This report is published to provide coastal engineers recent field experience with the design and construction of floating breakwaters on the west coast of the United States. A similar report will be published on field experience with floating breakwaters on the east coast; both reports should provide practical guidance for coastal engineers. The work was carried out under the U.S. Army Coastal Engineering Research Centers (CERC) Design of Floating Breakwaters work unit, Coastal Structure Evaluation and Design Prugram, Coastal Engineering Area of Civil Works Research and Development. MTe report was prepared by Professor Eugene P. Richey, Department of Civil Engineering, University of Washington, Seattle, Washington, under contra:t with the U.S. Army Engineer District, Seattle. J W. Heavner, Graduate Stadent, Department of Civil Engineering, University of Washington, assisted with field surveys and data collection
2 MR 82-5 Floating Bieakwater Field Experience, West Coast by Eugene P Richey MISCELLANEOUS REPORT NO 82-5 JULY 1982 COIaFS 0~'r _Ap'pr~o~ved_ fo-r -public -release; ~VI 98 distribution unlimited Prepared for U.S ARMY, CORPS OF ENGINEERS COASTAL ENGINEERING RESEARCH CENTER > C> C ) Kingman Building Fort Stlvoir, Va 22060 LA.~ JA ,,7 Reprint or republication of any of this material shall give appropriate credit to the U.S Army Coastal Engineering Research Center Limited free distribution within the United States of single copies of this publication has been made by this Center Additionai copies are available from: :.ationaZ Technical I,.ornmation Service 4:TTN: Operations Diviaior 5285 Foy't RoyaZ Reoc.d 17p Fp ngqfield, Vir•gi•nia 22162 Contents of Litis rt.port are not to be used for advertising, publicat ot!, or prumotional purposý.s Citatioli uf trade names does trot constitute ar:uEficial "endorsemtent or approva of the use of isuch commercial products The fittdings in thit report ire nut to be construed as an ofticial epartmen of the Army poiition unles6 so destat4d by other authorized documunts LIJCLASS IFIE1V SECURITY CLASSIPICATION OFFTHIS PAGE (0lo00 Doea fftn~rnoE) REPORT DOCUMENTATINPG REPORT7 NUMBE; fll' ION PAGEREAD INSTRUCTIONS BEFORE COMPLETING FORM 12 1OVY ACCESSION 1,10 82- IP1 jT'S CATALOG NUMBER 04 ~ !I TYPE OF REPORT PERIO0) COVERED ITLEit (j FLOATING BREAKWATER FIELD EXPERIENCE, Miscellaneous Report WEST COAST * AUTHOR(s) 11 PERFORMIN 4RACT ORG, RE PORT NUMBERt OR GRAiNTHMUER~O) Eiugene P1.rzeichy PERPONM#NG ORGANIZATION NAME AND AOORESS *S 10 o Etitcarvi;AREA Citl Depatmet Unive rs ity of Wa~shtington Seareic',, Washiington it 1)31671) CONTROLLING OFFICE NAME ANtO ADDRESS Departnene of the Army iEhgir'eering Researchi Center (CERPE-CS) Kingman fluildiny,, Fort Belvoir, Virginia 22960) -'Coastal tem CoatUa IS N-loSSYiNG AGENCY NAME a AOONE5Sit dIove mnI 3oW.) I2 REPORT DATE 1) NUMBER OF PAGES July 1982 64 IS SECURITY CLASS (at the I I5 * PROGRAM ELEMENT PROJECT TASK A *JRK UNiT NUMBERS anon) OEKCLASSIPI-cA-TION/o-wdtAIr SCHEDOULE to DISTRIBUTION STATEMENT (at Wei 8.flJ) Approved for public release, distribution unlit-ite'i 17 GIST RSBUTION STATEMENT (at tIA." ebaatefle 10 SUPLECMVOTARY NOTES 194 wEv noi (Coaslas an ey** Fhdld ada 14t0sy Or b49 si$ It ea*o" #e evaluation pertormAnee Ouhemuf) - Floating breakwaters to lacqhtag ftied tnkftosntýf ea the eaaotruettcnt tad aubeoqueai Ihtt COP0at Partially a&iuooons this dettetaacy by evaluattng AI eutettat floattng breakwaersa loc~a tedI the ratctle Mrtheioes The breakiatotao Coas~tat ct flee cCoutset eatioqo unit*, throO £AAkaa&-eoeanraa 09 lodder-tyieo breakatese eonotrgcto at pctea cd connte a11gnsto, a"e Comatrugtsd at surplus Oll ?trholl" aecttcat Sea (ke4jear floatitn-tlre W4419e bffaakwateg OWsad#e with catte ecaalatstg ot teats row ot plaone petaloes The repor4tlacluites a dorptc at ach ait and