other 13 winches have never been attached nor the anchors set. The marina manager claims that they are not needed due
to the stability of the unit. In the spring of 2003, the Phase II expansion of Paradise Cove took place, this time
with another major marina manufacturer. This included, due to cost considerations, a concrete breakwater in 50’ segments.
Paradise Cove continued to experience problems with structural failures on the original wave wall breakwater and problems
with it’s customers closest to the structure who were experiencing a continued hammering from waves and large boat wakes on
this high traffic part of the lake. So much so that some customers actually left because of the inability of the wave wall
unit to adequately protect the boat houses with which it was connected. In particular, the Northwest corner of the marina
was taking a severe beating. The wave wall manufacturer was prevailed upon to add an additional 10’ in width to the already
12’ wide wave wall structure making it a total of 22’ in width in an effort to cure the problem. This to no avail. The damage
continued. Out of frustration the marina manager towed the SITB from it’s location at the harbor entrance and placed it
in front of the wave wall structure at the Northwest corner of the marina. Again, only 5 winch lines were used even in this
extremely violent wake action area. The problems and damage ceased. Again, the SITB performed flawlessly even in this extreme
location. Due to permitting issues, Paradise Cove was required to move the SITB back to the harbor entrance and the severe
beating taken by the Northwest corner resumed. CONCLUSION In direct, same day, same condition observations on film we have
examined the performance of all three wave attenuators at Paradise Cove. It is this actual prototype installation in direct
comparison with two of the most popular wave attenuator types and continued success from the SITB which we derive most of
our conclusions made above. Paradise Cove continues to have structural problems with the wave wall wave attenuator and problems
with it’s customers due to the lack of performance of the wave wall in protecting their boats. The concrete wave attenuator
demonstrates large residual wakes and is impossible to walk on in heavy weather and when encountering moderate boat wakes.
The SITB, due to it’s neutrally buoyant ballast remains stable in the water, puts far less stress on anchoring systems, and
deprives waves or wakes of the ability to regenerate themselves as they roll forward. Less winches also means far less service
and maintenance. Less shock and movement also means less retightening of bolts. Paradise Cove, in over 18 months has not
been required to retighten any bolts on this structure. We at Galleon believe that the attributes of our proprietary “Submerged
Inertia Tube Breakwater” (Patent Pending) , give a better value, better service and better protection against waves and wakes
than the current common industry practice of continuing to pile on tons and tons of steel and concrete onto an equal amount
of flotation in an exercise in futility. Consequently, it is our considered opinion that wave studies conducted with regard
to previous wave attenuator technologies are irrelevant when considering SITB technology. Galleon, having taken this position,
fully expects to be attacked by experts offering these studies as well as the manufacturers of previous technologies. However,
we are a fully licensed engineering company with staff engineers, and we do assume full liability for our conclusions. Furthermore,
we say, “just go to Paradise Cove and see for yourself”.
|
