Sorrento Notes

Power and Performance

Sufficient power should be installed to maintain a minimum cruising speed of at least 16 1/2 knots. Cruising at lower speeds is inefficient and a waste of power. This does not mean that lower speeds cannot be maintained, but only that the hull is most efficient at the higher speeds. If these higher speeds are not desired, then a hull form such as a semi-displacement or full displacement type is more practical. The SPEED/POWER CHART will give an idea of the power required for a given speed. Either single or twin motors may be used, but a twin engine installation is recommended for best handling, reliability, and performance, especially if gasoline motors are used. The powerplant should be of the conventional type using a straight shaft, propeller, and proper reduction gear. Other power systems such as stern mounted engines with outdrive, v-drives, or jet drives are not recommended. Because of the centrally located engine, weight of the powerplant is not critical, even though lightweight, compact engines are desirable. Sufficient fuel capacity is provided for many hours of high-speed operation. In most cases, extra fuel may be added, but this will add to the weight and hence the power required to maintain a given speed. There is ample water capacity to provide the needs of a demand water system and use of showers.


SPEED/POWER CHART
Displacement = 15,600 lbs.
16.5 KNOTS 165 SHP*
19.5 KNOTS 220 SHP
22.5 KNOTS 280 SHP
25.5 KNOTS 360 SHP
28 KNOTS 450 SHP
34 KNOTS 640 SHP
*Mimimum planing speed

The calculated speeds listed are approximate and considered accurate on the listed displacement. Changes in displacement (or weight) will modify the figures and will not give the speeds listed. All speeds listed are in knots per hour. To convert to miles per hour, divide by .87. Note that the horsepower is given as SHAFT HORSEPOWER (SHP). Since most motors are listed at BRAKE HORSEPOWER (BHP), it will be necessary to reduce the BHP to SHP. A reliable factor to multiply the BHP by is .70 to determine the SHP. All speeds assume that the proper gear ratio and propeller size is used. For twin engines, divide the SHP figure by two in order to determine horsepower required for each engine.


Note: We have not attempted to verify the following figures; we pass them on, but recommend you check prices in your area.

Subject: Variant and Sorrento
Date: Tue, 21 Aug 2001 20:49:35 -0400
From: Charlie Moulton

Hello Barry,
Just spent the day doing a takeoff from the Bill of Material. The wood for the Variant is approximately $6700 and the Sorrento is $16,950. That is a lot closer estimate than the wild guess I asked you for, but unless it is against your policy, perhaps you can give the next person who asks this information and save them the hassle.

thanks,
Charlie

Sorrento body plan

Body Plan

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