25-Foot Cabin Cruiser Part II
Before you begin to set up your moulds, it would be advisable to finish the rabbet line, as you have only cut the stem. The rabbet line is supposed to be marked on the keel on either side, and inasmuch as the upper side of the keel as far aft as the shaft-log represents the inside of the planking, it is not a difficult matter to trim this rabbet at intervals, taking the proper bevel at the different stations from the lines you have laid down. Then fair up the places between the points you have spotted, or cut to the proper shape. Where the rabbet line crosses the knee and connects with the rabbet line on the stem you must be very careful to get it correct.
It would be advisable to get two pieces of oak. 1 inch thick, about 6 feet in length, to fasten to each side of the shaft-log and horn timber; they should be cut to the curve of the rabbet line and the proper bevel, and securely fastened. Cut out places in the lower edges of these pieces to receive the heels of the frames; of course you will understand that these pieces are to form a back rabbet for the garboards or the plank nearest to the keel and should be cut to the proper bevel of the inside of the plank. Having finished cutting the rabbet line along the keel, etc., you can now proceed to set up the moulds. Starting with No. 2, set this in position so that the forward side of the mould intersects with station No. 2 on the knee. Cut it over the knee and set it down so that the lower part of the mould intersects with the back rabbet; measure up from your base line to the L. W. L. on the mould and if it is 2 1/2 feet up, screw through the block into the knee to hold the mould, plumb the face of the mould and when you have levelled the cross pawl you can secure the mould with stay-laths. Moulds 4, 8, and 12 can be set' up in the same manner with the forward sides of the moulds intersecting with stations 4, 8, and 12 on the keel, but the moulds 16, 20, and 22 are to be set with the after side of the moulds intersecting with their respective stations. Perhaps it might be well to explain the reason for setting them in this manner and I would call your attention to the fact that the edges of the moulds are cut at right angles to the face and the shape of curve of the boat commences to narrow up from station 12 forward and from station 16 aft; therefore these moulds are so placed that the edges which the battens spring against are in a direct line with the stations for which the moulds were made. When all the moulds are properly stayed, it is a good plan to go carefully over them and see that they are perfectly plumb and the cross pawls level, and if you stretch your chalk line fore and aft in a line with the L. W. L. at the stem and stern, it should also intersect with the waterline on each mould. If it does you can rest assured that your moulds are set up properly. Fasten some stays from one mould to another and start to bend and fasten on the battens. For these you will need some nice, clear pieces of yellow pine or fir about 1 1/4 x 1 1/2 inches; if you get them long enough to extend from end to end in one piece so much the better, otherwise you can use shorter lengths and let them lap by one another. Fasten the end of one of the battens in the rabbet on stem, bend carefully around the moulds and fasten to same with long thin screws, putting washers under the heads of same to prevent them pulling through the battens. Set the first batten so that the lower edge touches the mark representing the sheer line on each mould; when you get to the transom you will probably find that the bevel of the cheek pieces does not allow the battens to bear the entire width, and in that case it must be pared until the batten has a good bearing, and the same thing applies to the other battens where they are fastened to the transom and stem; you must also see that there is the right bevel cut on the edge of the transom. It would be advisable to put about six battens on a side, space them about the same distance apart. If you have been careful in making and setting the moulds, you will find that the battens touch each one and at the same time have a nice fair curve.
Engine Bed Details
The frames, or timbers, should be cut from straight grained white oak; if you can procure some stock that has not been dried you will find it much easier to bend when it has been steamed than the seasoned stock. Under no conditions should you try to use kiln dried stock; it is almost an impossibility to bend it, and even if you do succeed in bending it you will find that it has a natural tendency to straighten instead of retaining its shape. The specifications call for the frames to be 1 1/8 x 1 1/8 inches, spaced 9 inches centre to centre. You will need 30 frames for each side. If, however, the frames from station No. 4 to the forward end of the shaft-log are in one piece from sheer to sheer, it will reduce the number of frames. You will need nineteen frames to run from sheer to sheer, and as you are liable to break some of them, it would be advisable to get out twenty-six. The longest frame will be about 14 feet, but you had better get 16-foot lengths; there are twenty-two short frames required, and if you are using 16-foot stock you can cut the pieces in two and use for the short frames. Don't forget that you may break some of these and that it is a good plan to get out a number of extra frames; even though you do not break a great number they will not be wasted as they can be used for the floors.