breske'uo attvLeturo a diocumulco at the beoakwaser'a paatowaace based c& stotelepnctteas awl dleeotusaoji with osAlrs, "Aettae epovetov*ate., &ada set at eeselusatc toe tho oenroll snaleatloa, of eta etuettaeo kitatotf lwjittoatugo an flcaitma breakwotora peftatoaatofa * to 640 WO.It 4hftrns Am LtOgof) DOD Pjg oft these structure* 9MO EWIOO hOMOUT LUCLASSIFIEP Sccumrv CLAWPSCAIIO*l OP T*01 i'AGE (9bo Dee Iaead) PREFACE This report is published to provide coastal engineers recent field experience with the design and construction of floating breakwaters on the west coast of the United States A similar report will be published on field experience with floating breakwaters on the east coast; both reports should provide practical guidance for coastal engineers The work was carried out under the U.S Army Coastal Engineering Research Center's (CERC) Design of Floating Breakwaters work unit, Coastal Structure Evaluation and Design Prugram, Coastal Engineering Area of Civil Works Research and Development MTe report was prepared by Professor Eugene P Engineering, University of Washington, Seattle, with the U.S Army Engineer District, Seattle dent, Department of Civil Engineering, University field surveys and data collection Richey, Department of Civil Washingt'on, under contra:t J W Heavner, Graduate Staof Washington, assisted with W.N Seelig was the CERC monitor for this effort, under the general supervision of Dr R.M Sorensen, Chief, Coastal Processes and Structures Branch, and Mr R.P Savage, Chief, Research Division Technical Director of CERC was Dr tion of the report Robert W .4halin, P.E., upon publica- Comments on this publication are invited Approved for pabltcation in accordance with Public Law 166, 79th Congress, &ýQproved 31 July 1945, as supplemented by Public Law 172, 68th Congress, approved Novembcr 1963 Colonel, Corps of er i Comiaa'der and Direc~dr 3~ roll• • 19i 1 !-4 i _ CONTENTS Page CONVERSION FACTORS, II FLOATING BREAKWATER SITES 12 KS'tckan,Alaska, U.S CUSTOMARY TO METRIC (SI) , * 15 ec00* Tenakee Springs, A Auke Bay, Alaska 23 29 Friday Harbor, Washington (Port of Friday Hataor) Friday Harbor, Washington (University of Washington 10 11 III * g Oceanographic Laboratory) * , Blaine, Washington g Langley, Washingt7on o Everett , Washington OO.* o o Port Orchard, Washington e o.e , Camas-Washougal, Washington SUMMARY AND CONCLUSIONS 33 39 42 50 53 56 60 TABLE Winds at Japonski Airport, 20 Sitka, Alaska FIGURES Ketchikan, * Alaska Photos of floating breakwater, Ketchikan, Alaska Typical breakwater Layout for Ketchikan floating breakwater e o.oeo .,o .o 13 Photos of gaps at both north and south of harbor, Ketchi•:an, 16 Sitka Sitka, Photos of facilities at Thomsen Harbor, Sitka, Alaska Photos of module connections, Thomsen Harbor.e e .o module Lwreakwater, Alaska , o c Tenakee Springs, 11 Floating breakwater layout, 12 Photos of floating breakwater, Tenakee Springs, 13 Replacement module connector for floating breakwater Tenakee Springs, 14 Tenakee Springs, Alaska 18 , 19 c e .0 •• 22 00 •*, 24 26 27 Alaska e, 12 17 Alaska.e e g 28 Alaska oo , 30 • • Photos of deterioration and patching, Tenakee Springs, c Alaska 10 Alaska ., , , 10 Ce 000 i -o °,,,,,,,., , r CONTENTS FIGURES-Continued Page 31 15 Auke Bay, Alaska 16 Photos of floating breakwater sections, 17 Friday Harbor, 18 Windspeed-duration curves, 19 Cross section of Port of Friday Harbor breakwater ., 36 20 Layout of Port of Friday Harbor breakwater 37 21 Photos of the Port of Friday Harbor floating breakwater 38 22 Photos of University of Washington Oceanographic Laboratory, Y'r day aro 41 23 Semriahmoo Spit Marina, Blaine, Washington 24 Module connection, 25 Semiahmoo Spit Marina anchor detail 45 26 Photos of the module detail of the Semiahmoo breakwater 46 27 Floating tire breakwater, 48 28 Windspeed-duration