Pennsylvania Angler & Boater www.fish.state.pa.us16

by Alex Zidock Jr.

Boat HullD E S I G NBoat HullD E S I G N

Huck Finn’s raft was a basic flat-bottom boat. So was Robert Fulton’sClermont, the first commercially suc-cessful steamboat. The design of aboat hull does not depend on overallsize, but on the intended use of theboat, or the results the boater wants toattain. Misuse of a boat whose hullwas designed for another applicationcould be costly.

When my son was about eight yearsold, we took our wide-bowed flat-bot-tom car-topper to a Van Sciver Lake,part of the privately run Penn WarnerClub, in Tullytown, Pennsylvania, foran afternoon of fishing. This portionof the lake was a result of a sand andgravel operation that left the entirebottom an almost perfect 20 feet deepwith few mounds and very little bot-tom structure. The spring day wasbright with no noticeable wind.

Launching the boat was usually aneasy one-man operation, except onthese weekend outings when it tookboth of us, “working together,” to getthe boat ready to sail. About an hourafter we were on the lake, I noticed aslight wind. About 15 minutes later, Icould feel the coffee-can cement an-chor begin to bounce as the wind andsmall waves lifted and settled the boat.Nothing to worry about, I thought,and probably if my son weren’t onboard and there was no lightning, I’djust ride it out.

My “time to head for shore” an-nouncement was met by a frown as heput his rod in the boat. With someanxiety in my voice I suggested hetighten the straps of his life jacket, andI pulled the 3 HP engine to life.

As I began our 100-yard journeyquartering into the wind, and back toshore where the station wagon wasparked, my concern for his safety grew.

The boat began to porpoise as the in-creasing wind quickly raised waves,and the bow of the boat began to scoopwater into the boat. Now I could seemy son’s grip tightening as he watchedmy reaction. This was the first time Iexperienced this problem with thelittle flat-bottom boat, and maybe itwas just because of his added weightnear the bow, but I knew I could notproceed on course or we’d swamp.

The wind wanted to blow us parallelto the shore and into a cove that hadsome lily pads. I quickly calculatedthat a long walk around the lower partof the lake was much better than ashort swim, so I slowed the motorenough to maintain a controlled drift,and the water no longer came in theboat. We floated into the pads, whichwere close to shore, and with the helpof the oars we reached safety. It couldhave been worse, and even though theflat-bottom johnboat was not theproblem, it met its match. A high-sided “V”-hull design soon found itsway to the racks on the wagon.

Flat-bottom boatsThe one thing you can say about

flat-bottom boats is that with theirlarge bottom area, the boat is verystable in calm weather. Characteristi-cally, however, the flat, broad bow areacreates a rough ride. These boats areusually limited to low horsepower mo-tors because they don’t handle well athigh speed. Flat-bottom boats aregreatly suited for fishing in skinny wa-ter from the Susquehanna River to theFlorida Keys, where a very shallowdraft is a must.

Early in our nautical history, boatswere powered by wind or by hand-stroked oars. Early boat designersfound that boats went faster, and were

Flat bottom with hard chines

chine➜

Flat bottom with soft chines

chine

➜

Vee bottom

Vee bottom with pad and strakes

padstrakes➜

➜

Vee bottom with strakes

strakes➜

Pennsylvania Angler & Boater www.fish.state.pa.us

illustration-Ted Walke

www.fish.state.pa.us Pennsylvania Angler & Boater 17

easier to steer, if the bow was pointed.They also soon discovered that by low-ering the center of gravity, the high sailmasts had better balance, and usuallykept the boat upright even in badweather.

Displacment, planing hullsThese early boats were constructed

with “displacement” hulls. This meansthat the hull would push through orcruise through the water. The properpropeller for a displacement hull is onewith a lower pitch when powered by anoutboard or stern drive. With the ad-vent of mechanical power came boatswith “planing” hulls, which lift theboat partially out of the water to skimon the surface. Today, it’s sometimesdifficult to tell the difference betweenthe two, but there are slight differences.Propellers on boats with planing hullsoften are not fully submerged, so theyneed to provide holding ability as wellas higher pitch and rake, because ofhigher top-end speeds.

Round-bottom hull,“V” bottoms

The round-bottom boat has mostly adisplacement hull and is usually usedfor dinghies, tenders, and some car-topboats. This boat style is usually easierto maneuver at slow speeds than theflat-bottom boat.

The “V”-bottom boat is probably themost common hull design. Mostmanufacturers of boats built today usemodifications of this design. This de-sign offers a good ride in rough wateras the pointed bow slices forward andthe “V”-shaped bottom softens the up-and-down movement of the boat. Thedegree of the angle of the “V” is called“deadrise.” As the “V” shape extends tothe back of the boat, it usually flattensout until it all but disappears at thetransom. Some “V”-bottom boats havea flat surface at the very bottom calleda “pad.” This pad allows a little moreplaning surface and at the sacrifice of alittle softness in the ride, but this addi-tion increases top speed.

Tri-hull, tunnel hullThere are many boats in Pennsylva-

nia waters that are a distinct

modification of the “V”-bottom thatare called tri-hulls and cathedral hulls.The tri-hull boat is the traditional “V”hull with additional outside hulls.This design is more stable than the“V”-bottom at rest, but it gives arougher ride in choppy water becauseof the increased surface at the bow.

Tunnel boats have been designed totrap a cushion of air beneath the hullto reduce drag on the outside hulls.This design is different from a catama-ran bottom because the inner edges ofthe outside hulls have sharp corners toimprove the handling of these boats atvery high speeds. Many race boats areconstructed with tunnel hulls and aresometimes called “hydroplanes.”

Pontoon boatVery popular in the Keystone State

are pontoon boats. And just as thename implies, the pontoon, or deckboat, is a flat, raised deck supportedwith two outer hulls (pontoons) thatare usually constructed of aluminum.These boats combine a lot of featuresof other boats. They ride very dry be-cause the deck is raised above thefloats. They are stable, and with thetransom mounted to the underside ofthe deck, they are easy to maneuverwith an outboard motor.

The boater who is looking for all-around use can make almost any hulldesign work for many water condi-tions. But even in the broadestmarkets, hull design is a continual re-search and development project. Inspecific niche markets, like water ski-ing, and now in the fastest growing ofthe water sports markets,wakeboarding, the competition forbetter hulls is tough.

When you are shopping for a newboat, first consider the water in whichyou’ll use the boat. Then take intoconsideration how many people willgenerally use the boat, and then deter-mine how the boat will be used. Boatscome in a wide range of colors andcockpit configurations that you canlive with if you like all of the other at-tributes the boat has to offer. But theone thing that should be at the top ofyour shopping list is what’s on the bot-tom of the boat you want to buy.

Catamaran

Pontoon

Tri-hull or cathedral hull

Tunnel bottom

Tunnel vee

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illustration-Ted Walke