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Summer Conditions of high temperature, low barometric pressure and high humidity all combine to reduce the engine power. This, in turn, is reflected in decreased boat speeds–as much as 2 or 3 miles-per-hour (3 or 5 Km per-hour) in some cases. Nothing will regain this speed for the boater, but the coming of cool, dry weather.
In pointing out the practical consequences of weather effects, an engine–running on a hot, humid summer day–may encounter a loss of as much as 14% of the horsepower it would produce on a dry, brisk spring or fall day. The horsepower, that any internal combustion engine produces, depends upon the density of the air that it consumes and, in turn, this density is dependent upon the temperature of the air, its barometric pressure and water vapor (or humidity) content.
Accompanying this weather-inspired loss of power is a second but more subtle loss. At rigging time in early spring, the engine was equipped with a propeller that allowed the engine to turn within its recommended rpm range at full throttle. With the coming of the summer weather and the consequent drop in available horsepower, this propeller will, in effect, become too large. Consequently, the engine operates at less than its recommended rpm.
Due to the horsepower/rpm characteristics of an engine, this will result in further loss of horsepower at the propeller with another decrease in boat speed. This secondary loss, however, can be regained by switching to a smaller pitch propeller that allows the engine to again run at recommended rpm.
For boaters to realize optimum engine performance under changing weather conditions, it is essential that the engine have the proper propeller to allow it to operate at or near the top end of the recommended maximum rpm range at wide-open-throttle with a normal boat load.
Not only does this allow the engine to develop full power, but equally important is the fact that the engine also will be operating in an rpm range that discourages damaging detonation. This, of course, enhances overall reliability and durability of the engine.
macro je napisao/la:Evo jos jedan utjecaj na izvedbu:Summer Conditions of high temperature, low barometric pressure and high humidity all combine to reduce the engine power. This, in turn, is reflected in ...
Ljetni uvjeti visoke temperature, niski barometarski tlak i visoka vlažnost kombinirani su kako bi se smanjila snaga motora. To se, pak, odražava u smanjenim brzinama broda - u nekim slučajevima čak 2 ili 3 milje po satu (3 ili 5 km po satu). Ništa neće vratiti ovu brzinu za plovilo, nego dolazak hladnog, suhog vremena.
Istaknuvši praktične posljedice vremenskih utjecaja, pokretanje motora na vrućem i vlažnom ljetnom danu, može doći do gubitka čak 14% konjske snage koju će proizvesti na suhom, bujnom proljetnom ili jesenskom danu. Konjska snaga, koju proizvodi svaki motor s unutarnjim izgaranjem, ovisi o gustoći zraka koji troši i, pak, ta gustoća ovisi o temperaturi zraka, njezinom barometrijskom tlaku i sadržaju vodene pare (ili vlage).
Prateći ovaj gubitak snage inspiriran vremenom, drugi je, ali suptilniji gubitak. Na vrijeme pričvršćivanja u rano proljeće, motor je bio opremljen propelerom koji je motoru omogućio da se okrene unutar svog preporučenog okretaja motora pri punom gasu. Dolaskom ljetnog vremena i posljedičnim padom raspoložive konjske snage, taj će propeler postati prevelik. Slijedom toga, motor radi na manje od preporučene brzine vrtnje.
Zbog karakteristika motornih snaga / okretaja motora, to će rezultirati daljnjim gubitkom konjske snage na propeleru s još jednim smanjenjem brzine broda. Ovaj se sekundarni gubitak, međutim, može vratiti prebacivanjem na manji propeler koji dopušta motoru da ponovno radi na preporučenim brojevima okretaja.
Za nautičare da ostvare optimalne performanse motora u promjenjivim vremenskim uvjetima, bitno je da motor ima odgovarajući propeler koji dopušta da radi na ili blizu vrha preporučenog maksimalnog broja okretaja motora pri širokom otvoru s normalnim plovilima ,
Ne samo da to dopušta motoru da razvije punu snagu, ali jednako je važno i činjenica da će motor također raditi u rasponu okretaja koji sprječava štetne detonacije. To, naravno, povećava ukupnu pouzdanost i izdržljivost motora.
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