Method of Bending Frames
Mark off on the keel the spacing of the frames, taking care not to measure along the top of the keel but in a straight line, and it is a good plan to mark the position of the frames on the centre and upper batten as this will save considerable time when you are bending in the frames. Put some of the frames in your' steam box and let them stay until they are well saturated, and are soft and pliable. It will probably take from 20 to 40 minutes, according to the amount of steam you have, and bear in mind that you do not require dry steam, it cannot be too wet. Having satisfied yourself that the frames are sufficiently well steamed you can proceed to bend the frames to the battens. If you have put in some of the long frames you can start anywhere along the widest part of the boat, gradually spring the frame down until it touches the keel; then, bearing your weight on same, work upwards on either side, fasten the frame to the keel with galvanized iron boat nails and clamp it to the battens, taking due care to see that it fits closely to the battens and stands perpendicular. There will be no trouble about it bеing perpendicular if you bring the edge to the mark on the battens. There is no need for me to tell you that this part of the work would be a great deal easier if you can have someone to assist in bending and fastening the clamps; it will also save you considerable climbing up and down, for the best way to bend these frames is to get inside of the framework and bear your whole weight on them. If you have only a few clamps you will probably need them for the next frame, and if so you can remove the clamps one at a time, and fasten the frame" to the bаttens with a wire nail through each batten. By the time you had bent in a few of the amidships frames — which are the easiest to bend in — you will have grasped the situation and find that there is nothing very difficult about this part of the work. The frames at the forward end will require a little more care as they must be cut to fit the sides of the stem and as they do not set square with the battens, you will have to twist them so that they fit close to each side of the battens. The frames aft of the forward end of the shaft-log will have the heels fitted in the mortises in the cheek pieces and fastened to same. These frames will also have to be twisted to get the right shape to make them set close to the battens with width of the frame, and a large monkey wrench would be of valuable assistance in twisting the frames. When you have finished framing you can put in the floors. These are to be 1 1/8 х 1 1/8 inches and should be about 3 feet in length. Beginning at station No. 4, all the floors should be on the after side of the frames until you reach station No. 14, and from this point aft all floors should be forward of the frames. Bend in the floors and fasten to the keel, then put three fastenings through the side of floor and frame on either side of the keel. For this purpose it is a good plan to use a galvanized wire nail, if the fastenings are to be of galvanized, iron as specified for this boat. The floors aft of the shaft-log are not bent to shape, but are to be cut out of 1 1/8-inch oak; cut them so that they fit over the upper side of the horn timber and the shaft-log and shape the underside the same as the frame; fasten to the horn timber and shaft-log and also through the sides of the frames. It is a good plan to cut a piece out of the corner of these cut floors or else bore holes through same so as to allow any water that may run in aft to find its way to the lowest point, and now that I have brought up the subject of limburs, I will call your attention to the fact that there has been no provision made for same in this boat, the frames and floors are small and to cut a limbur in them that would be of a suitable size would materially weaken both the floors and frames and I would suggest that you do not cut in any limburs, but when the boat is planked, take some Portland cement and pour in each bay until flush with the top of the lowest frame and in this manner you will have a clear passage for the water and no obstructions. This is an advantage in a motorboat, for it enables one not only to clean it out easily, but also when the craft is laid up in the Fall, it is much easier to remove the surplus oil and grease that will collect in the bottom of a boat of this description, no matter how careful one may be. If, however, your mind is set on having limburs cut in the frames, this is the time to do it, before you start to put on any plank, etc.
Figure 9
When you have completed the frames you can proceed to get out the planking. Fig. 9 shows a half section of the boat at station No. 12 and you will note that I have shown thirteen planks on each side from the garboard to the sheer strake. It is not necessary to use exactly this number of planks to a side; some builders prefer wider planks and of course there would not be as many if they were wider. However, it is better to use the narrow plank. The garboard, or plank next to the keel, is usually the widest and the planks narrow from that point to the turn of the bilge upwards where they should all be of one width with the exception of the sheer strake, which is usually made wider than the next four or five planks below it. The specifications call for yellow pine planking and if you use this material, there is no reason why you should not have it in lengths of about 28 feet, or long enough to reach from end to end without any butts. If you are unable to obtain the requisite lengths, the planks can be butted, and again if you cannot procure yellow pine or fir, you-could use cedar, cypress or white pine. Either of these materials would make good planking. As it is easier to put in the engine bed before the lower planks are put on, I am going to suggest that you start to put on the sheer strake first; select your plank and plane to 3/4 inch thickness, and before you can proceed to mark the shape of the sheer strake, you will have to find out the shape of this plank, and in order to do so, it is necessary to take a spilling. To do this take a piece of pine or cedar about 3-16 or 1/4 inch thick, б to 7 inches wide and about 26 feet in length, this is called a spilling batten or staff, and can be made up of two pieces fastened together if these are easier to obtain than one length. Bend this naturally around the moulds below the marks representing the sheer line, and with some small wire brads secure it in position, taking due care that the edge of the staff does not cover any of the marks representing the sheer line; take your pencil compasses and set them to such a width that the radius is slightly in excess of the widest place between the edge of the staff and sheer line, place the point of the compasses at the sheer line on each mould and sweep in an arc on the staff, mark the end of the staff where it intersects with the rabbet in stem, remove the staff and fasten it to the plank you intend to use for one of the sheer strakes, and with your compasses draw an arc, the point of the compasses being set on one side of the are on the staff. Then put the point of the compasses on the other side of the arc on staff and draw another arc on the plan. This arc will cross the first one drawn, and where these two arcs intersect or cross is the point you must work to when you draw the line representing the upper side of the sheer strake. You must repeat this process at each place where you have drawn an arc on the staff, and when you have them all marked, remove the staff, select a good batten and bend to the required shape so that a line drawn along the edge of same will cut through each of the arcs you have drawn where they intersect.