curves, Puget Sound 49 29 Photo of floating tire breakwater, 50 30 Port of Everett, Washington, iloating breakwater site , 31 Photos of the floating breakwater at the Port of Everett 32 Port Orchard floating breakwater site 54 33 Floating breakwater and marina, Port Orchard, Washington 55 34 Schematic drawing of module connection, Port Orchard floating breakwater , ° $55 * * Washington Auke Bay, Alaska , 34 Friday Harbor, Washington Semiahmoo Spit floating breakwater 32 35 43 ,6 Langley, Washington Langley, Washington ., 44 51 35 Photos of anchor chains ut the Port Orchard floating breakwater , 57 36 Camas-Washougal floating breakwater5 58 37 Photos of the Port of Cams-Washougal floating breakwater , 59 38 Photos of the main section of the Port of Camas-Washougal floating b -•= i_ , 4d.4j -' • * • •*" '.'t • s.W• * * 0'.', D ' CONVERSION FACTORS, U.S CUSTOMARY TO METRIC (SI) UNITS OF MEASUREMENT U.S customary units of measurement used in this report can bo converted to metric (SI) units as follows: Multiply inches by To obtain 25.4 2.54 6.452 1.39 millimeters centimeters square centimeters cubic centimeters square feet cubic feet 30.48 0.3048 0.0929 0.0283 centimeters meters square meters cubic meters yards square yards cubic yards 0.9144 0.836 0.7646 meters square meters cubic meters miles 1.6093 kilometers square inches cubic inches feet square miles 259.0 hectares knots 1.852 kilometers per hour acres 0.4047 hectares foot-pounds 1.3558 newton meters millibars 1.0197 x 10- kilograms per square centimeter ounces 28.35 pounds 453.6 0.4536 grams grams kilograms ton, long 1.0160 metric tons ton, short 0.9072 metric tons degrees (angle) 0.01745 radians Celsius dearees or Kelvins1 5/9 Fahreheit degrees ITo obtain Celetus (C) temperiture readings from Fahrenheit (F) readings, use formWla: C - (5/9) (F -32) To obtain Kelvin (K) readings, use formula: - .- - K , (519) (F -32) + 273.15 FLOATING BREiAKWATER FIELD EXPERIENCE, WEST COAST by Eugene P Riohey I INTRODUCTION The increased demand by the boating public and industry for more moorage facilities challenges the planners and designers of small-craft harbors to explore all alternatives in developing harbors that have adequate protection from wind waves and boat wakes Most of the naturaC harbors developed near population centers, where boating demands are greatest, are ov'vcrcowded Floating breakwaters have become an alternative with an active potential in future harbor-marina design The floating breakwater has been adopted at a number of sites where water depth or other constraints render a fixed structure too costly, and is proposed for countless others Although there are other uses for floating breakwaters, such as in waterfront construction and operation, log rafting in the timber harvesting industry, beach erosion control, etc., the most prominent applications relate to the small-craft harbor or marina On location, the floating breakwater is subject to random wave loadings which can induce motions with components in all directions The intended job of the breakwater is to reduce the incident wave system to an acceptable level The transmission characteristics of this reduction capability are very sensitive to the period (or length) of the incide:.t wave field Numerous reports on model tests of transmission characteristics are available, but reports on actual field experiences with floating breakwaters are few Although several floating breakwaters have been in use for as long as years, there has been little information excharged as to the type of breakwater, the anchorages, and the connections between units These are considered major points of interest in improving the design of floating break- waters To cover these points, the following questions were established as a checklist for eialuating field experience with construction