HARBOR SYSTEM MASTER PLAN - City and Borough of Sitka

SEALING COVE HARBOR BOAT LAUNCH RAMP
The boat launch ramp at Sealing Cove Harbor was designed by the State of Alaska, Department of
Transportation and Public Facilities in 1982 under the Sealing Cove Harbor construction.
The boat launch ramp is constructed from precast concrete ramp planks placed on rock fill at a -12% grade.
The ramp planks are 16 feet wide and extend from the top of the ramp at +16 ft elevation to where they
intersect the harbor basin at -2 ft elevation. The 220-ft long timber boarding float comprised of (11) 20-ft
long segmental units. The shoreward (3) modules are 6 foot wide timber framed units anchored in place by
piles external to the float. The seaward (8) float modules are of similar construction and condition, but are 8
feet wide and anchored in place by piles internal to the float.
Observations
Concrete Ramp Planks:
The concrete ramp planks are in fair condition. The surface of the individual planks has been worn to
exposed aggregate but the overall ramp surface is reasonably consistent and no significant potholes were
observed. Users of the ramp have stated that a hole at the toe of the ramp has been created as a result of
boats ‘power loading’ onto trailers. Power loading causes propeller wash to erode away sediment at the
bottom of the ramp and creates the potential for trailer tires to get stuck while attempting to launch at low
tidal elevations.
Boarding Float:
The structural timbers of the float appear to be in fair condition. The rubboard on the sides of the boarding
floats are detached in several areas which creates a docking hazard to boats. Many of the floatation billets
have damaged coatings and exposed polystyrene foam. Without coatings the foam becomes saturated and
reduces the freeboard capacity of the float. The concrete ramp planks do not extend beneath the boarding
floats and the boarding floats rest on a layer of gravel that has eroded to depths of 6” or more below the
ramp planks. The uneven ground causes torsion in the boarding floats and hinge assemblies when the float
grounds out. Along with the structural damage caused by the twisting and unevenness of the float, a safety
concern while walking across the float is also created. There is an approximate 3-in gap between float
modules which creates a potential trip hazard.
Piles:
The creosote treated timber piles appear to be structurally sound and in fair condition.
Upland Access and Parking:
The uplands consists of approximately .6 acres of asphalt surfaced area and provides parking for
approximately 50 vehicles. The upland parking facilities are generally in fair to good condition with an
estimated remaining safe and usable service life of approximately 10 years, provided interim patching and
crack sealing is soon accomplished.
Conclusions
Sitka Harbor System Master Plan
Condition Inventory
Overall the launch ramp is in fair condition but some of the components create potential safety hazards. The
gravel beneath the float should be regraded to level out the side to side list across the floats and the hole at
the bottom of the ramp should filled in with rock large enough to not be eroded by propeller wash. The
facility has an estimated remaining safe and usable service life of approximately 10 years.
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