Figure 10
Figure 11
Fig. 10 will help to explain this trifle more clearly, and Fig. 11 shows the staff fastened to the plank and the arcs marked on same and also the plank. To obtain the shape of the lower edge of the sheer strake you can mark at the centre the extreme width, which I have figured at 5 inches, then mark the width at each end, bend a good strong batten to these points until you have a fair line and cut to same. Bear in mind that you need two these pieces and therefore it is advisable to saw out another one for the opposite side before you begin tо fasten it to the frames. The sheerline as shown on the plans represents the height to the top of the deck and though this is short, it should be taken into consideration. The deck plank is to be 7/8 of an inch in thickness; therefore the sheer strake should be 7/8 of an inch below the sheerline marked on the moulds. Fit the forward end to the rabbet on the stem and fasten it, taking due care that the upper edge touches the marks 7/8 of an inch below the sheerline; hold it in position with clamps and fasten to the frames, countersinking for the nail heads so as to allow of their being covered with 7-16 inch diameter wood plugs. The after end must be carefully cut to fit the bevel of the transom and be well fastened to the cheek pieces on same. It is a good plan for the amateur to mark on the edges of the moulds or frames the width of the planks. Fig. 9 shows a half section at station No. 12 and you will note that there are thirteen planks to a side including the sheer strake and garboard; the upper strakes, representing the raised sheer, I have not taken into consideration as you are working from the sheerline. Starting from the sheerline on the mould representing station No. 12, make a mark 7/8 of an inch below same, then another one 5 inches below that. This will represent the sheer strake. Now start at the keel and mark 8 inches up, from this mark 7 inches upwards, and another 6 inches, and the remaining spaces you can divide equally into nine spaces. These will represent the greatest widths of the planks, and you should proceed to mark on the stem the height of the upper edge of the garboard and the lower edge of the sheer strake which should be considerably narrower at this end than at station No. 12. The transom should be marked in a similar manner and then, if you desire, you can mark out on each mould the widths of the planks; of course the garboard and the next two strakes will be wider in proportion than the others, but it is a simple matter to figure this out and have a good curve to all the planks.
The professional builder does not always lay out his plank in this manner, and some of you may know a much better method; this article, however, is not written for the practical boat builder, but for the amateur. Inasmuch as you are not going to fit in the garboards at present on account of the engine bed, we can at least work to the width laid out for the garboards and other plank and proceed to get out the next plank below the sheer strake. You can take a spilling from the lower edge of the sheer strake in a similar manner to the spilling of the sheer strake, except that in this case you work from the lower edge of the sheer strake in sweeping in the arcs on the staff. Be sure to make some marks on the sheer strake and staff so that when you have cut out your plank you can bring them to the same position as you had when you took the spilling. Mark the widths of this plank at intervals, bend a batten to it, draw a fair curve through these points and you have a line representing the lower edge of this plank. Cut out two planks to this shape. If you take this plank and bend around the moulds in order to see that it fits, you will most probably find that the seam is open quite wide in the centre of the boat but it closes at the stem and the temporarily. Now take your level and bring it up so that it just touches the underside of the line, see that it is horizontal and make a mark on one end of this template; repeat the operation at the opposite end, draw a line through the point, and you have the line of the centre of the shaft marked on same.
You can now proceed to get out the two bearers, adding to the size marked on the template the thickness of the frames, or better still, a quarter of an inch in excess of same, to allow for trimming, or, if you prefer, you can get out a template to fit exactly over the frames and floors and mark the shape of these bearers from same. It is simply a matter of choice which method you use. If you cut the underside of the bearers to the shape of the template, set in position, mark both sides with the compasses in order to get the height of the frames on the inside and outside, then mark the frames and floors, remove the bearer, cut to shape, and see that it fits properly; repeat this operation on the piece of stock for the other bearer, set in position, clamp it so as to keep it from moving and ascertain that it fits properly and is in line both fore and aft and also in a vertical position. If there is any part of these bearers that extend below the underside of the frames, you can easily remove the superfluous stock when you have the bearers fastened in, before you start to plank. The cross logs are 2 1/2 inches thick, and for these you will need one piece of oak 6 feet long and 1 foot wide, and another piece 5 feet long and about 8 inches wide; set these pieces on, the keel and the places indicated on the plans, or to suit the base of your engine if it is a different make or style, fasten them temporarily and mark out the shape of the underside of same on the forward and after sides; if you do this properly you can cut to the correct bevel the first time, and they will fit close to the inside of the plank where this part of the boat is planked. Cut the forward pieces to a depth of 5 inches to allow the fore and aft bearers to fit into same for that depth, fasten them securely to the keel, and then put in the fore and aft bearers, cutting them over the cross logs, securely bolt to same, and fasten up through the unde side of the frames into the bearers. If the underside of the flange of the engine bed is below the centre line of the shaft a certain distance, the bearers will have to be cut away that amount in order to have the shaft in line, and if the under side of the flange is above the centre line of the shaft, the bearers will have to be raised; this should be ascertained before the upper sides of the bearers are finished.
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