46 Professional BoatBuilder

Skate 15A racer/raider/cruiser

designed for kit construction offers

high performance for a cash-strapped

middle class.

by Brandon Davis

Walking into the shop of Turnpoint Design in Port Townsend, Washington, you never know what you’ll find—maybe something destined for outer space, or inner earth, or, trivially, a body of water. Last fall, owner Bran-don Davis and his crew were busy finishing something new—a sailboat that will definitely goose adrenaline levels. The Skate 15 (4.6m) is built from 6mm-okoume (0.24" ) British Standard 1088 Lloyd’s-certified plywood, carrying a maximum beam of 8' (2.44m) all the way to the transom, which is fitted with a serious-looking square

escape hatch and twin rudders. Other details that caught my eye: hard chines, a giant cockpit, daggerboard trunks on each side, and a surprisingly generous cabin with room for two adults to bunk in comfort. The Skate looked like a smaller, saner version of a Mini Transat 6.50. And that’s exactly what Davis and his partner in this venture, Josh Colvin, had in mind.

Here, Davis explains how the project came about, how he arrived at the design decisions, and where he and Colvin want to go with it. —Dieter Loibner

Above—The beam of the Skate 15 (4.6m) requires crew weight to leeward in light air to reduce wetted surface area. The boat’s final version will use either a taller Hobie 16 stick, or an optional custom carbon mast.

co

ur

tes

y B

ran

do

n d

avis

DESIGNBRIEF

June/July 2018 47

manageable by someone just getting started in performance boats. •Makeitassafeaspossibleandsea-

worthyenoughtosailtoAlaska.• Includeaveryusableinteriorthat

sleeps two adults.

Idon’tknowifColvinrealizedwhathe did to me with this suggestion, but thatlittleseedstartedtotakeroot,andbythefollowingweekIwassoobsessedwiththeideathatIhadtodrawitupinCAD to see if it couldwork out.Most of my crazy ideas die quicklyonce I see them in 3D and find theobviousreasonswhynobodyismak-ing something like that yet. But theSkatewasdifferent, and the concepthadsomemagictoit.ThedeeperIgotinto the design process, the better all thepuzzlepiecescame together.For

It all started with the innocent sug-gestionfromJoshColvin(editorof

Small Craft Advisor magazine and owner of Duckworks Boat Builder’sSupply): What the world needs is a smallwedgeofaboatofferedasakitthattheaverageJoecanafford.Some-thing that applies bits of the cool technologyfromthenewestoffshoreraceboats, but around 15' long with accommodations for two that could be raced around the buoys and com-peteinsmall-boatgatheringsknownas raids or the more ambitions Race to Alaska (a 750-mile contest fromPortTownsendtoKetchikan,Alaska,through the Inside Passage). At thesametime,italsoshouldbefunover-nightingwiththekids.This was his wish list, and here’s

howwebrokedownthedesigngoals:

Skate 15 Specifications Length: 15' (4.6m) Beam: 8' (2.44m) draft: 4.5'–6' (1.37m–1.83m) displ.: 450 lbs (204 kg) Water ballast: 200 lbs (91 kg) on centerline sail area: upwind: 230 sq ft (21.4m2) downwind: 460 sq ft (42.7m2)

Wells on side for bilge-daggerboards or drop-in pedal drives/dss boards

twin rudders

Build material: okoume plywood (kit)

www.turnpointdesign.com

•DistillaMiniTransat6.50downto its essentials to create a trailerable pocket racer/raid boat that wouldmakeanysailorsmile.• Keeptheboataffordabletobuild

and race. •Make the boat quick to rig and

launch from a trailer and towable by any car. •Keepweightaslowaspossibleby

using water ballast and lightweight construction, thus benefiting boat speed, ease of trailering, beaching, and building the boat in a garage. • Incorporateasmanyofthelatest

