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Bruce Roberts-Goodson




Spray Sailboats





For step by step Photographs of STEEL OR ALUMINUM PLANS & CUTTING FILES assembly click on one of the links below.
To read all about STEEL OR ALUMINUM PLANS & CUTTING FILES Contents & Assembly see text below the links.

The Bruce Roberts Steel or Aluminum STEEL OR ALUMINUM PLANS & CUTTING FILES contain:
All plate parts belonging to the hull, deck and superstructure that are accurately cut to size are included. The parts are marked with the appropriate part number and engraved matching marking lines to assist in the assembly and location of the part in its position. All framing, stringers, engine beds, 'T' sole bearers, deck beams, deck stringers and all exterior plating, plus 3 steel bulkheads and stiffeners is included. Windows and doorways are cut out as required.

In the case of radius-chine hulls, the radius plates a rolled to the perfect shape and NO fitting is required. Complete assembly and engineering boat plans supplied. A building jig is supplied with the STEEL OR ALUMINUM PLANS & CUTTING FILES.   Delivery is often included in the quoted price.

Cutting method is Plasma / Oxygen, ensuring highest accuracy and smooth edges. Plate parts are cut from either Marine Grade ALUMINUM or Grade ?A? Ship-building quality STEEL that has been coated with factory applied Sigma weld MC welding primer.  We use and recommend steel plate that has the official designation ISO standard 10474 or EN 10204 with 3.1.B certificate.

All pre-primed profiles belonging to the hull, deck and superstructure are supplied in sufficient quantity and are in factory lengths of 6 M / 20 ft, coated with factory applied Sigma weld MC welding primer.

Openings for windows and doors can be cut or only marked as per customer's preference. Bulkheads are supplied complete with stiffeners and are in accordance with Classification rules and safety regulations. Cold forming of plate parts is included where this requirement forms part of the design. Basic engine foundations are integrated into the construction.

A Setting up jig with the correct shape of the hull plates that can be used as building jig for the entire hull after reinforcement plus there is a extensive building manual including detailed drawings, parts list and welding instructions.

In these days where both the local authorities and the better informed builders themselves, it is important that the construction calculations are in accordance with prevailing Classification society so this factor is part of the preparation of any Bruce Roberts STEEL OR ALUMINUM PLANS & CUTTING FILES.

Each STEEL OR ALUMINUM PLANS & CUTTING FILES or set of cutting files comes complete with about 20 sheets of detailed assembly drawings with written instructions and check measurements for assembling each part of the STEEL OR ALUMINUM PLANS & CUTTING FILES. The drawings cover assembling the frames, setting up the building jig (supplied) on to I beams or similar base. These extensive drawings take you right through the welding up process from start to finish.
Also are included several sheets of detailed engineering drawings that cover the installation of the main engine(s), ?take home engine?, generating set, exhaust systems, fuel systems, fuel and water thanks etc.


Throughout these instructions we will use the word metal which may apply to steel, aluminium or copper-nickel. There will be variations between the handling of the various materials and these will be drawn to your attention as necessary. YOU WILL NEED TO READ and absorb all these instructions BEFORE you start the assembly of your STEEL OR ALUMINUM PLANS & CUTTING FILES. These instructions are intended to introduce you to building from a STEEL OR ALUMINUM PLANS & CUTTING FILES but are NOT intended to replace good metal boat building practice. If you are not already a competent welder then please seek assistance.

Few of you will understand (or want to know!) the huge amount of work that is required to turn any boat plan in to a cut-to-size boat STEEL OR ALUMINUM PLANS & CUTTING FILES. Every part has to exactly match that of its neighbor, the slots need to be exactly in the correct locations and everything must fit perfectly together to enable you to complete the assembly of the hull, deck, and superstructure with the minimum of problems.

Despite our best endeavors and attention to detail in developing the STEEL OR ALUMINUM PLANS & CUTTING FILES and the cutting of the metal parts, some parts may not fit or appear to have the wrong shape. Before rushing to cut and or shape parts to fit the hull, carefully check the drawings and measurements from the surrounding parts to ensure that nothing else is wrong.

The first thing to realize is that the STEEL OR ALUMINUM PLANS & CUTTING FILES differs in many ways from the methods you would use to build a metal boat from scratch. The STEEL OR ALUMINUM PLANS & CUTTING FILES is far superior to anything you could achieve by starting with the boat plans and delivery of raw steel plate and the various profile bars that are needed to build your metal boat.

