AMF Boat Company Limited

AMF Boat Company Limited
Offshore Power - Alloy Boat Builders

Thursday, August 25, 2011

Production Process of AMF Pro Sport Series 580, 610 & 660 Boats

Use of jigs is a substantial part of the quality control in the production of AMF boats. Just about all of AMF construction is using jigs and the jigs are very substantial structures at that. In New Zealand not many boat builders use jigs and when they do they are normally flimsy structures. By using substantially strong jigs AMF can be sure to have the same hull shape time and time again, not unlike a glass boat does from a mold. Before construction starts the jig is measured and checked. AMF have jigs for wheel houses, foredecks, side pockets, transom selves, the dash, targa tops, bait boards, boarding platforms, ladders, rocket launchers, even our own in house bollards. A lot of NZ boat builders build hulls straight off the floor. And a jig that twists out of shape when it is shifted is only going to build a problem into a boat.

All aluminium used in the construction of AMF is highest grade plate available. Plate used is 5083, Tread plate used is 5251 and all extrusions are 6061. If 5083 were rated ‘out of ten’ for marine use it would get a ‘ten’, to go one grade down in plate grade you would need to rate that plate at ‘five out of ten’ it is half the rating, then some boat builders are using grades of aluminium that you could only rate as ‘two to three out of ten’ suitability for marine use. It is important to check what the marine grade of plate being used is and is it being used on more than just the hull plates. AMF use only 5083, the highest marine grade available and we demand the best unmarked plate as our finished product, as the whole boat is clear Nyalic finish over acid washed aluminium. No Paint or bog filler to hide bad material or workmanship. AMF handle their plate as though it is glass.

AMF are very much about crafting a hull to achieve the ultimate build and performance. First of all a 10mm x 75mm Keel Bar is laid on the jig, this has a slight rocker in it. A rocker in the keel attributes to the hull being able to break free of the water surface as the hull powers onto the plane. This way the boat travels more efficiently and is able to be trimmed for all conditions, a very important ability in a big following sea or bar situation. Some boat builders get a sheet of aluminium and put a fold to create two hull plates; this gives the hull an absolutely straight keel with no shape to it at all.

Box beams are placed on the jig and these are trimmed to create a hull shape. The box beam creates a full depth girder system between the hull plates and the main deck. With this construction method there is no way the hull or deck will move and the hull won’t buckle out of shape, this also means your AMF won’t suffer a loss of performance over time. Mini bulkhead frames are fitted with in the box beams to add to the stiffness and then a bulkhead frame is added at the front of the box beams and at the front of the fuel tank position. The box beam is far superior to the old stringer system, 50x5mm stringers are still common with a lot of boat builders and often break away, crack, or wear through the bottom plate. If aluminium can move it will eventually fatigue and crack. AMF is built solid!

All of the welds from Box beam to hull plates are full length longitudinal, AMF don’t use lateral welds on the hull plates with water pressure hull plates push in at the hard point of a lateral weld and this again is another reason a hull can lose its fair shape. This won’t happen with an AMF. Each hull has 25 full length longitudinal hull welds alone, this at minimum of five meters per weld is around 125mtrs per boat. If a welder could work non stop this would be six and a quarter hours of continuous welding.

The transom is welded to the box beams and then one 6mm hull plate is welded full length to the keel bar and transom, then pulled around under tension and bolted to the jig. Then the other 6mm hull plate is welded full length to the keel bar and transom, then pulled around under tension to the jig and bolted down.

The belting is a 50 x 50 radius edge with its beefy 5mm wall thickness; this extra thick wall thickness isn’t easily dented and is handy when maneuvering around wharfs and Jetties. Far better than flimsy PVC bumper strips most boat builders use that damage so easily. This belting is welded to the keel bar at the bow and then pulled around the jig with a block and tackle and welded to the top of the transom.

Now its time for the side plates to be fitted, these side plates are again like the hull plates pulled around under tension and tortured into shape. Another benefit of 5083 and its High Tensile strength is it ideal for our compound curve construction, meaning the plates are pulled in both directions to create a compound curve giving egg shell type strength. This is far better than using a lower grade of alloy and using pressed ribs for strength, a technique very commonly used in aluminium boat building.

The chines are 50 x 50 x 5mm angle bar, after the side plate has been fully welded to the bottom plate this angle bar is pulled around and welded under tension. This is fully welded both side and when the inside hull weld is complete the chine will have four full length welds. In the worst case some boat builders will grind the out side weld off, and only have one and bit welds holding the chine together. These reverse angle chine works as a fantastic water deflector and will manage to keep the screen dry in most conditions. Some boat builders add a flat bar deflector to the outside of the bow to keep the boat dry, but in some conditions this can catch under the water and pull the boat over on its side.