and subeequent performatce of floating breakwaters: (1) What were breakwater chosen? the site conditions and why wac the fioating (2) Now was it deployed? (3) Were there any unusual installatton problems? (4) What anchoring and connector systems were used? * (5) lems! (6) have there been any fouling, corrosion, or fatigoaig probWhat maintenance has been carried out? (7) Have any environmental stability) been encountered? problems (shoreline changes, icing, (8) tion? Does the structure serve functions other than wave attenua- (9) What, changes in any step from design to operition would be done differently now? (10) Has the structure served its intended purpose? This report picovides an evaluation of 11 floating breakwater installaLions located in the Pacific Northwest the thrust of the evaluation being the quesThe results of each site evaluation are ,resented, and tions listed above a list of conclusions summarizes the overall field performance of floating breakwaters II FLOATING BREAKW.iTER SITES ,t Ketchikan, Alaska The Bac Point Harbor breakwater is located on the north a Location side of Tongass Narrows, a fjordlike waterway, at Ketchikan, Alaska (Figs There are 390 moorage spaces planned for both pleasure and fishing and 2) Most of the boating activity occurs in the period 15 June to I Novemcraft ber, which spans the seasons for tourism, pleasure craft) and fishing b Site Conditions The fetch toward the southeast is about miles, about a half-mile across the waterway and practically unlimited toward the Structures along the shoreline shield the breakwater along the northwest southeast-northwest line The wind waves travel neirly parallel to the breakwater, and sustained wiridspeeds of 45 to 50 miles per hour with gusts to 70 miles per 1our are to be expected most winters Tide data are as follows: •ighest (estimated): Mean higher high water (MMUW): 19.5 feet 15.4 feet Mean: 3.0 feet "Mean lower low water (MLLW): 0.0 fot Lowest (estimated): -5.0 feet ~iatuum Tidal currents are frea south to qortli on both flood and ebb, with ceanic and Umospheric about knota according to harbormaster; National Administration (NOAA) tidl current data report only 1.2 knots vations are as follows: !8 Along tater row of uchor4 -20 to -60 feet Alotg breakwater: -50 to -70 feet A o- orteor ei', isf 'vtchoras: -100 to -110 feet Bottom ele- 0,1 •f, , ' *14 - 2/ , \ !'\ "41 Ii, o2'' 2." 'POW , ,, ioo 22 Bar Harvbor Flooling Breokwoter P ~ 24 'It * S•Mar KET CH MIAN v~ I?~~ 1" I',,14 19 L .I" 1$ ' t'{ - • 60 \At t'tclk t Alta(r -X il 73) Lx, S, 11 A9 44 , , ' dP'Floa ,tin Brawae 14: : IX 'F' ~ /If / Poo I : jM,4 ~ Is V~' ~ 1*1 _ IOWN ~face %t / IL ~ bla Fi~gro i.ý ~ f 4*hftet", ~o~ttt-brozkw~tcr itt a.Pile bent floating breakwater Yt"Lurc )1 Iuit-ot Phtotm of d ofEeot tto.utlg brVaI04Le~r at OW Pr The breakwater was installed in 1979 at a coet of $273 per foot Vhe breakwater is anchored by pile bents, as itll:strated in Figure 31 Thooe "responsible for the breakwater design, construction, rand operation dre as follows: Omer-Operator: Port of EvervLt "Everett, WasitngtLon Designer; Retd, Hiddleton and Asvoci;Ates Edmonds, uashington Breakwater Desigiur-Fabrtcator;: elllingham Niri.ne tndostriev Hellinghama, Lhingtuon (2) Performance The breakwater has perform~ed favorably T'e boat channeI is easy to keep uwder survwillance, so boat sp,,ds are ld, tin c4eck 10 Port Orchard, Washixton a iocatton Port Bremerton, WaUhington Orchard (Fig 32) lieu across SticlAir Inlet from b Site Conditions lhe prevailing wttds in the ar,.,A are from the sootth so the harb site is well shielded from that direct:or Tte naI opoiwure5 are to the southwest and the northeast with fetches 1.5 and 'iuuttc•al Mtites, respectively Tht wiadspeed-duration curves in Figure 28 are the beat a-.