Most metal boats built from scratch are built upside-down…most boats built from cut-to-size metal STEEL OR ALUMINUM PLANS & CUTTING FILES are built UPRIGHT. Not only is this a more appropriate way to assemble the STEEL OR ALUMINUM PLANS & CUTTING FILES but also it saves cost and inconvenience of having to turn the hull.

To make sure that you take notice of one very important piece of advice, we will state it here as well as at the appropriate time:


Failure to observe this advice will almost certainly ensure you will end up with an unfair boat requiring a considerable amount of filler. In any case do NOT OVER-WELD or try and run long welds at one time.

Depending on your location or delivery arrangements your STEEL OR ALUMINUM PLANS & CUTTING FILES may arrive on a flatbed truck or in a container. You should be aware of these arrangements before the actual date of delivery so you can make the necessary preparations to receive your STEEL OR ALUMINUM PLANS & CUTTING FILES.

The STEEL OR ALUMINUM PLANS & CUTTING FILES are normally packed on pallet(s) and can be lifted off the transport using a small crane, front-end loader, or similar equipment. You may find it more convenient to "drag" your STEEL OR ALUMINUM PLANS & CUTTING FILES from the truck or container using a pair or planks as a ramp. Once you have unloaded your STEEL OR ALUMINUM PLANS & CUTTING FILES you must make provision to keep it covered until assembly is underway. Make sure that the metal parts are not in direct contact with cement-based floors like concrete, as this will affect the Sigmaweld primer.

You should go trough the STEEL OR ALUMINUM PLANS & CUTTING FILES and identify each part or group of parts so you can store these in the order that they will be required. Due to the requirement of packaging for transport it is impossible for the STEEL OR ALUMINUM PLANS & CUTTING FILES manufacturer to stack everything in the order you will be using the various parts…you must take care of this. Later in this text we will suggest the order of assembling your STEEL OR ALUMINUM PLANS & CUTTING FILES so you will be aware of which parts you will need at each stage. If you do not find a particular part at this stage …DO NOT PANIC…there will be so many pieces that it will be easy for you to overlook one or two at this stage. If after several checks you find one or more parts missing then do contact the supplier of your STEEL OR ALUMINUM PLANS & CUTTING FILES so they may put the matter right.

FOR MOST HULLS: The first item you will need is the setting up jig. The metal "castles" that come as part of your STEEL OR ALUMINUM PLANS & CUTTING FILES will support the transverse profile jigs. The setting up jig is intended to get the assembly of your hull started and is NOT INTENDED TO SUPPORT THE BOAT during the entire building process. After you have the bottom plates tacked together you should consider adding extra support and bracing to the structure.

For most hulls, the general assembly sequence is:

Assemble the jig.

Bottom plates into the jig; line up the markings for frames and tack weld together.

Assemble web-frames in accordance with drawings.

Position bottom longitudinal stiffeners on bottom plates (very small tack welds only).

Position frame over longitudinal stiffeners onto bottom plates, starting with the middle frame, work your way aft ships and then from the middle to the bow.

Tack-weld frames in position, observing the markings on the plates indiCATAMARANing the correct position of the frame. The direction of the arrow in the marking indiCATAMARANes the direction of the plate thickness. Always start tack welding at the bottom centerline working your way outward.

Tack-weld bottom longitudinal stiffeners to web-frames

Insert side longitudinal stiffeners into web-frames and continuously check the frame spacing.

Position side-hull plates starting at transom and tack weld to web-frames only.

Tack weld longitudinal stiffeners to side and aft-hull plates. For hulls with build-in spray-rails start at the bottom and work your way upwards.

Position rear hull panel (transom) and tack-weld to bottom and side plates.

Position longitudinal deck-stiffeners and tack-weld to web-frames.

Position deck-plates starting aft and tack-weld to web-frames only.

Tack-weld deck-longitudinal stiffeners to deck plates.

Position superstructure walls and tack-weld to web-frames.

Position and tack-weld roof-plates to deck.

This is the recommended sequence for most type hulls. Depending on the facilities of your workshop and building site, variations may be required or preferred. The better equipped your workshop is with overhead lifting equipment and equipment the easier and more smoothly will your job proceed. We do recommend that you read some of the literature available on metal boat building, which will answer many of those general metal boat building questions that are sure to need clarifying as the project proceeds, if only to get familiar with the terminology of parts and components of your STEEL OR ALUMINUM PLANS & CUTTING FILES. Contact your supplier for titles available in your area.