With both bottom hull plates having each received a full length weld to the keel bar it is now time to fit the 5mm doubler pad or wear strip this is a 100mm wide and tapers off to a vanishing point in the bow. This doubler pad is great for the wear and tear of launching of a beach or the hull touching the concrete ramp. With six full length welds holing the keel together you couldn’t get a stronger hull. As a comparison some boat builders don’t use keel bars or wear strips, and once they grind the outside weld off they are left with only a one and half welds holding the keel together. Badly designed/built aluminium boats will typically crack in the chine or keel.

The outboard pod is fitted. Platforms are made with curves by cutting tread plate with curved corners and then pulling an extrusion around this shape then welding and finishing. this again is far more complex and time consuming to fabricate than the easiest option of simply putting two down turn folds in a piece of plate welding the corner join and welding to the hull. A 15-20 minute process verses three hours for our platforms. Platforms are added, and then the platforms are built into buoyancy pods on each side of the engine bracket. Complex curves are used to create buoyancy pods with style and shape. This adds phenomenal strength to the transom of the boat, two more separate reserve buoyancy chambers, and extra floatation for handling the extra weight of four stroke outboard engines. Building these extra buoyancy tanks adds another day to the build.

At the transom, bottom and side plates over run past the transom leaving a full visible weld in stead of being ground off flush, this makes for a far stronger transom than one that has had its welds ground. If the hull was ground the transom has a far greater chance of staying intact, where as a transom that has had the welds ground can be ripped out.

After an AMF hull comes off the jig, the hull is bolted to the floor and has large steel beams fitted and chained to the floor to insure the hull measures the same as it was on the jig, then the hull is fully welded along every join.

The anchor bin bulkhead is fitted and fully welded, and then the base to the anchor bin is welded in place. There is a hefty lug welded in each anchor bin to shackle the Anchor rope off to.

The fuel tank 580 has a 120 litre, 610 has a 160 litre and 660 has a 220 litre fuel tank that has been pre made and this is suspended between the box beams and welded in place. It is better to weld the tank in place that to screw it in place with s/s screws that will only react with the aluminium and look messy. AMF have never had a fuel tank that has needed to be removed and one did need to be removed it could be removed quickly and efficiently with a skill saw along the welds. Each fuel tank is constructed of 4mm 5083 Marine Grade Aluminium with a 5mm Tread plate top to the tank, this top of the tank makes up part of the floor. Each tank has baffles with small cutaways in the corners and centers of each baffle. The 580 has three baffles, 610 four baffles and the 660 five baffles. The top of the tank then has drop down stiffener/baffles every 200mm. this helps control the movement of fuel and also keeps the floor sturdy and movement free. It certainly isn’t a nice feeling walking on a “soft floor” in an aluminium boat.

The each fuel tank has a large expansion box at the rear of the tank that comes up through the back shelf. This expansion box fills to floor level and breathes off the top of the box. This means that on level surface like for example at a fuel station the fuel tank will fill as fast as the pump will operate and when the pump “clicks off” the tank is full. On a hot summers day this expansion box can help prevent the spillage of fuel due to expansion of the fuel. By stopping at floor level the fuel has the whole expansion box and hose to expand into before overflowing. Another benefit of the fuel expansion box is the fuel lines and filler/breather hoses are kept short as they exit the transom, unlike a tank that has hoses coming up from an under floor/bilge cavity. It would be impossible for the fuel hose to fall off with this set up. The fuel filler used is a Perko with an incorporated breather so any fuel that is pushed up the breather should go back down the filler hose.

580 and 610 Models have a 5mm T-Bar stringer between the box beam and chine, the 660 has a full depth stringer welded each side. The 5mm tread plate centre floor panel complete with stiffeners is welded in front of the fuel tank and then the 5mm tread plate panels are welded in down the sides of the box beams. This completes the floor which is then flooded with water and pressure tested. Any pin holes in the welds are then re welded. You can hear the pressure release when the bung is removed. A lot of boats still use blocks of foam or injected foam as buoyancy. Foam holds moisture either from water entry or condensation between the foam and aluminum and you have the effect of a battery happening, meaning you end up with pitting/pin whole corrosion through your hull plates. A lot of aluminium manufacturers still use ply wood covered in vinyl for their flooring. The advantages are: cheaper to buy, quicker to screw down, the disadvantages how ever means that dirt and grime gets through the internal hull and cant be cleaned properly, and eventually causes corrosion. The vinyl flooring has a very limited life. And if it breaks away in a sinking the blocks of foam buoyancy are lost.