MiniTransatdesignfeaturesaspossi-blewithoutbreakingthebankormak-ing the boat too complex. •Makeitappropriateforsailorsof

all levels—funandchallenging for acompetent dinghy sailor, yet still

courtesy turnpoint design

48 Professional BoatBuilder

Design Brief: Skate 15

HATCHES, HOLDERS & HINGES

Your boats deserve Beckson!

www.beckson.com/oem

HATCHESDRINK HOLDERSHINGESPORTS & COMPONENTSDRAIN PLUGSFITTINGS & FASTENERSCERTIFIED DECK PLATES

OUR PRODUCTS ARE MADE FOR YOUR BOATS

oemsales@beckson.comCALL 203.333.1412

example, the wide beam necessitated foot braces for when the boat heeled, because there is no way you can stretch yourlegstotheothersideofthecock-pit. And that magically opened up the perfectspaceforadoublebunkunderthecockpit sole.Simultaneously, theextreme beam and the stern shape shouldmaketheSkateahoottosail,andalsogiveitatremendousamountofinitialstabilityforitssize,makingita great boat for leisure sailing or cruis-ing.Thebeammakesiteasytosteponboard from the dock and keeps theboatfromrockingatrest,soitismorecomfortable at anchor, too.

Brandon Davis and the prototype in the finishing stages. Note the commodious cockpit and interior space forward, the escape hatch in the stern, and the long, curved traveler track for the boomless mainsail.

die

ter

Lo

iBn

er

June/July 2018 49

outsidetheharborlikewedohereinthePacificNorthwest.

After much debate and some calcu-lations, we initially considered twin kick-up3°-toe-inbilgedaggerboardsonthesideofthecockpit.Theyrunintrunks that also can accommodate

waterplaneskewsabout8° from the centerlineof the boat, which means a fixed dagger-boardwouldalsohaveto be skewed by thesameangle.Atfirst,wethought about using a jibing daggerboard that aligns with the waterplane upwind andlocksoncenterlineoffthewind.However, the feedback in Colvin’smagazineindicatedtherewasdemandforakick-upcenterboard.Iguessnoteveryonehasahundredfeet(30.5m)ormoreofwaterunderthekeelright

Awordabouttherig:Wespecifieda modern boomless fat-head mainsail set on a sealed wing mast (an oldHobie 14 spar that was sealed to be watertight),whichprevents theboatfromturningturtleincaseofcapsize.There’s also a retractable bowsprit(couldbeanoldwindsurfermast)tosetanasymmetricalspinnakerorcodezero, effectivelymore thandoublingsailareafrom200sqftupwindto430sqftdownwind(18.6m2to39.9m2). Foranyboat that tries to satisfya

diversesetofrequirements,compro-mises have to be made. But in thiscase, as luckwouldhave it,manyofthesecompromisesactuallyimprovedthe design. One of the biggest chal-lenges was the wetted surface area suchaflatandwidehullshapeinevi-tablycarries.Itbecameapparentthatit will be best to sail the boat upwind on its chine at 15° to 20° of heel toreduce drag. At this heel, the

The prototype’s retract-able bowsprit, made

from a repurposed wind-surfing mast, is used to fly a large gennaker off

the breeze.

die

ter

Lo

iBn

er

50 Professional BoatBuilder

Design Brief: Skate 15

was the dump valve bor-rowedfromtheMiniTransatdesigns. The setup is dead simple: a straight 4"(102mm)pipe with a 4" gate valvebetweenthetanks.Thecon-trol leads to the cockpit, sothe crew only needs to pull a ripcordandholdonfor6to8seconds as the water rushes to the other side. Another great thing about this system is that the plumbing is inex-pensiveandsimple.Youneedtofillatankonlyonceatthebeginning of your race or cruise, and then pull a cord

beforeeverytackorjibe.Themoredifficultnuttocrackwas

fillinganddraining.Theeasiestsolu-tion would be a handheld bilge pump (whichyouwillneedonboardanyway)thatfitsintothescrew-offportsinthecockpit. This allows more budget-minded owners to fill or evacuate atank during a race and to manually

weknewthattheboatneededtwolat-eralballast tanks,but it tookquiteawhile to come up with a simplifiedcontrol system. We didn’t want aChernobyl’s worth of plumbing andpumps belowdecks, as it violated animportant rule that guided the design: KISS(keepitsimple,stupid).Thefirstdetailthathelpedsolvethechallenge

drop-in pedal drives for human-powered propulsion, if desired. The drawbackisaddedcomplexity,butonthe upside it would eliminate the centerboard trunk in themiddle ofthe cabin, opening up the interior tremendously.