The Spray and similar hulls are unusual in that the keel structure should be assembled at the same time as the bottom plating. Take care that you do not "squeeze' in the tops of the keel, use the webs as spacers. After you have positioned the bottom plates, the keel sections and the transverse profile jigs in their correct location you may start to tack weld the bottom plates to the keel sides.


Sailboats with deep keels will have the keel installed after the hull is completed. The "canoe body" should be built from the bottom of the hull upwards in a similar manner used to assemble a powerboat hull. The webs will be arranged so you can later add the keel after raising the hull into the correct elevation.

The idea of this method is to allow you to work on the hull deck and superstructure while the boat is lower and thus more accessible. The exact method and order of assembly may depend on the availability of lifting equipment and your general work environment.


In most cases you can start by laying the bottom plates in the transverse profile jigs and with the aid of the "castles" so position the plates that you can start to tack the hull plating together along the centerline. You will next be able to install the bottom sections of the frames and webs in their correct location.


Attempting to construct a metal boat STEEL OR ALUMINUM PLANS & CUTTING FILES leads us to believe that at least the basics of arc and or Co2 welding are known. If in doubt about your abilities to weld, improving your skills on some scrap pieces of metal would be advisable as there are no great secrets in general steel welding but practicing would set you of to a good start right at the beginning.

Welding aluminium or copper nickel should not be attempted without proper knowledge of the materials and welding sequences involved and should always be carried out in covered and clean surroundings.

The metal STEEL OR ALUMINUM PLANS & CUTTING FILES are constructed in such a manner that the strength of the hull & deck is created from the build up of the frames and stringers as interlocking sections, HEAVY AND CONTINUOUS WELDING OF FRAMES AND STRINGERS SHOULD BE AVOIDED AT ALL TIMES.

Especially important for all plate joints during the assembly of the hull is DO NOT APPLY CONTINUOUS WELDS. The plate joints should be ONLY TACK WELDED in three locations, one weld at the each of the ends of the join and one in the centre of the join. These tacks should be no more than 2 inches or 50mm long. If you weld the plates on the floor you will end up with a "hard-spot" in the hull plating.

All parts of your STEEL OR ALUMINUM PLANS & CUTTING FILES are cut to a precision of 2 mm and are designed to be welded together without any opening between the parts. Some plates will need to be beveled before tacking in place or you may prefer to make the bevels after you have tack welded the plates and just before running the final welds. In all cases good metal boat building practices will prevail.

After the hull & deck are COMPLETELY TACK-WELDED together, the process of finishing welding can take place. The secret of creating a fair hull & deck after tack welding is completed is to use a fairly high amperage and speed setting of your welding equipment. Welding with too low amperage and slow speed will create lots of heat on the spot and less penetration of weld material in the seam, causing strength problems and lots of grinding weld material away to obtain a smooth surface afterwards. This in turn would weaken the weld again.

Using common sense and practice should leave you to create a smooth and fair hull & deck structure with very little distortion. IF IN DOUBT ABOUT YOUR SKILLS, SEEK ADVICE.

Any metal construction company or competent welder can help you with the basics. Always observe personal protection and safety regulations.


With the arrival of your metal STEEL OR ALUMINUM PLANS & CUTTING FILES, you received a packing list containing the names, numbers, and quantities of all the parts in the metal package.You also received one or more large-scale drawings showing all the parts as flat surfaces and more or less grouped together as they appear in the metal STEEL OR ALUMINUM PLANS & CUTTING FILES and a number of small drawings showing the assembly of the frames with the appropriate measurements.

Studying the large scale drawings will give you a first insight in the position of the various parts and it becomes apparent that the numbering is as much as possible a logical sequence of the way the parts assembly progresses.

Prior to using these drawings, we advise to make some copies of the drawings or parts there off or cover them with plastic as they could easily be destroyed during the construction and welding.

Using the packing list and the drawings you can now make a check to see if all the parts are present. For ease of recognition you will find that frames etc. are numbered with 4A, 4B, 4C etc. thus every time you find a number 4 and extension A or B etc., they belong to the frame no.4.