In the next step side deck are fitted, AMF boats are designed so you can comfortably sit and fish on the side decks, or gear up with dive equipment etc. with no hand rails or clutter on the side decks you wont foul dive gauges etc when entering the water. Wide sides decks also give you toe space when standing at the side of the boat. This allows you to stand straight and have the side deck against your thighs. With Narrow side decks you feel like you are going to fall out of the boat when you lean against the gunnels.

The side pockets are welded to a forward side pocket stanchions and welded to the transom. There is large post under the side pocket that gives this pocket rigidity and strength. The side pocket is not welded to the side panels of the boat. A non acid cure sealant is used to bond the side pocket to the side panel of the boat. If this was welded all the tension that was put into the side sheets with the compound curve would be lost. This would make the side plates ripple. AMF boats boast very fair sides

The fully enclosed back tray is fitted; this is a tricky shape to fit, having to be maneuvered into position around side pockets and top of the fuel tank turret. A large plastic hatch is fitted port and starboard. These large hatches are great for keeping batteries and oil tanks up high and protected from the elements. A smaller hatch is fitted in the middle of the two large hatches for access to fuel fittings. A lot of boats have batteries and oil tanks mounted on the floor or worse still in the bilge sump. In the worst event of taking water on board, these boats are compromised. The back shelf has been mounted high enough to slide a fish bin under each side. Or handles dive bottles laid down in this area.

Models with cabins have a raised foredeck; the sides of the raised foredeck are 4mm plate curved around the top of the belting, using 4mm helps to keep this panel fair. Then a jig is placed in position so the tread plate foredeck can be pulled around under tension and welded to the raised sides. This creates foredeck with curve from side to side as well as front to back. This creates a strong stylish shape, and is a contrast to the use of angular sheet metal folds most aluminium boat builders use. A large parcel shelf/dash is then mounted with a depth of 450mm and a 70mm lip this creates a great area for electronics to be mounted and safe place for sunglass, sunscreen etc, or a dry place for clothes while down diving.

Because a curved foredeck has been created the foredeck access hatch needs a flat frame to mount into. So a 3mm x40mm x 40mm box section is used. The frame is constructed and the corners are fabricated to create round corners, the anchor bin framing is incorporated into the base for the fore deck access hatch. Boat builders that construct flat fore decks with no shape for style or strength can screw a hatch straight onto the flat surface. For economy a lot of boat build fabricate their own access hatch from alloy, this doesn’t allow any light to enter the cabin. AMF use weaver hatches, renowned world wide for building a quality hatch.

When it comes to the windscreen on the AMF cabin models AMF cut out a full 3mm aluminium dodger (very bad shape for cost effectiveness) then it is folded to create the sides on the screen. This large folded sheet of plate aluminum is then fitted to the fore deck to create an aluminum dodger, and then a 50 x 25x3mm radius edge extrusion is shaped to the curve of the screen and then slotted to cap the dodger off. This capping is then slotted in place and welded on to the dodger. A 50mm perspex bonding area is marked out for the windscreen. Once this is aluminium is cut out, the off cuts are laid out on the Perspex, marked and cut out. Then the bonding area is buffed and rubber blocks are mounted to the alloy to guarantee the thickness of the sealant. This also allows for the movement in the Perspex due to temperature change. Then the screen mounting area is covered in seven tubes of black, polymer natural cure sealant the Perspex is fitted and the corner caps are made of alloy and painted and screwed in place, this gives the three panes of Perspex room to expand and contract with the change of temperature. This screen makes up around 10% of the value of the boat. It is about 3- 4 day procedure and makes for the most amazingly strong windscreen. You have a great hand hold that will take no end of punishment. Terrific to mount the rocket launcher from which keeps the rods forward and the deck area clear for fishing. Just about all boat builders use commercially available windscreens to bolt on to the cabin top. These screens can be fitted in fifteen minutes with a tube of sealant and amount to about 10% of the value of the AMF screen.

AMF hardtop models are built on a jig; this way when the hull starts on the wheel house can be started on a separate jig, once the hull has had the fore deck fitted the wheel house is ready to be fitted and welded to the foredeck. The front of the wheel house is cut in one piece and folded to create the mounting area for the front screen; the sides are welded to this. Again there is a great amount of wastage as the area for the windows is cut out. The side panels are folded and to create the down pipe guttering for the roof, this also creates an extremely strong pillar for the rear of the hardtop. Each of the three front corners has a u shape extrusion welded in to create a full length pillar and an area to run cables in to the ceiling cavity if required. The brow is again a bad shape for cost effectiveness but is pulled around and built in solid, the side roll up and curve around the built in rocket launcher, giving the brow the strong look that it deserves. 6mm toughened glass windows are set into genuine aluminium boat window frames. These window sets are then bonded and screwed in place. Some boat builders will bond the glass straight to the aluminium while others use perspex. AMF wheel house windows are large and set on the perfect angles for maximum visibility. Side sliding windows are standard on all wheel house models. Hand rails are placed on either side of the roof to make access around the out side of the boat easier. Hand rails at the back of the wheel house are angled in side the boat to keep your knuckles out of the wind chill.