We also gained the ability to run up on a beach or hit a deadhead at speed without doing too much damage to the boat, because the plywood of the bottom panel is 9mm (0.35" ) thickandhastwolayersof6-ozglassmatforbeaching and planing loads. This will maketheSkate15anidealcandidatefor shallow-water racing such as the Texas200ortheEvergladesChallengeandalsomoreforgivingforsomeonelikeme,whocangetalittledistractedwhen the family is on board. Anotherdetailwestewedoverwas

the water-ballast system. We thought

Davis stirs the epoxy pot for some finish work on the CNC-cut appendages. To the left is one of the two daggerboards; on the right, one of the twin kick-up rudder blades.

Hard chines are popular for performance boats these days, but, in

this case, they are also beneficial for DIY stitch-and-glue construction. The well for the daggerboard also accepts a custom-

designed drop-in pedal drive. die

ter

Lo

iBn

er (B

oth

)

52 Professional BoatBuilder

Design Brief: Skate 15

part—a coffee-cup-sized 3D-printedplasticvalvewithaT-handleaccessi-blefromthedeck.

Onewouldthinkthatwinterisnotthe ideal time to sea-trial boats in

PortTownsend,butwewantedtofindout how well our execution matched theoriginalidea.Itwasasurpriseonmany levels: First and foremost, thelargebeammakestheSkateasstableasthe familyBuick, figuratively speak-ing. Stepping on board andwalkingaround in the cockpitwon’t put thefear into anyone, which is good news for the cruising crowd and families withsmallchildren.Becausetheboat’sinitial stability is high, we decided to maketheswitchfromthenifty500-lbtotal-capacity(227-kg)two-tanksys-tem we agonized about to a single-tank system installed on centerline,whichaddsonly200lbs(91kg)whenfull. So much for the connecting pipes andthegatevalve,butthiswillmakethe boat simpler and easier to sail.

Our tests in light air suggested that the boat can easily handle a bit more horsepower, so instead of a Hobie 14 mast,we’llgowithaHobie16stick,whichwilladdabout30sqft(2.8m2) more sail area to the main and the asymmetrical. That will help heel the boat so she sails on her chines, and it will add more scream on the reaches and downwind legs if needed or wanted.Andfinally,we’llshortentherudders a bit to help with tight turns. Weexpect toship thefirstkits in

spring 2018 through Small Craft Advisor magazine,whichalsowillsellplans. Pricing for the plywood kitonlywillbe$3,500;fortheCNC-cutfoil kit, $900; and approximately$1,250forthesails.Ifyouwanttogoreallycrazy,wehaveonemoreaceupthe sleeve, or rather on the shelf: apair of Dynamic Stability Systemsfoils that will add another dimension totheperformanceoftheSkate15.

About the Author: Brandon Davis is the owner of Turnpoint Design, in Port Townsend, Washington.

forwardintothewaterflowtofill,orturnedtofaceafttoempty,thetank.With the handle pulled up, the scoop is closed and perfectly flush with the bottom of the boat. An O-ring seals the opening from water ingress. The nicest thing about this system is its simplicity.Yes,itmightsoundcompli-cated, but it has only one moving

pump water to the high side if someone forgets to pull the gate valve beforechanging tacks or jibes.The secondoptionismoretechnical:asimplifiedversion of the scoops from FrenchsupplierSofoMarinthatoceanracersuse to fill tanks. It’s nothing but aroundscoop/valvebuiltintothetankbottom that can be turned to face