The cutting, collecting, and identifiCATAMARANion of parts during production is a manual process. This is why parts may be given incorrect numbers and even get lost, in spite of our thorough quality and quantity control procedure. Checking and verifying all parts against the packing list provided and keeping unidentified parts aside until the end enables you to identify the missing parts and incorrect markings on parts for clarifiCATAMARANion with the supplier.

Apart from the plate parts, your STEEL OR ALUMINUM PLANS & CUTTING FILES also includes a selection of profiles, supplied at factory lengths, as listed the Packing list. Each bar needs to be cut to the length required in its position in the construction as detailed on the Construction Plan provided in the set of drawings.

Now that you have collected and sorted all the parts, the frames can be tack-welded together by using the small drawings and the given measurements as reference.

Prior to welding, use an angle grinder and create a "V" of approx. 60 at the seam to be welded.

This means 30 angle at each plate edge. Doing this will give you better penetration of the welding material, adding strength to the hull. We use the word tack-welding again as it would be tempting to finish welding the seams fully.

Some models have flat or angled bars added on the inside edge of the frame plates for additional strength. Check the Construction Plan provided. These so called Girders are best fitted as soon as the frame parts are tacked together, before placing the frame in its position in the hull.

On larger boats it might be an advantage to only weld the bottom parts of the frames together and put the side frames up after the frames are in place on the bottom plates. Your own judgement is important here.

Having prepared all the frames in this manner it is now time to prepare the building jig.

With the metal STEEL OR ALUMINUM PLANS & CUTTING FILES you have received 2 or more jig parts as shown below.


The supplied jig parts could be placed on a concrete underground, leveled, and stiffened.

In case no solid underground is available, the use of a couple of heavy RSJ’s picked up from a

local scrap dealer could do the trick. The distance between the jigs is determined by the position of each frame (web) in the hull, whereby the jig number is the same as the frame number (f.e. Jig-part J5-2 is at frame 5).

In case the "jig" parts stay in place during the entire construction, it would be advisable to tack-weld a flat bar across the top of the plates to spread the point loading and avoid possible damage to the hull plating.

Now place the bottom plates on the prepared jigs or building frame and tack-weld together at a number of points.

We refer here to paragraph 2 in relation to sailboats like the Spray series where also the keel is placed under the bottom plates at this stage.

For those of you who are new to this type of boat building, having placed the bottom plates on the jigs, it seems they are never going to fit.

Start tack welding at the location roughly in the middle or somewhat aft of the middle after lining up the lines on the plates and position of the plates.

When you now go forward or backwards from the tack-welded position you can help the plates get in shape by having some helpers pull up the sides and using a trolley jack underneath the middle join of the plates until the seams touch. Now tack-weld at this point and go to the next position. At the bow you would probably need a hand block and tackle to pull the sides of the plates together as some tension will be experienced here.


Having finished tack-welding the bottom plates together, start placing the longitudinal stiffeners at the markings on the bottom plates whilst lining-up the slots with the position of the frames (webs), as indiCATAMARANed by lines on the plates and use the large scale drawing(s) as reference. Only tack-weld these longitudinals to keep them in place for the time being. As frames will have to be slotted over these longitudinals, we recommend to tack-weld only to the bottom plate in the middle between frame positions, which allows you to align these when putting the frames in position.

Then start placing the frames (webs) which slot in the longitudinals. Position the middle frame first and tack-weld it to the bottom-plates in the centre, then pull up the bottom plates towards the frames until they fit snugly and tack-weld.

Depending on the shape of your hull, we recommend to work your way aft first, thereafter from the middle to the bow.

If you have put the frames together completely, use some temporary bracing on the upright sides of the frames, as they are likely to flop about a bit.

Now we place the stringers in the slots of the frames on the sides and slightly tack-weld at some spots to keep them in position.

We do emphasize again, ONLY TACK-WELDING.

At this stage you have already created a strong and solid base of the hull and the time has come to bring the side plates into position. This is best done by using a simple overhead gantry or the use of a forklift truck.

Pick up the side plate(s) by using a plate clamp on a chain connected to a block and tackle or forklift leg, make sure the plate is more or less in balance when it is hanging in the air and bring to its allocated position.

Use a helper to put a point of the seam in the right position and tack-weld.

Continue by moving the plate up or down a bit with the block and tackle until the entire side is in position and tack-welded. Place some tack-welds on the uprights of the frames as well.

