In general, there are three arrangements of clamps and shelves in common use. First, as shown in Figs. 87 to 89 inclusive, we have clamps only, an arrangement that may be used only where a hanging knee is fitted under each beam. Second, in Fig. 90, we have an arrangement of light shelves and clamps, in combination with hanging knees, the latter being fitted under approximately every other beam. Third, and last, we have the heavy shelf and clamp arrangement shown in Fig. 91, in which there are no hanging knees.

Fastening arrangements which have been used are shown in each figure and are self-explanatory. It will be noted that in all types except Fig. 91 the fastenings are driven in the middle of the frame timber. The arrangement in Fig. 91 is an unusual one. The space between the center of the timber and the side is generally reserved for planking fastening much of which has to be driven through frame and ceiling. Where both systems are ranged on the same line it makes it very difficult to get the planking fastening through without striking iron.

Clamp And Shelf Scarfs

Clamp strakes should be of the longest possible length and scarfed strictly according to rule, that is, insofar as the length of the scarf is concerned. Where the rule lengths do not land the nibs on the frames properly the length should be increased, not decreased.

Scarfs jn clamps may be either flat or edge scarfs, and if made flat there should be very little if any reduction in length under that required for the edge scarf. Modern practice leans somewhat toward the flat scarf as all of the main fastenings then pass through both parts of the scarf, while in an edge scarf the edge bolting constitutes the only direct connection between the two parts. Edge scarfs should have standard nibs. Flat scarfs should have the inboard nib of standard depth, while the outboard nib, which should always rest against a frame, may be from one inch in depth to a feathered edge. The cutting of any outboard nib at all in a flat scarf makes the fitting of the scarf very difficult, and inasmuch as the outboard nib is supported by the frame it may just as well be feathered off, in which case the fitting of the inboard nib and the scarf becomes a very simple and ordinary operation.

All scarfs in shelves should have standard nibs. Assuming that the least dimension of the shelf strakes is the molded, or vertical, dimension, the scarfs would ordinarily be edge scarfs and would have extra edge bolting as driven in clamp edge scarfs.

As has already been mentioned, the clamps should be of the longest available timbers, and it follows that the scarfs should be well shifted. In determining the proper shift of scarfs in the clamps it is necessary to consider also the shelves and waterways as they are also important strength members of the same group. There should be no overlap of scarfs unless there are more than a total of eight strakes in the entire system of shelves, clamps and waterways. Scarfs in adjoining strakes should have from six to eight frames spaces between them wherever possible. To follow out the above rules strictly requires very long timbers, which, in some localities are not available. The plans for the vessel generally take into account the available lengths of timbers and therefore considerable variation from the rules stated here may be found in practice.