-ilable dati - Tide data are as follows: ,: Highaest (estimated); 14.7 fetutKL MawI: IL.7 i~et 6.8 toeet -La et: (otW.d: MLLW: T1it c:treronts axe less thaat c 0.0 toot kwt teNrtptton ireakter (1) 4S toot lstga as t k utAllattoit ~nr~ ~ ad Tho 11 bkte L41 long And cawpoe4 of t rtt,•b eet oreed eofteto Styrooia cve utt5 I 4ky 12 toot and 21 oclaug, vith Thre* O Lh5~ ghteh te w the tour 1IoACteCtor5 ctiortsreqetla ""ra.ogttut p one ~h i two -E I'sw~ toot eoAt uver golid 1e~tit oi 1.d toet r to forif 04-too't Lsidtdei ith the o stt wetitally U4011.t •4(0 joftt The t OWCtit-W tto412)l• wvait4 ei by by 42 toec 4"4 ,,l ut u ifti W Uut 14i TheW L-iihiped tit0fi n ti •iitae 1; oC aidttat o4 ti 3, 39 41 • '*.2 40 44 43 39 ,a, 39 40 Al _34 27 A\34 ,Breowter 34 34 W ,.,3 39 i e 31 I0 28 S "* O" S31 24 , S ' " UAW ~ •d • ,,.,:: :':'' '.: C '- - 77 "Fgue3 rotti :C •.• •:"~ • dS $s " 34A.3 _C S "3 20 • 31 3 Flooling 30 • L"34 • 44; -4 S36 - A 39 ,43 32 3583 -MIAý11ht l NAIIII(*Al Mill.1 °090 loo, mJl •°• •,•(:01116-f-[ 3 37 At384 38 37 36 43 43 39 44 *1 MARKER 4! 0.1 '40 39 46 42 34 •,41 S"42 43 439434 412 42, 40 3, 1ir'.e 42 > - o|;Ortir , br'kvaer_ - ,r , Y - - (rd oNSdar - Se) ' " ff" _'q Figure 33 Floating breakwater and marina, Port Orchard, Washington Bolt * IN 4•IE Connector BREAKWATER ///~MODULE/ " Rubber Donut Figure 34 Schematic drawing of module connection, Port Orchard floating breakwater 55 The L-shaped section is anchored by a composite 24-inch anchor line of 3/8-inch welded alloy chain, braided nylon line and a lower length of chain fastened to stake piles The chains cross beneath the breakwater to provide as much clearance as possible close to the breakwater The west section is restrained by pile bents A deep, soft muck is the typical foundation material at the site Those responsible are as follows: for the breakwater design, Owner/Operator: Washington Designer: Reid, Middleton and Associates Edmonds, Washington Fabricator: Bellingham Marine Industries Bellingham, Washington (2) Performance tion with the breakwater tion, with the exception and operation Port of Bremnerton Bremerton, storms with construction, The management and boat owners expressed satisfacStorm damage has been handled well since installaof the western seL ion which has been hit by two reported significant wave heights of feet well in excess of design values When the waves incident to the west breakwater exceed heights of about feet, there is a greater transmission than desired, but this is not a severe problem The north breakwater has performed very well One connection failure was probably due to a faulty fabrication detail; it waa successfully repaired All the anchor chains have corroded badly and are being replaced The original ones were made of 3/8-inch chain, with no cathodic protection; the replacements are of 1/2-inch chain, with zinc anode sacrificial bLocks by by 30 inches with two placed on each anchor line The cost of the anchor line repair is estimated at $30,000 Figure 35 illustrates the piling and chain connections Some of the anchor piles have been attacked by marine borers Replaceto be out of reach of these borers only a small area of concrete spalling in the center of two pontoons "ments will be cut off below the mudline, There is d Discussion The west breakwater was apparently underdesigned for the wave climate that develops from the west Other design aspects have worked out well, except for the anchor chains The new design with both a heavier chain and cathodic protection should ensure a much longer life than the yaars for the initial system Boat wake from the larger vessels passes through the breakwater, but users appear to have adapted to this inconvenience 11 Camas-Washougal,•Waihington a Location The breakwater at Port of Camas-Washougal, about 20 miles east of Vancouver, Washington (Figs 36 and 37), parallels the north shore