Knight's Mechanical Encyclopedia, B., Boat Low′er-ing and De-taching Ap-paratus.

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19th-Century American

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Boat Low′er-ing and De-taching Ap-paratus.

The ordinary boat lowering and hoisting apparatus consists merely of two falls passing through double blocks and suspended from the davits. The lower blocks hook into rings at each end of the boat, and are unhooked by hand after the boat is lowered. In lowering a boat in a heavy sea, this arrangement is troublesome and inconvenient, as a failure to detach both hooks simultaneously may lead to the swamping of the boat. To remedy this, and to enable both ends of the boat to be cast off at one operation, a number of contrivances have been devised. These devices generally take the form of means for casting loose the hooks fore and aft with absolute certainty and simultaneously. Sometimes it is a rod which is withdrawn so as to let the hooks fly loose. Of this character is the device shown in Fig. 748, in which the eyes of the davit-fall blocks are engaged by pivoted hooks at the stem and stern respectively of the boat. The hooks are detained by links, which are simultaneously withdrawn by lever connection with a rotating shaft amidships.

There are various modifications of this form of the device.

In Fig. 749 the davits are hinged in such manner as to swing freely in vertical planes toward and from the water, and to vibrate above and below a horizontal plane intersecting their axis of motion.

Curved sections are applied to the upper ends of the davits, which are hinged at their lower ends, so that said sections can be turned around independently of the standards to which they are attached.

The davits are counterpoised by a force sufficient to raise them without the boat, but easily overcome by the weight of the boat.

1877.

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Knight's Mechanical Encyclopedia
Knight, Ed.

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Boat Low′er-ing and De-taching Ap-paratus.

Knight's Mechanical Encyclopedia Knight, Ed.

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Table of Contents:

Boat Low′er-ing and De-taching Ap-paratus.

Knight's Mechanical Encyclopedia
Knight, Ed.