For an AMF runabout model the floor in the bow area is raised to give a dry area for gear stowage. If the boat is a Cabin model the floor is lowered to create a foot well for the vee berth bunks. Both the 580 and 610 cabin bunks are 1.6mtrs long and the 660 bunks are 2mtrs long. Under the floor in the bow area in all boats have 50x5mm stringers running off the end of the box beams until the join back up with the keel bar. With out this continuation of the boxes beams a weak point would be created and lots of other brands have substantial cracking problems at chine/console area. The framing for the bunks is built in place before the Skippers console and Passenger console/bulkhead are fitted. The consoles are full length built in panels unlike some boat builders who make the most minimal sized console for fitting gauges and steering. The console is set to the perfect angle for a comfortable steering position. The whole shelf, console area has been engineered into an extremely strong structure.

Rocket launchers are made from heavy wall tube and are built in a jig. Mounting plates for navigation lights and aerials are provided, by mounting them on the rocket launcher the rest of the boat is kept clear. Rod buckets have gimble pins welded in place so rods don’t swivel under way. The rocket launcher is so solid it is a hand hold that can be depended on in the heaviest of sea conditions. The rocket launcher folds for garaging.

Bow rails are built in a jig. AMF use a low split rail. Low bow rails are excellent for boarding when pushing off the bank/ramp and boarding the bow. Jumping of the bow on to land, and when maneuvering around wharves and jetties. The split bow rail opposed to a full bow rail makes deploying, retrieving and changing anchors easier. A large heavy wall tube is used. Some other brands don’t have bow rails, this also makes it hard to push the boat around on a trailer with no hand holds, some are to flimsy to hang on to and put any weight on. And others have no style and shape and could more appropriately be called a handle than a full bow rail.

Targa Tops are welded in a jig; this keeps the targa top consistent with the jig built rocket launcher. Most canopies and targa tops are flimsy structures, AMF have built a robust Targa top that serves as a great hand hold when walking around the side of the boat. The frame has been built to put great shape and style into the canvas work. And the canvas is taught so flapping canvas isn’t and issue. The Targa top folds for garaging

Pedestals, transducers, and anything else that is mounted to the pressure tested hull have doubler pads that they are mounted to, so that fixings don’t compromise the buoyancy chamber.

All aluminium edges are de burred before they are welded in place. Grinding and sanding is kept to a minimum, almost all welds are fully visible, and most panels don’t have any sanding. At AMF the aluminium is treated with great care to provide an aluminium boat in its purest form.

The boat is chemical washed next, this gives the boat its white finish, and it cleans the oils from the plate and blends the welds into the plate and extrusions. Once the boat is dry Nyalic clear coat is applied and this prevents the boat from oxidizing and turning a dark grey colour. Like all coatings Nyalic does need to be up kept, but from AMF’s point of view it is the best way of keeping an aluminium boat functional and looking great with the easiest care when required in time.

The AMF is then moved into the finishing bay, flexible marine carpet is then fitted in the cabin area this lines out the area making it soft and comfortable. The side pockets, dash, back tray and foot well are lined with a stiff backed marine carpet. This helps with noise, protects stored items and adding colour breaks up the look of the aluminium boat. All panels of carpet that lay flat are able to be lifted out to dry, this is important to prevent corrosion problems occurring. If aluminium can not breathe it will corrode due to oxygen depletion. A lot of manufacturers will glue carpet straight to the floor – seriously reducing the life span of their customer’s hull. Fore deck hatches, rod holders, bungs, steering, bilge pumps, navigation lights etc are fitted at this stage. The weight of carpet used is twice the thickness of the weight most manufacturers use and stands to reason it works out to be twice cost. But the finish is quality and the AMF will still look good long after it has left the show room.

The basic wiring is completed, navigation lights, bilge pump, main engine loom, switch panel and fuse box. Wiring used is tinned copper and appropriate weight of cable is used for each job.

Entirely through out the boats production AMF use construction techniques that don’t just take 10% longer to do but three to four + times longer. The materials used to create AMF’s time consuming curved shapes equates to far more than that of some cleaver sheet metal designed boats are built to a price, and you definitely get or (don’t get) what you pay for. But with an AMF you end up with is a hull where no compromises have been made, a boat that is functional and performance based, An AMF has been built with permanence in mind.

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