The side plates nearer to and at the underside of the bow will show some tension and can be pulled in place by attaching a chain on the outside of the plates and pulling them into position.

To attach a chain and/or block and tackle to a plate, tack-weld a temporary eye or something similar to the plate. By only welding on one side of such plate(s), you can easily remove these again by bending this plate until the weld breaks.

Note: In the case of radius chine sailboats, the radius chine sections are not used at this stage; we will come back to those later.
Next the transom plates, bathing platform where applicable, stern plates and all other plates belonging to the hull are offered up in position and tack-welded in position.

Especially where rounded corners are used, offer the particular plate up to the position it is to be used and check or make the correct radius in the plate prior to tack welding.


Now the deck plates, superstructure, fly-bridge where applicable and all other super structure plates can be offered up to the hull and tack-welded into position using the gantry or forklift truck to lift them onto the hull.

Do make sure the support strip(s) under the deck and cabin roofs, where applicable, are placed first in its slot(s) in the frames and beams.

In those cases where professional lifting equipment and space is available, an option would be to tack-weld the superstructure together at floor level, braise temporarily and than lift the entire sub structure onto the hull.

Having tack-welded the entire boat together, you now turn your attention to the radius section(s).

We have supplied you with the appropriate amount of section to fit in the left over opening in the hull.

As you checked the metal STEEL OR ALUMINUM PLANS & CUTTING FILES on delivery, you have seen they are all similar sections, just one radius rolled into them.

Now you can carefully hold a section against a position on the opening in the hull and using a helper scribe the plate with a sharp tool or pencil and grind, nibble or cut the edges until the plate fits in position.

Tack-weld into position and continue until all radius plate sections are in place.

CONGRATULATIONS, you are now looking at the shapely result of your perseverance.

Of course you have run into some difficulties during the building process and maybe even cursed a couple of times but it must be clear by now why we told you time and time during this manual ONLY TACK-WELDING. Any possible mistake you may have made was fairly easy to rectify, as you only had to grind a couple of small welds away.

However careful the cutting of the material was prepared and cut, the material can behave unexpectedly, for example the grain in the plate runs diagonal and will resist shaping into the required form. This will require additional effort and force to get the plate to fit.

Although we aim for perfection, mistakes do occur, however the general consensus is that if you have to cut or reshape a plate (with the exception of radius plates) somewhere something is not right.

Now the time has come to finish the welding process.

Firstly, finish welding all the seams between the frame sections applying a full weld. All slotted connections between frames and bottom and side longitudinals are to be welded in full on at least two opposite sides of the connection.

Then apply intermittent welds on all frames and stringers to the hull and superstructure plating using the rule 50 mm. (2") weld, 200 mm. (6") clear, 50 mm. (2") weld. Alternate the weld one side of plate, other side of plate and so on.

DO NOT CONTINUOUSLY WELD ON ONE SIDE OF THE HULL but weld a bit one side, the other side and so on to avoid pulling. Do not underestimate the forces coming free when welding.

Now the hull should be welded.

In case you have not made a 60 "V" between the seams of the plates yet, no problem, use an angle grinder and cutting disc and cut a groove in the plate where the seam is located. Not as nice as having a "V" made first but the result will be the same. As explained before, alternate welding from side to side and finish the welding process.

The hull under the waterline must be welded inside and out. All other welding can be done one side only.

Grind away surplus welding whereby we advise to pre-grind the welds with a heavy duty grinding disc and finish grinding with one of these softer flexible discs, ready available in the trade, to avoid having to use filler on the weld seams.Clean the surface and apply a coat of primer and the basics of your pride and joy are ready for finishing.

We recommend you postpone the engine as long as you can, not because of the weight, more because these parts cannot be placed in their final position at this stage and tend to be very much in the way / get damaged easily as long as they are only temporary supported inside
the hull.

If you still prefer to lift the engine in, no problem as long as you make sure that you spread the weight of the engine over at least three transverse frames and always over two cradled frames.
Use some serious timber beams running parallel to the CVK and support the beams on the lower horizontal part of the transverse frames.

Obviously best to skip # 9 which is still loose by putting some extra dunnage on the adjacent frames to raise the timber beams. This will also give you sufficient room to run final welds at the bottom, especially important for the welding of the keel from the inside.

Handle the generator in the same way. Before you do all the above, make sure your hull plating fully follows and touches the cradle parts that have the same shape as the hull on all stations.