of the Chlumbia River, and serves to protect a marina catering ItArgely to pleas- ure craft 56 a Weakened anchor pile of,, b Corroded anchor chaini with nylon anchor 1itie ~tgu~ 3~ PhIpolace-l t'o an' elainet Oretad floatW6 bretkwuiter 57 I Pr I! It ,\4, II, 4- Ou ul Z 01 44 Ce-.4 / 4, ')-7' J 0' 404 -, 4,1 404 7, e~ N itC I, 01 Uj4U QD C3 C14 a b Floating breaskwater section Debris twrrier 4adwI nt~u tloutttg buew4kuacr Vigatr 31 Mtotors ot the Port utCs4ihos1 59 b Site Conditions The important winds come downriver from the east where tie fetch is about 1.9 miles No tidal current measurements have been msade at the site, but speeds of to knots have been estimated, with higher speeds possible during periods of peak flood flows over Winds blowing down the Columbia River develop wavetn that break and pass the top of the breakwater, but have not caused problems with moored boats c Breakwater Design (1) Design and Installation The breakwater is a caisson-type strucof lightweight, reinforced concrete cast over Styrofoam blocks ini units by 10 feet in the cross section and 12 feet long, drafting about 18 inches T1e units are held together with timber walers The main section parallel to the shore (and river) is 1,073 feet long, and is held by guide pile dolphins spac-ed about 84 feet apart (Fig 38) A 233-focýt section of breakwater is set at about a 450 angle to the upstream end of the main breakwater to serve as a trash deflector (Fig 37,b) The breakwater is designed to provide transient moorage and public access with special fishing facilities provided It was installed in early 1979 Those responsible for the breakwater design, construction, and installation are as follows: "ture constructed Owner-Operator: Port of Camas-Washougal, Waviington Project Designer: Parietrix, Inc Van.:ouver, Washington Breakwater Designer-Fabricator: HelLingham Marine Industries Bel inghau, Washington (2) Performance The wind waves wcve nearly parallel to the breakwaterr, so t 7Wr-li _Ceffctively attenuated Vhe only problem reported is that from the boat wake generated by vessels pass.t% close to the breakwater at high speeds The trash deflector it not effective togs tend to jam up on it and then work uadernt.atilh tr a.tt move into the marina The river current keeps the breakwater s.nugged up against the pile reatraints d Discussito The overall system meets to be perforwing very well, and the owner Is satisfied This site could serve as a field monitoring station for force on pile-restrainted breakwaters, although the river crrent would be "an Qevr-prvoent additive to the wave loadtins frod wind or boat IMl SUM.MKY AW tCLUSIO(S Line of tho more perplextig proble"s facing the designer for a floatin breakwater is the spactficatino of realistic wave ctitmte Local data 4re rarely av4ilabl4atd coatetporry awthods ot developittg a•Aappropriate design spectra for Ohe vartable fetch eanditions usually wOuivttorOd at potential floating brea•ier •i•tes leave much subjective freedo&m tit scitying principal praneters Ropefulty, th1 two-diwatsiopA wave "elo beitn developed Vill nfrro OWe proiesent no" of utwirt4taty '.3I b W~ide pile detail Ftpure ia ehoLuM of the win sect ion of the Port ot Catas-UAshc~ug4tl tloauiew breakwater At some sites, boat wake loadings may be more important than those from the wind-generated waves Better models depicting wake loadings are needed The floating breakwater transmission characteristics are sensitive to the wake from certain hull-speed distance-orientation cases The recently developed analytical methods treating the floating breakwater as a dynamic system are an improvement over static methods, but field data are still needed to refine the values of the various coefficients in the analyses and to verify the general methodology Possible field installations should be screened as