being a stout screw, and the other two, ordinary nut and screw bolts; but in this case the nuts are placed on the underside of the thwart and screwed up on stout washers, with the points of the bolts slightly clenched over the nuts. If the nuts were secured on the horizontal arm of the knee, they would be a source of danger to men running along the side benches, and tend to throw them overboard. It is usual to fit a protecting strip of wood, or

FIG. 88.-Method of fitting thwart knees and side benches.

listing, attached to the thwart, to keep the buoyancy air-cases off

the nuts.

Fig. 88 shows the details of the securities for iron knees of the ordinary pattern.

Table XVIII. has been drawn up to simplify the work of the boatbuilder and smith; if the various dimensions are adhered to, the combinations in way of the gunwale will be so placed as to always allow the securities to coincide with the holes already drilled by the smith in the thwart knee. It often prevents the bolts being inserted at a great bevel, or missing the rubber altogether, and necessitating the bolt being secured to the binding or upper strake.

Single knees are permissible in boats of 24 ft. in length and under, but it is the general impression among boatbuilders and others that this is a very prominent weakness in the present

instructions, and that double knees should be fitted to the thwarts of all boats, particularly in way of the securing gripes, in fact, this has become the unalterable practice of most firms of repute.

TABLE XVIII,

DIMENSIONS OF IRON THWART KNEES, ETC., FOR OPEN BOATS OF CLASSES I

NOTE. If sufficient seating accommodation is obtained without fitting side benches in Class III. boats, then the depth of knees at “A” must be increased one inch.

Solid hardwood chocks are fitted behind the knees. These are arranged to grip two timbers, whether the knees are single or

double, so as to be of some substantial support to the com

binations.

When single knees are fitted the scantlings are increased.

A concession has recently been granted to fit knees of convex

CENTRE OF GUNWALE BOLT

CENTRE OF RUBBER BOLT

B

FIG. 89.

iron, § in. in thickness, in boats of 24 ft. in length and under. No reason is seen for lowering the standard in this respect. This practice was never seen by the author in yards of good boat

SECTION

PLAN

FIG. 90.-Details of Hornby's patent knee. (No. 10,754.)

builders, but it naturally follows that the competing firms will be guided by the minimum standard.

All iron thwart knees must be galvanised.

In lieu of the double iron knees, a special type of wroughtiron single knee having double palms, is sometimes fitted. The

upper or vertical arm is hooked over and well fitted to the gunwale and sheer strake. The horizontal arm has double palms which are secured to the thwart. An illustration of the arrangement is shown in Fig. 86.

To provide efficient securities for the reasons previously given, these double palm knees should be so designed as to allow one of the bolts to pass through the rubber. There is certainly a saving of weight with this type of knee, but not very much advantage is gained in cost. The greatest care has to be exercised in making each knee fit at the gunwale at the particular thwart, to prevent the necessity of fitting filling pieces.

A very efficient type of single knee having double palms, is that which has been patented by Mr. Hornby, of Seacombe, near

UPPER STRACE

GUNWALE

FILLING BETWEEN

TIMBERS

IRON BREASTHOOK

STEM

BUTT

OF CAPPING

CAPPING

Liverpool, the details of which are given in Fig. 90.

The difference between this method of forming the knee and the approved convex pattern is very marked.

Breasthooks and Floors. -Reference has already been made to the necessity of providing efficient combinations at the ends of boats to meet the heavy stresses which come upon them from the lifting-hooks, etc. Stout breasthooks must be fitted at the aprons and gunwale ends; the securities of which are similar to those of the thwart knees, having a throat bolt which passes through to the face of the stem or sternpost. (See Fig. 91.)

FIG. 91. Plan of upper breasthook.

When made of wrought iron, the breasthook should be of substantial thickness and not less than 1 in. at the throat. The use of cope iron should be entirely avoided.

Wooden breasthooks are cut from material grown to shape. Lifeboats over 24 ft. in length must be fitted with an upper and a lower breasthook, both at the stem and the sternpost.

When the lifeboats are lifted from near the ends, as with the Welin davits, a lower breasthook, or deep floor, is essential in all boats, irrespective of length.

This lower breasthook is fitted midway between the deadwood and apron scarph and the upper breasthook, and is usually

incorporated with the ending of the bilge stringer. Chocks being fitted between the timbers in way of the iron breasthook. (See Fig. 92.)

The writer has a preference for a good stout wooden breasthook with a throat bolt well secured to the face of the stem or sternpost, and having arms of sufficient length to allow for through fastenings at two of the timbers, on each side of the boat. In this case the breasthook is checked over the timbers and just touches, but does not unduly bear hard on the planking, the full bearing being taken by the timbers. Care must be taken to fit wedgeshaped liners, or filling pieces, behind the timbers in way of the breasthook to prevent the planks being drawn at their centre and splitting.

The fitting of floors at the ends of a boat depends on the type

and position of the lifting-hooks. Provided the timbers have been checked into the deadwood, it is usually only necessary to fit one deep floor at each end of the boat, near the lifting-hooks, checked over the keelson and incorporated with the timbers.

When the timbers are not checked into the deadwood some specifications insist on floors being fitted at every third timber which does not cross the deadwood or hog.

The working conditions of the smaller type of coasting steamer, particularly in regard to trawlers, make it necessary for their boats to be constructed on lines which are suitable to their requirements, and it is usual to fit a heavier form of hog and dispense with the keelson, as the latter would interfere with the usefulness of the boat. Good stout floors are fitted at the ends, as the boats are usually lifted on board with a wire sling.

Rubbers and Anti-fouling Arrangements.-Rubbers are usually