Finally, when placing the engine in it's temporary position, put it in a place not interfering with your longitudinal alignment check which should be done at regular intervals during the assembly process.

For the tanks, assuming you will be using pre-fabriCATAMARANed tanks, I would recommend to leave those loose and get them inside the hull when convenient. (normally make nice chairs or tool shelves during the assembly). Weight is not an issue here.
The shape and dimensions of the tanks should always be checked in place (as would the fuel-tightness), very difficult to modify tanks or tank brackets when hull closed.


Due to the cost and time involved in developing complete metal STEEL OR ALUMINUM PLANS & CUTTING FILES to our many designs plus the different methods of putting  STEEL OR ALUMINUM PLANS & CUTTING FILES together we are developing a complete range of new boats, designed to parallel our existing designs.

Some are very nearly identical to the original design but even these designs do have different scantling sizes and stringer placements. While there are complete construction drawings for the STEEL OR ALUMINUM PLANS & CUTTING FILES at present there are no complete boat plans and full size patterns for building from scratch.

With only the very slight differences mentioned above from our full construction boat plans any Bruce Roberts design can be modeled into a STEEL OR ALUMINUM PLANS & CUTTING FILES boat. Contact Bruce ROBERTS CUSTOM YACHTS for details. For an explanation about STEEL OR ALUMINUM PLANS & CUTTING FILES, their construction and assembly please read on..

Over the past thirty years the Bruce Roberts Design team has produced hundreds of designs and developed numerous building techniques from which over20,000 boats have been built world wide, including power and sail pleasure boats, commercial and fishing boats. From this we have gained a depth of knowledge and experience allowing us to participate in advanced computer development for metal boats which has resulted in a range of designs to 20 meter’s and which are now available in "flat pack" steel STEEL OR ALUMINUM PLANS & CUTTING FILES form for delivery world wide. All steel is "Grade A" with Lloyds certificate and cut on an "NC" driven plasma-oxygen cutting machine for minim distortion.

Radius chine STEEL OR ALUMINUM PLANS & CUTTING FILES are available as well as single and multi chine packages. These STEEL OR ALUMINUM PLANS & CUTTING FILES appear to provide the elusive link between computer-aided design and the latest fabrication techniques. Individuals and shipyards, particularly small enterprises can now benefit from modern cost-effective methods without major investment. With these techniques, you can obtain millimeter accuracy with great surface finish. To quote from one builder, Roger Lasham, in the UK, "I had completed the bottom plating which was only tack welded in place, yet when it rained overnight and the wind pulled the tarp aside allowing water to collect in the bow, it did not leak away so accurate was the fit".

Steel STEEL OR ALUMINUM PLANS & CUTTING FILES only require semi skilled labor for assembly and all steel plates, excepting 3mm, are shot blasted and primed with "Sigmaweld-mc" zinc rich primer which is especially formulated to allow the builder to weld the plates without destroying the adjacent prime coating. Another feature of this weld primer is that it does not give off toxic fumes, nor is there any weld "splatter". Each STEEL OR ALUMINUM PLANS & CUTTING FILES is "computer developed" and the parts are all nestled including all the plating so that you can easily assemble the hull, deck and superstructure in a very short time compared to conventional building and there is no wastage. All windows, doors, scuppers, prop and rudder tube holes are cut out and a pre-cut building cradle is supplied. Bruce Robert is able to develop any existing design into a steel STEEL OR ALUMINUM PLANS & CUTTING FILES or provide modifications to an existing design to be incorporated into a STEEL OR ALUMINUM PLANS & CUTTING FILES. Labor saving can be as much as 75% on conventional hull building times.

These metal STEEL OR ALUMINUM PLANS & CUTTING FILES are produced in such a manner that even an experienced builder will save many hours on the preparation work because the plates, frames, longitudinal and stringers and further necessary parts for the hull and superstructure are supplied pre-cut and accurate. No trimming is required. All the parts fit perfectly. On radius chine STEEL OR ALUMINUM PLANS & CUTTING FILES, the radius panels are rolled to the correct radius and you will only need to trim the edges after you have installed the rest of the hull plating which, does not need trimming. All plates have marking lines for positioning of frames, etc. and all plates are numbered and come with clear instruction and part drawings showing all items. Maximum plate size is 6 x 2 meter. Metal STEEL OR ALUMINUM PLANS & CUTTING FILES are available in steel or aluminum.