potential field measurement sites The system being fabricated for Semiahmoo Spit Marina, Blaine, Washington, looks promising because the exposure is such that frequent winds of the 30- to 50-knot range should occur most of the winter season The water depth is shallow, which will restrict wave buildup The users of the floating breakwaters of the concrete caisson or ladder (Alaskan) type seem to be quite satisfied with their effectiveness and mainSome of this satisfaction is likely attributable to an adjusttenance costs ment in expectation of what can be accomplished in reducing wave heights within a given budget, developing adequate mooring techniques, and an awareness of crowded conditions at all moorage sites The use of this type of breakwater seems to be confined to the western Pacific coast Tenakee Springs, installed in 1973, followed by Sitka and Port Orchard (installed in 1974), are the sites with the longest history of performance for the concrete units Early problems at Tenakee related to -Alinement and module connections have been corrected; anchor cha-is are being replaced at Port Orchard Presetit design knowledge would have avoided these tw problems Otherwise, the units have performed very satisfactorily The other early breakwater of major dimension (for the area surveyed) was the one at Friday Harbor (installed in 1973), consisting of large plastic flotation tanks with a timber deck A major storm shortly after installation caused extensive dazna&;e Plans are underway for replacement with a concrete caisson and an enlarged configuration to accommodate the expanding demand for moo rages, The floating tire breakwaters should be restricted to sites where wave conditioas are quite mild Experiences to date show that, when subject.ed to an active wave climate, there is a rapid deterioration in buoyancy due to breakdo~i of flot~ttion and fatiguing of the systems used to hold the tires together Karine growLth will aiso diminish scructural buoyancy Bottom conditions at a proposed itte should be determined carefully to provide a sound basis for specification of another type Extra costs have been incurred at Ketchikan and at the Friday Harbor Oceenogruphic L4boratory Piite due to unforeseen foundation Conditious No damage to anchor ough anchor inspections tation However, systems from wave loadings has been reported Thorbocause of marine growths 4od sedimenare ditticult there ar- many instances where an Anchor litte could tw dis- connected at the breakwater and be partially exponva tor a look Tite one data point on longevity of a•tchor chain is that Orchard installation, wbere a rOpl4cetmnt 4fttr yC4rs It" bWte 62 wrire detailed the Port Lcnw "Cessary design with larger chain and cathodic protection is expected However, longnewtime to last a the "The connections between modules have been the "Acnille's Heel" in floating Experience has had to substitute for analysis in evaluabreakwater design The recent dynamic ting the loadings to be transferred between modules str-actural response modules are expected to provide realistic design values, Some design prothereby replacing the costly empirical experience approach The rubber in gressiuns show tip in the installations covered in this report the chain-bumper system of the initial Tenakee design took a permanent set and The replacement deaign eliminated the set problem Sallowed slack to develop The connecby connecting the flexible rubber fender rigidly to each module tiong of the breakwater deck to the flotation modules in the Friday Harbor breakwater invited stress reversals and concentrations 'iith subsequent fatigue failures The layout of the connections for the Srmialunoo Harina looked like a practical way of provltiiig a resilient, flexible connection well suited to Its performance, however, suggests it was unlderdesigned for field assembly the the loading imposed by the high winds experienced in the 198L-82 winter current design trend for the caisson-type breakwater is to replace the flexible connection by postteasioning modules to form a continuous structure Although more expensive, fabrication and field assembly procedures are more "exacting; therefore, the final product should be cost-effective the pile-restrained breakwater have * rather weak base loadings on such piling can lead to forces Dynamic i;,talysis will require the that not appear to develop in the fialt resolution of the interaction between the piling and the breakwater; such a synthesis would be aided greatly by some prototype data The floating breakwater at Camas-Washougal would be a possible site for tietd experiments, as An etiergy absorbing connection betwe.tn the would the unit at Evo-rett Harbor A sugpile collar and the breakwater would relieve some of the dynftnic load Design data for "Logical assumptions about wave with the annulus taken up tby gested design would be concentric annular rings, rubber fendertig material The pros and cons of lightweight versus regular weight cnciete may have Suitable lightweight aggregate has becowd been resolved by market conditions very expensive Some htaadardization of breakwater dimensIont could lead to lower dedign atl fabrication costs Those breakwaters where the freeboard is safety ladders provided at intervals of about climb onto the breakwater Navigation or radar more thati I toot should have ISO fNet to allow a persou to assisted targe-it siuhld We placed at raore frequent that those required by U.S Coast Guard re~ulatiorts ti difficult to see under dark Some designers intervals Vw floatit.g breakwater otoray conditions strongly pr'efr chain or chtait-aylof line anchnr lttns ovV cable, Which it.s likly to be twre vulnerable to cetion etottin ateqOitt coverrtoAlt Quality control in fabrication isa v"ry it age of retnforcement and strict adherence to dilntsitots so the utritl wilt float with Untformt ad sptdecifd freoboard 63 Neither of tIM installations 3t Sitka or Tenakue Springs any iring of consequence, TheC Puget Sound sites are ice-free experienced Wat-r quality problems that could arise in a small-craft hIrbo•r enclosed by an io•permeahle harrier are avoided by the floating breakwaters IInmany rases, tOe floating breakwater an4 anchor lines enhance or provide additional habitat "Some designs for the concrete raisson breakwater have proposed a hullow stru,:-ure, thus eliminating the rost of the usual Styrofoam rore, and then "relying on Lite integrity of the cotncrete shell ntid inspections to avoid loss of buoyancy throtigh leakage The koam core provides a good foirm for casting and also allows the box to be formed by a continuosis pour However, care must N! exCrCised to assutre that the foam does ttot rompress duringt the p)ouring operattions, thereby alteritig the design freeboard levels It is suggested that fabricators b! allowed the option of which merild is the mW)st economical, or Othit close cost comparisons be mtde before a design is fixed The foam Core is good insurance againsL flooding i!!, i$4 - -e a c~ c O-.C u V0 3,0 -,c jG i C 02J C j -I0 -c 0.*VCC c : w C IV cCGm ) m 2)UCD D J ) C I CL W WC a cc, 0~0 0)-~~ w , w.- Ln -V00 ZIP MO Z a t, %co > go r_ C w *0c Z tD A c X U w~ %00 *.0.4) 21 -~~~~W CcD 00 2)0 00 a z)C w 1c U u- 30 2) 4) r *00 l (h c 00a tA m~ L w c D 0~~4 13< - ~ CO U-O go w~0a ** *3-3 tc w r) ~~~ 911 ) IV, 002)/~ GD4) 50 ) VD > ml, 13 ) >.I400 O cc luW w pe o L' vD I 3GD 20)-~~~~30 10 o -,C -M m 0l.02 -)U w)~le4 W D ~ C6 GU) *C *.lC 0.0f.0.~ ) *x o A ,1 4))W aDG 44 c A mu * C1 I 004 - U~~C -A 0V OO -0~ -A D Go -3 a, v v4~*aDU~ IOV~ v D D aC fa G acJ ) 0 0~ to3)" C0 0~ aCa 0c0c c 3)> 1w C U d c D1D ; 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